bgs.3class.geo-training-data.txt

All	O
glacigenic	O
deposits	O
mapped	O
in	O
NO76NW	O
are	O
assigned	O
to	O
the	O
Mearns	LEXICON
Glacigenic	LEXICON
Subgroup	LEXICON
of	O
the	O
Caledonia	LEXICON
Glacigenic	LEXICON
Group	LEXICON
.	O

This	O
subgroup	O
,	O
which	O
is	O
equivalent	O
to	O
the	O
Mearns	LEXICON
Drift	LEXICON
Group	LEXICON
of	O
Merritt	O
et	O
al.	O
,	O
,	O
comprises	O
Mill	LEXICON
of	LEXICON
Forest	LEXICON
Till	LEXICON
,	O
Ury	LEXICON
Silts	LEXICON
,	O
and	O
Drumlithie	LEXICON
Sand	LEXICON
And	LEXICON
Gravel	LEXICON
formations	O
.	O

The	O
highly	O
irregular	O
middle	O
zone	O
is	O
underlain	O
by	O
Permian	CHRONOSTRAT
and	O
Triassic	CHRONOSTRAT
rocks	O
;	O
the	O
Permian	CHRONOSTRAT
strata	O
include	O
Upper	CHRONOSTRAT
Permian	CHRONOSTRAT
Zechstein	LEXICON
sedimentary	O
rocks	O
that	O
locally	O
crop	O
out	O
in	O
the	O
study	O
area	O
.	O

Abbreviations	O
:	O
FHA	O
,	O
St.	LEXICON
Andrew	LEXICON
's	LEXICON
Bay	LEXICON
Member	LEXICON
;	O
SBB	O
,	O
St.	LEXICON
Abbs	LEXICON
Formation	LEXICON
;	O
WBA	O
,	O
Wee	LEXICON
Bankie	LEXICON
Formation	LEXICON
.	O

Sedimentary	O
rocks	O
of	O
Silurian	CHRONOSTRAT
age	O
occur	O
in	O
a	O
series	O
of	O
inliers	O
along	O
the	O
southern	O
margin	O
of	O
the	O
Midland	O
Valley	O
.	O

The	O
inliers	O
afford	O
some	O
insight	O
into	O
the	O
development	O
of	O
early	O
Phanerozoic	CHRONOSTRAT
basins	O
in	O
northern	O
Britain	O
but	O
the	O
geological	O
setting	O
of	O
the	O
inliers	O
,	O
in	O
terms	O
of	O
the	O
relative	O
positions	O
of	O
lithospheric	O
plates	O
in	O
Silurian	CHRONOSTRAT
times	O
,	O
remains	O
conjectural	O
.	O

The	O
inliers	O
lie	O
on	O
opposite	O
sides	O
of	O
the	O
NE-trending	O
Kerse	O
Loch	O
Fault	O
which	O
clearly	O
was	O
active	O
in	O
late	O
-	O
Silurian	CHRONOSTRAT
times	O
,	O
with	O
an	O
effective	O
downthrow	O
towards	O
the	O
north	O
.	O

It	O
has	O
been	O
suggested	O
that	O
in	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
times	O
the	O
Midland	O
Valley	O
and	O
Southern	O
Uplands	O
depositional	O
basins	O
lay	O
some	O
distance	O
apart	O
and	O
were	O
juxtaposed	O
by	O
sinistral	O
strike-slip	O
fault	O
movements	O
associated	O
with	O
the	O
oblique	O
collision	O
in	O
late	O
-	O
Silurian	CHRONOSTRAT
times	O
of	O
the	O
East	O
Avalonian	CHRONOSTRAT
and	O
Laurentian	CHRONOSTRAT
plates	O
.	O

The	O
stratigraphy	O
was	O
greatly	O
elaborated	O
by	O
Jennings	O
who	O
named	O
many	O
new	O
formations	O
which	O
he	O
placed	O
in	O
three	O
groups	O
,	O
in	O
ascending	O
order	O
:	O
Priesthill	LEXICON
,	O
Waterhead	LEXICON
and	O
Dungavel	LEXICON
groups	O
.	O

The	O
lower	O
part	O
of	O
the	O
sequence	O
of	O
greywackes	O
and	O
siltstones	O
formerly	O
assigned	O
to	O
the	O
Patrick	LEXICON
Burn	LEXICON
Formation	LEXICON
is	O
referred	O
instead	O
to	O
the	O
newly	O
recognised	O
Ponesk	LEXICON
Burn	LEXICON
Formation	LEXICON
,	O
on	O
the	O
grounds	O
that	O
derived	O
faunas	O
found	O
in	O
greywacke	O
beds	O
in	O
the	O
latter	O
include	O
brachiopods	O
,	O
trilobites	O
and	O
crinoids	O
,	O
indicative	O
of	O
an	O
open	O
sea	O
marine	O
environment	O
,	O
whereas	O
in	O
the	O
former	O
the	O
derived	O
faunas	O
in	O
the	O
greywacke	O
beds	O
are	O
mainly	O
molluscan	O
and	O
of	O
low	O
diversity	O
--	O
typical	O
of	O
a	O
restricted	O
marine	O
basin	O
.	O

The	O
boundaries	O
of	O
the	O
Castle	LEXICON
,	O
Kip	LEXICON
Burn	LEXICON
and	O
Blaeberry	LEXICON
formations	O
have	O
also	O
been	O
redefined	O
to	O
take	O
account	O
of	O
the	O
new	O
fossil	O
evidence	O
and	O
a	O
reassessment	O
of	O
the	O
faulting	O
that	O
affects	O
the	O
rocks	O
around	O
the	O
Logan	O
Reservoir	O
.	O

At	O
the	O
top	O
of	O
the	O
group	O
,	O
the	O
Passage	LEXICON
Formation	LEXICON
has	O
been	O
eliminated	O
and	O
the	O
predominantly	O
argillaceous	O
strata	O
in	O
its	O
lower	O
part	O
assigned	O
to	O
the	O
Dunside	LEXICON
Formation	LEXICON
.	O

The	O
fauna	O
differs	O
significantly	O
from	O
the	O
mainly	O
molluscan	O
,	O
low-diversity	O
fauna	O
found	O
in	O
the	O
overlying	O
Patrick	LEXICON
Burn	LEXICON
Formation	LEXICON
.	O

The	O
strata	O
in	O
this	O
formation	O
are	O
generally	O
similar	O
to	O
those	O
in	O
the	O
Ponesk	LEXICON
Burn	LEXICON
Formation	LEXICON
,	O
consisting	O
of	O
series	O
of	O
turbiditic	O
flow	O
units	O
with	O
intercalations	O
,	O
up	O
to	O
20m	O
thick	O
,	O
of	O
grey	O
siltstone	O
and	O
silty	O
mudstone	O
with	O
laminae	O
of	O
carbonaceous	O
siltstone	O
.	O

Siltstone	O
beds	O
with	O
the	O
characteristic	O
fauna	O
including	O
Ceratiocaris	O
occur	O
throughout	O
the	O
Patrick	LEXICON
Burn	LEXICON
Formation	LEXICON
.	O

As	O
a	O
result	O
of	O
the	O
large	O
fault	O
which	O
forms	O
the	O
southern	O
margin	O
of	O
its	O
outcrop	O
,	O
little	O
more	O
than	O
100m	O
of	O
strata	O
in	O
the	O
upper	O
part	O
of	O
the	O
formation	O
are	O
present	O
at	O
Priesthill	O
.	O

The	O
distinctive	O
massive	O
siltstone	O
beds	O
,	O
which	O
are	O
interbedded	O
with	O
bedded	O
grey	O
siltstones	O
,	O
occur	O
through	O
a	O
thickness	O
of	O
only	O
about	O
25	O
to	O
30m	O
,	O
but	O
the	O
formation	O
is	O
widespread	O
and	O
maintains	O
its	O
stratigraphical	O
position	O
in	O
relation	O
to	O
the	O
succeeding	O
Kip	LEXICON
Burn	LEXICON
Formation	LEXICON
.	O

Siltstones	O
in	O
the	O
Eaglin	O
Burn	O
-LSB-	O
NS	O
760	O
349	O
-RSB-	O
,	O
placed	O
in	O
the	O
Castle	LEXICON
Formation	LEXICON
by	O
Jennings	O
,	O
are	O
now	O
considered	O
part	O
of	O
the	O
Blaeberry	LEXICON
Formation	LEXICON
on	O
faunal	O
evidence	O
obtained	O
during	O
the	O
resurvey	O
.	O

The	O
base	O
of	O
the	O
formation	O
is	O
seen	O
at	O
Shank	O
's	O
Castle	O
where	O
carbonaceous	O
siltstones	O
pass	O
up	O
by	O
rapid	O
transition	O
from	O
the	O
massive	O
siltstones	O
and	O
mudstones	O
of	O
the	O
Castle	LEXICON
Formation	LEXICON
.	O

It	O
follows	O
that	O
,	O
according	O
to	O
the	O
definition	O
of	O
its	O
boundaries	O
proposed	O
by	O
Jennings	O
and	O
adopted	O
here	O
,	O
the	O
Kip	LEXICON
Burn	LEXICON
Formation	LEXICON
includes	O
only	O
the	O
uppermost	O
part	O
of	O
the	O
`	O
Ceratiocaris	LEXICON
Beds	LEXICON
'	O
of	O
Peach	O
and	O
Horne	O
,	O
the	O
remainder	O
lying	O
within	O
the	O
upper	O
part	O
of	O
the	O
Patrick	LEXICON
Burn	LEXICON
Formation	LEXICON
.	O

The	O
strata	O
in	O
its	O
upper	O
part	O
are	O
well	O
seen	O
in	O
the	O
Blaeberry	O
Burn	O
section	O
-LSB-	O
NS	O
736	O
356	O
-RSB-	O
,	O
which	O
is	O
terminated	O
to	O
the	O
east	O
by	O
a	O
fault	O
which	O
throws	O
down	O
strata	O
of	O
the	O
Blaeberry	LEXICON
Formation	LEXICON
.	O

The	O
outcrop	O
of	O
the	O
formation	O
,	O
displaced	O
by	O
numerous	O
faults	O
,	O
can	O
be	O
traced	O
eastwards	O
to	O
the	O
Logan	O
Water	O
,	O
and	O
south-westwards	O
by	O
Kip	O
Burn	O
,	O
Leaze	O
Burn	O
,	O
Patrick	O
Burn	O
and	O
the	O
streams	O
above	O
Waterhead	O
to	O
those	O
on	O
the	O
lower	O
slopes	O
of	O
Middlefield	O
Law	O
,	O
including	O
Lamon	O
Burn	O
.	O

The	O
strata	O
in	O
the	O
lower	O
part	O
of	O
the	O
succession	O
are	O
bioturbated	O
and	O
fossiliferous	O
,	O
the	O
fauna	O
resembling	O
that	O
in	O
the	O
underlying	O
Blaeberry	LEXICON
Formation	LEXICON
.	O

This	O
assemblage	O
is	O
comparable	O
to	O
that	O
in	O
the	O
Parishholm	LEXICON
Conglomerate	LEXICON
of	O
the	O
Hagshaw	O
Hills	O
Inlier	O
.	O

However	O
,	O
the	O
contact	O
of	O
the	O
formation	O
with	O
the	O
underlying	O
Birkenhead	LEXICON
Sandstone	LEXICON
is	O
nowhere	O
exposed	O
.	O

The	O
Monument	LEXICON
Formation	LEXICON
is	O
also	O
exposed	O
in	O
ditches	O
on	O
the	O
eastern	O
slopes	O
of	O
Middlefield	O
Law	O
and	O
,	O
together	O
with	O
the	O
Dippal	LEXICON
Burn	LEXICON
Formation	LEXICON
,	O
is	O
involved	O
in	O
a	O
complicated	O
fault	O
structure	O
in	O
the	O
headwaters	O
of	O
the	O
Kip	O
Burn	O
.	O

These	O
beds	O
are	O
similar	O
in	O
lithology	O
and	O
fauna	O
to	O
the	O
Dippal	LEXICON
Burn	LEXICON
Formation	LEXICON
and	O
prior	O
to	O
the	O
work	O
of	O
Jennings	O
the	O
two	O
sequences	O
were	O
regarded	O
as	O
the	O
same	O
.	O

Near	O
the	O
base	O
of	O
the	O
sequence	O
are	O
grey	O
and	O
red	O
variegated	O
mudstones	O
which	O
are	O
transitional	O
from	O
the	O
red	O
Monument	LEXICON
Formation	LEXICON
beneath	O
.	O

This	O
formation	O
shows	O
a	O
return	O
of	O
the	O
conditions	O
which	O
existed	O
while	O
the	O
Monument	LEXICON
Formation	LEXICON
was	O
laid	O
down	O
.	O

Jennings	O
considered	O
the	O
formation	O
to	O
be	O
only	O
8m	O
thick	O
where	O
exposed	O
in	O
the	O
Birkenhead	O
Burn	O
-LSB-	O
NS	O
767	O
360	O
-RSB-	O
but	O
its	O
contact	O
with	O
the	O
Middlefield	LEXICON
Conglomerate	LEXICON
to	O
the	O
east	O
is	O
faulted	O
.	O

The	O
Plewland	LEXICON
Sandstone	LEXICON
is	O
overlain	O
with	O
apparent	O
conformity	O
by	O
the	O
Greywacke	LEXICON
Conglomerate	LEXICON
,	O
which	O
is	O
arbitrarily	O
taken	O
as	O
the	O
base	O
of	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
.	O

A	O
stratigraphy	O
for	O
the	O
Silurian	CHRONOSTRAT
rocks	O
was	O
first	O
proposed	O
by	O
Peach	O
and	O
Horne	O
.	O

The	O
greatest	O
thickness	O
is	O
seen	O
in	O
the	O
Ree	O
Burn	O
,	O
where	O
about	O
125m	O
of	O
strata	O
crop	O
out	O
between	O
the	O
fault	O
and	O
the	O
base	O
of	O
the	O
Ree	LEXICON
Burn	LEXICON
Formation	LEXICON
.	O

The	O
Smithy	LEXICON
Burn	LEXICON
Siltstone	LEXICON
is	O
poorly	O
fossiliferous	O
.	O

The	O
greywacke	O
member	O
has	O
also	O
been	O
recognised	O
also	O
in	O
the	O
Monks	O
Water	O
and	O
in	O
the	O
Smithy	O
Burn	O
.	O

The	O
best	O
exposures	O
of	O
the	O
formation	O
are	O
at	O
the	O
type	O
section	O
in	O
Ree	O
Burn	O
-LSB-	O
NS	O
763	O
281	O
to	O
NS	O
761	O
276	O
-RSB-	O
,	O
south	O
of	O
Parish	O
Holm	O
,	O
where	O
a	O
transitional	O
boundary	O
with	O
the	O
underlying	O
Smithy	LEXICON
Burn	LEXICON
Siltstone	LEXICON
is	O
seen	O
.	O

As	O
defined	O
by	O
Rolfe	O
,	O
this	O
group	O
consisted	O
of	O
four	O
formations	O
--	O
in	O
upwards	O
sequence	O
,	O
the	O
Douglas	LEXICON
Water	LEXICON
Arenite	LEXICON
,	O
the	O
Dovestone	LEXICON
Redbeds	LEXICON
,	O
the	O
Fish	LEXICON
Bed	LEXICON
Formation	LEXICON
and	O
the	O
Gully	LEXICON
Redbeds	LEXICON
--	O
all	O
of	O
terrestrial	O
origin	O
.	O

It	O
is	O
proposed	O
here	O
that	O
the	O
definition	O
of	O
the	O
group	O
be	O
altered	O
so	O
as	O
to	O
include	O
the	O
Parishholm	LEXICON
Conglomerate	LEXICON
at	O
its	O
base	O
.	O

The	O
Glenbuck	LEXICON
Group	LEXICON
then	O
becomes	O
the	O
approximate	O
equivalent	O
of	O
the	O
Waterhead	LEXICON
Group	LEXICON
of	O
the	O
Lesmahagow	O
Inlier	O
.	O

The	O
Parishholm	LEXICON
Conglomerate	LEXICON
succeeds	O
the	O
Ree	LEXICON
Burn	LEXICON
Formation	LEXICON
without	O
apparent	O
angular	O
unconformity	O
,	O
although	O
there	O
is	O
a	O
sharp	O
lithological	O
contrast	O
between	O
the	O
two	O
formations	O
and	O
comparison	O
with	O
the	O
succession	O
in	O
the	O
Lesmahagow	O
Inlier	O
suggests	O
that	O
the	O
boundary	O
marks	O
a	O
major	O
non-sequence	O
.	O

The	O
Douglas	LEXICON
Water	LEXICON
Arenite	LEXICON
succeeds	O
the	O
Parishholm	LEXICON
Conglomerate	LEXICON
with	O
apparent	O
conformity	O
.	O

The	O
Dovestone	LEXICON
Red	LEXICON
Beds	LEXICON
follow	O
the	O
Douglas	LEXICON
Water	LEXICON
Arenite	LEXICON
without	O
a	O
noticeable	O
break	O
.	O

The	O
formation	O
is	O
exposed	O
at	O
the	O
east	O
end	O
of	O
Glenbuck	O
Loch	O
-LSB-	O
NS	O
762	O
284	O
-RSB-	O
and	O
in	O
the	O
Shiel	O
Burn	O
tributary	O
of	O
the	O
Monks	O
Water	O
and	O
there	O
are	O
small	O
exposures	O
of	O
the	O
formation	O
in	O
the	O
Douglas	O
Water	O
north-west	O
of	O
Urit	O
Hill	O
.	O

However	O
,	O
an	O
assemblage	O
of	O
miospores	O
recently	O
collected	O
from	O
exposures	O
at	O
Glenbuck	O
Loch	O
is	O
said	O
to	O
indicate	O
an	O
earliest	O
Wenlock	CHRONOSTRAT
age	O
for	O
the	O
strata	O
.	O

The	O
fish	O
bed	O
probably	O
correlates	O
with	O
the	O
Dippal	LEXICON
Burn	LEXICON
Fish	O
Bed	O
of	O
Lesmahagow	O
.	O

The	O
Gully	LEXICON
Red	LEXICON
Beds	LEXICON
is	O
the	O
topmost	O
subdivision	O
of	O
the	O
Glenbuck	LEXICON
Group	LEXICON
and	O
indicates	O
a	O
return	O
to	O
conditions	O
similar	O
to	O
those	O
which	O
existed	O
during	O
deposition	O
of	O
the	O
Dovestone	LEXICON
Red	LEXICON
Beds	LEXICON
.	O

The	O
exposures	O
in	O
the	O
Monks	O
Water	O
consist	O
of	O
fine-grained	O
red	O
sandstone	O
and	O
dark	O
red-brown	O
silty	O
mudstone	O
which	O
is	O
finely	O
micaceous	O
,	O
its	O
colour	O
being	O
altered	O
by	O
reduction	O
to	O
pale	O
grey-green	O
in	O
places	O
.	O

In	O
order	O
to	O
achieve	O
a	O
consistent	O
approach	O
to	O
the	O
stratigraphy	O
of	O
the	O
Silurian	CHRONOSTRAT
inliers	O
,	O
it	O
is	O
proposed	O
that	O
the	O
youngest	O
formations	O
,	O
the	O
Hareshaw	LEXICON
Conglomerate	LEXICON
and	O
Quarry	LEXICON
Arenite	LEXICON
,	O
be	O
assigned	O
to	O
a	O
new	O
group	O
,	O
namely	O
the	O
Monks	LEXICON
Water	LEXICON
Group	LEXICON
.	O

The	O
Hareshaw	LEXICON
Conglomerate	LEXICON
is	O
considered	O
to	O
be	O
generally	O
equivalent	O
to	O
the	O
Middlefield	LEXICON
Conglomerate	LEXICON
of	O
the	O
Lesmahagow	O
Inlier	O
.	O

The	O
contact	O
with	O
the	O
underlying	O
Gully	LEXICON
Red	LEXICON
Beds	LEXICON
is	O
nowhere	O
exposed	O
but	O
,	O
as	O
only	O
a	O
short	O
distance	O
separates	O
exposures	O
of	O
the	O
two	O
formations	O
,	O
an	O
abrupt	O
lithological	O
change	O
is	O
indicated	O
.	O

On	O
the	O
northern	O
limb	O
of	O
the	O
Hagshaw	O
Hills	O
Anticline	O
,	O
where	O
the	O
formation	O
is	O
estimated	O
to	O
be	O
65m	O
to	O
70m	O
thick	O
,	O
there	O
are	O
exposures	O
in	O
the	O
Douglas	O
Water	O
,	O
north-west	O
of	O
Dovestone	O
Rig	O
-LSB-	O
NS	O
753	O
273	O
-RSB-	O
,	O
at	O
the	O
east	O
end	O
of	O
Glenbuck	O
Loch	O
-LSB-	O
NS	O
762	O
286	O
-RSB-	O
,	O
in	O
an	O
unnamed	O
right-hand	O
tributary	O
-LSB-	O
NS	O
771	O
291	O
-RSB-	O
of	O
the	O
Monks	O
Water	O
,	O
and	O
in	O
the	O
Podowrin	O
and	O
Smithy	O
burns	O
.	O

The	O
Quarry	LEXICON
Arenite	LEXICON
overlies	O
the	O
Hareshaw	LEXICON
Conglomerate	LEXICON
.	O

and	O
is	O
considered	O
to	O
be	O
generally	O
equivalent	O
to	O
the	O
Plewland	LEXICON
Sandstone	LEXICON
of	O
the	O
Lesmahagow	O
Inlier	O
.	O

Fossil	O
assemblages	O
recovered	O
from	O
the	O
two	O
Silurian	CHRONOSTRAT
inliers	O
in	O
the	O
Hamilton	O
district	O
differ	O
somewhat	O
and	O
they	O
are	O
therefore	O
described	O
separately	O
.	O

It	O
would	O
appear	O
that	O
the	O
faunas	O
in	O
the	O
lower	O
part	O
of	O
the	O
succession	O
in	O
the	O
Hagshaw	O
Hills	O
Inlier	O
are	O
more	O
closely	O
allied	O
to	O
those	O
of	O
the	O
Girvan	O
and	O
the	O
Pentland	O
Hills	O
areas	O
than	O
are	O
those	O
of	O
the	O
Ponesk	LEXICON
and	O
Patrick	LEXICON
Burn	LEXICON
Formations	LEXICON
of	O
the	O
Lesmahagow	O
Inlier	O
.	O

This	O
is	O
similar	O
to	O
the	O
assemblage	O
described	O
from	O
the	O
Knockgardner	LEXICON
Formation	LEXICON
of	O
the	O
Girvan	O
area	O
age	O
for	O
the	O
formation	O
and	O
considered	O
the	O
fauna	O
to	O
be	O
characteristic	O
of	O
deposition	O
under	O
fairly	O
shallow	O
marine	O
conditions	O
.	O

Recent	O
work	O
on	O
the	O
graptolite	O
faunas	O
of	O
the	O
Blair	LEXICON
Shale	LEXICON
Formation	LEXICON
which	O
underlies	O
the	O
Knockgardner	LEXICON
Formation	LEXICON
at	O
Girvan	O
suggests	O
that	O
this	O
too	O
may	O
be	O
of	O
earliest	O
Wenlock	CHRONOSTRAT
rather	O
than	O
late	O
Llandovery	CHRONOSTRAT
age	O
.	O

It	O
thus	O
remains	O
unclear	O
whether	O
the	O
oldest	O
known	O
fossiliferous	O
rocks	O
in	O
the	O
Lesmahagow	O
Inlier	O
are	O
of	O
late	O
Telychian	CHRONOSTRAT
or	O
early	O
Sheinwoodian	CHRONOSTRAT
age	O
,	O
no	O
graptolites	O
having	O
,	O
as	O
yet	O
,	O
been	O
found	O
.	O

The	O
fauna	O
is	O
distinguished	O
from	O
that	O
previously	O
described	O
by	O
a	O
greater	O
presence	O
of	O
benthonic	O
elements	O
,	O
although	O
the	O
brachiopods	O
still	O
suggest	O
a	O
source	O
in	O
which	O
fairly	O
shallow-water	O
marine	O
conditions	O
prevailed	O
as	O
compared	O
to	O
the	O
constricted	O
marine	O
environment	O
indicated	O
by	O
the	O
mainly	O
molluscan	O
fauna	O
found	O
in	O
the	O
greywacke	O
beds	O
of	O
the	O
succeeding	O
Patrick	LEXICON
Burn	LEXICON
Formation	LEXICON
.	O

The	O
fauna	O
contains	O
elements	O
in	O
common	O
with	O
the	O
fauna	O
described	O
by	O
Liljedahl	O
from	O
rocks	O
of	O
Homerian	CHRONOSTRAT
age	O
in	O
Gotland	O
.	O

Turner	O
considered	O
that	O
the	O
thelodont	O
fish	O
from	O
the	O
upper	O
part	O
of	O
the	O
formation	O
were	O
of	O
lower	O
Wenlock	CHRONOSTRAT
age	O
.	O

Fish-bearing	O
finely	O
laminated	O
siltstones	O
and	O
mudstones	O
,	O
similar	O
to	O
those	O
in	O
the	O
Dippal	LEXICON
Burn	LEXICON
Formation	LEXICON
,	O
are	O
associated	O
with	O
greenish	O
mudstones	O
containing	O
indeterminate	O
plant	O
debris	O
,	O
possibly	O
algal	O
.	O

Richardson	O
and	O
Ford	O
,	O
quoted	O
by	O
Selden	O
and	O
White	O
,	O
suggest	O
that	O
miospores	O
from	O
the	O
overlying	O
Logan	LEXICON
Formation	LEXICON
are	O
no	O
older	O
than	O
late	O
Ludlow	CHRONOSTRAT
in	O
age	O
.	O

Turner	O
suggested	O
that	O
the	O
thelodont	O
fishes	O
from	O
the	O
Dippal	LEXICON
Burn	LEXICON
and	O
Slot	LEXICON
Burn	LEXICON
formations	O
were	O
of	O
late	O
Wenlock	CHRONOSTRAT
to	O
early	O
Ludlow	CHRONOSTRAT
age	O
.	O

No	O
biostratigraphically	O
useful	O
material	O
has	O
been	O
recovered	O
from	O
Dungavel	LEXICON
Group	LEXICON
strata	O
.	O

If	O
correctly	O
determined	O
M.	O
spiralis	O
would	O
suggest	O
a	O
late	O
Telychian	CHRONOSTRAT
age	O
.	O

The	O
trilobite	O
fauna	O
bears	O
a	O
closer	O
resemblance	O
to	O
that	O
from	O
the	O
Pentland	O
Hills	O
and	O
from	O
the	O
Knockgardner	LEXICON
Formation	LEXICON
of	O
Girvan	O
than	O
does	O
the	O
fauna	O
of	O
the	O
Ponesk	LEXICON
Formation	LEXICON
.	O

The	O
species	O
occurs	O
in	O
rocks	O
ranging	O
in	O
age	O
from	O
the	O
crenulata	BIOZONE
Biozone	BIOZONE
to	O
the	O
centrifugus	BIOZONE
Biozone	BIOZONE
,	O
thus	O
spanning	O
the	O
Llandovery	CHRONOSTRAT
to	O
early	O
Wenlock	CHRONOSTRAT
interval	O
,	O
similar	O
to	O
that	O
suggested	O
by	O
the	O
non-graptolitic	O
faunas	O
.	O

The	O
middle	O
part	O
of	O
the	O
formation	O
is	O
characterised	O
by	O
beds	O
of	O
thinly	O
laminated	O
siltstone	O
with	O
calcareous	O
nodules	O
containing	O
Ceratiocaris	O
papilio	O
,	O
similar	O
to	O
the	O
beds	O
in	O
the	O
upper	O
part	O
of	O
the	O
Patrick	LEXICON
Burn	LEXICON
Formation	LEXICON
.	O

However	O
,	O
the	O
general	O
aspect	O
of	O
the	O
flora	O
and	O
fauna	O
more	O
closely	O
resembles	O
that	O
of	O
the	O
Slot	LEXICON
Burn	LEXICON
horizon	LEXICON
.	O

Wellman	O
and	O
Richardson	O
also	O
examined	O
material	O
from	O
this	O
and	O
nearby	O
localities	O
and	O
concluded	O
that	O
the	O
plant	O
assemblages	O
obtained	O
were	O
of	O
earliest	O
Sheinwoodian	CHRONOSTRAT
to	O
latest	O
Sheinwoodian	CHRONOSTRAT
or	O
Homerian	CHRONOSTRAT
age	O
,	O
similar	O
to	O
those	O
from	O
the	O
Dippal	LEXICON
Burn	LEXICON
and	O
Slot	LEXICON
Burn	LEXICON
formations	O
of	O
the	O
Lesmahagow	O
Inlier	O
.	O

The	O
successions	O
in	O
all	O
the	O
Midland	O
Valley	O
Silurian	CHRONOSTRAT
inliers	O
reflect	O
a	O
passage	O
from	O
a	O
wholly	O
marine	O
to	O
a	O
terrestrial	O
environment	O
.	O

In	O
the	O
Hagshaw	O
Hills	O
the	O
transition	O
appears	O
abrupt	O
because	O
there	O
is	O
a	O
large	O
hiatus	O
in	O
the	O
sequence	O
,	O
there	O
being	O
no	O
representatives	O
of	O
the	O
strata	O
of	O
the	O
Patrick	LEXICON
Burn	LEXICON
to	O
Leaze	LEXICON
formations	O
inclusive	O
.	O

The	O
oldest	O
sedimentary	O
rocks	O
of	O
Silurian	CHRONOSTRAT
age	O
in	O
the	O
district	O
are	O
the	O
massive	O
or	O
poorly	O
laminated	O
,	O
somewhat	O
carbonaceous	O
or	O
pyritous	O
,	O
argillaceous	O
rocks	O
of	O
the	O
Smithy	LEXICON
Burn	LEXICON
Siltstone	LEXICON
of	O
the	O
Hagshaw	O
Hills	O
Inlier	O
.	O

Conditions	O
were	O
significantly	O
different	O
while	O
the	O
succeeding	O
Ree	LEXICON
Burn	LEXICON
Formation	LEXICON
of	O
the	O
Hagshaw	O
Hills	O
Inlier	O
was	O
laid	O
down	O
.	O

There	O
is	O
a	O
gap	O
in	O
the	O
succession	O
above	O
the	O
Ree	LEXICON
Burn	LEXICON
Formation	LEXICON
in	O
the	O
Hagshaw	O
Hills	O
Inlier	O
.	O

In	O
the	O
Lesmahagow	O
Inlier	O
,	O
however	O
,	O
the	O
rocks	O
of	O
the	O
Ponesk	LEXICON
Burn	LEXICON
Formation	LEXICON
,	O
which	O
bear	O
a	O
close	O
similarity	O
to	O
those	O
of	O
the	O
Ree	LEXICON
Burn	LEXICON
Formation	LEXICON
,	O
are	O
succeeded	O
by	O
the	O
Patrick	LEXICON
Burn	LEXICON
Formation	LEXICON
the	O
greywacke	O
component	O
of	O
which	O
contains	O
a	O
low	O
diversity	O
,	O
mainly	O
molluscan	O
fauna	O
.	O

During	O
deposition	O
of	O
the	O
Kip	LEXICON
Burn	LEXICON
Formation	LEXICON
,	O
greywacke	O
deposition	O
no	O
longer	O
reached	O
the	O
Lesmahagow	O
area	O
,	O
perhaps	O
because	O
of	O
a	O
failure	O
of	O
the	O
sediment	O
supply	O
,	O
and	O
only	O
carbonaceous	O
mudstones	O
and	O
siltstones	O
were	O
laid	O
down	O
in	O
quiet-water	O
conditions	O
in	O
a	O
greatly	O
constricted	O
basin	O
.	O

Subsequently	O
,	O
water	O
depths	O
decreased	O
and	O
,	O
during	O
Blaeberry	LEXICON
Formation	LEXICON
times	O
,	O
mud	O
and	O
silt	O
were	O
laid	O
down	O
,	O
possibly	O
in	O
the	O
distal	O
parts	O
of	O
deltas	O
.	O

The	O
salinity	O
was	O
less	O
than	O
fully	O
marine	O
as	O
is	O
indicated	O
by	O
a	O
fauna	O
of	O
Lingula	O
,	O
ostracods	O
and	O
molluscs	O
analogous	O
to	O
that	O
found	O
in	O
the	O
Ballagan	LEXICON
Formation	LEXICON
of	O
the	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
.	O

As	O
the	O
deltas	O
advanced	O
into	O
the	O
basin	O
,	O
fluviatile	O
deposits	O
appear	O
in	O
the	O
sequence	O
for	O
the	O
first	O
time	O
,	O
represented	O
by	O
the	O
cross-bedded	O
sandstones	O
with	O
rip-up	O
clasts	O
of	O
mudstone	O
in	O
the	O
upper	O
part	O
of	O
the	O
Dunside	LEXICON
Formation	LEXICON
.	O

By	O
the	O
close	O
of	O
the	O
Dunside	LEXICON
Formation	LEXICON
,	O
silting	O
up	O
of	O
the	O
basin	O
in	O
the	O
Lesmahagow	O
area	O
was	O
complete	O
and	O
the	O
red-brown	O
sandstones	O
and	O
siltstones	O
of	O
the	O
Leaze	LEXICON
Formation	LEXICON
were	O
laid	O
down	O
in	O
the	O
channels	O
and	O
floodplains	O
of	O
rivers	O
,	O
which	O
were	O
probably	O
sustained	O
by	O
a	O
low	O
to	O
moderate	O
,	O
strongly	O
seasonal	O
rainfall	O
.	O

The	O
abrupt	O
lithological	O
change	O
that	O
occurs	O
at	O
the	O
base	O
of	O
the	O
Birkenhead	LEXICON
Sandstone	LEXICON
in	O
the	O
Lesmahagow	O
area	O
probably	O
reflects	O
a	O
non-sequence	O
which	O
is	O
not	O
,	O
however	O
,	O
as	O
marked	O
as	O
that	O
which	O
preceded	O
deposition	O
of	O
its	O
supposed	O
equivalent	O
in	O
the	O
Hagshaw	O
Hills	O
Inlier	O
,	O
that	O
is	O
,	O
the	O
Parishholm	LEXICON
Conglomerate	LEXICON
.	O

The	O
two	O
inliers	O
occur	O
on	O
opposite	O
sides	O
of	O
the	O
NE-trending	O
Kerse	O
Loch	O
Fault	O
and	O
it	O
seems	O
likely	O
that	O
this	O
structure	O
,	O
which	O
had	O
a	O
major	O
effect	O
on	O
sedimentation	O
during	O
the	O
Carboniferous	CHRONOSTRAT
period	O
,	O
was	O
active	O
during	O
the	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
.	O

The	O
beds	O
of	O
laminated	O
grey-green	O
and	O
dark	O
grey	O
mudstone	O
and	O
siltstone	O
in	O
the	O
lower	O
parts	O
of	O
the	O
Dippal	LEXICON
Burn	LEXICON
and	O
Slot	LEXICON
Burn	LEXICON
formations	O
of	O
the	O
Lesmahagow	O
Inlier	O
and	O
the	O
Fish	LEXICON
Bed	LEXICON
Formation	LEXICON
of	O
the	O
Hagshaw	O
Hills	O
Inlier	O
were	O
laid	O
down	O
while	O
water	O
depths	O
were	O
at	O
their	O
greatest	O
.	O

The	O
deposition	O
of	O
conglomerates	O
and	O
pebbly	O
sandstones	O
in	O
the	O
basal	O
parts	O
of	O
the	O
Dungavel	LEXICON
Group	LEXICON
of	O
the	O
Lesmahagow	O
Inlier	O
and	O
the	O
Monks	LEXICON
Water	LEXICON
Group	LEXICON
of	O
the	O
Hagshaw	O
Hills	O
Inlier	O
marks	O
a	O
significant	O
change	O
in	O
environmental	O
conditions	O
.	O

The	O
stratigraphical	O
classification	O
adopted	O
,	O
comprising	O
in	O
ascending	O
sequence	O
the	O
Greywacke	LEXICON
Conglomerate	LEXICON
,	O
the	O
Swanshaw	LEXICON
Formation	LEXICON
and	O
the	O
Duneaton	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
is	O
that	O
proposed	O
by	O
Smith	O
to	O
the	O
south	O
.	O

Tectonic	O
activity	O
accompanied	O
by	O
uplift	O
during	O
the	O
Middle	CHRONOSTRAT
Devonian	CHRONOSTRAT
period	O
meant	O
that	O
either	O
no	O
deposits	O
of	O
this	O
age	O
were	O
laid	O
down	O
within	O
the	O
Midland	O
Valley	O
or	O
any	O
such	O
deposits	O
,	O
as	O
well	O
as	O
most	O
or	O
locally	O
all	O
of	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
,	O
were	O
removed	O
by	O
erosion	O
.	O

As	O
a	O
result	O
of	O
regional	O
subsidence	O
,	O
sedimentation	O
resumed	O
within	O
this	O
valley	O
during	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
times	O
but	O
did	O
not	O
extend	O
into	O
the	O
Hamilton	O
district	O
.	O

The	O
conglomerate	O
rests	O
upon	O
an	O
eroded	O
surface	O
which	O
can	O
be	O
seen	O
cutting	O
across	O
beds	O
of	O
the	O
underlying	O
Quarry	LEXICON
Arenite	LEXICON
.	O

This	O
subdivision	O
includes	O
the	O
strata	O
overlying	O
the	O
Greywacke	LEXICON
Conglomerate	LEXICON
and	O
below	O
the	O
thin	O
development	O
of	O
lavas	O
and	O
volcaniclastic	O
rocks	O
seen	O
in	O
tributaries	O
of	O
the	O
Wood	O
Burn	O
-LSB-	O
NS	O
615	O
293	O
-RSB-	O
.	O

A	O
fault	O
following	O
the	O
course	O
of	O
the	O
burn	O
,	O
throws	O
down	O
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
to	O
the	O
west	O
.	O

The	O
district	O
includes	O
parts	O
of	O
three	O
coal	O
basins	O
,	O
namely	O
the	O
Central	O
,	O
Douglas	O
and	O
Muirkirk	O
coalfields	O
,	O
each	O
with	O
its	O
own	O
stratigraphy	O
and	O
local	O
coal	O
seam	O
names	O
.	O

As	O
a	O
result	O
of	O
late	O
-	O
Devonian	CHRONOSTRAT
uplift	O
and	O
erosion	O
no	O
rocks	O
of	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
exist	O
in	O
the	O
district	O
and	O
the	O
oldest	O
Carboniferous	CHRONOSTRAT
strata	O
,	O
which	O
are	O
placed	O
in	O
the	O
Inverclyde	LEXICON
Group	LEXICON
,	O
rest	O
unconformably	O
on	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
or	O
older	O
rocks	O
.	O

The	O
most	O
widespread	O
of	O
these	O
constitute	O
marker	O
horizons	O
and	O
have	O
been	O
used	O
in	O
the	O
subdivision	O
of	O
the	O
sequence	O
with	O
the	O
bases	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
and	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
marking	O
the	O
bases	O
of	O
the	O
Clackmannan	LEXICON
Group	LEXICON
and	O
Coal	LEXICON
Measures	LEXICON
Group	LEXICON
,	O
respectively	O
.	O

In	O
the	O
western	O
Midland	O
Valley	O
,	O
the	O
group	O
contains	O
three	O
formations	O
:	O
in	O
upwards	O
succession	O
,	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
the	O
Ballagan	LEXICON
Formation	LEXICON
and	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
known	O
occurrences	O
of	O
Inverclyde	LEXICON
Group	LEXICON
strata	O
are	O
entirely	O
in	O
the	O
south	O
,	O
where	O
there	O
are	O
outcrops	O
around	O
Middlefield	O
,	O
along	O
the	O
northern	O
margin	O
of	O
the	O
Carboniferous	CHRONOSTRAT
outcrop	O
at	O
Glenbuck	O
,	O
and	O
along	O
the	O
western	O
edge	O
of	O
the	O
Douglas	O
Coalfield	O
between	O
Wedder	O
Hill	O
and	O
North	O
Bankend	O
where	O
the	O
thickest	O
and	O
most	O
complete	O
sequence	O
lies	O
in	O
the	O
area	O
around	O
Burnside	O
.	O

North	O
of	O
the	O
fault	O
,	O
in	O
the	O
area	O
around	O
Strathaven	O
and	O
Kirkmuirhill	O
,	O
strata	O
of	O
the	O
group	O
are	O
entirely	O
absent	O
and	O
rocks	O
of	O
the	O
Strathclyde	LEXICON
Group	LEXICON
rest	O
directly	O
on	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
.	O

The	O
present	O
distribution	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
in	O
the	O
district	O
Figure	O
4is	O
attributed	O
to	O
mid	O
-	O
Dinantian	CHRONOSTRAT
earth	O
movements	O
,	O
involving	O
northerly	O
upthrow	O
on	O
elements	O
in	O
the	O
Kerse	O
Loch	O
Fault	O
zone	O
,	O
followed	O
by	O
erosion	O
which	O
,	O
at	O
least	O
in	O
the	O
Strathaven-Kirkmuirhill	O
area	O
,	O
eliminated	O
the	O
entire	O
group	O
.	O

The	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
which	O
was	O
previously	O
regarded	O
as	O
part	O
of	O
the	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
and	O
may	O
be	O
partly	O
of	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
,	O
is	O
present	O
throughout	O
the	O
Inverclyde	LEXICON
Group	LEXICON
outcrop	O
.	O

The	O
Ballagan	LEXICON
Formation	LEXICON
is	O
developed	O
in	O
the	O
Middlefield	O
area	O
but	O
the	O
sequence	O
here	O
does	O
not	O
extend	O
up	O
to	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

In	O
Dalfram	O
No.	O
2	O
Borehole	O
,	O
sited	O
about	O
2km	O
to	O
the	O
south	O
of	O
the	O
district	O
,	O
grey	O
shales	O
and	O
cementstones	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
appeared	O
to	O
be	O
directly	O
overlain	O
by	O
a	O
sequence	O
of	O
ash	O
and	O
agglomerate	O
which	O
is	O
presumed	O
to	O
belong	O
to	O
the	O
Strathclyde	LEXICON
Group	LEXICON
.	O

There	O
are	O
exposures	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
but	O
the	O
presence	O
of	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
can	O
not	O
be	O
confirmed	O
at	O
outcrop	O
.	O

In	O
the	O
area	O
east	O
of	O
North	O
Bankend	O
,	O
where	O
there	O
are	O
good	O
exposures	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
there	O
is	O
no	O
evidence	O
which	O
confirms	O
or	O
denies	O
the	O
presence	O
of	O
the	O
Ballagan	LEXICON
or	O
Clyde	LEXICON
Sandstone	LEXICON
formations	O
.	O

Its	O
base	O
is	O
nowhere	O
exposed	O
but	O
is	O
taken	O
at	O
the	O
unconformable	O
junction	O
with	O
rocks	O
of	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
or	O
Silurian	CHRONOSTRAT
age	O
.	O

The	O
thickest	O
exposed	O
sequence	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
is	O
in	O
the	O
Back	O
Burn	O
-LSB-	O
NS	O
667	O
294	O
-RSB-	O
,	O
about	O
1200m	O
west	O
of	O
Middlefield	O
.	O

Throughout	O
this	O
distance	O
,	O
the	O
calcrete-bearing	O
sandstones	O
are	O
overlain	O
by	O
strata	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
.	O

The	O
Burnside	O
Borehole	O
,	O
a	O
little	O
distance	O
to	O
the	O
north-east	O
,	O
was	O
terminated	O
in	O
strata	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
but	O
,	O
as	O
there	O
is	O
no	O
known	O
locality	O
in	O
Scotland	O
where	O
this	O
formation	O
is	O
not	O
underlain	O
by	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
the	O
presence	O
here	O
of	O
calcrete-bearing	O
sandstones	O
can	O
be	O
assumed	O
.	O

The	O
base	O
of	O
the	O
formation	O
is	O
transitional	O
from	O
the	O
underlying	O
Kinnesswood	LEXICON
Formation	LEXICON
and	O
is	O
taken	O
at	O
the	O
base	O
of	O
the	O
lowest	O
bed	O
of	O
grey	O
mudstone	O
.	O

The	O
Strathclyde	LEXICON
Group	LEXICON
comprises	O
,	O
in	O
upwards	O
succession	O
,	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
and	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
Figure	O
5	O
.	O

Conversely	O
,	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
tends	O
to	O
be	O
thicker	O
where	O
volcanic	O
rocks	O
are	O
not	O
present	O
,	O
as	O
around	O
the	O
western	O
margin	O
of	O
the	O
Douglas	O
Coalfield	O
.	O

The	O
base	O
of	O
the	O
formation	O
is	O
seen	O
,	O
however	O
,	O
in	O
the	O
smaller	O
outcrop	O
east	O
of	O
Sandford	O
,	O
where	O
the	O
lavas	O
rest	O
unconformably	O
on	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
.	O

The	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
is	O
thinner	O
east	O
of	O
the	O
fault	O
zone	O
,	O
and	O
continues	O
to	O
thin	O
eastwards	O
until	O
it	O
is	O
eventually	O
overlapped	O
by	O
strata	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
,	O
which	O
accordingly	O
rest	O
upon	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
.	O

Variations	O
in	O
thickness	O
of	O
the	O
Namurian	CHRONOSTRAT
sedimentary	O
formations	O
across	O
the	O
line	O
of	O
the	O
Inchgotrick	O
Fault	O
in	O
Ayrshire	O
have	O
been	O
attributed	O
to	O
contemporaneous	O
movements	O
on	O
the	O
fault	O
.	O

The	O
rapid	O
south-eastwards	O
thinning	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
around	O
Sandford	O
suggests	O
that	O
movements	O
on	O
the	O
fault-line	O
in	O
Dinantian	CHRONOSTRAT
times	O
may	O
have	O
generated	O
a	O
topographical	O
high	O
which	O
restricted	O
the	O
spread	O
of	O
the	O
lavas	O
.	O

The	O
names	O
given	O
to	O
the	O
lava	O
types	O
refer	O
to	O
localities	O
in	O
central	O
and	O
southern	O
Scotland	O
and	O
the	O
classification	O
is	O
applied	O
only	O
to	O
basic	O
igneous	O
rocks	O
of	O
Carboniferous	CHRONOSTRAT
and	O
Permian	CHRONOSTRAT
age	O
in	O
the	O
Midland	O
Valley	O
of	O
Scotland	O
.	O

The	O
formation	O
contains	O
material	O
derived	O
by	O
erosion	O
from	O
rocks	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
usually	O
consists	O
of	O
red	O
or	O
purplish	O
brown	O
,	O
poorly	O
bedded	O
,	O
blocky-weathering	O
mudstone	O
and	O
silty	O
mudstone	O
.	O

However	O
,	O
north-east	O
of	O
Strathaven	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
appears	O
to	O
be	O
absent	O
and	O
coal-bearing	O
strata	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
rest	O
directly	O
on	O
lavas	O
.	O

In	O
the	O
Coldwakning	O
Burn	O
section	O
,	O
only	O
a	O
metre	O
or	O
so	O
of	O
strata	O
intervene	O
between	O
the	O
top	O
of	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
and	O
the	O
base	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
.	O

Marine	O
shells	O
obtained	O
from	O
mudstone	O
of	O
the	O
formation	O
at	O
a	O
now-degraded	O
exposure	O
,	O
south	O
of	O
East	O
Kilbride	O
,	O
suggest	O
correlation	O
with	O
the	O
Stonehouse	LEXICON
Under	LEXICON
Limestone	LEXICON
which	O
lies	O
at	O
a	O
high	O
stratigraphical	O
position	O
in	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
.	O

The	O
formation	O
crops	O
out	O
along	O
the	O
northern	O
flank	O
of	O
the	O
area	O
of	O
Lower	O
Carboniferous	CHRONOSTRAT
rocks	O
around	O
Glenbuck	O
,	O
where	O
it	O
is	O
estimated	O
to	O
be	O
about	O
120m	O
thick	O
.	O

The	O
Muirkirk	LEXICON
Under	LEXICON
Limestone	LEXICON
,	O
the	O
local	O
equivalent	O
of	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
,	O
is	O
almost	O
2m	O
thick	O
and	O
lies	O
about	O
15m	O
below	O
the	O
top	O
of	O
the	O
formation	O
.	O

There	O
are	O
few	O
exposures	O
in	O
the	O
area	O
which	O
flanks	O
the	O
Douglas	O
Coalfield	O
on	O
the	O
west	O
.	O

The	O
sandstones	O
in	O
the	O
lowest	O
10m	O
are	O
conglomeratic	O
in	O
places	O
,	O
with	O
pebbles	O
and	O
boulders	O
up	O
to	O
10cm	O
across	O
of	O
`	O
felsite	O
'	O
,	O
`	O
porphyrite	O
'	O
,	O
greywacke	O
and	O
chert	O
,	O
presumably	O
derived	O
by	O
erosion	O
from	O
Silurian	CHRONOSTRAT
and	O
Devonian	CHRONOSTRAT
rocks	O
.	O

The	O
Douglas	LEXICON
Under	LEXICON
Limestone	LEXICON
,	O
as	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
is	O
known	O
locally	O
,	O
is	O
2.51m	O
thick	O
at	O
a	O
depth	O
of	O
34.90m	O
.	O

The	O
Craigburn	LEXICON
Limestone	LEXICON
,	O
is	O
represented	O
by	O
a	O
bed	O
of	O
shelly	O
calcareous	O
mudstone	O
,	O
0.85m	O
thick	O
,	O
at	O
a	O
depth	O
of	O
51.72m	O
.	O

In	O
the	O
faulted	O
outlier	O
at	O
Drumclog	O
,	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
is	O
represented	O
by	O
an	O
attenuated	O
sequence	O
,	O
little	O
more	O
than	O
15m	O
thick	O
at	O
maximum	O
,	O
which	O
rests	O
on	O
reddish	O
brown	O
tuffaceous	O
mudstones	O
of	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
.	O

A	O
bed	O
of	O
limestone	O
,	O
0.5m	O
thick	O
with	O
gigantid	O
productids	O
,	O
seen	O
550m	O
west	O
of	O
Snabe	O
-LSB-	O
NS	O
6370	O
3912	O
-RSB-	O
in	O
an	O
unnamed	O
tributary	O
of	O
the	O
Avon	O
Water	O
,	O
was	O
taken	O
by	O
Richey	O
to	O
be	O
either	O
the	O
correlative	O
of	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
or	O
of	O
the	O
combined	O
Mid	LEXICON
and	O
Main	LEXICON
Hosie	LEXICON
limestones	O
.	O

However	O
,	O
the	O
limestone	O
and	O
associated	O
shelly	O
calcareous	O
mudstones	O
,	O
with	O
a	O
total	O
thickness	O
of	O
1.35m	O
,	O
were	O
penetrated	O
at	O
a	O
depth	O
of	O
34.91m	O
by	O
the	O
Fore	O
Hareshaw	O
Borehole	O
and	O
the	O
fauna	O
shows	O
it	O
to	O
be	O
the	O
equivalent	O
of	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
.	O

At	O
an	O
intervening	O
locality	O
-LSB-	O
NS	O
6475	O
4002	O
-RSB-	O
,	O
the	O
limestone	O
is	O
absent	O
and	O
only	O
a	O
thin	O
coal	O
and	O
its	O
seat	O
lie	O
between	O
the	O
top	O
of	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
and	O
the	O
base	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

The	O
formation	O
is	O
thin	O
or	O
possibly	O
absent	O
to	O
the	O
west	O
and	O
south	O
of	O
East	O
Kilbride	O
,	O
where	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
is	O
well	O
developed	O
-LRB-	O
Figure	O
4	O
.	O

It	O
is	O
present	O
in	O
an	O
isolated	O
outcrop	O
north-east	O
of	O
the	O
town	O
and	O
in	O
the	O
valley	O
of	O
the	O
Rotten	O
Calder	O
,	O
where	O
the	O
Basket	O
Shell	O
Bed	O
and	O
the	O
Netherfield	LEXICON
Limestone	LEXICON
are	O
still	O
visible	O
.	O

The	O
formation	O
thins	O
again	O
farther	O
east	O
where	O
it	O
rests	O
unconformably	O
on	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
,	O
all	O
older	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
strata	O
having	O
been	O
overlapped	O
.	O

The	O
horizon	O
known	O
as	O
the	O
Netherfield	LEXICON
Limestone	LEXICON
,	O
a	O
little	O
above	O
the	O
coal	O
,	O
consists	O
of	O
a	O
series	O
of	O
shelly	O
mud-stones	O
with	O
thin	O
lenticular	O
beds	O
of	O
bioclastic	O
limestone	O
,	O
which	O
have	O
been	O
correlated	O
with	O
the	O
Dykebar	LEXICON
Limestone	LEXICON
of	O
the	O
Central	O
Coalfield	O
sequence	O
.	O

The	O
Cot	LEXICON
Castle	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
,	O
about	O
0.3m	O
thick	O
,	O
near	O
the	O
base	O
of	O
the	O
section	O
,	O
is	O
not	O
now	O
visible	O
.	O

However	O
,	O
the	O
overlying	O
Basket	LEXICON
Shell	LEXICON
Bed	LEXICON
,	O
the	O
probable	O
local	O
representative	O
of	O
the	O
Hollybush	LEXICON
Limestone	LEXICON
,	O
is	O
still	O
exposed	O
and	O
consists	O
of	O
about	O
1.7m	O
of	O
mudstone	O
containing	O
a	O
diverse	O
marine	O
fauna	O
.	O

Above	O
the	O
shell	O
bed	O
are	O
mudstones	O
,	O
3	O
to	O
4m	O
thick	O
,	O
containing	O
ironstone	O
bands	O
--	O
the	O
Cot	LEXICON
Castle	LEXICON
Clayband	LEXICON
ironstones	O
.	O

The	O
limestone	O
,	O
which	O
is	O
taken	O
to	O
be	O
equivalent	O
to	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
,	O
rests	O
upon	O
about	O
1m	O
of	O
fossiliferous	O
mudstone	O
,	O
which	O
in	O
turn	O
overlies	O
a	O
similar	O
thickness	O
of	O
seatrock	O
.	O

The	O
strata	O
between	O
the	O
Tree	O
Coal	O
and	O
the	O
Stonehouse	LEXICON
Under	LEXICON
Limestone	LEXICON
are	O
predominantly	O
arenaceous	O
.	O

Approximately	O
15m	O
of	O
mainly	O
arenaceous	O
strata	O
,	O
tuffaceous	O
in	O
places	O
,	O
lie	O
between	O
the	O
top	O
of	O
the	O
limestone	O
and	O
the	O
top	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
.	O

A	O
fine-grained	O
grey	O
rubbly	O
sparsely	O
shelly	O
limestone	O
,	O
exposed	O
at	O
a	O
point	O
about	O
30m	O
downstream	O
,	O
is	O
thought	O
to	O
be	O
at	O
the	O
horizon	O
of	O
the	O
Basket	LEXICON
Shell	LEXICON
Bed	LEXICON
.	O

The	O
Netherfield	LEXICON
Coal	LEXICON
was	O
worked	O
in	O
the	O
lands	O
of	O
Netherfield	O
and	O
Floors	O
,	O
east	O
of	O
Strathaven	O
.	O

In	O
the	O
Birkwood	O
Burn	O
-LSB-	O
NS	O
798	O
420	O
-RSB-	O
,	O
the	O
formation	O
is	O
only	O
about	O
15m	O
thick	O
and	O
rests	O
unconformably	O
upon	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
sandstones	O
.	O

The	O
White	LEXICON
Coral	LEXICON
Limestone	LEXICON
,	O
which	O
is	O
taken	O
as	O
the	O
equivalent	O
of	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
,	O
is	O
well	O
exposed	O
and	O
contains	O
a	O
rich	O
fauna	O
including	O
colonial	O
corals	O
.	O

The	O
Clackmannan	LEXICON
Group	LEXICON
comprises	O
,	O
in	O
upwards	O
succession	O
,	O
the	O
Lower	LEXICON
Limestone	LEXICON
,	O
Limestone	LEXICON
Coal	LEXICON
,	O
Upper	LEXICON
Limestone	LEXICON
and	O
Passage	LEXICON
formations	O
.	O

The	O
group	O
straddles	O
the	O
Dinantian	CHRONOSTRAT
-	O
Silesian	CHRONOSTRAT
boundary	O
,	O
which	O
is	O
taken	O
at	O
a	O
position	O
a	O
little	O
below	O
the	O
top	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

Where	O
the	O
formation	O
is	O
fully	O
developed	O
,	O
its	O
base	O
is	O
taken	O
at	O
the	O
base	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
of	O
the	O
Central	O
Coalfield	O
sequence	O
or	O
its	O
correlatives	O
,	O
the	O
Muirkirk	LEXICON
Main	LEXICON
Limestone	LEXICON
in	O
the	O
Muirkirk	O
area	O
,	O
the	O
Douglas	LEXICON
Main	LEXICON
Limestone	LEXICON
in	O
the	O
Douglas	O
Coalfield	O
,	O
the	O
Main	LEXICON
Limestone	LEXICON
of	O
Drumclog	O
in	O
the	O
Drumclog	O
area	O
and	O
the	O
Stonehouse	LEXICON
Main	LEXICON
Limestone	LEXICON
in	O
the	O
Strathaven	O
area	O
.	O

The	O
top	O
of	O
the	O
formation	O
is	O
defined	O
at	O
the	O
top	O
of	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
or	O
its	O
equivalents	O
,	O
the	O
Calderwood	O
Cement	O
in	O
the	O
East	O
Kilbride	O
area	O
and	O
the	O
uppermost	O
of	O
the	O
series	O
of	O
limestones	O
known	O
in	O
the	O
Muirkirk	O
and	O
Douglas	O
areas	O
as	O
the	O
McDonald	LEXICON
Limestones	LEXICON
-LRB-	O
Table	O
3	O
.	O

Apart	O
from	O
the	O
topmost	O
metre	O
or	O
two	O
,	O
which	O
are	O
of	O
Pendleian	CHRONOSTRAT
Stage	O
.	O

The	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
is	O
at	O
surface	O
or	O
present	O
at	O
shallow	O
depth	O
in	O
a	O
wide	O
area	O
around	O
East	O
Kilbride	O
,	O
and	O
occurs	O
also	O
in	O
a	O
discontinuous	O
series	O
of	O
outcrops	O
which	O
extends	O
from	O
Glassford	O
to	O
Kirkmuirhill	O
.	O

The	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
at	O
the	O
base	O
,	O
is	O
usually	O
2	O
to	O
3m	O
thick	O
,	O
consisting	O
of	O
posts	O
of	O
dark	O
grey	O
,	O
hard	O
,	O
crinoidal	O
limestone	O
interbedded	O
with	O
calcareous	O
mudstone	O
,	O
and	O
has	O
been	O
quarried	O
extensively	O
.	O

The	O
Wilsontown	LEXICON
Smithy	LEXICON
Coal	LEXICON
,	O
which	O
is	O
up	O
to	O
0.6m	O
thick	O
,	O
lies	O
approximately	O
5m	O
higher	O
in	O
the	O
succession	O
.	O

A	O
further	O
5m	O
higher	O
in	O
the	O
sequence	O
,	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
,	O
which	O
is	O
known	O
locally	O
as	O
the	O
Foul	LEXICON
Hosie	LEXICON
Limestone	LEXICON
,	O
and	O
the	O
overlying	O
fossiliferous	O
calcareous	O
mudstones	O
of	O
the	O
Neilson	LEXICON
Shell	LEXICON
Bed	LEXICON
are	O
well	O
exposed	O
in	O
the	O
unnamed	O
tributary	O
of	O
the	O
Avon	O
Water	O
-LSB-	O
NS	O
740	O
456	O
-RSB-	O
,	O
near	O
Cot	O
Castle	O
,	O
and	O
also	O
in	O
the	O
Avon	O
Water	O
-LSB-	O
NS	O
721	O
447	O
-RSB-	O
south	O
of	O
Waulkmill	O
.	O

The	O
upper	O
part	O
of	O
the	O
formation	O
contains	O
four	O
beds	O
of	O
limestone	O
,	O
the	O
Main	LEXICON
Hosie	LEXICON
limestones	O
,	O
the	O
local	O
names	O
being	O
given	O
in	O
parentheses	O
.	O

Known	O
collectively	O
as	O
the	O
Hosie	LEXICON
Limestones	LEXICON
,	O
all	O
four	O
beds	O
are	O
exposed	O
in	O
the	O
Avon	O
Water	O
between	O
Braehead	O
-LSB-	O
NS	O
738	O
462	O
-RSB-	O
and	O
St	O
Ninian	O
's	O
Church	O
,	O
Stonehouse	O
-LSB-	O
NS	O
747	O
471	O
-RSB-	O
,	O
and	O
in	O
Calderwood	O
Glen	O
-LSB-	O
NS	O
659	O
544	O
-RSB-	O
at	O
East	O
Kilbride	O
.	O

To	O
the	O
west	O
of	O
East	O
Kilbride	O
,	O
the	O
Main	LEXICON
and	O
Mid	LEXICON
Hosie	LEXICON
Limestone	LEXICON
coalesce	O
to	O
form	O
the	O
Hairmyres	LEXICON
Limestone	LEXICON
.	O

The	O
Hawthorn	LEXICON
Limestone	LEXICON
,	O
at	O
the	O
base	O
,	O
is	O
considered	O
with	O
some	O
reservations	O
to	O
be	O
equivalent	O
to	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
of	O
the	O
Central	O
Coalfield	O
sequence	O
.	O

The	O
Muirkirk	LEXICON
Wee	LEXICON
Limestone	LEXICON
,	O
regarded	O
as	O
the	O
local	O
equivalent	O
of	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
of	O
the	O
Central	O
Coalfield	O
sequence	O
,	O
is	O
up	O
to	O
1.3m	O
thick	O
and	O
lies	O
approximately	O
10m	O
higher	O
in	O
the	O
succession	O
.	O

A	O
series	O
of	O
up	O
to	O
four	O
limestones	O
,	O
the	O
base	O
of	O
the	O
lowest	O
of	O
which	O
is	O
from	O
7	O
to	O
9m	O
stratigraphically	O
above	O
the	O
Muirkirk	LEXICON
Wee	LEXICON
Limestone	LEXICON
,	O
is	O
known	O
collectively	O
as	O
the	O
McDonald	LEXICON
Limestones	LEXICON
.	O

The	O
uppermost	O
of	O
the	O
limestones	O
is	O
correlated	O
with	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
of	O
the	O
Central	O
Coalfield	O
.	O

Grey	O
bioclastic	O
limestone	O
interbedded	O
with	O
fossiliferous	O
mudstone	O
,	O
exposed	O
along	O
the	O
east	O
bank	O
of	O
the	O
River	O
Nethan	O
-LSB-	O
NS	O
791	O
360	O
-RSB-	O
,	O
north	O
of	O
Over	O
Stockbriggs	O
,	O
is	O
considered	O
to	O
be	O
the	O
Douglas	LEXICON
Main	LEXICON
Limestone	LEXICON
.	O

At	O
a	O
section	O
farther	O
downstream	O
-LSB-	O
NS	O
793	O
360	O
-RSB-	O
,	O
two	O
beds	O
of	O
grey	O
limestone	O
separated	O
by	O
about	O
2.5m	O
of	O
shelly	O
mudstone	O
probably	O
lie	O
in	O
the	O
lower	O
part	O
of	O
the	O
McDonald	LEXICON
Limestones	LEXICON
.	O

The	O
thickness	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
in	O
the	O
area	O
is	O
not	O
known	O
.	O

Only	O
the	O
lower	O
part	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
is	O
present	O
in	O
the	O
fault-bounded	O
outlier	O
at	O
Drumclog	O
.	O

The	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
which	O
is	O
up	O
to	O
5.5m	O
thick	O
,	O
has	O
been	O
extensively	O
worked	O
,	O
notably	O
in	O
quarries	O
around	O
Meadowfoot	O
-LSB-	O
NS	O
632	O
394	O
-RSB-	O
and	O
WNW	O
of	O
Snabe	O
.	O

The	O
stratigraphical	O
position	O
of	O
these	O
seams	O
was	O
uncertain	O
though	O
a	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
age	O
was	O
suggested	O
by	O
Richey	O
.	O

The	O
coal	O
seams	O
are	O
presumed	O
to	O
correspond	O
to	O
the	O
Wilsontown	LEXICON
Smithy	LEXICON
Coal	LEXICON
.	O

Sedimentary	O
strata	O
between	O
the	O
top	O
of	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
and	O
the	O
base	O
of	O
the	O
Index	LEXICON
Limestone	LEXICON
are	O
assigned	O
to	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
,	O
which	O
is	O
of	O
lowest	O
Namurian	CHRONOSTRAT
,	O
Pendleian	CHRONOSTRAT
age	O
.	O

Deltaic	O
sedimentation	O
was	O
interrupted	O
on	O
two	O
occasions	O
by	O
marine	O
incursions	O
,	O
in	O
the	O
course	O
of	O
which	O
widespread	O
marine	O
deposits	O
--	O
the	O
Black	LEXICON
Metals	LEXICON
and	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
--	O
were	O
laid	O
down	O
.	O

At	O
East	O
Kilbride	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
lies	O
approximately	O
40m	O
above	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
,	O
the	O
intervening	O
strata	O
consisting	O
mainly	O
of	O
mudstone	O
in	O
the	O
lower	O
part	O
and	O
predominantly	O
of	O
sandstone	O
above	O
.	O

A	O
persistent	O
but	O
variable	O
series	O
of	O
coals	O
,	O
approximately	O
midway	O
between	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
and	O
the	O
Black	LEXICON
Metals	LEXICON
,	O
is	O
named	O
the	O
Lesmahagow	LEXICON
Main	LEXICON
Gas	LEXICON
Coal	LEXICON
in	O
the	O
area	O
south	O
of	O
Stonehouse	O
where	O
there	O
are	O
two	O
leaves	O
,	O
each	O
about	O
0.25m	O
thick	O
.	O

In	O
the	O
area	O
between	O
East	O
Kilbride	O
and	O
Stonehouse	O
,	O
three	O
seams	O
are	O
present	O
in	O
this	O
position	O
,	O
in	O
upwards	O
succession	O
the	O
Smithy	O
,	O
Jaunt	LEXICON
and	O
House	LEXICON
coals	O
,	O
which	O
are	O
collectively	O
known	O
as	O
the	O
Crutherland	LEXICON
Coals	LEXICON
.	O

The	O
Black	LEXICON
Metals	LEXICON
lie	O
around	O
75	O
to	O
80m	O
above	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
,	O
with	O
the	O
Black	LEXICON
Metals	LEXICON
Marine	LEXICON
Band	LEXICON
in	O
the	O
lower	O
part	O
.	O

Like	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
,	O
the	O
unit	O
is	O
composed	O
predominantly	O
of	O
mudstones	O
but	O
there	O
are	O
several	O
lenticular	O
beds	O
of	O
clayband	O
ironstone	O
,	O
known	O
as	O
the	O
Maggie	O
Bands	O
.	O

In	O
the	O
Lanark	O
district	O
around	O
Braidwood	O
-LSB-	O
NS	O
842	O
477	O
-RSB-	O
,	O
the	O
Auchenheath	LEXICON
Dross	LEXICON
Coal	LEXICON
,	O
the	O
Wee	LEXICON
Gas	LEXICON
Coal	LEXICON
,	O
and	O
the	O
Auchenheath	LEXICON
Smithy	LEXICON
Coal	LEXICON
have	O
been	O
worked	O
.	O

There	O
is	O
little	O
information	O
on	O
the	O
upper	O
part	O
of	O
the	O
formation	O
in	O
the	O
East	O
Kilbride	O
area	O
but	O
it	O
is	O
now	O
apparent	O
that	O
some	O
of	O
the	O
workings	O
formerly	O
considered	O
to	O
be	O
in	O
the	O
House	LEXICON
Coal	LEXICON
are	O
actually	O
in	O
a	O
seam	O
higher	O
in	O
the	O
sequence	O
,	O
at	O
a	O
level	O
approximately	O
97m	O
above	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
.	O

It	O
is	O
proposed	O
to	O
name	O
the	O
seam	O
the	O
East	LEXICON
Kilbride	LEXICON
Common	LEXICON
Coal	LEXICON
as	O
an	O
imprecisely	O
located	O
plan	O
shows	O
workings	O
in	O
the	O
neighbourhood	O
of	O
the	O
former	O
common	O
,	O
near	O
Mount	O
Cameron	O
-LSB-	O
NS	O
644	O
539	O
-RSB-	O
.	O

The	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
is	O
approximately	O
95m	O
thick	O
near	O
Glenbuck	O
but	O
thickens	O
to	O
around	O
120m	O
at	O
Muirkirk	O
in	O
the	O
New	O
Cumnock	O
district	O
.	O

Two	O
of	O
these	O
involved	O
major	O
incursions	O
of	O
the	O
sea	O
during	O
which	O
the	O
fossiliferous	O
mudstones	O
of	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
and	O
the	O
Black	LEXICON
Metals	LEXICON
Marine	LEXICON
Band	LEXICON
were	O
laid	O
down	O
.	O

The	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
,	O
approximately	O
10m	O
above	O
the	O
base	O
of	O
the	O
formation	O
,	O
consists	O
of	O
dark	O
grey	O
mudstones	O
with	O
ironstone	O
ribs	O
.	O

It	O
overlies	O
the	O
McDonald	LEXICON
Coal	LEXICON
,	O
from	O
0.25	O
to	O
1.82m	O
thick	O
,	O
which	O
was	O
formerly	O
worked	O
,	O
as	O
also	O
was	O
the	O
Low	O
Band	O
Ironstone	O
within	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
.	O

Two	O
important	O
coal	O
seams	O
,	O
the	O
Six	LEXICON
Foot	LEXICON
Coal	LEXICON
and	O
the	O
Thirty	LEXICON
Inch	LEXICON
Coal	LEXICON
,	O
lie	O
between	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
and	O
the	O
Black	LEXICON
Metals	LEXICON
.	O

The	O
formation	O
in	O
the	O
western	O
part	O
of	O
the	O
Douglas	O
Coalfield	O
is	O
about	O
90m	O
thick	O
and	O
,	O
as	O
at	O
Glenbuck	O
,	O
is	O
composed	O
of	O
relatively	O
thick	O
fluviodeltaic	O
cycles	O
.	O

Deltaic	O
sedimentation	O
was	O
interrupted	O
on	O
two	O
occasions	O
by	O
incursions	O
of	O
the	O
sea	O
in	O
the	O
course	O
of	O
which	O
the	O
fossiliferous	O
mudstones	O
of	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
and	O
the	O
Black	LEXICON
Metals	LEXICON
Marine	LEXICON
Band	LEXICON
were	O
laid	O
down	O
.	O

The	O
McDonald	LEXICON
Coal	LEXICON
which	O
lies	O
beneath	O
the	O
Johnstone	O
Shell	O
Bed	O
was	O
little	O
worked	O
underground	O
but	O
recently	O
has	O
been	O
exploited	O
by	O
opencast	O
methods	O
.	O

Strata	O
in	O
this	O
area	O
shown	O
as	O
Limestone	LEXICON
Coal	LEXICON
Group	LEXICON
on	O
earlier	O
editions	O
of	O
the	O
Geological	O
Sheet	O
23	O
,	O
are	O
now	O
considered	O
to	O
belong	O
to	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

This	O
formation	O
comprises	O
the	O
strata	O
that	O
lie	O
above	O
the	O
base	O
of	O
the	O
Index	LEXICON
Limestone	LEXICON
.	O

These	O
consist	O
,	O
in	O
upwards	O
succession	O
,	O
of	O
the	O
Index	LEXICON
Limestone	LEXICON
,	O
the	O
Lyoncross	LEXICON
and	O
the	O
Plean	LEXICON
Nos.	LEXICON
1	LEXICON
and	O
2	LEXICON
limestones	O
.	O

The	O
entire	O
formation	O
is	O
of	O
Namurian	CHRONOSTRAT
age	O
,	O
the	O
lower	O
part	O
being	O
Pendleian	CHRONOSTRAT
.	O

The	O
full	O
thickness	O
of	O
the	O
formation	O
is	O
present	O
also	O
in	O
the	O
Glenbuck	O
area	O
but	O
only	O
the	O
basal	O
few	O
metres	O
of	O
the	O
Douglas	O
Coalfield	O
development	O
of	O
the	O
formation	O
lie	O
within	O
the	O
district	O
.	O

This	O
variation	O
is	O
largely	O
attributable	O
to	O
erosion	O
associated	O
with	O
uplift	O
in	O
the	O
period	O
prior	O
to	O
deposition	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
.	O

Thus	O
,	O
at	O
Motherwell	O
where	O
the	O
sequence	O
is	O
most	O
complete	O
,	O
the	O
base	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
is	O
at	O
a	O
level	O
approximately	O
5m	O
above	O
Plean	LEXICON
No.	LEXICON
2	LEXICON
Limestone	LEXICON
,	O
whereas	O
near	O
Kirkmuirhill	O
it	O
lies	O
about	O
13m	O
above	O
the	O
Orchard	LEXICON
Limestone	LEXICON
.	O

However	O
,	O
in	O
the	O
Darngaber	O
Burn	O
,	O
the	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
is	O
cut	O
out	O
by	O
erosion	O
in	O
places	O
,	O
and	O
in	O
the	O
Larkhall-Stonehouse	O
area	O
the	O
erosion	O
surface	O
lies	O
not	O
far	O
above	O
the	O
Calmy	LEXICON
Limestone	LEXICON
,	O
at	O
a	O
level	O
some	O
25	O
to	O
30m	O
higher	O
than	O
at	O
Kirkmuirhill	O
.	O

Although	O
the	O
information	O
is	O
scant	O
,	O
it	O
is	O
possible	O
that	O
not	O
all	O
of	O
the	O
variation	O
in	O
thickness	O
can	O
be	O
accounted	O
for	O
by	O
pre	O
-	O
Passage	LEXICON
Formation	LEXICON
erosion	O
.	O

Thus	O
the	O
strata	O
between	O
the	O
Index	LEXICON
Limestone	LEXICON
and	O
the	O
Orchard	LEXICON
Limestone	LEXICON
are	O
about	O
45m	O
thick	O
at	O
Motherwell	O
and	O
are	O
even	O
thicker	O
south-west	O
of	O
Hamilton	O
,	O
but	O
at	O
Kirkmuirhill	O
they	O
appear	O
to	O
be	O
less	O
than	O
35m	O
thick	O
.	O

As	O
in	O
the	O
other	O
parts	O
of	O
the	O
Central	O
Coalfield	O
,	O
the	O
Index	LEXICON
Limestone	LEXICON
is	O
a	O
hard	O
compact	O
bioclastic	O
limestone	O
,	O
1.5	O
to	O
2m	O
thick	O
.	O

The	O
Lyoncross	LEXICON
Limestone	LEXICON
,	O
up	O
to	O
38m	O
above	O
the	O
Index	LEXICON
Limestone	LEXICON
,	O
is	O
underlain	O
by	O
a	O
persistent	O
seatrock	O
above	O
which	O
the	O
Lyoncross	LEXICON
Coal	LEXICON
is	O
developed	O
in	O
places	O
.	O

The	O
Orchard	LEXICON
Limestone	LEXICON
consists	O
of	O
hard	O
bioclastic	O
limestone	O
from	O
0.4	O
to	O
0.8m	O
thick	O
at	O
the	O
base	O
of	O
a	O
5	O
to	O
6m	O
thick	O
sequence	O
of	O
shelly	O
mudstone	O
.	O

A	O
thick	O
development	O
of	O
cross-bedded	O
sandstone	O
lying	O
between	O
the	O
Orchard	LEXICON
and	O
Calmy	LEXICON
limestones	O
was	O
formerly	O
worked	O
for	O
freestone	O
in	O
a	O
quarry	O
-LSB-	O
NS	O
717	O
514	O
-RSB-	O
,	O
north-west	O
of	O
Kilnhill	O
.	O

The	O
Calmy	LEXICON
Limestone	LEXICON
is	O
everywhere	O
present	O
except	O
in	O
the	O
neighbourhood	O
of	O
Kirkmuirhill	O
where	O
it	O
is	O
believed	O
to	O
have	O
been	O
eroded	O
prior	O
to	O
deposition	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
.	O

The	O
limestone	O
seen	O
in	O
this	O
section	O
was	O
shown	O
on	O
the	O
previous	O
edition	O
of	O
the	O
geological	O
map	O
as	O
the	O
Castlecary	LEXICON
Limestone	LEXICON
but	O
is	O
now	O
considered	O
to	O
be	O
the	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
.	O

In	O
the	O
bore	O
,	O
the	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
lies	O
approximately	O
27m	O
above	O
the	O
Calmy	LEXICON
Limestone	LEXICON
and	O
is	O
represented	O
by	O
a	O
thin	O
band	O
of	O
`	O
earthy	O
'	O
limestone	O
and	O
fossiliferous	O
calcareous	O
mudstone	O
.	O

A	O
bed	O
of	O
crinoidal	O
limestone	O
,	O
0.5m	O
thick	O
,	O
seen	O
in	O
a	O
stream	O
section	O
-LSB-	O
NS	O
7223	O
5007	O
-RSB-	O
north	O
of	O
Crookedstone	O
,	O
may	O
be	O
the	O
Plean	LEXICON
No.	LEXICON
2	LEXICON
Limestone	LEXICON
.	O

Strata	O
in	O
the	O
uppermost	O
part	O
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
,	O
consisting	O
mainly	O
of	O
ripple-laminated	O
and	O
cross-bedded	O
,	O
yellow-weathering	O
sandstone	O
,	O
are	O
exposed	O
in	O
a	O
tributary	O
of	O
the	O
River	O
Clyde	O
-LSB-	O
NS	O
796	O
502	O
-RSB-	O
,	O
near	O
Auldton	O
.	O

The	O
Index	LEXICON
Limestone	LEXICON
is	O
1.5	O
to	O
3m	O
thick	O
and	O
is	O
overlain	O
by	O
up	O
to	O
9m	O
of	O
silty	O
mudstone	O
with	O
limestone	O
ribs	O
.	O

The	O
Birchlaw	LEXICON
Limestone	LEXICON
,	O
which	O
lies	O
on	O
average	O
18m	O
above	O
the	O
Index	LEXICON
Limestone	LEXICON
,	O
does	O
not	O
appear	O
to	O
have	O
an	O
equivalent	O
in	O
the	O
Central	O
Coalfield	O
area	O
.	O

The	O
Cokeyard	LEXICON
Coal	LEXICON
,	O
which	O
lies	O
about	O
37m	O
above	O
the	O
Index	LEXICON
Limestone	LEXICON
and	O
varies	O
from	O
0.7	O
to	O
1.5m	O
in	O
thickness	O
,	O
was	O
worked	O
locally	O
but	O
is	O
commonly	O
split	O
into	O
several	O
leaves	O
none	O
of	O
which	O
reaches	O
workable	O
thickness	O
.	O

Tibbie	LEXICON
Pagan	LEXICON
's	LEXICON
Limestone	LEXICON
lies	O
approximately	O
60m	O
stratigraphically	O
higher	O
than	O
the	O
Index	LEXICON
Limestone	LEXICON
and	O
is	O
correlated	O
with	O
the	O
Lyoncross	LEXICON
Limestone	LEXICON
of	O
the	O
Central	O
Coalfield	O
area	O
.	O

The	O
base	O
of	O
the	O
Orchard	LEXICON
Beds	LEXICON
,	O
a	O
series	O
of	O
mudstones	O
with	O
limestone	O
ribs	O
,	O
up	O
to	O
12m	O
thick	O
,	O
lies	O
80	O
to	O
90m	O
above	O
the	O
Index	LEXICON
Limestone	LEXICON
.	O

The	O
Blue	LEXICON
Tour	LEXICON
Limestone	LEXICON
,	O
taken	O
as	O
equivalent	O
to	O
the	O
Calmy	LEXICON
Limestone	LEXICON
,	O
lies	O
approximately	O
30m	O
above	O
the	O
Orchard	LEXICON
Beds	LEXICON
,	O
with	O
the	O
Blue	LEXICON
Tour	LEXICON
Coal	LEXICON
some	O
2m	O
below	O
its	O
base	O
.	O

A	O
limestone	O
which	O
lies	O
approximately	O
60m	O
above	O
the	O
Blue	LEXICON
Tour	LEXICON
Limestone	LEXICON
in	O
borehole	O
NS72NW/28	O
-LSB-	O
NS	O
7442	O
2842	O
-RSB-	O
is	O
possibly	O
the	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
,	O
although	O
there	O
is	O
limited	O
information	O
about	O
this	O
part	O
of	O
the	O
sequence	O
.	O

The	O
older	O
of	O
the	O
two	O
occurs	O
at	O
the	O
base	O
of	O
the	O
sequence	O
,	O
which	O
rests	O
on	O
strata	O
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
ranging	O
in	O
stratigraphical	O
position	O
from	O
a	O
little	O
above	O
the	O
Calmy	LEXICON
Limestone	LEXICON
to	O
above	O
the	O
Plean	LEXICON
No.	LEXICON
2	LEXICON
Limestone	LEXICON
.	O

The	O
younger	O
of	O
the	O
two	O
unconformities	O
was	O
identified	O
by	O
Ross	O
to	O
lie	O
at	O
a	O
stratigraphical	O
level	O
above	O
No.	LEXICON
6	LEXICON
Marine	LEXICON
Band	LEXICON
Group	LEXICON
of	O
the	O
Stirling	O
succession	O
.	O

If	O
the	O
Namurian	CHRONOSTRAT
-	O
Westphalian	CHRONOSTRAT
boundary	O
lies	O
near	O
the	O
top	O
of	O
No.	LEXICON
6	LEXICON
Marine	LEXICON
Band	LEXICON
Group	LEXICON
,	O
as	O
Neves	O
et	O
al.	O
have	O
suggested	O
,	O
then	O
it	O
follows	O
that	O
all	O
the	O
Passage	LEXICON
Formation	LEXICON
strata	O
in	O
the	O
Hamilton	O
district	O
may	O
be	O
of	O
Westphalian	CHRONOSTRAT
age	O
.	O

The	O
basal	O
beds	O
of	O
the	O
formation	O
are	O
seen	O
in	O
the	O
Darngaber	O
Burn	O
-LSB-	O
NS	O
724	O
502	O
-RSB-	O
,	O
east	O
of	O
Burnbrae	O
,	O
where	O
they	O
rest	O
unconformably	O
on	O
seatrocks	O
at	O
a	O
level	O
below	O
the	O
Plean	LEXICON
No.	LEXICON
2	LEXICON
Limestone	LEXICON
in	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

Sandstones	O
of	O
the	O
formation	O
are	O
also	O
exposed	O
farther	O
downstream	O
-LSB-	O
NS	O
7275	O
5055	O
-RSB-	O
,	O
where	O
they	O
are	O
faulted	O
against	O
strata	O
of	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
,	O
and	O
in	O
the	O
Crookedstone	O
Burn	O
at	O
Wellbog	O
Plantation	O
-LSB-	O
NS	O
7295	O
5015	O
-RSB-	O
.	O

The	O
thickest	O
known	O
development	O
of	O
the	O
formation	O
in	O
the	O
district	O
was	O
cut	O
by	O
NS75SE/333	O
,	O
which	O
penetrated	O
a	O
sequence	O
,	O
about	O
33m	O
thick	O
,	O
of	O
grey	O
sandstones	O
with	O
thin	O
beds	O
of	O
rooty	O
siltstone	O
and	O
a	O
0.6m	O
thick	O
seam	O
of	O
soft	O
coal	O
,	O
possibly	O
the	O
Bowhousebog	LEXICON
Coal	LEXICON
,	O
near	O
the	O
base	O
.	O

The	O
group	O
contains	O
three	O
formations	O
,	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
,	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
and	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
Figure	O
7	O
.	O

There	O
is	O
evidence	O
that	O
,	O
as	O
in	O
earlier	O
periods	O
of	O
the	O
Carboniferous	CHRONOSTRAT
,	O
deposition	O
was	O
influenced	O
by	O
the	O
differential	O
rates	O
of	O
subsidence	O
of	O
fault-bounded	O
blocks	O
.	O

The	O
deposits	O
laid	O
down	O
in	O
the	O
course	O
of	O
these	O
trangressions	O
,	O
the	O
Vanderbeckei	LEXICON
Marine	LEXICON
Band	LEXICON
and	O
the	O
Aegiranum	LEXICON
Marine	LEXICON
Band	LEXICON
have	O
been	O
regarded	O
as	O
marker	O
horizons	O
and	O
used	O
to	O
delimit	O
the	O
formations	O
.	O

Conventionally	O
,	O
the	O
base	O
of	O
the	O
group	O
is	O
taken	O
at	O
the	O
base	O
of	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
strata	O
are	O
entirely	O
of	O
Westphalian	CHRONOSTRAT
age	O
.	O

The	O
Lower	LEXICON
and	O
Upper	LEXICON
Slatyband	LEXICON
ironstones	O
,	O
associated	O
with	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
and	O
Mill	LEXICON
Coal	LEXICON
respectively	O
,	O
have	O
been	O
worked	O
in	O
the	O
area	O
around	O
Crookedstone	O
,	O
otherwise	O
this	O
part	O
of	O
the	O
sequence	O
contains	O
no	O
mineral	O
seams	O
of	O
workable	O
thickness	O
and	O
has	O
been	O
penetrated	O
in	O
full	O
by	O
relatively	O
few	O
boreholes	O
.	O

The	O
position	O
of	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
can	O
be	O
recognised	O
but	O
a	O
fauna	O
,	O
including	O
Lingula	O
sp.	O
,	O
has	O
been	O
recovered	O
only	O
in	O
the	O
Dykehead	O
Borehole	O
-LSB-	O
NS	O
7564	O
5267	O
-RSB-	O
and	O
at	O
an	O
exposure	O
in	O
the	O
Dalserf	O
Burn	O
-LSB-	O
NS	O
7955	O
4990	O
-RSB-	O
,	O
east	O
of	O
Ashgill	O
.	O

The	O
Colinburn	LEXICON
Coal	LEXICON
is	O
generally	O
thin	O
,	O
its	O
mudstone	O
roof	O
yielding	O
nonmarine	O
bivalves	O
in	O
boreholes	O
at	O
Dykehead	O
and	O
Garriongill	O
.	O

The	O
horizons	O
of	O
the	O
Auldshiels	O
Mussel	O
Band	O
and	O
the	O
Armadale	LEXICON
Main	LEXICON
and	O
Ball	LEXICON
coals	O
can	O
usually	O
be	O
identified	O
,	O
the	O
roof	O
of	O
the	O
last	O
containing	O
Carbonicola	O
pseudorobusta	O
at	O
Dykehead	O
.	O

The	O
Mill	LEXICON
Coal	LEXICON
,	O
with	O
Carbonicola	O
in	O
its	O
roof	O
at	O
Ferniegair	O
-LSB-	O
NS	O
7525	O
5441	O
-RSB-	O
,	O
reaches	O
a	O
maximum	O
thickness	O
of	O
0.4	O
m.	O

Similar	O
faunas	O
come	O
from	O
the	O
mudstone	O
above	O
the	O
thin	O
Shott	LEXICON
's	LEXICON
Gas	LEXICON
Coal	LEXICON
.	O

The	O
strata	O
between	O
the	O
Mill	LEXICON
and	O
Lower	LEXICON
Drumgray	LEXICON
coals	O
are	O
seen	O
in	O
exposures	O
along	O
the	O
Crookedstone	O
Burn	O
,	O
where	O
they	O
consist	O
of	O
sandstones	O
and	O
siltstones	O
with	O
seatrocks	O
,	O
the	O
total	O
thickness	O
being	O
about	O
19m	O
.	O

The	O
Lower	LEXICON
Drumgray	LEXICON
Coal	LEXICON
is	O
not	O
seen	O
in	O
the	O
section	O
.	O

Still	O
farther	O
upstream	O
-LSB-	O
NS	O
7584	O
5000	O
-RSB-	O
,	O
the	O
Wellbog	O
Musselband	O
at	O
the	O
horizon	O
of	O
the	O
Mill	LEXICON
Coal	LEXICON
,	O
contains	O
a	O
fauna	O
of	O
nonmarine	O
bivalves	O
.	O

Elsewhere	O
it	O
is	O
thin	O
or	O
absent	O
but	O
,	O
in	O
the	O
Larkhall-Stonehouse	O
area	O
,	O
it	O
is	O
associated	O
with	O
the	O
Watstone	LEXICON
Musselband	LEXICON
Ironstone	LEXICON
which	O
was	O
worked	O
locally	O
.	O

The	O
Mid	LEXICON
and	O
Upper	LEXICON
Drumgray	LEXICON
coals	LEXICON
were	O
worked	O
from	O
adits	O
on	O
the	O
valley	O
sides	O
of	O
the	O
Avon	O
Water	O
in	O
the	O
vicinity	O
of	O
the	O
Larkhall	O
Viaduct	O
.	O

The	O
strata	O
between	O
the	O
top	O
of	O
the	O
Kiltongue	LEXICON
Coal	LEXICON
and	O
the	O
top	O
of	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
,	O
taken	O
at	O
the	O
base	O
of	O
the	O
Queenslie	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
vary	O
from	O
about	O
37m	O
to	O
more	O
than	O
50m	O
thick	O
.	O

The	O
Airdrie	LEXICON
Virtuewell	LEXICON
Coal	LEXICON
,	O
near	O
the	O
top	O
of	O
sequence	O
,	O
has	O
been	O
extensively	O
worked	O
.	O

The	O
Bellside	LEXICON
Ironstone	LEXICON
,	O
which	O
was	O
widely	O
worked	O
in	O
the	O
area	O
east	O
of	O
Wishaw	O
,	O
does	O
not	O
reach	O
workable	O
thickness	O
in	O
the	O
district	O
.	O

The	O
Kiltongue	LEXICON
Mussel	LEXICON
Band	LEXICON
,	O
a	O
conspicuous	O
horizon	O
recognisable	O
in	O
almost	O
every	O
borehole	O
,	O
lies	O
at	O
a	O
distance	O
above	O
the	O
Kiltongue	LEXICON
Coal	LEXICON
that	O
varies	O
from	O
less	O
than	O
10m	O
to	O
about	O
18m	O
.	O

In	O
the	O
sequence	O
above	O
the	O
Kiltongue	LEXICON
Mussel	LEXICON
Band	LEXICON
,	O
the	O
Ladygrange	LEXICON
Coal	LEXICON
,	O
with	O
a	O
fauna	O
of	O
Naiadites	O
and	O
ostracods	O
in	O
its	O
roof	O
,	O
and	O
the	O
Bellside	LEXICON
Ironstone	LEXICON
can	O
be	O
recognised	O
in	O
places	O
,	O
neither	O
being	O
present	O
in	O
workable	O
thickness	O
.	O

Bivalves	O
were	O
found	O
at	O
a	O
horizon	O
between	O
the	O
Kiltongue	LEXICON
Mussel	LEXICON
Band	LEXICON
and	O
the	O
Airdrie	LEXICON
Virtuewell	LEXICON
Coal	LEXICON
in	O
the	O
Dalserf	O
Burn	O
-LSB-	O
NS	O
7987	O
5044	O
-RSB-	O
,	O
120m	O
upstream	O
from	O
the	O
road	O
bridge	O
.	O

Some	O
3	O
to	O
5m	O
of	O
mainly	O
argillaceous	O
strata	O
lie	O
between	O
the	O
Airdrie	LEXICON
Virtuewell	LEXICON
Coal	LEXICON
and	O
the	O
Queenslie	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
base	O
of	O
the	O
formation	O
is	O
taken	O
at	O
the	O
base	O
of	O
the	O
Queenslie	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

More	O
commonly	O
,	O
the	O
horizon	O
is	O
taken	O
to	O
lie	O
within	O
a	O
thin	O
development	O
of	O
argillaceous	O
strata	O
some	O
3	O
to	O
5m	O
above	O
the	O
Airdrie	LEXICON
Virtuewell	LEXICON
Coal	LEXICON
.	O

The	O
Airdrie	LEXICON
Blackband	LEXICON
Coal	LEXICON
is	O
up	O
to	O
0.75	O
thick	O
and	O
has	O
been	O
extensively	O
worked	O
in	O
the	O
north-west	O
,	O
around	O
Hamilton	O
.	O

The	O
associated	O
Airdrie	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
has	O
been	O
worked	O
only	O
around	O
Quarter	O
.	O

The	O
Coatbridge	LEXICON
Mussel	LEXICON
Band	LEXICON
,	O
consisting	O
of	O
up	O
to	O
4m	O
of	O
mudstone	O
with	O
pale	O
brown	O
ironstone	O
bands	O
,	O
lies	O
about	O
halfway	O
between	O
the	O
Airdrie	LEXICON
Blackband	LEXICON
position	O
and	O
the	O
base	O
of	O
the	O
Glasgow	LEXICON
Splint	LEXICON
Coal	LEXICON
.	O

There	O
is	O
no	O
workable	O
coal	O
at	O
this	O
position	O
;	O
nor	O
is	O
there	O
at	O
the	O
horizon	O
of	O
the	O
Virgin	LEXICON
Coal	LEXICON
,	O
2	O
to	O
4m	O
below	O
the	O
Glasgow	LEXICON
Splint	LEXICON
Coal	LEXICON
,	O
except	O
in	O
a	O
small	O
area	O
-LSB-	O
NS	O
783	O
483	O
-RSB-	O
,	O
near	O
Millburn	O
.	O

The	O
thickness	O
of	O
the	O
sequence	O
from	O
the	O
base	O
of	O
the	O
Glasgow	LEXICON
Splint	LEXICON
to	O
the	O
base	O
of	O
the	O
Glasgow	LEXICON
Main	LEXICON
Coal	LEXICON
exceeds	O
25m	O
in	O
the	O
area	O
south	O
of	O
Wishaw	O
but	O
decreases	O
in	O
all	O
directions	O
to	O
less	O
than	O
20m	O
,	O
except	O
in	O
Whistleberry	O
No.	O
1	O
Pit	O
-LSB-	O
NS	O
7025	O
5725	O
-RSB-	O
where	O
the	O
sequence	O
is	O
27m	O
thick	O
.	O

The	O
strata	O
between	O
the	O
Glasgow	LEXICON
Splint	LEXICON
Coal	LEXICON
and	O
the	O
Humph	LEXICON
Coal	LEXICON
are	O
mainly	O
arenaceous	O
and	O
vary	O
in	O
thickness	O
from	O
about	O
6	O
to	O
14m	O
,	O
being	O
thickest	O
and	O
having	O
the	O
greatest	O
ratio	O
of	O
sandstone	O
in	O
a	O
belt	O
extending	O
WSW	O
through	O
South	O
Quarter	O
.	O

The	O
Pyotshaw	LEXICON
Coal	LEXICON
is	O
everywhere	O
workable	O
,	O
locally	O
reaching	O
a	O
thickness	O
of	O
more	O
than	O
1m	O
.	O

It	O
is	O
separated	O
from	O
the	O
Glasgow	LEXICON
Main	LEXICON
Coal	LEXICON
by	O
mainly	O
argillaceous	O
strata	O
which	O
range	O
in	O
thickness	O
from	O
little	O
more	O
than	O
a	O
parting	O
in	O
the	O
area	O
south	O
of	O
Wishaw	O
,	O
where	O
the	O
seam	O
was	O
worked	O
jointly	O
with	O
the	O
Main	LEXICON
Coal	LEXICON
,	O
to	O
more	O
than	O
13m	O
.	O

Up	O
to	O
five	O
fossiliferous	O
horizons	O
have	O
been	O
recognised	O
in	O
the	O
beds	O
above	O
the	O
Glasgow	LEXICON
Upper	LEXICON
Coal	LEXICON
.	O

Fossils	O
were	O
also	O
found	O
in	O
the	O
Ashgillhead	O
Borehole	O
at	O
three	O
higher	O
levels	O
in	O
the	O
sequence	O
;	O
the	O
lowest	O
was	O
probably	O
the	O
horizon	O
of	O
the	O
Palacecraig	LEXICON
Coal	LEXICON
and	O
the	O
middle	O
one	O
possibly	O
at	O
the	O
horizon	O
of	O
the	O
Carnbroe	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
although	O
only	O
nonmarine	O
bivalves	O
and	O
Euestheria	O
were	O
found	O
.	O

A	O
recently	O
drilled	O
series	O
of	O
boreholes	O
near	O
Quarter	O
,	O
recovered	O
fossils	O
from	O
beds	O
above	O
and	O
below	O
a	O
possible	O
correlative	O
of	O
the	O
Glasgow	LEXICON
Upper	LEXICON
Coal	LEXICON
.	O

A	O
musselband	O
,	O
180m	O
upstream	O
from	O
Blackbog	O
-LSB-	O
NS	O
7181	O
5181	O
-RSB-	O
,	O
yielded	O
a	O
fauna	O
of	O
nonmarine	O
bivalves	O
which	O
suggests	O
a	O
position	O
above	O
the	O
Glasgow	LEXICON
Upper	LEXICON
Coal	LEXICON
.	O

In	O
the	O
lower	O
half	O
of	O
the	O
sequence	O
,	O
the	O
thick	O
Chatelherault	LEXICON
Sandstone	LEXICON
below	O
and	O
the	O
Hamilton	LEXICON
Sandstone	LEXICON
above	O
are	O
separated	O
by	O
a	O
variable	O
sequence	O
of	O
seatearths	O
,	O
mudstones	O
and	O
thin	O
coals	O
,	O
termed	O
the	O
Barncluith	LEXICON
Coal	LEXICON
Group	LEXICON
by	O
Carruthers	O
and	O
Dinham	O
but	O
here	O
referred	O
to	O
as	O
the	O
Barncluith	O
Coals	O
.	O

Downstream	O
in	O
the	O
Meikle	O
Burn	O
,	O
the	O
argillaceous	O
sequence	O
passes	O
beneath	O
soft	O
yellow	O
sandstone	O
,	O
which	O
is	O
probably	O
at	O
the	O
lowest	O
part	O
of	O
the	O
Chatelherault	LEXICON
Sandstone	LEXICON
.	O

At	O
a	O
hitherto	O
unrecorded	O
occurrence	O
-LSB-	O
NS	O
7938	O
5075	O
-RSB-	O
,	O
about	O
80m	O
upstream	O
from	O
the	O
Lanark	O
Road	O
,	O
Skipsey	LEXICON
's	LEXICON
Marine	LEXICON
Band	LEXICON
consists	O
of	O
dark	O
grey	O
carbonaceous	O
mudstone	O
with	O
a	O
fauna	O
which	O
includes	O
Posidonia	O
.	O

It	O
is	O
probable	O
that	O
a	O
fault	O
throwing	O
down	O
to	O
the	O
north	O
separates	O
this	O
argillaceous	O
sequence	O
from	O
the	O
exposures	O
of	O
the	O
Chatelherault	LEXICON
Sandstone	LEXICON
to	O
the	O
south	O
.	O

In	O
the	O
Meikle	O
Burn	O
below	O
its	O
confluence	O
with	O
the	O
Eddlewood	O
Burn	O
,	O
and	O
probably	O
on	O
the	O
downthrown	O
side	O
of	O
another	O
east-west	O
fault	O
,	O
the	O
contact	O
of	O
the	O
argillaceous	O
sequence	O
with	O
the	O
overlying	O
Hamilton	LEXICON
Sandstone	LEXICON
is	O
seen	O
for	O
a	O
distance	O
of	O
some	O
900m	O
.	O

Following	O
a	O
hiatus	O
,	O
sedimentation	O
resumed	O
in	O
the	O
district	O
with	O
the	O
deposition	O
of	O
the	O
calcrete-bearing	O
rocks	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

As	O
a	O
result	O
,	O
the	O
Ballagan	LEXICON
Formation	LEXICON
was	O
deposited	O
in	O
a	O
shallow-water	O
environment	O
with	O
restricted	O
access	O
to	O
the	O
open	O
sea	O
and	O
subject	O
to	O
marked	O
changes	O
of	O
salinity	O
and	O
periodic	O
desiccation	O
.	O

The	O
Midland	O
Valley	O
basin	O
at	O
this	O
time	O
was	O
presumably	O
more	O
extensive	O
than	O
during	O
deposition	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
but	O
there	O
is	O
no	O
known	O
locality	O
where	O
rocks	O
of	O
this	O
age	O
are	O
overlapped	O
by	O
the	O
cementstone-bearing	O
sequences	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
.	O

Just	O
as	O
the	O
onset	O
of	O
marine	O
conditions	O
was	O
gradual	O
,	O
so	O
also	O
was	O
the	O
resumption	O
of	O
fluvial	O
sedimentation	O
towards	O
the	O
end	O
of	O
Ballagan	LEXICON
Formation	LEXICON
times	O
,	O
with	O
deposition	O
of	O
the	O
calcrete-bearing	O
sequences	O
of	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Uplift	O
accompanied	O
by	O
movement	O
on	O
faults	O
,	O
almost	O
certainly	O
in	O
some	O
cases	O
involving	O
the	O
reactivation	O
of	O
more-ancient	O
fractures	O
,	O
induced	O
the	O
removal	O
by	O
erosion	O
of	O
part	O
,	O
and	O
locally	O
all	O
,	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
strata	O
previously	O
laid	O
down	O
.	O

It	O
is	O
possible	O
that	O
the	O
uplift	O
may	O
be	O
partly	O
attributable	O
to	O
the	O
development	O
beneath	O
the	O
western	O
part	O
of	O
the	O
Midland	O
Valley	O
of	O
the	O
large	O
magma	O
chamber	O
which	O
eventually	O
gave	O
rise	O
to	O
the	O
lavas	O
and	O
associated	O
volcanodetrital	O
rocks	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

The	O
mid	O
-	O
Dinantian	CHRONOSTRAT
erosion	O
surface	O
marks	O
an	O
important	O
stage	O
in	O
the	O
structural	O
development	O
of	O
the	O
Midland	O
Valley	O
.	O

The	O
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
were	O
extruded	O
subaerially	O
and	O
generated	O
a	O
relief	O
which	O
probably	O
amounted	O
to	O
several	O
hundred	O
metres	O
in	O
places	O
.	O

During	O
later	O
Strathclyde	LEXICON
Group	LEXICON
times	O
,	O
the	O
volcaniclastic	O
detritus	O
of	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
accumulated	O
on	O
the	O
low	O
ground	O
within	O
and	O
adjacent	O
to	O
this	O
lava	O
pile	O
,	O
encroaching	O
farther	O
on	O
to	O
the	O
lavas	O
as	O
subsidence	O
continued	O
.	O

The	O
lavas	O
continued	O
to	O
contribute	O
material	O
to	O
the	O
basin	O
almost	O
until	O
the	O
end	O
of	O
Strathclyde	LEXICON
Group	LEXICON
times	O
,	O
as	O
shown	O
by	O
the	O
occurrence	O
within	O
the	O
detritus	O
of	O
a	O
possible	O
correlative	O
of	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
,	O
and	O
in	O
adjacent	O
districts	O
the	O
lava	O
pile	O
was	O
not	O
completely	O
buried	O
until	O
well	O
into	O
Clackmannan	LEXICON
Group	LEXICON
times	O
.	O

The	O
relationship	O
of	O
the	O
two	O
formations	O
with	O
one	O
another	O
is	O
strongly	O
diachronous	O
and	O
in	O
the	O
west	O
,	O
for	O
example	O
at	O
Fore	O
Hareshaw	O
,	O
the	O
oldest	O
strata	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
are	O
at	O
a	O
level	O
only	O
a	O
little	O
below	O
the	O
horizon	O
of	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
.	O

During	O
the	O
final	O
stages	O
of	O
the	O
cycle	O
,	O
soils	O
developed	O
on	O
the	O
interdistributary	O
floodplains	O
under	O
the	O
hot	O
,	O
wet	O
to	O
humid	O
climatic	O
conditions	O
which	O
were	O
initiated	O
in	O
late	O
Inverclyde	LEXICON
Group	LEXICON
times	O
,	O
and	O
layers	O
of	O
vegetable	O
material	O
were	O
laid	O
down	O
.	O

Visean	O
rocks	O
of	O
various	O
ages	O
rest	O
on	O
either	O
the	O
volcanic	O
detritus	O
overlying	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
for	O
example	O
south-west	O
and	O
west	O
of	O
East	O
Kilbride	O
and	O
in	O
the	O
Strathaven	O
and	O
Drumclog	O
areas	O
,	O
or	O
on	O
an	O
unfossiliferous	O
sequence	O
of	O
siltstones	O
and	O
sandstones	O
of	O
uncertain	O
age	O
,	O
as	O
in	O
the	O
Coalburn	O
and	O
Muirkirk	O
areas	O
.	O

In	O
the	O
area	O
east	O
of	O
Strathaven	O
this	O
limestone	O
is	O
represented	O
by	O
the	O
Basket	LEXICON
or	O
Cot	LEXICON
Castle	LEXICON
Shell	LEXICON
Bed	LEXICON
,	O
still	O
visible	O
in	O
the	O
River	O
Avon	O
at	O
Cot	O
Castle	O
-LSB-	O
NS	O
7398	O
4575	O
;	O
NS	O
7380	O
4576	O
-RSB-	O
.	O

At	O
the	O
north	O
end	O
of	O
the	O
Muirkirk	O
area	O
the	O
Muirkirk	LEXICON
Under	LEXICON
Limestone	LEXICON
rests	O
on	O
unfossiliferous	O
strata	O
considered	O
to	O
belong	O
to	O
the	O
Inverclyde	LEXICON
Group	LEXICON
.	O

In	O
the	O
western	O
outlier	O
at	O
Drumclog	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
known	O
locally	O
as	O
the	O
Main	LEXICON
Limestone	LEXICON
,	O
was	O
extensively	O
quarried	O
.	O

The	O
fauna	O
is	O
more	O
varied	O
than	O
that	O
occurring	O
in	O
the	O
Blackbyre	LEXICON
Limestone	LEXICON
and	O
includes	O
,	O
amongst	O
other	O
species	O
,	O
Dibunophyllum	O
muirheadi	O
,	O
Angiospirifer	O
cf.	O
trigonalis	O
,	O
Antiquatonia	O
hindi	O
,	O
Beecheria	O
sp.	O
,	O
Eomarginifera	O
spp.	O
,	O
Gigantoproductus	O
giganteus	O
,	O
Latiproductus	O
latissimus	O
,	O
Pleuropugnoides	O
pleurodon	O
,	O
Productus	O
cf.	O
concinnus	O
,	O
Pugilis	O
pugilis	O
,	O
Rugosochonetes	O
celticus	O
,	O
Aviculopecten	O
spp.	O
,	O
Leiopteria	O
cf.	O
hendersoni	O
,	O
Limipecten	O
sp.	O
,	O
Myalina	O
cf.	O
flemingi	O
,	O
Pernopecten	O
sowerbii	O
and	O
Streblochondria	O
sp	O
.	O

has	O
been	O
recorded	O
in	O
workings	O
from	O
the	O
mudstone	O
above	O
the	O
Wilsontown	LEXICON
Smithy	LEXICON
Coal	LEXICON
but	O
elsewhere	O
the	O
bed	O
appears	O
barren	O
.	O

However	O
,	O
at	O
Drumclog	O
,	O
in	O
the	O
BGS	O
Fore	O
Hareshaw	O
Borehole	O
,	O
the	O
roof	O
of	O
the	O
seam	O
above	O
the	O
local	O
`	O
Main	LEXICON
Limestone	LEXICON
'	O
carries	O
a	O
small	O
marine	O
fauna	O
consisting	O
principally	O
of	O
poorly	O
preserved	O
productoids	O
,	O
and	O
may	O
represent	O
the	O
position	O
of	O
the	O
Craigenhill	LEXICON
Limestone	LEXICON
of	O
the	O
Lanark	O
district	O
.	O

The	O
Blackhall	LEXICON
Limestone	LEXICON
is	O
thin	O
and	O
may	O
lie	O
close	O
to	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
in	O
the	O
area	O
to	O
the	O
west	O
of	O
East	O
Kilbride	O
around	O
Thorntonhall	O
,	O
in	O
the	O
Kilmarnock	O
district	O
.	O

The	O
overlying	O
mudstones	O
,	O
which	O
have	O
been	O
termed	O
the	O
Neilson	LEXICON
Shell	LEXICON
Bed	LEXICON
,	O
contain	O
a	O
typical	O
fauna	O
with	O
Crurithyris	O
urii	O
,	O
Tornquistia	O
youngi	O
,	O
Glabrocingulum	O
atomarium	O
,	O
Retispira	O
spp.	O
,	O
Nuculopsis	O
gibbosa	O
,	O
Anthraconeilo	O
spp.	O
,	O
Pernopecten	O
fragilis	O
,	O
Posidonia	O
corrugata	O
,	O
Catastroboceras	O
sp	O
.	O

Around	O
Strathaven	O
the	O
limestone	O
may	O
be	O
recognised	O
by	O
the	O
accompanying	O
Neilson	LEXICON
Shell	LEXICON
Bed	LEXICON
which	O
has	O
a	O
characteristic	O
fauna	O
including	O
Fenestella	O
sp.	O
,	O
Crurithyris	O
urii	O
,	O
Eomarginifera	O
spp.	O
,	O
Rugosochonetes	O
speciosus	O
,	O
Tornquistia	O
polita	O
,	O
T.	O
youngi	O
,	O
Euphemites	O
sp.	O
,	O
Glabrocingulum	O
atomarium	O
,	O
Straparollus	O
carbonarius	O
,	O
Strobeus	O
spp.	O
,	O
Euchondria	O
sp.	O
,	O
Nuculopsis	O
gibbosa	O
,	O
Phestia	O
attenuata	O
,	O
Reticycloceras	O
sp	O
.	O

Farther	O
south	O
,	O
in	O
the	O
Coalburn	O
area	O
,	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
is	O
known	O
as	O
the	O
Douglas	LEXICON
Wee	LEXICON
Limestone	LEXICON
,	O
and	O
in	O
the	O
Lanark	O
district	O
is	O
associated	O
with	O
a	O
Neilson	LEXICON
Shell	LEXICON
Bed	LEXICON
fauna	O
.	O

In	O
the	O
Muirkirk	O
area	O
the	O
corresponding	O
Muirkirk	LEXICON
Wee	LEXICON
Limestone	LEXICON
also	O
contains	O
Gigantoproductus	O
sp.	O
,	O
together	O
with	O
Composita	O
sp.	O
,	O
Rugosochonetes	O
sp	O
.	O

The	O
Second	LEXICON
Hosie	LEXICON
Limestone	LEXICON
contains	O
a	O
variety	O
of	O
brachiopod	O
species	O
including	O
Eomarginifera	O
lobata	O
,	O
Pugilis	O
sp.	O
,	O
Spirifer	O
sp	O
.	O

and	O
Spiriferellina	O
sp.	O
,	O
together	O
with	O
Euphemites	O
urii	O
,	O
Pernopecten	O
sowerbii	O
and	O
Streblochondria	O
sp.	O
;	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
is	O
associated	O
with	O
overlying	O
mudstones	O
which	O
contain	O
an	O
abundance	O
of	O
Posidonia	O
corrugata	O
.	O

She	O
drew	O
attention	O
to	O
the	O
similarity	O
of	O
this	O
species	O
to	O
Cravenoceras	O
leion	O
the	O
first	O
appearance	O
of	O
which	O
has	O
been	O
taken	O
to	O
mark	O
the	O
base	O
of	O
the	O
Namurian	CHRONOSTRAT
in	O
the	O
British	O
Isles	O
.	O

On	O
the	O
western	O
margin	O
of	O
the	O
Coalburn	O
area	O
,	O
in	O
the	O
discontinuous	O
section	O
-LSB-	O
NS	O
7928	O
3604	O
-RSB-	O
in	O
the	O
River	O
Nethan	O
near	O
Over	O
Stockbriggs	O
,	O
beds	O
probably	O
within	O
the	O
lower	O
portion	O
of	O
the	O
McDonald	LEXICON
Limestones	LEXICON
contain	O
Angiospirifer	O
cf.	O
trigonalis	O
,	O
Buxtonia	O
sp.	O
,	O
Composita	O
ambigua	O
,	O
Eomarginifera	O
lobata	O
,	O
Krotovia	O
sp.	O
,	O
Rugosochonetes	O
celticus	O
,	O
Euphemites	O
urii	O
and	O
Pernopecten	O
sowerbii	O
.	O

The	O
fauna	O
as	O
a	O
whole	O
is	O
characteristic	O
of	O
calcareous	O
strata	O
throughout	O
the	O
Dinantian	CHRONOSTRAT
of	O
the	O
Midland	O
Valley	O
.	O

The	O
uppermost	O
bed	O
of	O
the	O
McDonald	LEXICON
Limestones	LEXICON
has	O
been	O
correlated	O
with	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
of	O
the	O
Central	O
Coalfield	O
.	O

Wilson	O
has	O
already	O
noted	O
that	O
it	O
was	O
not	O
until	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
transgression	O
that	O
the	O
region	O
was	O
wholly	O
covered	O
by	O
sea	O
.	O

The	O
faunas	O
of	O
earlier	O
incursions	O
depend	O
,	O
at	O
least	O
in	O
part	O
,	O
on	O
the	O
relationship	O
of	O
the	O
present	O
outcrop	O
to	O
the	O
Carboniferous	CHRONOSTRAT
shorelines	O
at	O
the	O
time	O
of	O
the	O
incursion	O
.	O

At	O
most	O
locations	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
is	O
overlain	O
by	O
a	O
considerable	O
thickness	O
of	O
mudstone	O
.	O

In	O
both	O
the	O
Coalburn	O
and	O
Muirkirk	O
areas	O
the	O
mudstones	O
overlying	O
the	O
McDonald	LEXICON
Limestones	LEXICON
are	O
thin	O
with	O
Lingula	O
sp	O
.	O

In	O
the	O
Muirkirk	O
Basin	O
the	O
same	O
marine	O
band	O
overlies	O
the	O
Thirty	LEXICON
Inch	LEXICON
Coal	LEXICON
and	O
contains	O
Lingula	O
sp	O
.	O

Minor	O
cycles	O
such	O
as	O
the	O
Huntershill	LEXICON
Limestone	LEXICON
and	O
the	O
Plean	LEXICON
Limestones	LEXICON
are	O
poorly	O
developed	O
,	O
particularly	O
in	O
the	O
south	O
.	O

The	O
faunas	O
of	O
all	O
these	O
beds	O
have	O
been	O
discussed	O
by	O
Wilson	O
who	O
drew	O
attention	O
to	O
the	O
geographical	O
variations	O
apparently	O
related	O
to	O
the	O
thickness	O
of	O
sediment	O
in	O
the	O
interval	O
between	O
the	O
Index	LEXICON
and	O
Calmy	LEXICON
limestones	O
.	O

Goniatites	O
of	O
zonal	O
significance	O
are	O
rare	O
in	O
the	O
Scottish	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
but	O
sufficient	O
have	O
been	O
discovered	O
to	O
demonstrate	O
that	O
the	O
boundary	O
between	O
the	O
Pendleian	CHRONOSTRAT
and	O
Arnsbergian	CHRONOSTRAT
stages	O
must	O
lie	O
between	O
the	O
Lyoncross	LEXICON
and	O
Orchard	LEXICON
limestones	O
.	O

In	O
the	O
Coalburn	O
area	O
the	O
Index	LEXICON
Limestone	LEXICON
is	O
the	O
only	O
horizon	O
in	O
the	O
formation	O
which	O
has	O
been	O
examined	O
;	O
around	O
Auchenbeg	O
-LSB-	O
NS	O
798	O
361	O
-RSB-	O
the	O
limestone	O
and	O
its	O
associated	O
mudstones	O
contain	O
Gigantoproductus	O
cf.	O
irregularis	O
,	O
Latiproductus	O
cf.	O
latissimus	O
,	O
Pleuropugnoides	O
sp.	O
,	O
Schellwienella	O
sp.	O
,	O
Myalina	O
sp	O
.	O

Above	O
the	O
Calmy	LEXICON
Limestone	LEXICON
,	O
mudstones	O
with	O
Leptagonia	O
smithi	O
,	O
Pugnax	O
cf.	O
pugnus	O
,	O
Rugosochonetes	O
caledonicus	O
,	O
Euphemites	O
ardenensis	O
,	O
Glabrocingulum	O
sp.	O
,	O
Nuculopsis	O
gibbosa	O
,	O
Anthroconeilo	O
cf.	O
laevirostrum	O
and	O
Tylonautilus	O
?	O

The	O
overlying	O
Plean	LEXICON
limestones	LEXICON
are	O
variably	O
present	O
.	O

The	O
Castlecary	LEXICON
Limestone	LEXICON
at	O
the	O
top	O
of	O
the	O
formation	O
appears	O
to	O
be	O
absent	O
throughout	O
the	O
district	O
.	O

In	O
the	O
area	O
flanking	O
the	O
gorge	O
of	O
the	O
River	O
Avon	O
-LSB-	O
NS	O
759	O
495	O
-RSB-	O
much	O
of	O
the	O
formation	O
is	O
absent	O
and	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
the	O
local	O
base	O
of	O
the	O
Coal	O
Measures	O
,	O
lies	O
stratigraphically	O
close	O
to	O
the	O
Calmy	LEXICON
Limestone	LEXICON
.	O

The	O
musselband	O
above	O
the	O
Upper	LEXICON
Drumgray	LEXICON
Coal	LEXICON
,	O
commonly	O
highly	O
fossiliferous	O
in	O
the	O
area	O
around	O
Shotts	O
in	O
the	O
adjacent	O
Lanark	O
district	O
,	O
is	O
here	O
poorly	O
fossiliferous	O
,	O
but	O
the	O
characteristic	O
Carbonicola	O
cf.	O
pseudorobusta	O
is	O
present	O
in	O
the	O
fauna	O
from	O
this	O
horizon	O
in	O
Stonehouse	O
No.	O
77	O
Borehole	O
and	O
around	O
Canderside	O
-LSB-	O
NS	O
777	O
463	O
-RSB-	O
.	O

The	O
Kiltongue	LEXICON
Musselband	LEXICON
,	O
containing	O
Anthraconaia	O
sp.	O
,	O
Anthracosia	O
spp.	O
,	O
Carbonicola	O
oslancis	O
and	O
Geisina	O
arcuata	O
,	O
is	O
widespread	O
and	O
has	O
been	O
taken	O
as	O
the	O
base	O
of	O
the	O
modiolaris	BIOZONE
Biozone	BIOZONE
.	O

The	O
Vanderbeckei	LEXICON
Marine	LEXICON
Band	LEXICON
is	O
poorly	O
developed	O
in	O
the	O
Hamilton	O
district	O
and	O
only	O
foraminifera	O
and	O
Lingula	O
mytilloides	O
have	O
been	O
recovered	O
from	O
boreholes	O
and	O
field	O
exposures	O
.	O

The	O
roof	O
of	O
the	O
Airdrie	LEXICON
Blackband	LEXICON
Coal	LEXICON
contains	O
a	O
limited	O
fauna	O
including	O
Anthracosia	O
aquilina	O
,	O
A.	O
beaniana	O
,	O
A.	O
ovum	O
and	O
A.	O
phrygiana	O
.	O

Surface	O
exposures	O
of	O
the	O
various	O
beds	O
up	O
to	O
the	O
Aegiranum	LEXICON
Marine	LEXICON
Band	LEXICON
are	O
uncommon	O
and	O
only	O
the	O
Dalserf	O
Musselband	O
fauna	O
is	O
well	O
represented	O
.	O

The	O
Aegiranum	LEXICON
Marine	LEXICON
Band	LEXICON
at	O
the	O
base	O
is	O
found	O
at	O
a	O
number	O
of	O
locations	O
,	O
notably	O
in	O
Stewart	O
Gill	O
-LSB-	O
NS	O
7938	O
5075	O
-RSB-	O
,	O
the	O
River	O
Avon	O
at	O
Hamilton	O
High	O
Parks	O
-LSB-	O
NS	O
7349	O
5297	O
;	O
NS	O
7360	O
5355	O
-RSB-	O
,	O
the	O
River	O
Clyde	O
-LSB-	O
NS	O
7976	O
5075	O
-RSB-	O
and	O
the	O
railway	O
cutting	O
near	O
Parkhead	O
,	O
Motherwell	O
-LSB-	O
NS	O
7510	O
5640	O
-RSB-	O
.	O

The	O
Bothwell	LEXICON
Bridge	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
so	O
named	O
from	O
an	O
exposure	O
in	O
the	O
River	O
Clyde	O
-LSB-	O
NS	O
7085	O
5766	O
-RSB-	O
on	O
the	O
adjacent	O
Airdrie	O
district	O
,	O
is	O
present	O
in	O
the	O
Craighead	O
Borehole	O
at	O
a	O
depth	O
of	O
72	O
m.	O

The	O
position	O
has	O
been	O
correlated	O
with	O
the	O
Shafton	LEXICON
Marine	LEXICON
Band	LEXICON
of	O
the	O
Pennine	O
succession	O
.	O

The	O
oldest	O
and	O
most	O
numerous	O
were	O
probably	O
emplaced	O
during	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
,	O
around	O
400	O
million	O
years	O
ago	O
,	O
into	O
the	O
Silurian	CHRONOSTRAT
and	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
of	O
the	O
Lesmahagow	O
Inlier	O
.	O

A	O
number	O
of	O
bodies	O
of	O
mainly	O
basic	O
,	O
in	O
some	O
cases	O
heavily	O
altered	O
,	O
material	O
,	O
cutting	O
Carboniferous	CHRONOSTRAT
rocks	O
,	O
are	O
considered	O
to	O
have	O
been	O
intruded	O
at	O
various	O
periods	O
during	O
the	O
Carboniferous	CHRONOSTRAT
.	O

This	O
is	O
especially	O
true	O
of	O
the	O
numerous	O
bodies	O
of	O
mainly	O
acid	O
composition	O
,	O
ranging	O
in	O
thickness	O
from	O
less	O
than	O
a	O
metre	O
to	O
more	O
than	O
100m	O
,	O
which	O
are	O
intruded	O
into	O
the	O
Silurian	CHRONOSTRAT
and	O
Devonian	CHRONOSTRAT
rocks	O
in	O
the	O
south	O
.	O

An	O
Rb-Sr	O
isochron	O
of	O
age	O
412.8	O
_	O
5.6	O
Ma	O
,	O
determined	O
for	O
the	O
body	O
from	O
fresh	O
biotite	O
and	O
plagioclase	O
separates	O
and	O
a	O
whole	O
rock	O
granodiorite	O
by	O
Thirlwall	O
,	O
suggests	O
that	O
it	O
was	O
emplaced	O
during	O
the	O
earliest	O
Devonian	CHRONOSTRAT
.	O

The	O
most	O
prominent	O
intrusions	O
are	O
the	O
suite	O
of	O
lenticular	O
,	O
sheet-like	O
bodies	O
of	O
mainly	O
acid	O
intermediate	O
composition	O
which	O
cut	O
Silurian	CHRONOSTRAT
and	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
in	O
the	O
south	O
of	O
the	O
district	O
.	O

Where	O
thin	O
sill-like	O
bodies	O
are	O
intruded	O
into	O
grey	O
Silurian	CHRONOSTRAT
turbidites	O
they	O
may	O
be	O
difficult	O
to	O
distinguish	O
in	O
the	O
field	O
from	O
beds	O
of	O
greywacke	O
.	O

Sills	O
of	O
olivine-dolerite	O
crop	O
out	O
extensively	O
in	O
the	O
area	O
between	O
Nethershields	O
-LSB-	O
NS	O
700	O
488	O
-RSB-	O
and	O
Craigthorn	O
-LSB-	O
NS	O
735	O
484	O
-RSB-	O
,	O
intruding	O
strata	O
of	O
the	O
Lawmuir	LEXICON
and	O
Limestone	LEXICON
Coal	LEXICON
formations	O
.	O

To	O
the	O
southeast	O
of	O
Stonehouse	O
,	O
in	O
the	O
neighbourhood	O
of	O
Draffen	O
-LSB-	O
NS	O
794	O
453	O
-RSB-	O
,	O
doleritic	O
sills	O
have	O
been	O
encountered	O
in	O
underground	O
workings	O
in	O
the	O
Lesmahagow	LEXICON
Main	LEXICON
Gas	LEXICON
Coal	LEXICON
.	O

An	O
east-west-trending	O
dyke	O
composed	O
of	O
heavily	O
altered	O
dolerite	O
,	O
exposed	O
-LSB-	O
NS	O
7472	O
4930	O
-RSB-	O
south	O
of	O
Corslet	O
,	O
in	O
an	O
unnamed	O
tributary	O
of	O
the	O
Darngaber	O
Burn	O
,	O
probably	O
belongs	O
to	O
the	O
extensive	O
suite	O
of	O
dykes	O
of	O
this	O
trend	O
which	O
was	O
emplaced	O
during	O
the	O
late	O
Carboniferous	CHRONOSTRAT
or	O
early	O
Permian	CHRONOSTRAT
.	O

A	O
sub-cylindrical	O
body	O
of	O
trachyte	O
,	O
which	O
forms	O
the	O
conspicuous	O
skyline	O
feature	O
of	O
Loudoun	O
Hill	O
,	O
is	O
considered	O
to	O
be	O
a	O
plug	O
infilling	O
the	O
feeder	O
pipe	O
of	O
a	O
vent	O
active	O
during	O
eruption	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

In	O
the	O
south-west	O
,	O
four	O
bodies	O
consisting	O
mainly	O
of	O
basaltic	O
breccia	O
,	O
cutting	O
strata	O
ranging	O
in	O
age	O
from	O
Silurian	CHRONOSTRAT
to	O
early	O
Namurian	CHRONOSTRAT
are	O
regarded	O
as	O
vents	O
associated	O
with	O
late	O
Carboniferous	CHRONOSTRAT
to	O
Permian	CHRONOSTRAT
volcanicity	O
.	O

The	O
Distinkhorn	O
Plutonic	O
Complex	O
is	O
made	O
up	O
bodies	O
of	O
granodioritic	O
and	O
dioritic	O
composition	O
.	O

Information	O
relating	O
to	O
the	O
earliest	O
development	O
of	O
this	O
ancient	O
feature	O
,	O
and	O
in	O
particular	O
of	O
the	O
fault	O
system	O
which	O
forms	O
its	O
southern	O
boundary	O
,	O
is	O
provided	O
by	O
the	O
Silurian	CHRONOSTRAT
rocks	O
of	O
the	O
Lesmahagow	O
and	O
Hagshaw	O
Hills	O
inliers	O
.	O

Re-activation	O
of	O
these	O
faults	O
at	O
various	O
times	O
had	O
an	O
especially	O
marked	O
effect	O
on	O
the	O
distribution	O
of	O
the	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
.	O

During	O
the	O
Silurian	CHRONOSTRAT
period	O
,	O
closure	O
of	O
the	O
Iapetus	O
Ocean	O
by	O
subduction	O
processes	O
brought	O
the	O
Eastern	O
Avalonian	O
plate	O
into	O
oblique	O
collision	O
with	O
the	O
Laurentian	O
plate	O
.	O

In	O
the	O
Lesmahagow	O
and	O
Hagshaw	O
Hills	O
inliers	O
,	O
it	O
is	O
probable	O
that	O
a	O
stratigraphical	O
break	O
occurs	O
between	O
the	O
Silurian	CHRONOSTRAT
rocks	O
and	O
those	O
assigned	O
to	O
the	O
Devonian	CHRONOSTRAT
,	O
although	O
there	O
is	O
no	O
marked	O
angular	O
unconformity	O
corresponding	O
with	O
that	O
in	O
the	O
Pentland	O
Hills	O
.	O

The	O
onset	O
of	O
sedimentation	O
was	O
delayed	O
until	O
early	O
Carboniferous	CHRONOSTRAT
times	O
when	O
the	O
cornstone-bearing	O
sandstones	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
were	O
laid	O
down	O
under	O
quiet	O
tectonic	O
conditions	O
by	O
NE-flowing	O
rivers	O
in	O
a	O
subsiding	O
basin	O
at	O
least	O
as	O
broad	O
as	O
the	O
present	O
Midland	O
Valley	O
.	O

Continuing	O
subsidence	O
for	O
a	O
time	O
allowed	O
deposition	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
in	O
a	O
coastal	O
sabkha	O
or	O
restricted	O
marine	O
environment	O
subject	O
to	O
fluctuating	O
salinities	O
and	O
periodic	O
desiccation	O
before	O
uplift	O
of	O
the	O
upland	O
source	O
areas	O
restored	O
fluvial	O
conditions	O
towards	O
the	O
end	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
period	O
.	O

The	O
evidence	O
is	O
sparse	O
but	O
in	O
places	O
removal	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
was	O
mainly	O
or	O
entirely	O
complete	O
before	O
extrusion	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
lavas	O
,	O
especially	O
over	O
a	O
tract	O
in	O
the	O
west-central	O
part	O
of	O
the	O
Midland	O
Valley	O
which	O
appears	O
to	O
have	O
been	O
bounded	O
in	O
the	O
south	O
by	O
the	O
Inchgotrick	O
Fault	O
,	O
and	O
in	O
the	O
west	O
by	O
the	O
Largs	O
Ruck	O
Figure	O
8	O
.	O

It	O
has	O
been	O
suggested	O
that	O
the	O
uplift	O
was	O
due	O
to	O
magmatic	O
updoming	O
prior	O
to	O
extrusion	O
of	O
the	O
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

One	O
such	O
is	O
the	O
NW-trending	O
fracture	O
zone	O
,	O
represented	O
by	O
the	O
post	O
-	O
Westphalian	CHRONOSTRAT
Dechmont	O
Fault	O
which	O
forms	O
the	O
eastern	O
boundary	O
of	O
the	O
North	O
Ayrshire	O
Block	O
.	O

This	O
block	O
,	O
which	O
contains	O
the	O
thick	O
lava	O
pile	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
remained	O
relatively	O
buoyant	O
through	O
much	O
of	O
the	O
later	O
Carboniferous	CHRONOSTRAT
,	O
possibly	O
as	O
a	O
result	O
of	O
isostatic	O
response	O
to	O
crustal	O
thickening	O
caused	O
by	O
emplacement	O
of	O
a	O
high-level	O
magma	O
chamber	O
.	O

During	O
deposition	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
,	O
movements	O
on	O
the	O
Inchgotrick	O
and	O
Strathaven	O
faults	O
,	O
at	O
the	O
southern	O
margin	O
of	O
the	O
North	O
Ayrshire	O
Block	O
,	O
may	O
account	O
for	O
the	O
unusually	O
thick	O
sequence	O
contained	O
in	O
a	O
narrow	O
basin	O
at	O
Strathaven	O
.	O

In	O
the	O
Douglas	O
Basin	O
especially	O
,	O
thicker	O
sequences	O
of	O
the	O
Lawmuir	LEXICON
,	O
Upper	LEXICON
Limestone	LEXICON
and	O
Passage	LEXICON
formations	O
were	O
laid	O
down	O
than	O
occur	O
elsewhere	O
in	O
the	O
Hamilton	O
district	O
.	O

Basin	O
subsidence	O
in	O
the	O
district	O
was	O
halted	O
by	O
uplift	O
,	O
presumably	O
as	O
a	O
result	O
of	O
transpressional	O
movements	O
,	O
late	O
in	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
times	O
and	O
during	O
deposition	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
.	O

It	O
is	O
probable	O
that	O
most	O
of	O
the	O
extensive	O
system	O
of	O
faults	O
of	O
east-west	O
and	O
NW-SE	O
trend	O
Figure	O
9	O
,	O
which	O
cut	O
the	O
youngest	O
Carboniferous	CHRONOSTRAT
rocks	O
in	O
the	O
district	O
,	O
date	O
from	O
the	O
latest	O
Carboniferous	CHRONOSTRAT
or	O
early	O
Permian	CHRONOSTRAT
.	O

In	O
the	O
Hamilton	O
district	O
almost	O
all	O
evidence	O
of	O
earlier	O
glaciations	O
and	O
interglacials	O
was	O
removed	O
by	O
erosion	O
during	O
the	O
last	O
main	O
late	O
Devensian	CHRONOSTRAT
.	O

Late	CHRONOSTRAT
Quaternary	CHRONOSTRAT
drift	O
deposits	O
blanket	O
much	O
of	O
the	O
area	O
of	O
the	O
Hamilton	O
district	O
,	O
particularly	O
on	O
the	O
low	O
ground	O
,	O
masking	O
a	O
land	O
surface	O
which	O
had	O
evolved	O
during	O
the	O
Tertiary	CHRONOSTRAT
and	O
the	O
early	O
Quaternary	CHRONOSTRAT
.	O

Extensive	O
drift	O
deposits	O
cover	O
the	O
less	O
resistent	O
Devonian	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
sedimentary	O
rocks	O
in	O
the	O
northern	O
half	O
of	O
the	O
Hamilton	O
district	O
except	O
where	O
these	O
deposits	O
have	O
been	O
cut	O
through	O
by	O
later	O
erosion	O
in	O
the	O
incised	O
valleys	O
draining	O
into	O
the	O
River	O
Clyde	O
or	O
by	O
the	O
recent	O
activities	O
of	O
man	O
.	O

The	O
Flandrian	CHRONOSTRAT
Stage	O
commenced	O
at	O
10000	O
BP	O
,	O
with	O
a	O
rapid	O
rise	O
in	O
temperature	O
.	O

Finally	O
,	O
man	O
has	O
left	O
his	O
imprint	O
on	O
the	O
landscape	O
during	O
the	O
last	O
two	O
centuries	O
of	O
industrial	O
activity	O
,	O
particularly	O
in	O
the	O
areas	O
underlain	O
by	O
coal-bearing	O
Carboniferous	CHRONOSTRAT
rocks	O
in	O
the	O
northern	O
half	O
and	O
the	O
extreme	O
south-east	O
of	O
the	O
district	O
.	O

The	O
deposit	O
is	O
a	O
continuation	O
of	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
,	O
named	O
after	O
the	O
Wilderness	O
Plantation	O
north	O
of	O
Bishopbriggs	O
in	O
the	O
Glasgow	O
district	O
.	O

In	O
areas	O
of	O
Carboniferous	CHRONOSTRAT
sedimentary	O
rocks	O
the	O
till	O
is	O
a	O
dark	O
grey	O
silty	O
clay	O
with	O
pebbles	O
and	O
boulders	O
mainly	O
of	O
Carboniferous	CHRONOSTRAT
sandstones	O
and	O
limestones	O
.	O

Over	O
Devonian	CHRONOSTRAT
outcrops	O
,	O
the	O
till	O
consists	O
of	O
reddish	O
sandy	O
clay	O
with	O
predominantly	O
red	O
sandstone	O
clasts	O
.	O

There	O
are	O
few	O
exposures	O
of	O
till	O
in	O
the	O
mainly	O
peat-covered	O
ground	O
over	O
the	O
outcrop	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
but	O
here	O
the	O
deposit	O
tends	O
to	O
be	O
variegated	O
with	O
mainly	O
igneous	O
pebbles	O
and	O
boulders	O
.	O

In	O
areas	O
of	O
Silurian	CHRONOSTRAT
rocks	O
,	O
where	O
the	O
till	O
is	O
commonly	O
confined	O
to	O
the	O
lower	O
valley-sides	O
and	O
valley-bottoms	O
,	O
there	O
is	O
a	O
predominance	O
of	O
tabular	O
greywacke	O
and	O
siltstone	O
clasts	O
in	O
an	O
assemblage	O
which	O
also	O
includes	O
clasts	O
of	O
quartzite	O
,	O
chert	O
,	O
jasper	O
and	O
the	O
various	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
intrusive	O
rocks	O
.	O

Till	O
is	O
normally	O
the	O
deposit	O
lying	O
immediately	O
on	O
the	O
bedrock	O
and	O
underlies	O
most	O
of	O
the	O
other	O
Quaternary	CHRONOSTRAT
deposits	O
.	O

North-east	O
of	O
a	O
line	O
connecting	O
the	O
Renfrewshire	O
Hills	O
to	O
the	O
high	O
ground	O
over	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
west	O
of	O
Strathaven	O
,	O
glacial	O
striae	O
and	O
drumlins	O
are	O
aligned	O
NW-SE	O
whereas	O
to	O
the	O
south-west	O
they	O
have	O
a	O
SW-NE	O
trend	O
.	O

The	O
lower	O
part	O
of	O
the	O
deposit	O
consists	O
of	O
laminated	O
clay	O
and	O
silt	O
assigned	O
to	O
the	O
Bellshill	LEXICON
Formation	LEXICON
,	O
the	O
upper	O
part	O
,	O
composed	O
mainly	O
of	O
sand	O
with	O
gravel	O
in	O
places	O
,	O
is	O
referred	O
to	O
the	O
Ross	LEXICON
Formation	LEXICON
.	O

At	O
a	O
late	O
stage	O
in	O
the	O
lifetime	O
of	O
Lake	O
Clydesdale	O
,	O
perhaps	O
while	O
the	O
ice	O
dam	O
lay	O
at	O
the	O
suggested	O
terminal	O
moraine	O
of	O
Blantyreferme	O
ridge	O
-LSB-	O
NS	O
673	O
595	O
-RSB-	O
a	O
short	O
distance	O
north	O
of	O
the	O
district	O
boundary	O
,	O
a	O
thick	O
body	O
of	O
sand	O
and	O
gravel	O
of	O
the	O
Ross	LEXICON
Formation	LEXICON
was	O
contributed	O
to	O
the	O
lake	O
infill	O
in	O
the	O
neighbourhood	O
of	O
Ferniegair	O
by	O
the	O
northward	O
flowing	O
Avon	O
Water	O
.	O

Screes	O
,	O
such	O
as	O
the	O
one	O
on	O
Loudoun	O
Hill	O
,	O
may	O
have	O
been	O
initiated	O
by	O
during	O
periglacial	O
conditions	O
but	O
continued	O
to	O
form	O
throughout	O
the	O
Flandrian	CHRONOSTRAT
.	O

Most	O
of	O
the	O
geological	O
processes	O
that	O
shaped	O
the	O
landforms	O
throughout	O
the	O
Flandrian	CHRONOSTRAT
probably	O
had	O
started	O
in	O
the	O
Late	CHRONOSTRAT
Devensian	CHRONOSTRAT
:	O
screes	O
,	O
incised	O
gorges	O
,	O
landslips	O
,	O
lacustrine	O
deposits	O
and	O
fluvial	O
deposits	O
.	O

Despite	O
these	O
depredations	O
,	O
hill	O
peat	O
still	O
covers	O
much	O
of	O
the	O
Silurian	CHRONOSTRAT
hills	O
in	O
the	O
south	O
and	O
Clyde	LEXICON
Plateau	LEXICON
lavas	O
hills	O
in	O
the	O
west	O
of	O
the	O
district	O
,	O
notably	O
at	O
Mossmulloch	O
-LSB-	O
NS	O
635	O
415	O
-RSB-	O
.	O

These	O
form	O
spectacular	O
rock	O
gorges	O
,	O
such	O
as	O
those	O
in	O
the	O
Avon	O
Water	O
and	O
in	O
the	O
Rotten	O
Calder	O
near	O
East	O
Kilbride	O
,	O
cut	O
mainly	O
in	O
lower	O
Carboniferous	CHRONOSTRAT
sedimentary	O
rocks	O
with	O
normally	O
only	O
a	O
thin	O
cover	O
of	O
superficial	O
deposits	O
-LRB-	O
Figures	O
10and	O
11	O
.	O

In	O
age	O
the	O
lacustrine	O
deposits	O
probably	O
range	O
from	O
the	O
earliest	O
Flandrian	CHRONOSTRAT
almost	O
to	O
Recent	O
and	O
may	O
even	O
date	O
back	O
to	O
the	O
latest	O
Devensian	CHRONOSTRAT
.	O

McMillan	O
assigned	O
such	O
deposits	O
formed	O
during	O
the	O
Flandrian	CHRONOSTRAT
to	O
the	O
Kelvin	LEXICON
Formation	LEXICON
.	O

Throughout	O
the	O
Flandrian	CHRONOSTRAT
extensive	O
alluvial	O
deposits	O
built	O
up	O
as	O
the	O
post	O
-	O
Devensian	CHRONOSTRAT
drainage	O
system	O
developed	O
.	O

Coarse-grained	O
Flandrian	CHRONOSTRAT
sediments	O
to	O
the	O
Law	O
Formation	O
.	O

Beds	O
of	O
mudstone	O
within	O
the	O
bedrock	O
offer	O
more	O
uniform	O
material	O
,	O
possible	O
horizons	O
being	O
the	O
Black	LEXICON
Metals	LEXICON
and	O
the	O
mudstones	O
that	O
overlie	O
the	O
Top	LEXICON
Hosie	LEXICON
,	O
Index	LEXICON
,	O
Orchard	LEXICON
and	O
Calmy	LEXICON
limestones	O
.	O

Thick	O
mudstones	O
also	O
occur	O
above	O
the	O
Glasgow	LEXICON
Ell	LEXICON
Coal	LEXICON
.	O

Within	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
mudstones	O
associated	O
with	O
the	O
Chatelherault	LEXICON
and	O
Hamilton	LEXICON
sandstones	O
have	O
been	O
worked	O
at	O
Carscallan	O
-LSB-	O
NS	O
723	O
523	O
-RSB-	O
,	O
near	O
Hamilton	O
.	O

The	O
Chatelherault	LEXICON
and	O
Hamilton	LEXICON
sandstones	O
of	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
in	O
the	O
Hamilton	O
area	O
were	O
formerly	O
an	O
important	O
source	O
of	O
building	O
stone	O
.	O

A	O
sandstone	O
lying	O
a	O
little	O
above	O
the	O
Kiltongue	LEXICON
Musselband	LEXICON
was	O
quarried	O
and	O
mined	O
for	O
building	O
stone	O
at	O
Overwood	O
-LSB-	O
NS	O
771	O
461	O
-RSB-	O
,	O
south-east	O
of	O
Stonehouse	O
.	O

The	O
thick	O
sandstone	O
which	O
lies	O
between	O
the	O
Orchard	LEXICON
and	O
Calmy	LEXICON
limestones	LEXICON
was	O
worked	O
west	O
of	O
Quarter	O
-LSB-	O
NS	O
717	O
514	O
-RSB-	O
.	O

The	O
highly	O
siliceous	O
sandstone	O
beneath	O
the	O
Calmy	LEXICON
Limestone	LEXICON
was	O
formerly	O
mined	O
for	O
refractory	O
use	O
in	O
the	O
Avon	O
Water	O
gorge	O
-LSB-	O
NS	O
764	O
494	O
-RSB-	O
at	O
Larkhall	O
.	O

Workings	O
in	O
the	O
Hurlet	LEXICON
and	O
Calmy	LEXICON
limestones	LEXICON
were	O
particularly	O
common	O
.	O

The	O
thickest	O
beds	O
of	O
cornstone	O
in	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
were	O
also	O
exploited	O
.	O

The	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
,	O
although	O
relatively	O
thin	O
,	O
was	O
mined	O
on	O
account	O
of	O
its	O
properties	O
as	O
a	O
natural	O
cement	O
,	O
in	O
the	O
East	O
Kilbride	O
area	O
-LSB-	O
NS	O
660	O
545	O
-RSB-	O
under	O
its	O
local	O
name	O
the	O
Calderwood	O
Cement	O
.	O

Ironstone	O
developed	O
at	O
about	O
the	O
position	O
of	O
the	O
Crutherland	LEXICON
Coals	LEXICON
was	O
worked	O
around	O
Earnockmuir	O
-LSB-	O
NS	O
688	O
526	O
-RSB-	O
,	O
south-east	O
of	O
East	O
Kilbride	O
.	O

The	O
Maggie	O
Bands	O
,	O
the	O
collective	O
name	O
for	O
the	O
clayband	O
ironstones	O
at	O
the	O
position	O
of	O
the	O
Black	LEXICON
Metals	LEXICON
in	O
the	O
Central	O
Coalfield	O
,	O
have	O
been	O
worked	O
sporadically	O
in	O
association	O
with	O
coal	O
extraction	O
.	O

The	O
Crossbasket	LEXICON
Ironstones	LEXICON
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
were	O
mined	O
around	O
Auchentibber	O
-LSB-	O
NS	O
668	O
552	O
-RSB-	O
and	O
near	O
Craigendhill	O
-LSB-	O
NS	O
692	O
513	O
-RSB-	O
,	O
east	O
of	O
East	O
Kilbride	O
.	O

Clayband	O
and	O
blackband	O
ironstones	O
in	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
were	O
worked	O
beside	O
the	O
Avon	O
Water	O
at	O
Cot	O
Castle	O
-LSB-	O
NS	O
739	O
458	O
-RSB-	O
near	O
Stonehouse	O
.	O

Two	O
ironstones	O
seams	O
,	O
known	O
as	O
the	O
Mid	O
and	O
High	O
Band	O
ironstones	O
and	O
lying	O
at	O
a	O
similar	O
stratigraphical	O
position	O
to	O
the	O
Maggie	O
Bands	O
of	O
the	O
Central	O
Coalfield	O
,	O
were	O
of	O
the	O
considerable	O
economic	O
importance	O
in	O
the	O
Glenbuck-Muirkirk	O
area	O
,	O
as	O
was	O
a	O
lower	O
ironstone	O
,	O
known	O
as	O
the	O
Low	O
Band	O
,	O
which	O
lies	O
just	O
above	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
.	O

Ironstones	O
at	O
other	O
positions	O
,	O
such	O
as	O
the	O
Cleland	LEXICON
Roughband	LEXICON
Ironstone	LEXICON
,	O
Watstone	LEXICON
Musselband	LEXICON
Ironstone	LEXICON
,	O
Upper	LEXICON
and	O
Lower	LEXICON
Slatyband	LEXICON
Ironstones	LEXICON
and	O
the	O
Airdrie	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
,	O
have	O
also	O
been	O
exploited	O
to	O
some	O
extent	O
.	O

The	O
`	O
shale	O
'	O
which	O
commonly	O
occurs	O
at	O
the	O
Kiltongue	LEXICON
Musselband	LEXICON
position	O
has	O
been	O
worked	O
for	O
oil	O
beside	O
the	O
Avon	O
Water	O
at	O
Stonehouse	O
-LSB-	O
NS	O
760	O
476	O
-RSB-	O
.	O

The	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
is	O
composed	O
predominantly	O
of	O
basaltic	O
lavas	O
,	O
with	O
occurrences	O
of	O
trachytic	O
lava	O
in	O
western	O
parts	O
of	O
the	O
district	O
.	O

Coal	O
occurs	O
at	O
two	O
main	O
levels	O
in	O
the	O
succession	O
,	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
and	O
in	O
the	O
Lower	LEXICON
and	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

Many	O
of	O
the	O
thinner	O
coals	O
in	O
the	O
lower	O
half	O
of	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
have	O
been	O
exploited	O
by	O
underground	O
working	O
to	O
a	O
limited	O
extent	O
only	O
.	O

The	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
contains	O
few	O
thick	O
coals	O
but	O
the	O
relatively	O
close	O
spacing	O
of	O
seams	O
,	O
such	O
as	O
the	O
Crutherland	LEXICON
Coals	LEXICON
in	O
East	O
Kilbride	O
area	O
for	O
instance	O
,	O
means	O
that	O
opencast	O
extraction	O
may	O
be	O
economic	O
.	O

Deeper	O
groundwater	O
circulation	O
is	O
present	O
only	O
in	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

Modest	O
supplies	O
for	O
domestic	O
use	O
have	O
been	O
obtained	O
from	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
and	O
from	O
the	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sequence	O
,	O
including	O
the	O
lavas	O
.	O

At	O
Cleland	O
,	O
up	O
to	O
770m3/d	O
of	O
alkaline	O
fluid	O
with	O
a	O
high	O
biological	O
oxygen	O
demand	O
was	O
discharged	O
into	O
workings	O
of	O
the	O
Glasgow	LEXICON
Main	LEXICON
Coal	LEXICON
,	O
the	O
workings	O
in	O
the	O
Glasgow	LEXICON
Ell	LEXICON
Coal	LEXICON
,	O
at	O
a	O
shallower	O
depth	O
,	O
being	O
dry	O
.	O

Only	O
two	O
formations	O
above	O
the	O
basement	O
within	O
the	O
district	O
have	O
geothermal	O
potential	O
--	O
sandstones	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
at	O
the	O
base	O
of	O
the	O
Carboniferous	CHRONOSTRAT
and	O
sandstones	O
of	O
the	O
Namurian	LEXICON
Passage	LEXICON
Formation	LEXICON
.	O

However	O
,	O
the	O
geological	O
evidence	O
suggests	O
that	O
the	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
is	O
unlikely	O
to	O
reach	O
this	O
depth	O
and	O
overlies	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
with	O
little	O
geothermal	O
potential	O
.	O

One	O
of	O
the	O
lines	O
Figure	O
14	O
,	O
line	O
QB-3	O
-RRB-	O
traversed	O
the	O
line	O
of	O
the	O
Distinkhorn	O
Plutonic	O
Complex	O
which	O
was	O
interpreted	O
as	O
a	O
steep-sided	O
body	O
intruded	O
only	O
in	O
the	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
rocks	O
of	O
the	O
Lesmahagow	O
Inlier	O
.	O

Where	O
the	O
line	O
crossed	O
the	O
eastern	O
margin	O
of	O
the	O
outcrop	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
a	O
6.0kms-1	O
refractor	O
was	O
identified	O
at	O
a	O
depth	O
of	O
about	O
4km	O
.	O

The	O
Ordovician	CHRONOSTRAT
and	O
Silurian	CHRONOSTRAT
greywackes	O
of	O
the	O
Southern	O
Uplands	O
have	O
a	O
mean	O
saturated	O
density	O
close	O
to	O
2.72Mgm-3	O
but	O
this	O
figure	O
can	O
be	O
expected	O
to	O
increase	O
slightly	O
with	O
depth	O
.	O

There	O
is	O
no	O
evidence	O
that	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
are	O
present	O
in	O
the	O
district	O
but	O
,	O
in	O
the	O
Midland	O
Valley	O
as	O
a	O
whole	O
,	O
rocks	O
of	O
this	O
age	O
have	O
been	O
given	O
a	O
mean	O
saturated	O
density	O
of	O
2.41Mgm-3	O
.	O

The	O
carbonate-bearing	O
sandstones	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
which	O
are	O
mainly	O
,	O
if	O
not	O
entirely	O
,	O
of	O
lower	O
Carboniferous	CHRONOSTRAT
age	O
,	O
are	O
assigned	O
the	O
significantly	O
higher	O
value	O
of	O
2.58Mgm-3	O
.	O

The	O
Dinantian	CHRONOSTRAT
sedimentary	O
sequence	O
has	O
a	O
mean	O
density	O
of	O
about	O
2.58Mgm-3	O
;	O
the	O
Namurian	CHRONOSTRAT
and	O
Westphalian	CHRONOSTRAT
sedimentary	O
rocks	O
have	O
a	O
density	O
of	O
about	O
2.55Mgm-3	O
.	O

Many	O
of	O
the	O
Carboniferous	CHRONOSTRAT
extrusive	O
rocks	O
in	O
the	O
Midland	O
Valley	O
have	O
a	O
low	O
intensity	O
of	O
Natural	O
Remanent	O
Magnetism	O
.	O

Minor	O
intrusions	O
of	O
gabbroic	O
or	O
dioritic	O
composition	O
into	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
have	O
susceptibilities	O
at	O
outcrop	O
up	O
to	O
0.04	O
SI	O
units	O
,	O
similar	O
to	O
that	O
of	O
the	O
Distinkhorn	O
Plutonic	O
Complex	O
.	O

The	O
suggested	O
values	O
are	O
2.5	O
to	O
3.5	O
km	O
s-1	O
for	O
the	O
Carboniferous	CHRONOSTRAT
and	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
sequence	O
and	O
4.0	O
to	O
5.5	O
km	O
s-1	O
for	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
and	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
sequences	O
.	O

A	O
large	O
gravity	O
high	O
over	O
the	O
North	O
Ayrshire	O
Block	O
and	O
the	O
associated	O
magnetic	O
magnetic	O
anomalies	O
over	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

Alomari	O
suggested	O
that	O
the	O
gravity	O
low	O
of	O
the	O
Hamilton-Wishaw	O
area	O
was	O
related	O
either	O
to	O
a	O
granite	O
which	O
extended	O
from	O
depths	O
of	O
4	O
to	O
12km	O
or	O
to	O
an	O
8km	O
thick	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
basin	O
with	O
its	O
base	O
at	O
a	O
depth	O
of	O
12km	O
.	O

Alternative	O
interpretations	O
attributing	O
the	O
anomaly	O
to	O
a	O
thick	O
sequence	O
of	O
low	O
density	O
post-Lower	O
Devonian	O
rocks	O
appear	O
to	O
be	O
supported	O
by	O
the	O
close	O
correspondence	O
of	O
the	O
trend	O
of	O
the	O
Bouguer	O
anomaly	O
contours	O
with	O
the	O
boundaries	O
of	O
the	O
Carboniferous	CHRONOSTRAT
outcrops	O
and	O
with	O
mapped	O
faults	O
.	O

The	O
large	O
gravity	O
high	O
over	O
the	O
North	O
Ayrshire	O
Block	O
is	O
associated	O
with	O
outcrops	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
also	O
with	O
high	O
amplitude	O
magnetic	O
anomalies	O
Figure	O
15	O
.	O

However	O
,	O
interpretation	O
of	O
the	O
magnetic	O
anomalies	O
suggests	O
that	O
they	O
can	O
not	O
be	O
caused	O
by	O
the	O
inferred	O
thickness	O
of	O
lavas	O
alone	O
but	O
are	O
probably	O
also	O
partly	O
due	O
to	O
underlying	O
penecontemporaneous	O
basic	O
,	O
probably	O
gabbroic	O
,	O
intrusions	O
about	O
1.5	O
-	O
2.0km	O
thick	O
emplaced	O
within	O
high	O
density	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
rocks	O
and/or	O
to	O
relatively	O
dense	O
,	O
strongly	O
magnetic	O
rocks	O
within	O
the	O
basement	O
.	O

Evans	O
et	O
al.	O
suggested	O
that	O
the	O
source	O
of	O
the	O
anomalies	O
was	O
a	O
composite	O
volcanic	O
centre	O
of	O
Devonian	CHRONOSTRAT
-	O
Carboniferous	CHRONOSTRAT
age	O
with	O
superimposed	O
Dinantian	CHRONOSTRAT
extrusive	O
activity	O
.	O

The	O
outcrop	O
and	O
aureole	O
of	O
the	O
intrusion	O
lie	O
within	O
sedimentary	O
rocks	O
of	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
and	O
,	O
to	O
the	O
south-east	O
,	O
Silurian	CHRONOSTRAT
age	O
.	O

The	O
existence	O
of	O
the	O
gravity	O
high	O
probably	O
indicates	O
that	O
the	O
concealed	O
part	O
of	O
the	O
intrusion	O
consists	O
mainly	O
of	O
diorite	O
but	O
part	O
of	O
the	O
anomaly	O
could	O
be	O
due	O
to	O
the	O
presence	O
of	O
relatively	O
high	O
density	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
sedimentary	O
rocks	O
.	O

The	O
acoustic	O
impedance	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
is	O
generally	O
much	O
higher	O
than	O
that	O
of	O
sedimentary	O
rocks	O
with	O
the	O
result	O
that	O
its	O
boundaries	O
have	O
high	O
reflection	O
coefficients	O
,	O
preventing	O
much	O
energy	O
from	O
reaching	O
greater	O
depths	O
.	O

The	O
deepest	O
reflector	O
,	O
at	O
about	O
2km	O
,	O
was	O
interpreted	O
as	O
the	O
top	O
of	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
.	O

The	O
MAVIS	O
and	O
quarry	O
blast	O
surveys	O
have	O
been	O
interpreted	O
in	O
terms	O
of	O
a	O
four-layer	O
upper	O
crust	O
:	O
0.5	O
-	O
3.0km	O
thick	O
Carboniferous	CHRONOSTRAT
and	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
strata	O
1.0	O
-	O
5.0km	O
thick	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
and	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
strata	O
gneissose	O
crystalline	O
basement	O
at	O
depths	O
of	O
3.0	O
-	O
6.0km	O
high-grade	O
metamorphic	O
basement	O
of	O
pyroxene	O
granulite	O
facies	O
at	O
depths	O
greater	O
than	O
8.0km	O
.	O

Three	O
formations	O
have	O
been	O
recognised	O
,	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
,	O
the	O
Beinn	LEXICON
Bheula	LEXICON
Schist	LEXICON
and	O
the	O
Bullrock	LEXICON
Greywacke	LEXICON
,	O
of	O
which	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
appears	O
to	O
be	O
the	O
oldest	O
.	O

On	O
the	O
coast	O
north	O
of	O
Cove	O
,	O
a	O
change	O
from	O
blue-grey	O
phyllites	O
to	O
greenish	O
grey	O
cleaved	O
siltstones	O
marks	O
the	O
contact	O
of	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
with	O
the	O
Beinn	LEXICON
Bheula	LEXICON
Schist	LEXICON
.	O

The	O
southern	O
boundary	O
of	O
the	O
formation	O
is	O
taken	O
at	O
a	O
rapid	O
transition	O
from	O
dark	O
phyllites	O
with	O
limestone	O
lenses	O
to	O
a	O
sequence	O
of	O
coarse	O
,	O
pebbly	O
greywackes	O
,	O
assigned	O
to	O
the	O
Bullrock	LEXICON
Greywacke	LEXICON
.	O

Greywackes	O
in	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
are	O
mainly	O
confined	O
to	O
the	O
southern	O
part	O
of	O
the	O
outcrop	O
and	O
usually	O
occur	O
as	O
separate	O
,	O
graded	O
beds	O
.	O

The	O
pebbly	O
greywackes	O
contain	O
only	O
minor	O
amounts	O
of	O
potash	O
feldspar	O
granules	O
,	O
a	O
feature	O
which	O
distinguishes	O
them	O
from	O
the	O
pink-tinged	O
,	O
more	O
feldspathic	O
pebbly	O
greywackes	O
of	O
the	O
Bullrock	LEXICON
Greywacke	LEXICON
.	O

The	O
Bullrock	LEXICON
Greywacke	LEXICON
consists	O
mainly	O
of	O
pink-weathering	O
cleaved	O
feldspathic	O
pebbly	O
greywacke	O
,	O
interbedded	O
with	O
green	O
cleaved	O
siltstone	O
.	O

Farther	O
south-west	O
in	O
Cowal	O
,	O
black	O
slates	O
and	O
limestones	O
within	O
the	O
Bullrock	LEXICON
Greywacke	LEXICON
outcrop	O
are	O
placed	O
in	O
a	O
separate	O
lithostratigraphical	O
unit	O
,	O
the	O
Innellan	LEXICON
Group	LEXICON
.	O

The	O
sedimentary	O
character	O
of	O
most	O
of	O
the	O
Dalradian	LEXICON
rocks	O
is	O
consistent	O
with	O
deposition	O
in	O
submarine	O
fans	O
by	O
turbidity	O
currents	O
and	O
mass	O
flow	O
.	O

In	O
terms	O
of	O
the	O
models	O
proposed	O
for	O
submarine	O
fans	O
by	O
Middleton	O
and	O
Hampton	O
,	O
it	O
is	O
inferred	O
that	O
the	O
Bullrock	LEXICON
Greywacke	LEXICON
was	O
laid	O
down	O
in	O
an	O
inner	O
-	O
or	O
mid-fan	O
environment	O
.	O

The	O
portion	O
of	O
the	O
Beinn	LEXICON
Bheula	LEXICON
Schist	LEXICON
which	O
is	O
present	O
in	O
the	O
Greenock	O
district	O
may	O
have	O
been	O
deposited	O
on	O
the	O
outermost	O
parts	O
of	O
a	O
fan	O
.	O

The	O
Dunoon	LEXICON
Phyllite	LEXICON
appears	O
to	O
have	O
been	O
laid	O
down	O
in	O
a	O
more	O
distal	O
situation	O
,	O
perhaps	O
in	O
an	O
interfan	O
environment	O
.	O

The	O
Dalradian	LEXICON
rocks	O
lie	O
within	O
the	O
Tay	O
Nappe	O
,	O
a	O
major	O
recumbent	O
Fl	O
structure	O
which	O
dominates	O
the	O
Southern	O
Highlands	O
.	O

An	O
overall	O
change	O
in	O
younging	O
direction	O
takes	O
place	O
close	O
to	O
the	O
southeast	O
margin	O
of	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
,	O
inverted	O
beds	O
predominating	O
to	O
the	O
north-west	O
and	O
right-way-up	O
strata	O
being	O
more	O
usual	O
to	O
the	O
south-east	O
.	O

Within	O
and	O
immediately	O
NNW	O
of	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
outcrop	O
,	O
Si	O
and	O
S2	O
may	O
combine	O
to	O
form	O
a	O
composite	O
fabric	O
which	O
is	O
represented	O
on	O
the	O
map	O
as	O
a	O
single	O
cleavage	O
.	O

All	O
the	O
Dalradian	LEXICON
rocks	O
in	O
the	O
district	O
have	O
been	O
affected	O
by	O
a	O
still	O
later	O
deformational	O
event	O
,	O
which	O
,	O
by	O
correlation	O
with	O
the	O
structural	O
sequence	O
in	O
the	O
adjoining	O
Ben	O
Lomond	O
district	O
,	O
is	O
termed	O
D4	O
.	O

They	O
may	O
,	O
however	O
,	O
relate	O
to	O
movements	O
on	O
fractures	O
in	O
the	O
Highland	O
Boundary	O
Fault-system	O
,	O
which	O
continued	O
to	O
be	O
active	O
during	O
Devonian	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
times	O
.	O

Over	O
most	O
of	O
this	O
distance	O
the	O
Complex	O
occurs	O
along	O
the	O
south-eastern	O
margin	O
of	O
the	O
Southern	LEXICON
Highland	LEXICON
Group	LEXICON
but	O
at	O
Loch	O
Lomond	O
,	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
are	O
faulted	O
down	O
between	O
it	O
and	O
the	O
Dalradian	LEXICON
.	O

Fossil	O
evidence	O
from	O
sedimentary	O
rocks	O
of	O
the	O
Complex	O
at	O
Aberfoyle	O
and	O
elsewhere	O
indicates	O
an	O
Ordovocian	CHRONOSTRAT
age	O
.	O

The	O
unconformable	O
base	O
of	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
is	O
not	O
seen	O
in	O
the	O
district	O
but	O
to	O
the	O
north-east	O
,	O
at	O
Aberfoyle	O
and	O
Comrie	O
,	O
and	O
to	O
the	O
south-west	O
on	O
Arran	O
,	O
the	O
oldest	O
strata	O
present	O
almost	O
certainly	O
belong	O
to	O
the	O
Arbuthnott	LEXICON
Group	LEXICON
.	O

They	O
have	O
been	O
placed	O
in	O
the	O
Arbuthnott	LEXICON
Group	LEXICON
.	O

The	O
Inchmurrin	LEXICON
Conglomerate	LEXICON
is	O
well	O
sorted	O
and	O
consists	O
of	O
well-rounded	O
pebbles	O
,	O
cobbles	O
and	O
boulders	O
up	O
to	O
0.2m	O
in	O
diameter	O
set	O
in	O
a	O
coarse	O
sandstone	O
matrix	O
.	O

Near	O
the	O
Highland	O
Boundary	O
Fault-system	O
,	O
the	O
quartzite	O
clasts	O
have	O
been	O
deformed	O
by	O
brittle	O
fracture	O
,	O
probably	O
in	O
Middle	CHRONOSTRAT
Devonian	CHRONOSTRAT
times	O
,	O
and	O
in	O
places	O
show	O
the	O
effects	O
of	O
pressure	O
solution	O
where	O
one	O
clast	O
impinges	O
upon	O
another	O
.	O

In	O
the	O
present	O
district	O
,	O
Garvock	LEXICON
Group	LEXICON
sediments	O
are	O
exposed	O
6nly	O
along	O
the	O
coast	O
south	O
of	O
Ardmore	O
.	O

Two	O
formations	O
of	O
the	O
Strathmore	LEXICON
Group	LEXICON
,	O
the	O
Cromlix	LEXICON
Formation	LEXICON
and	O
the	O
overlying	O
Teith	LEXICON
Formation	LEXICON
,	O
are	O
represented	O
in	O
the	O
present	O
district	O
.	O

The	O
Cromlix	LEXICON
Formation	LEXICON
consists	O
predominantly	O
of	O
poorly	O
bedded	O
,	O
poorly	O
sorted	O
,	O
silty	O
mudstone	O
.	O

However	O
,	O
Armstrong	O
and	O
Paterson	O
considered	O
that	O
it	O
was	O
represented	O
by	O
the	O
`	O
lower	O
purple	O
sandstone	O
facies	O
'	O
,	O
the	O
oldest	O
of	O
three	O
divisions	O
recognised	O
in	O
the	O
Teith	LEXICON
Formation	LEXICON
in	O
this	O
area	O
by	O
Francis	O
et	O
al.	O
.	O

The	O
Teith	LEXICON
Formation	LEXICON
occupies	O
by	O
far	O
the	O
greater	O
part	O
of	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
outcrop	O
in	O
the	O
district	O
.	O

This	O
suggests	O
a	O
lower	O
Emsian	CHRONOSTRAT
age	O
for	O
these	O
strata	O
.	O

East	O
of	O
the	O
Leven	O
valley	O
the	O
highest	O
beds	O
of	O
the	O
formation	O
show	O
considerable	O
reddening	O
,	O
suggesting	O
proximity	O
to	O
the	O
unconformity	O
with	O
the	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
.	O

The	O
quantity	O
and	O
coarseness	O
of	O
the	O
fan	O
material	O
,	O
represented	O
by	O
the	O
conglomerates	O
in	O
the	O
Arbuthnott	LEXICON
and	O
Garvock	LEXICON
groups	O
,	O
suggests	O
that	O
deposition	O
of	O
these	O
formations	O
took	O
place	O
in	O
the	O
vicinity	O
of	O
scarps	O
controlled	O
by	O
major	O
growth	O
faults	O
.	O

Erosion	O
in	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
times	O
,	O
following	O
uplift	O
to	O
the	O
north	O
on	O
faults	O
now	O
concealed	O
beneath	O
later	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
strata	O
,	O
may	O
partly	O
explain	O
the	O
absence	O
of	O
the	O
Dunnottar	LEXICON
and	O
Crawton	LEXICON
groups	O
and	O
part	O
of	O
the	O
Arbuthnott	LEXICON
Group	LEXICON
.	O

While	O
the	O
finer-grained	O
parts	O
of	O
the	O
Garvock	LEXICON
and	O
Strathmore	LEXICON
groups	O
were	O
being	O
laid	O
down	O
,	O
it	O
is	O
clear	O
that	O
the	O
basin	O
margin	O
had	O
migrated	O
some	O
distance	O
to	O
the	O
north-west	O
,	O
to	O
a	O
position	O
within	O
the	O
south-east	O
Highlands	O
.	O

During	O
deposition	O
of	O
the	O
Cromlix	LEXICON
Formation	LEXICON
,	O
which	O
has	O
been	O
interpreted	O
as	O
a	O
playa	O
lake	O
deposit	O
,	O
the	O
axial	O
component	O
of	O
the	O
drainage	O
would	O
appear	O
to	O
have	O
greatly	O
diminished	O
,	O
possibly	O
as	O
a	O
result	O
of	O
more	O
arid	O
climatic	O
conditions	O
.	O

Axial	O
drainage	O
was	O
re-established	O
during	O
deposition	O
of	O
the	O
Teith	LEXICON
Formation	LEXICON
,	O
as	O
a	O
result	O
either	O
of	O
renewed	O
uplift	O
of	O
the	O
Highland	O
source	O
areas	O
or	O
of	O
increased	O
rainfall	O
;	O
the	O
environment	O
was	O
predominantly	O
one	O
of	O
meandering	O
streams	O
on	O
a	O
broad	O
floodplain	O
.	O

Strata	O
consisting	O
mainly	O
of	O
red-brown	O
,	O
commonly	O
pebbly	O
,	O
cross-bedded	O
sandstones	O
and	O
subordinate	O
conglomerates	O
formerly	O
referred	O
to	O
the	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
are	O
now	O
assigned	O
to	O
the	O
Stratheden	LEXICON
Group	LEXICON
.	O

The	O
top	O
of	O
the	O
group	O
is	O
taken	O
at	O
the	O
base	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
a	O
sequence	O
of	O
cornstone-bearing	O
sandstones	O
and	O
silty	O
mudstones	O
previously	O
placed	O
in	O
the	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
.	O

At	O
Wemyss	O
Bay	O
the	O
formation	O
is	O
overlain	O
,	O
with	O
an	O
erosive	O
contact	O
,	O
by	O
the	O
coarse-grained	O
Skelmorlie	LEXICON
Conglomerate	LEXICON
.	O

In	O
the	O
upper	O
part	O
of	O
the	O
formation	O
,	O
the	O
grain	O
size	O
diminishes	O
,	O
there	O
are	O
beds	O
of	O
coarse	O
pebbly	O
sandstone	O
and	O
the	O
conglomerate	O
passes	O
gradationally	O
into	O
the	O
overlying	O
Kelly	LEXICON
Burn	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
Skelmorlie	LEXICON
Conglomerate	LEXICON
is	O
considered	O
to	O
have	O
been	O
laid	O
down	O
as	O
an	O
alluvial	O
fan	O
deposit	O
by	O
braided	O
rivers	O
.	O

The	O
clast	O
composition	O
indicates	O
that	O
,	O
in	O
all	O
probability	O
,	O
the	O
source	O
rocks	O
consisted	O
of	O
conglomerates	O
and	O
lavas	O
or	O
lava-conglomerates	O
of	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
,	O
in	O
addition	O
to	O
Dalradian	LEXICON
metasediments	O
.	O

The	O
great	O
bulk	O
of	O
the	O
Stratheden	LEXICON
Group	LEXICON
south	O
of	O
the	O
River	O
Clyde	O
is	O
assigned	O
to	O
the	O
Kelly	LEXICON
Burn	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
Kelly	LEXICON
Burn	LEXICON
Sandstone	LEXICON
Formation	LEXICON
as	O
a	O
whole	O
is	O
considered	O
to	O
have	O
been	O
laid	O
down	O
by	O
a	O
braided	O
river	O
system	O
,	O
which	O
,	O
as	O
indicated	O
by	O
the	O
cross-bedding	O
directions	O
,	O
flowed	O
generally	O
towards	O
the	O
north-east	O
.	O

The	O
source-terrain	O
of	O
the	O
sandstones	O
apparently	O
was	O
composed	O
largely	O
of	O
Dalradian	LEXICON
metasediments	O
which	O
,	O
however	O
,	O
were	O
still	O
partly	O
covered	O
by	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
or	O
by	O
strata	O
deposited	O
earlier	O
in	O
the	O
Stratheden	LEXICON
Group	LEXICON
period	O
.	O

The	O
formation	O
is	O
best	O
exposed	O
south	O
of	O
the	O
present	O
district	O
,	O
along	O
the	O
shore	O
between	O
Seamill	O
and	O
Fairlie	O
,	O
and	O
in	O
the	O
glens	O
of	O
Fairlie	O
and	O
Kelburn	O
,	O
where	O
it	O
passes	O
gradationally	O
into	O
the	O
succeeding	O
Fairlie	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Here	O
,	O
beds	O
of	O
cross-laminated	O
sandstone	O
with	O
scattered	O
quartz	O
pebbles	O
and	O
green	O
siltstone	O
clasts	O
alternate	O
with	O
beds	O
in	O
which	O
the	O
sandstones	O
display	O
a	O
close	O
flat	O
lamination	O
similar	O
to	O
that	O
which	O
characterises	O
the	O
Knox	LEXICON
Pulpit	LEXICON
Formation	LEXICON
of	O
central	O
Fife	O
.	O

In	O
the	O
Largs	O
Borehole	O
,	O
white	O
cross-bedded	O
pebbly	O
sandstones	O
lying	O
beneath	O
cornstone-bearing	O
strata	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
may	O
belong	O
to	O
the	O
Fairlie	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

In	O
the	O
Helensburgh	O
--	O
Dumbarton	O
area	O
,	O
the	O
Rosneath	LEXICON
Conglomerate	LEXICON
is	O
well	O
exposed	O
along	O
the	O
foreshore	O
between	O
Rosneath	O
Point	O
-LSB-	O
NS	O
275	O
805	O
-RSB-	O
and	O
Kilcreggan	O
.	O

On	O
earlier	O
maps	O
of	O
the	O
Greenock	O
district	O
,	O
conglomerates	O
at	O
Cardross	O
-LSB-	O
NS	O
335	O
774	O
-RSB-	O
and	O
Overtoun	O
Muir	O
-LSB-	O
NS	O
370	O
800	O
-RSB-	O
and	O
some	O
of	O
those	O
on	O
Ardmore	O
peninsula	O
-LSB-	O
NS	O
315	O
785	O
-RSB-	O
were	O
placed	O
in	O
the	O
Lower	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
.	O

In	O
these	O
respects	O
they	O
more	O
closely	O
resemble	O
the	O
Rosneath	LEXICON
Conglomerate	LEXICON
than	O
any	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
in	O
the	O
neighbourhood	O
.	O

The	O
quartzite	O
clasts	O
are	O
considered	O
to	O
have	O
been	O
derived	O
from	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
conglomerates	O
and	O
the	O
fact	O
that	O
a	O
number	O
of	O
them	O
have	O
been	O
split	O
and	O
subsequently	O
abraded	O
is	O
evidence	O
that	O
they	O
have	O
been	O
recycled	O
.	O

The	O
lower	O
part	O
of	O
the	O
Stockiemuir	LEXICON
Sandstone	LEXICON
Formation	LEXICON
consists	O
of	O
red-brown	O
fine-grained	O
cross-bedded	O
quartzose	O
relatively	O
mature	O
sandstones	O
with	O
a	O
few	O
pebbly	O
beds	O
and	O
rare	O
mudstone	O
layers	O
.	O

As	O
a	O
result	O
of	O
regional	O
uplift	O
associated	O
with	O
Middle	CHRONOSTRAT
Devonian	CHRONOSTRAT
earth	O
movements	O
,	O
a	O
major	O
east-north-east-trending	O
intermontane	O
basin	O
was	O
eroded	O
across	O
central	O
Scotland	O
.	O

During	O
the	O
later	O
part	O
of	O
the	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
,	O
aeolian	O
sediments	O
were	O
laid	O
down	O
in	O
places	O
,	O
particularly	O
along	O
the	O
axis	O
of	O
the	O
main	O
basin	O
.	O

The	O
relatively	O
mature	O
Seamill	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
which	O
was	O
laid	O
down	O
by	O
a	O
generally	O
northwards-directed	O
drainage	O
,	O
and	O
the	O
water-laid	O
parts	O
of	O
the	O
Stockiemuir	LEXICON
Sandstone	LEXICON
,	O
probably	O
represent	O
the	O
deposit	O
of	O
the	O
axial	O
drainage	O
of	O
the	O
main	O
basin	O
.	O

By	O
contrast	O
,	O
the	O
coarse	O
lithic	O
arenites	O
of	O
the	O
Kelly	LEXICON
Burn	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
the	O
Skelmorlie	LEXICON
Conglomerate	LEXICON
,	O
and	O
the	O
bulk	O
of	O
the	O
Rosneath	LEXICON
Conglomerate	LEXICON
,	O
are	O
considered	O
to	O
have	O
been	O
laid	O
down	O
in	O
the	O
more	O
distal	O
parts	O
of	O
a	O
major	O
alluvial	O
fan	O
which	O
entered	O
the	O
Greenock	O
district	O
from	O
the	O
west	O
,	O
by	O
way	O
of	O
Bute	O
.	O

However	O
,	O
the	O
generally	O
well-rounded	O
boulders	O
of	O
quartzite	O
,	O
lava	O
and	O
granite	O
are	O
considered	O
to	O
have	O
had	O
their	O
source	O
in	O
conglomerates	O
of	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
,	O
as	O
there	O
are	O
no	O
other	O
rocks	O
of	O
suitable	O
composition	O
in	O
the	O
area	O
upstream	O
of	O
the	O
fan	O
.	O

South-eastward	O
palaeocurrents	O
inferred	O
for	O
the	O
Ardmore	LEXICON
conglomerates	O
and	O
some	O
beds	O
in	O
the	O
lower	O
part	O
of	O
the	O
Rosneath	LEXICON
sequence	O
indicate	O
deposition	O
in	O
another	O
alluvial	O
fan	O
,	O
which	O
entered	O
the	O
main	O
basin	O
from	O
the	O
north	O
.	O

The	O
persistence	O
of	O
conglomerate	O
in	O
the	O
Stratheden	LEXICON
Group	LEXICON
in	O
the	O
north-western	O
part	O
of	O
the	O
Greenock	O
district	O
suggests	O
that	O
the	O
relief	O
of	O
the	O
Highland	O
source	O
areas	O
which	O
supplied	O
the	O
alluvial	O
fans	O
was	O
maintained	O
by	O
contemporaneous	O
movements	O
on	O
faults	O
,	O
probably	O
fractures	O
within	O
or	O
parallel	O
to	O
the	O
Highland	O
Boundary	O
Fault-system	O
.	O

During	O
deposition	O
of	O
the	O
Stratheden	LEXICON
Group	LEXICON
,	O
the	O
rainfall	O
was	O
probably	O
moderate	O
and	O
somewhat	O
seasonal	O
but	O
the	O
presence	O
of	O
presumed	O
aeolian	O
sediments	O
in	O
the	O
Stockiemuir	LEXICON
and	O
Fairlie	LEXICON
sandstones	O
suggests	O
that	O
the	O
rainfall	O
and	O
the	O
relief	O
may	O
have	O
diminished	O
through	O
the	O
period	O
.	O

These	O
formations	O
were	O
probably	O
laid	O
down	O
throughout	O
the	O
entire	O
Greenock	O
district	O
but	O
prior	O
to	O
deposition	O
of	O
the	O
succeeding	O
Inverclyde	LEXICON
Group	LEXICON
were	O
removed	O
by	O
erosion	O
from	O
the	O
area	O
west	O
of	O
a	O
line	O
passing	O
through	O
Largs	O
and	O
Greenock	O
,	O
as	O
a	O
result	O
of	O
uplift	O
on	O
the	O
Largs	O
Fault-zone	O
.	O

Rocks	O
formerly	O
included	O
in	O
the	O
Calciferous	LEXICON
Sandstone	LEXICON
Measures	LEXICON
,	O
together	O
with	O
an	O
underlying	O
sequence	O
of	O
sandstones	O
and	O
siltstones	O
with	O
pedogenic	O
carbonate	O
at	O
the	O
top	O
of	O
the	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
,	O
are	O
now	O
assigned	O
to	O
two	O
new	O
units	O
,	O
the	O
Inverclyde	LEXICON
Group	LEXICON
and	O
the	O
Strathclyde	LEXICON
Group	LEXICON
.	O

For	O
strata	O
above	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
the	O
existing	O
classification	O
is	O
retained	O
,	O
except	O
in	O
the	O
Lochwinnoch	O
area	O
,	O
where	O
a	O
local	O
succession	O
is	O
employed	O
.	O

In	O
much	O
of	O
the	O
district	O
,	O
the	O
Inverclyde	LEXICON
Group	LEXICON
comprises	O
the	O
Kinnesswood	LEXICON
,	O
Ballagan	LEXICON
and	O
Clyde	LEXICON
Sandstone	LEXICON
formations	O
.	O

The	O
mainly	O
arenaceous	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
at	O
the	O
base	O
of	O
the	O
group	O
,	O
was	O
formerly	O
regarded	O
as	O
part	O
of	O
the	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
.	O

However	O
,	O
it	O
is	O
readily	O
distinguished	O
from	O
the	O
strata	O
of	O
the	O
Stratheden	LEXICON
Group	LEXICON
by	O
the	O
presence	O
of	O
nodules	O
and	O
beds	O
of	O
concretionary	O
carbonate	O
of	O
pedogenic	O
origin	O
,	O
a	O
feature	O
which	O
it	O
shares	O
with	O
parts	O
of	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Disarticulated	O
scales	O
of	O
the	O
fossil	O
fish	O
Bothriolepis	O
and	O
Holoptyckius	O
,	O
found	O
in	O
the	O
basal	O
conglomerate	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
at	O
Fairy	O
Knowe	O
Quarry	O
-LSB-	O
NS	O
369	O
789	O
-RSB-	O
,	O
near	O
Dumbarton	O
,	O
are	O
of	O
Famennian	CHRONOSTRAT
age	O
but	O
they	O
may	O
have	O
been	O
reworked	O
from	O
older	O
deposits	O
.	O

The	O
grey	O
mudstones	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
commonly	O
contain	O
a	O
moderately	O
abundant	O
fauna	O
of	O
ostracods	O
,	O
fish	O
scraps	O
and	O
Modiolus	O
,	O
and	O
Lingula	O
was	O
found	O
at	O
a	O
single	O
locality	O
-LSB-	O
NS	O
419	O
785	O
-RSB-	O
near	O
Renton	O
.	O

Miospore	O
assemblages	O
recovered	O
from	O
argillaceous	O
beds	O
in	O
the	O
Ballagan	LEXICON
and	O
Clyde	LEXICON
Sandstone	LEXICON
formations	O
,	O
penetrated	O
by	O
BGS	O
boreholes	O
at	O
Barnhill	O
and	O
Loch	O
Humphrey	O
,	O
sited	O
a	O
little	O
to	O
the	O
east	O
of	O
the	O
present	O
district	O
,	O
are	O
considered	O
by	O
Dr	O
B	O
Owens	O
to	O
indicate	O
an	O
upper	O
Tournaisian	CHRONOSTRAT
age	O
.	O

Hence	O
it	O
is	O
probable	O
that	O
at	O
least	O
part	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
is	O
of	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
age	O
,	O
although	O
its	O
basal	O
part	O
may	O
be	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
.	O

The	O
strata	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
consist	O
of	O
beds	O
of	O
red	O
and	O
white	O
sandstone	O
and	O
red-brown	O
,	O
green-spotted	O
silty	O
mudstone	O
arranged	O
in	O
upward-fining	O
fluvial	O
cycles	O
.	O

At	O
Auchengarth	O
-LSB-	O
NS	O
190	O
645	O
-RSB-	O
,	O
where	O
cross-bedding	O
in	O
the	O
sandstones	O
indicates	O
deposition	O
by	O
southward-flowing	O
rivers	O
,	O
a	O
20m	O
sequence	O
consisting	O
mainly	O
of	O
red-brown	O
and	O
purple-grey	O
silty	O
mudstone	O
occurs	O
in	O
the	O
lower	O
part	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

The	O
sharp	O
basal	O
contact	O
of	O
the	O
formation	O
with	O
Stratheden	LEXICON
Group	LEXICON
sandstones	O
and	O
conglomerates	O
is	O
visible	O
east	O
of	O
the	O
bathing	O
pool	O
on	O
the	O
shore	O
at	O
Gourock	O
-LSB-	O
NS	O
2379	O
7768	O
-RSB-	O
.	O

North	O
of	O
the	O
River	O
Clyde	O
,	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
is	O
generally	O
thicker	O
and	O
more	O
arenaceous	O
than	O
to	O
the	O
south	O
.	O

On	O
the	O
hillslopes	O
above	O
Greenock	O
,	O
strata	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
were	O
formerly	O
exposed	O
in	O
a	O
number	O
of	O
stream	O
sections	O
now	O
lost	O
through	O
expansion	O
of	O
the	O
built-up	O
area	O
.	O

In	O
ascending	O
order	O
they	O
are	O
the	O
Knocknairshill	LEXICON
Member	LEXICON
.	O

North	O
of	O
the	O
River	O
Clyde	O
,	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
represented	O
by	O
the	O
Overtoun	LEXICON
Sandstone	LEXICON
Member	LEXICON
.	O

The	O
Gourock	LEXICON
Sandstone	LEXICON
Member	LEXICON
is	O
broadly	O
similar	O
but	O
is	O
distinguished	O
by	O
the	O
presence	O
of	O
thick	O
multistorey	O
bodies	O
of	O
white	O
pebbly	O
sandstone	O
.	O

The	O
Broadlee	LEXICON
Glen	LEXICON
Sandstone	LEXICON
Member	LEXICON
crops	O
out	O
mainly	O
in	O
the	O
northern	O
part	O
of	O
Leapmoor	O
Plantation	O
where	O
it	O
consists	O
of	O
white	O
and	O
cream-coloured	O
,	O
trough	O
cross-stratified	O
sandstone	O
with	O
thin	O
lenticular	O
beds	O
of	O
grey	O
siltstone	O
and	O
abundant	O
coalified	O
wood	O
fragments	O
.	O

North	O
of	O
the	O
River	O
Clyde	O
the	O
formation	O
is	O
represented	O
only	O
by	O
the	O
Overtoun	LEXICON
Sandstone	LEXICON
Member	LEXICON
.	O

The	O
Strathclyde	LEXICON
Group	LEXICON
comprises	O
the	O
rocks	O
lying	O
between	O
the	O
base	O
of	O
the	O
thick	O
sequence	O
of	O
lavas	O
and	O
associated	O
volcaniclastic	O
sediments	O
known	O
as	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
the	O
base	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
.	O

Three	O
divisions	O
are	O
recognised	O
,	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
and	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
.	O

Because	O
of	O
earth	O
movements	O
and	O
the	O
erosion	O
that	O
took	O
place	O
towards	O
the	O
end	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
period	O
,	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
rests	O
disconformably	O
on	O
strata	O
ranging	O
from	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
to	O
the	O
Stratheden	LEXICON
Group	LEXICON
.	O

The	O
lavas	O
to	O
the	O
east	O
of	O
Lochwinnoch	O
,	O
which	O
are	O
separated	O
from	O
the	O
main	O
outcrop	O
by	O
the	O
major	O
structure	O
known	O
as	O
the	O
Paisley	LEXICON
Ruck	LEXICON
,	O
may	O
be	O
only	O
about	O
300m	O
thick	O
.	O

Build-up	O
of	O
the	O
lava	O
pile	O
was	O
accompanied	O
by	O
regional	O
subsidence	O
,	O
and	O
after	O
volcanic	O
activity	O
came	O
to	O
an	O
end	O
the	O
volcanic	O
formation	O
was	O
progressively	O
buried	O
beneath	O
sedimentary	O
rocks	O
of	O
late	O
Dinantian	CHRONOSTRAT
age	O
.	O

In	O
accordance	O
with	O
usual	O
practice	O
in	O
the	O
Scottish	O
Dinantian	CHRONOSTRAT
volcanic	O
sequences	O
,	O
these	O
rocks	O
have	O
been	O
classified	O
as	O
mugearites	O
,	O
although	O
the	O
available	O
analyses	O
show	O
that	O
they	O
range	O
from	O
hawaiite	O
through	O
mugearite	O
to	O
benmoreite	O
or	O
trachyandesite	O
in	O
composition	O
.	O

Fine-grained	O
,	O
with	O
accretionary	O
lapill	O
i	O
,	O
in	O
basal	O
3m	O
Mudstone	O
,	O
silty	O
,	O
purple-brown	O
,	O
mainly	O
11.16	O
162.38	O
massive	O
Sandstone	O
,	O
tuffaceous	O
,	O
grey-purple	O
and	O
7.07	O
169.45	O
purple-brown	O
with	O
clasts	O
of	O
lava	O
and	O
quartz	O
In	O
this	O
area	O
,	O
east	O
of	O
the	O
Largs	O
Fault-zone	O
,	O
the	O
deposit	O
rests	O
upon	O
cornstone-bearing	O
sandstones	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

Farther	O
north	O
,	O
in	O
the	O
area	O
west	O
of	O
the	O
Largs	O
Fault-zone	O
between	O
Outerwards	O
Reservoir	O
and	O
Routen	O
Bridge	O
,	O
the	O
Noddsdale	LEXICON
Volcaniclastic	LEXICON
Beds	LEXICON
are	O
up	O
to	O
200m	O
thick	O
and	O
rest	O
upon	O
strata	O
high	O
in	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
lowest	O
lavas	O
in	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
form	O
the	O
major	O
scarp	O
on	O
the	O
east	O
side	O
of	O
Noddsdale	O
,	O
south	O
of	O
the	O
Muirshiel	O
Fault	O
,	O
and	O
can	O
be	O
traced	O
northwards	O
in	O
the	O
steep	O
belt	O
adjacent	O
to	O
the	O
Largs	O
Fault-zone	O
on	O
the	O
east	O
side	O
of	O
Knockencorsan	O
Hill	O
and	O
in	O
the	O
Rotten	O
Burn	O
.	O

From	O
Cloch	O
Point	O
and	O
Dunrod	O
Hill	O
to	O
Port	O
Glasgow	O
,	O
the	O
Strathgryfe	O
Lavas	O
rest	O
directly	O
upon	O
strata	O
at	O
various	O
levels	O
within	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
with	O
no	O
intervening	O
lower	O
lava	O
unit	O
.	O

Poorly	O
exposed	O
Dalmeny	O
basalts	O
,	O
which	O
appear	O
to	O
be	O
overlain	O
by	O
volcaniclastic	O
sediments	O
of	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
in	O
downfaulted	O
blocks	O
,	O
occupy	O
low	O
ground	O
between	O
West	O
Gavin	O
-LSB-	O
NS	O
380	O
590	O
-RSB-	O
and	O
the	O
Black	O
Cart	O
Water	O
.	O

Correlation	O
with	O
the	O
lavas	O
of	O
the	O
Renfrewshire	O
Hills	O
is	O
difficult	O
,	O
as	O
the	O
two	O
outcrops	O
are	O
separated	O
from	O
each	O
other	O
by	O
the	O
continuation	O
of	O
the	O
Paisley	LEXICON
Ruck	LEXICON
.	O

Some	O
6km	O
to	O
the	O
east	O
of	O
the	O
present	O
district	O
,	O
the	O
Glenburn	O
Borehole	O
showed	O
that	O
the	O
basal	O
lavas	O
of	O
the	O
Beith	O
-	O
Barrhead	O
sequence	O
rest	O
directly	O
upon	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

Hence	O
it	O
appears	O
that	O
the	O
lower	O
lava	O
groups	O
of	O
the	O
Renfrewshire	O
Hills	O
die	O
out	O
to	O
the	O
south-east	O
,	O
across	O
the	O
Paisley	LEXICON
Ruck	LEXICON
.	O

The	O
Kirkwood	LEXICON
Formation	LEXICON
consists	O
of	O
a	O
highly	O
variable	O
thickness	O
of	O
detrital	O
material	O
derived	O
by	O
erosion	O
from	O
the	O
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

It	O
rests	O
on	O
the	O
uneven	O
weathered	O
surface	O
of	O
the	O
latter	O
and	O
is	O
notably	O
diachronous	O
,	O
interdigitating	O
with	O
the	O
Lawmuir	LEXICON
and	O
Lugton	LEXICON
Limestone	LEXICON
formations	O
at	O
levels	O
ranging	O
from	O
below	O
the	O
Newton	LEXICON
and	O
Castlehead	LEXICON
coals	O
east	O
of	O
Howwood	O
to	O
below	O
the	O
Dockra	LEXICON
Limestone	LEXICON
west	O
of	O
Lochwinnoch	O
.	O

The	O
Lawmuir	LEXICON
Formation	LEXICON
includes	O
the	O
strata	O
above	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
and	O
Kirkwood	LEXICON
formations	LEXICON
and	O
below	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
.	O

The	O
formation	O
occurs	O
in	O
a	O
belt	O
up	O
to	O
3km	O
wide	O
along	O
the	O
south-eastern	O
margin	O
of	O
the	O
district	O
from	O
north	O
of	O
Houston	O
to	O
Howwood	O
and	O
varies	O
in	O
thickness	O
from	O
less	O
than	O
20m	O
to	O
150m	O
;	O
it	O
is	O
absent	O
farther	O
to	O
the	O
south-west	O
,	O
around	O
Lochwinnoch	O
,	O
where	O
the	O
timeequivalent	O
strata	O
are	O
probably	O
included	O
in	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
.	O

The	O
sequence	O
in	O
the	O
lower	O
part	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
shows	O
marked	O
lateral	O
variation	O
,	O
but	O
in	O
the	O
upper	O
part	O
the	O
strata	O
are	O
organised	O
in	O
generally	O
upward-coarsening	O
cycles	O
.	O

The	O
Newton	LEXICON
Coal	LEXICON
is	O
the	O
lowest	O
of	O
the	O
seams	O
which	O
,	O
at	O
Johnstone	O
,	O
just	O
east	O
of	O
the	O
district	O
,	O
combine	O
to	O
form	O
the	O
Quarrelton	LEXICON
Thick	LEXICON
Coal	LEXICON
,	O
the	O
others	O
being	O
the	O
Castlehead	LEXICON
Lower	LEXICON
and	O
Upper	LEXICON
coals	O
.	O

They	O
are	O
absent	O
under	O
the	O
Howwood	O
Syncline	O
but	O
form	O
a	O
diminished	O
representative	O
of	O
the	O
Quarrelton	LEXICON
Thick	LEXICON
Goal	LEXICON
around	O
Kilbarchan	O
.	O

The	O
strata	O
above	O
the	O
Castlehead	LEXICON
Upper	LEXICON
Coal	LEXICON
are	O
mostly	O
sandstones	O
but	O
include	O
three	O
variable	O
coals	O
.	O

A	O
marine	O
band	O
that	O
occurs	O
in	O
a	O
thin	O
mudstone	O
about	O
10m	O
below	O
the	O
Dykebar	LEXICON
Limestone	LEXICON
is	O
the	O
lowest	O
fossiliferous	O
horizon	O
above	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

The	O
Dykebar	LEXICON
Limestone	LEXICON
is	O
generally	O
represented	O
by	O
a	O
massive	O
calcareous	O
mudstone	O
with	O
a	O
marine	O
fauna	O
of	O
bivalves	O
and	O
brachiopods	O
including	O
,	O
in	O
particular	O
,	O
Spirifer	O
cf.	O
crassus	O
.	O

It	O
lies	O
about	O
30m	O
below	O
the	O
Hollybush	LEXICON
Limestone	LEXICON
.	O

The	O
intervening	O
strata	O
consist	O
largely	O
of	O
the	O
Dykebar	LEXICON
Marls	LEXICON
--	O
a	O
sequence	O
of	O
poorly	O
bedded	O
,	O
variegated	O
mudstones	O
locally	O
containing	O
clusters	O
of	O
sphaerosiderite	O
grains	O
and	O
with	O
roots	O
in	O
places	O
.	O

The	O
Sandholes	LEXICON
Coal	LEXICON
is	O
only	O
recognisable	O
north	O
of	O
Kilbarchan	O
.	O

It	O
is	O
up	O
to	O
1.15m	O
thick	O
in	O
several	O
leaves	O
,	O
lies	O
12m	O
to	O
20m	O
below	O
the	O
Hollybush	LEXICON
Limestone	LEXICON
and	O
was	O
mined	O
to	O
some	O
extent	O
at	O
its	O
type	O
locality	O
-LSB-	O
NS	O
412	O
643	O
-RSB-	O
.	O

The	O
Hollybush	LEXICON
Limestone	LEXICON
consists	O
of	O
two	O
or	O
more	O
beds	O
of	O
Limestone	O
within	O
several	O
metres	O
of	O
calcareous	O
mudstone	O
that	O
are	O
visible	O
in	O
two	O
old	O
quarries	O
-LSB-	O
NS	O
412	O
666	O
;	O
NS	O
411	O
606	O
-RSB-	O
and	O
in	O
the	O
River	O
Gryfe	O
-LSB-	O
NS	O
399	O
657	O
;	O
NS	O
415	O
664	O
;	O
NS	O
416	O
663	O
-RSB-	O
.	O

They	O
contain	O
the	O
lowest	O
rich	O
marine	O
fauna	O
in	O
the	O
Carboniferous	CHRONOSTRAT
of	O
western	O
Scotland	O
.	O

Between	O
the	O
marine	O
beds	O
and	O
the	O
variable	O
Lady	LEXICON
Ann	LEXICON
Coal	LEXICON
,	O
which	O
in	O
places	O
in	O
0.66m	O
thick	O
,	O
are	O
10m	O
of	O
sandstone	O
and	O
2m	O
of	O
seatrock	O
.	O

The	O
Blackbyre	LEXICON
Limestone	LEXICON
consists	O
of	O
2	O
to	O
5m	O
of	O
limestone	O
with	O
bands	O
of	O
calcareous	O
mudstone	O
.	O

It	O
lies	O
close	O
below	O
the	O
Hurlet	LEXICON
Coal	LEXICON
,	O
and	O
locally	O
has	O
been	O
leached	O
and	O
affected	O
by	O
the	O
roots	O
of	O
the	O
coal-forming	O
plants	O
.	O

The	O
Blackbyre	LEXICON
Limestone	LEXICON
contains	O
a	O
rich	O
marine	O
fauna	O
including	O
corals	O
such	O
as	O
Diphyphyllum	O
and	O
brachiopods	O
such	O
as	O
Echinoconchus	O
cf.	O
punctatus	O
and	O
Pleuropugnoides	O
.	O

Up	O
to	O
5m	O
of	O
seatclay	O
separate	O
it	O
from	O
the	O
Hurlet	LEXICON
Coal	LEXICON
.	O

The	O
Hurlet	LEXICON
Coal	LEXICON
is	O
a	O
low-quality	O
,	O
pyritous	O
seam	O
up	O
to	O
1.5m	O
thick	O
,	O
locally	O
in	O
leaves	O
.	O

The	O
mudstone	O
between	O
it	O
and	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
is	O
known	O
as	O
the	O
Alum	LEXICON
Shale	LEXICON
because	O
it	O
was	O
exploited	O
for	O
alum	O
at	O
Lennoxtown	O
,	O
north	O
of	O
Glasgow	O
.	O

A	O
layer	O
of	O
basaltic	O
tuff	O
and	O
agglomerate	O
which	O
underlies	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
in	O
the	O
Howwood	O
area	O
may	O
replace	O
the	O
Hurlet	LEXICON
Coal	LEXICON
in	O
places	O
.	O

The	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
occurs	O
only	O
in	O
the	O
south-east	O
of	O
the	O
district	O
,	O
between	O
Bridge	O
of	O
Weir	O
and	O
Kilbarchan	O
,	O
in	O
the	O
Howwood	O
Syncline	O
,	O
and	O
at	O
Lochwinnoch	O
.	O

Information	O
comes	O
largely	O
from	O
boreholes	O
,	O
supplemented	O
by	O
stream	O
sections	O
in	O
the	O
River	O
Gryfe	O
and	O
Locher	O
Water	O
and	O
by	O
quarries	O
in	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
in	O
the	O
Howwood	O
Syncline	O
.	O

The	O
base	O
of	O
the	O
unit	O
was	O
formerly	O
taken	O
at	O
the	O
base	O
of	O
the	O
Hurlet	LEXICON
Coal	LEXICON
but	O
is	O
now	O
drawn	O
at	O
the	O
base	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
;	O
the	O
top	O
is	O
at	O
the	O
top	O
of	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
.	O

The	O
limestones	O
which	O
give	O
the	O
group	O
its	O
name	O
are	O
marine	O
and	O
up	O
to	O
seven	O
in	O
number	O
,	O
excluding	O
the	O
limy	O
ironstones	O
just	O
below	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
,	O
which	O
contain	O
only	O
ostracods	O
and	O
fish	O
debris	O
.	O

The	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
which	O
varies	O
in	O
thickness	O
from	O
1.7	O
to	O
12.7m	O
,	O
consists	O
of	O
argillaceous	O
shelly	O
limestone	O
with	O
calcareous	O
mudstone	O
partings	O
;	O
to	O
the	O
east	O
of	O
the	O
district	O
,	O
in	O
the	O
Paisley	O
area	O
,	O
it	O
is	O
generally	O
a	O
crinoidal	O
limestone	O
less	O
than	O
1m	O
thick	O
.	O

Most	O
of	O
the	O
limestones	O
are	O
composed	O
largely	O
of	O
crinoid	O
columnals	O
but	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
is	O
very	O
argillaceous	O
with	O
scattered	O
shell	O
and	O
crinoid	O
debris	O
.	O

Clayband	O
ironstones	O
are	O
scattered	O
throughout	O
the	O
sequence	O
,	O
occurring	O
in	O
abundance	O
just	O
below	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
and	O
midway	O
between	O
it	O
and	O
the	O
Main	LEXICON
Hosie	LEXICON
Limestone	LEXICON
.	O

A	O
more	O
persistent	O
seam	O
,	O
the	O
Lillie	LEXICON
's	LEXICON
Shale	LEXICON
Coal	LEXICON
,	O
normally	O
consists	O
of	O
0.2m	O
of	O
coal	O
on	O
0.2m	O
of	O
cannel	O
or	O
cannelly	O
mudstone	O
but	O
reaches	O
0.2m	O
of	O
coal	O
on	O
0.25m	O
of	O
`	O
shale	O
'	O
in	O
the	O
Locher	O
Water	O
-LSB-	O
NS	O
402	O
648	O
-RSB-	O
and	O
0.4m	O
of	O
coal	O
on	O
0.45m	O
of	O
`	O
shale	O
'	O
in	O
a	O
nearby	O
borehole	O
-LSB-	O
NS	O
421	O
658	O
-RSB-	O
.	O

The	O
limestones	O
and	O
associated	O
mudstones	O
are	O
marine	O
and	O
some	O
,	O
such	O
as	O
the	O
Neilson	LEXICON
Shell	LEXICON
Bed	LEXICON
above	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
,	O
yield	O
rich	O
faunas	O
.	O

Such	O
faunas	O
occur	O
particularly	O
between	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
and	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
.	O

The	O
Hosie	LEXICON
Sandstone	LEXICON
,	O
which	O
most	O
unusually	O
for	O
a	O
Scottish	O
Carboniferous	CHRONOSTRAT
sandstone	O
contains	O
a	O
marine	O
fauna	O
,	O
mainly	O
of	O
brachiopods	O
,	O
is	O
represented	O
by	O
a	O
bed	O
of	O
silty	O
sandstone	O
below	O
the	O
Main	LEXICON
Hosie	LEXICON
Limestone	LEXICON
.	O

Only	O
the	O
upper	O
part	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
,	O
referred	O
to	O
the	O
Lugton	LEXICON
Limestone	LEXICON
Formation	LEXICON
,	O
is	O
present	O
.	O

The	O
Dockra	LEXICON
Limestone	LEXICON
,	O
which	O
lies	O
near	O
the	O
base	O
in	O
the	O
Lochwinnoch	O
area	O
,	O
is	O
equivalent	O
to	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
of	O
the	O
Kilbarchan	O
--	O
Howwood	O
area	O
and	O
there	O
is	O
no	O
local	O
representative	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
.	O

In	O
the	O
Lora	O
Burn	O
Borehole	O
,	O
the	O
Dockra	LEXICON
Limestone	LEXICON
is	O
about	O
15m	O
thick	O
and	O
consists	O
of	O
medium-grey	O
calcareous	O
mudstone	O
which	O
passes	O
upward	O
into	O
dark	O
grey	O
argillaceous	O
limestone	O
.	O

The	O
strata	O
overlying	O
the	O
Dockra	LEXICON
Limestone	LEXICON
,	O
consisting	O
mainly	O
of	O
interbedded	O
mudstones	O
and	O
limestones	O
,	O
are	O
equivalent	O
to	O
the	O
Hosie	LEXICON
limestones	LEXICON
elsewhere	O
in	O
the	O
Greenock	O
district	O
.	O

A	O
rooty	O
bed	O
of	O
variable	O
thickness	O
,	O
at	O
the	O
position	O
of	O
the	O
Lillie	LEXICON
's	LEXICON
Shale	LEXICON
Coal	LEXICON
,	O
divides	O
the	O
sequence	O
into	O
two	O
units	O
.	O

The	O
top	O
of	O
the	O
Lugton	LEXICON
Limestone	LEXICON
Formation	LEXICON
is	O
taken	O
at	O
the	O
top	O
of	O
the	O
uppermost	O
of	O
the	O
Hosie	LEXICON
limestones	O
.	O

The	O
strata	O
consist	O
of	O
dark	O
grey	O
bedded	O
mudstones	O
very	O
similar	O
to	O
those	O
in	O
the	O
underlying	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
.	O

They	O
include	O
several	O
clayband	O
ironstones	O
,	O
the	O
thickest	O
of	O
which	O
is	O
the	O
Johnstone	LEXICON
Clayband	LEXICON
Ironstone	LEXICON
.	O

The	O
immediately	O
overlying	O
mudstones	O
contain	O
alternating	O
developments	O
of	O
Lingula	O
squamiformis	O
and	O
Naiadites	O
,	O
in	O
places	O
in	O
very	O
close	O
association	O
,	O
but	O
the	O
mudstones	O
around	O
and	O
above	O
the	O
Johnstone	LEXICON
Clayband	LEXICON
Ironstones	LEXICON
are	O
usually	O
barren	O
.	O

The	O
strata	O
overlying	O
the	O
Lugton	LEXICON
Limestone	LEXICON
Formation	LEXICON
consist	O
mainly	O
of	O
mudstones	O
with	O
a	O
number	O
of	O
thin	O
ironstone	O
bands	O
,	O
most	O
notably	O
the	O
Dalry	LEXICON
Clayband	LEXICON
Ironstone	LEXICON
,	O
which	O
lies	O
at	O
the	O
horizon	O
of	O
the	O
Johnstone	LEXICON
Clayband	LEXICON
Ironstone	LEXICON
.	O

The	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
,	O
a	O
widespread	O
marine	O
horizon	O
,	O
is	O
also	O
present	O
in	O
the	O
Lochwinnoch	O
area	O
and	O
is	O
useful	O
in	O
relating	O
the	O
sequences	O
of	O
the	O
Greenock	O
district	O
with	O
those	O
developed	O
to	O
the	O
south	O
,	O
in	O
Ayrshire	O
.	O

The	O
sediments	O
of	O
the	O
Kilbirnie	LEXICON
Mudstone	LEXICON
Formation	LEXICON
are	O
succeeded	O
by	O
a	O
sequence	O
of	O
mudstone	O
,	O
siltstone	O
,	O
sandstone	O
,	O
seatrock	O
and	O
coal	O
,	O
arranged	O
in	O
cycles	O
.	O

These	O
strata	O
are	O
assigned	O
to	O
the	O
Dalry	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Grey	O
mudstone	O
with	O
Lingula	O
exposed	O
here	O
is	O
considered	O
to	O
be	O
the	O
local	O
representative	O
of	O
the	O
Black	LEXICON
Metals	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
a	O
prominent	O
marker	O
horizon	O
in	O
the	O
Paisley	O
district	O
.	O

Clayband	O
ironstone	O
nodules	O
and	O
beds	O
within	O
the	O
mudstone	O
,	O
referred	O
to	O
in	O
Ayrshire	O
as	O
Logan	LEXICON
's	LEXICON
Bands	LEXICON
,	O
locally	O
reach	O
workable	O
thickness	O
in	O
the	O
Lochwinnoch	O
area	O
.	O

Towards	O
the	O
top	O
of	O
the	O
Dalry	LEXICON
Formation	LEXICON
,	O
coals	O
,	O
known	O
locally	O
as	O
the	O
`	O
Peel	O
Coals	O
'	O
and	O
tentatively	O
correlated	O
with	O
the	O
Main	LEXICON
and	O
Smithy	LEXICON
coals	O
of	O
north	O
Ayrshire	O
,	O
attain	O
workable	O
thickness	O
and	O
have	O
been	O
mined	O
in	O
places	O
.	O

After	O
a	O
period	O
at	O
the	O
end	O
of	O
Stratheden	LEXICON
Group	LEXICON
times	O
during	O
which	O
local	O
erosion	O
took	O
place	O
,	O
sedimentation	O
in	O
the	O
districtresumed	O
as	O
a	O
result	O
of	O
renewed	O
regional	O
subsidence	O
.	O

The	O
early	O
Carboniferous	CHRONOSTRAT
basin	O
was	O
more	O
extensive	O
than	O
that	O
in	O
which	O
the	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
was	O
laid	O
down	O
,	O
and	O
in	O
large	O
parts	O
of	O
the	O
southern	O
Midland	O
Valley	O
the	O
basal	O
beds	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
overlap	O
the	O
entire	O
Stratheden	LEXICON
Group	LEXICON
to	O
rest	O
upon	O
rocks	O
of	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
or	O
older	O
.	O

The	O
thick	O
,	O
relatively	O
arenaceous	O
Kinnesswood	LEXICON
Formation	LEXICON
of	O
the	O
Helensburgh	O
--	O
Dumbarton	O
area	O
was	O
probably	O
laid	O
down	O
by	O
braided	O
rivers	O
which	O
flowed	O
into	O
the	O
basin	O
from	O
the	O
north-west	O
.	O

As	O
a	O
result	O
,	O
the	O
Ballagan	LEXICON
Formation	LEXICON
was	O
laid	O
down	O
in	O
a	O
shallow-water	O
environment	O
with	O
restricted	O
access	O
to	O
the	O
open	O
sea	O
,	O
subject	O
to	O
marked	O
changes	O
of	O
salinity	O
and	O
periodic	O
desiccation	O
.	O

Just	O
as	O
the	O
onset	O
of	O
marine	O
conditions	O
was	O
gradual	O
,	O
so	O
also	O
was	O
the	O
resumption	O
of	O
fiuvial	O
sedimentation	O
towards	O
the	O
end	O
of	O
Ballagan	LEXICON
Formation	LEXICON
times	O
,	O
probably	O
as	O
a	O
result	O
of	O
rejuvenation	O
of	O
the	O
upland	O
source	O
areas	O
.	O

Deposition	O
of	O
sandstones	O
probably	O
commenced	O
first	O
in	O
the	O
north-western	O
part	O
of	O
the	O
Greenock	O
district	O
but	O
gradually	O
extended	O
southwards	O
and	O
eastwards	O
over	O
the	O
Ballagan	O
Formation	O
mudflats	O
,	O
with	O
the	O
result	O
that	O
the	O
base	O
of	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
strongly	O
diachronous	O
.	O

The	O
abundance	O
of	O
calcrete	O
in	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
and	O
lower	O
part	O
of	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
consistent	O
with	O
a	O
climate	O
having	O
a	O
mean	O
annual	O
temperature	O
of	O
about	O
160C	O
and	O
a	O
moderately	O
seasonal	O
rainfall	O
.	O

As	O
a	O
result	O
of	O
the	O
reducing	O
conditions	O
thereby	O
introduced	O
,	O
the	O
strata	O
of	O
the	O
Overtoun	LEXICON
Sandstone	LEXICON
Member	LEXICON
and	O
Broadilee	LEXICON
Glen	LEXICON
Sandstone	LEXICON
Member	LEXICON
are	O
generally	O
grey	O
in	O
colour	O
and	O
contain	O
much	O
finely	O
disseminated	O
carbon	O
as	O
well	O
as	O
plant	O
debris	O
.	O

Deposition	O
of	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
the	O
Greenock	O
district	O
was	O
brought	O
to	O
an	O
end	O
by	O
uplift	O
caused	O
by	O
east	O
--	O
west	O
compressional	O
stresses	O
.	O

In	O
the	O
core	O
of	O
one	O
of	O
these	O
folds	O
,	O
the	O
Leap	O
Moor	O
Syncline	O
,	O
the	O
thickest	O
Inverclyde	LEXICON
Group	LEXICON
sequence	O
is	O
preserved	O
.	O

As	O
a	O
consequence	O
,	O
the	O
volcanic	O
rocks	O
of	O
the	O
Strathclyde	LEXICON
Group	LEXICON
locally	O
rest	O
upon	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

After	O
eruption	O
of	O
the	O
lavas	O
and	O
tuffs	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
the	O
volcaniclastic	O
Kirkwood	LEXICON
Formation	LEXICON
initially	O
began	O
to	O
accumulate	O
in	O
late	O
Dinantian	CHRONOSTRAT
times	O
on	O
low	O
ground	O
within	O
and	O
adjacent	O
to	O
the	O
thick	O
volcanic	O
pile	O
of	O
the	O
Renfrewshire	O
Hills	O
.	O

The	O
deposits	O
of	O
the	O
lower	O
part	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
consist	O
largely	O
of	O
quartzose	O
sand	O
,	O
but	O
include	O
some	O
volcaniclastic	O
material	O
because	O
the	O
lavas	O
remained	O
uncovered	O
in	O
places	O
till	O
almost	O
the	O
whole	O
of	O
the	O
formation	O
had	O
been	O
laid	O
down	O
.	O

These	O
attained	O
their	O
maximum	O
extent	O
towards	O
the	O
end	O
of	O
Dinantian	CHRONOSTRAT
times	O
.	O

The	O
oldest	O
were	O
probably	O
emplaced	O
during	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
,	O
about	O
400	O
million	O
years	O
ago	O
,	O
into	O
the	O
Dalradian	LEXICON
rocks	O
of	O
the	O
south-west	O
Highlands	O
.	O

The	O
youngest	O
were	O
intruded	O
about	O
52	O
million	O
years	O
ago	O
,	O
during	O
the	O
Tertiary	CHRONOSTRAT
period	O
.	O

The	O
most	O
extensive	O
and	O
varied	O
suite	O
of	O
intrusions	O
relates	O
to	O
the	O
early	O
Carboniferous	CHRONOSTRAT
eruptive	O
episode	O
which	O
gave	O
rise	O
to	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

Two	O
north-east-trending	O
dykes	O
cutting	O
Dalradian	LEXICON
rocks	O
have	O
been	O
classed	O
as	O
lamprophyre	O
and	O
are	O
considered	O
to	O
be	O
of	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
.	O

Large	O
numbers	O
of	O
minor	O
intrusions	O
,	O
both	O
within	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
in	O
the	O
underlying	O
sediments	O
have	O
strong	O
petrological	O
affinities	O
with	O
the	O
volcanic	O
rocks	O
and	O
are	O
assumed	O
to	O
be	O
contemporaneous	O
with	O
them	O
.	O

Outwith	O
the	O
centre	O
,	O
plugs	O
are	O
difficult	O
to	O
identify	O
within	O
the	O
mainly	O
basaltic	O
succession	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
owing	O
to	O
the	O
close	O
correspondence	O
in	O
rock	O
type	O
between	O
lavas	O
and	O
intrusions	O
.	O

Four	O
basaltic	O
vents	O
,	O
cutting	O
the	O
Devonian	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
sediments	O
beneath	O
the	O
volcanic	O
rocks	O
,	O
have	O
been	O
recognised	O
in	O
the	O
area	O
south	O
of	O
the	O
Clyde	O
.	O

North	O
of	O
the	O
River	O
Clyde	O
at	O
Dumbarton	O
,	O
a	O
group	O
of	O
vents	O
cutting	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sediments	O
lies	O
at	O
the	O
southwestern	O
end	O
of	O
the	O
Dumbarton	O
--	O
Fintry	O
line	O
of	O
volcanic	O
centres	O
.	O

North	O
of	O
the	O
River	O
Clyde	O
,	O
dykes	O
are	O
abundant	O
close	O
to	O
the	O
vents	O
of	O
the	O
Dumbarton	O
area	O
,	O
in	O
the	O
Murroch	O
Burn	O
and	O
south-west	O
of	O
Renton	O
,	O
where	O
they	O
are	O
intruded	O
into	O
rocks	O
of	O
the	O
Kinnesswood	LEXICON
and	O
Ballagan	LEXICON
formations	O
.	O

A	O
persistent	O
north-east-trending	O
dyke	O
,	O
which	O
crops	O
out	O
on	O
both	O
sides	O
of	O
the	O
Gare	O
Loch	O
at	O
Shandon	O
,	O
has	O
textural	O
similarities	O
to	O
the	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
dykes	O
and	O
has	O
been	O
classed	O
tentatively	O
as	O
a	O
dolerite	O
of	O
transitional	O
Markie/Dunsapie	O
type	O
.	O

An	O
irregular	O
sheet-like	O
body	O
of	O
medium-grained	O
dolerite	O
crops	O
out	O
on	O
Knockencorsan	O
Hill	O
-LSB-	O
NS	O
240	O
666	O
-RSB-	O
,	O
where	O
it	O
is	O
seen	O
to	O
cut	O
Inverclyde	LEXICON
Group	LEXICON
sediments	O
and	O
the	O
Noddsdale	O
Volcaniclastic	O
Beds	O
on	O
opposite	O
sides	O
of	O
a	O
NW	O
--	O
SE	O
fault	O
.	O

At	O
Craigmuschat	O
-LSB-	O
NS	O
240	O
775	O
-RSB-	O
,	O
Gourock	O
,	O
a	O
westward-dipping	O
lenticular	O
body	O
,	O
up	O
to	O
100m	O
thick	O
,	O
of	O
heavily	O
altered	O
,	O
haematite-stained	O
feldsparphyric	O
trachyte	O
is	O
intruded	O
into	O
sandstones	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

The	O
most	O
extensive	O
sill	O
is	O
intruded	O
slightly	O
discordantly	O
,	O
close	O
to	O
the	O
boundary	O
between	O
the	O
Stratheden	LEXICON
and	O
Inverclyde	LEXICON
groups	O
.	O

A	O
number	O
of	O
east	O
--	O
west	O
or	O
ENE-trending	O
quartz-dolerite	O
dykes	O
in	O
the	O
district	O
are	O
part	O
of	O
a	O
major	O
swarm	O
of	O
late	O
Westphalian	CHRONOSTRAT
to	O
early	O
Stephanian	CHRONOSTRAT
age	O
.	O

In	O
the	O
district	O
they	O
are	O
only	O
seen	O
to	O
cut	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
older	O
rocks	O
,	O
but	O
elsewhere	O
in	O
central	O
Scotland	O
the	O
swarm	O
cuts	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

A	O
sill-complex	O
consisting	O
of	O
several	O
leaves	O
of	O
ophitic	O
olivine	O
-	O
dolerite	O
is	O
intruded	O
into	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
in	O
the	O
south-east	O
corner	O
of	O
the	O
district	O
.	O

The	O
stratigraphical	O
level	O
at	O
which	O
the	O
sill	O
is	O
emplaced	O
ranges	O
from	O
below	O
the	O
Castlehead	LEXICON
Lower	LEXICON
Coal	LEXICON
to	O
just	O
above	O
the	O
Hollybush	LEXICON
Limestone	LEXICON
.	O

Several	O
leaves	O
of	O
the	O
complex	O
,	O
cutting	O
deformed	O
strata	O
within	O
the	O
Paisley	LEXICON
Ruck	LEXICON
,	O
were	O
proved	O
in	O
a	O
borehole	O
north-east	O
of	O
Howwood	O
-LSB-	O
NS	O
405	O
612	O
-RSB-	O
and	O
,	O
in	O
eastern	O
Glasgow	O
,	O
sills	O
of	O
similar	O
composition	O
cut	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

The	O
structural	O
history	O
of	O
the	O
Greenock	O
district	O
can	O
be	O
traced	O
from	O
the	O
early	O
part	O
of	O
the	O
Caledonian	O
Orogeny	O
,	O
in	O
late	O
Precambrian	CHRONOSTRAT
times	O
,	O
to	O
the	O
end	O
of	O
the	O
Palaeozoic	CHRONOSTRAT
Era	CHRONOSTRAT
.	O

During	O
the	O
early	O
part	O
of	O
the	O
Caledonian	O
Orogeny	O
,	O
in	O
what	O
has	O
been	O
termed	O
the	O
Grampian	O
event	O
,	O
the	O
Dalradian	LEXICON
rocks	O
were	O
deformed	O
into	O
a	O
series	O
of	O
major	O
folds	O
.	O

The	O
date	O
of	O
initiation	O
of	O
the	O
important	O
Highland	O
Boundary	O
Fault-system	O
is	O
unknown	O
but	O
it	O
has	O
been	O
suggested	O
that	O
it	O
already	O
existed	O
as	O
a	O
basement	O
fault	O
during	O
deposition	O
of	O
the	O
Dalradian	LEXICON
.	O

The	O
varied	O
assemblage	O
of	O
rocks	O
known	O
as	O
the	O
Highland	LEXICON
Boundary	LEXICON
Complex	LEXICON
,	O
which	O
includes	O
strata	O
of	O
Middle	CHRONOSTRAT
Ordovician	CHRONOSTRAT
age	O
,	O
was	O
juxtaposed	O
against	O
the	O
Dalradian	LEXICON
in	O
late	O
Ordovician	CHRONOSTRAT
or	O
earliest	O
Silurian	CHRONOSTRAT
times	O
.	O

There	O
is	O
no	O
evidence	O
in	O
the	O
district	O
which	O
relates	O
to	O
sedimentary	O
or	O
structural	O
events	O
during	O
the	O
Silurian	CHRONOSTRAT
period	O
but	O
late	O
-	O
Silurian	CHRONOSTRAT
sediments	O
a	O
little	O
to	O
the	O
south	O
at	O
Farland	O
Head	O
-LSB-	O
NS	O
178	O
484	O
-RSB-	O
are	O
generally	O
fine	O
grained	O
and	O
show	O
no	O
sign	O
of	O
having	O
been	O
deposited	O
in	O
the	O
vicinity	O
of	O
a	O
highland	O
front	O
.	O

During	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
,	O
however	O
,	O
the	O
Greenock	O
district	O
was	O
part	O
of	O
a	O
major	O
north-east-trending	O
subsiding	O
basin	O
centred	O
on	O
the	O
Midland	O
Valley	O
and	O
flanked	O
to	O
north	O
and	O
south	O
by	O
upland	O
areas	O
.	O

Palaeomagnetic	O
measurements	O
indicate	O
,	O
however	O
,	O
that	O
the	O
Highlands	O
and	O
the	O
Midland	O
Valley	O
have	O
occupied	O
similar	O
positions	O
in	O
relation	O
to	O
each	O
other	O
since	O
Ordovician	CHRONOSTRAT
times	O
.	O

It	O
is	O
likely	O
that	O
the	O
input	O
of	O
coarse	O
detritus	O
into	O
the	O
Midland	O
Valley	O
basin	O
during	O
the	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
was	O
maintained	O
by	O
rejuvenation	O
of	O
the	O
Highland	O
source	O
area	O
by	O
intermittent	O
uplift	O
on	O
the	O
Highland	O
Boundary	O
Fault-system	O
.	O

Although	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
strata	O
almost	O
certainly	O
encroached	O
upon	O
the	O
Highlands	O
,	O
it	O
is	O
probable	O
that	O
in	O
the	O
Greenock	O
district	O
they	O
do	O
not	O
now	O
extend	O
beyond	O
the	O
line	O
of	O
the	O
South	O
Inchmurrin	O
Fault	O
and	O
its	O
inferred	O
south-westwards	O
extension	O
.	O

During	O
the	O
Middle	CHRONOSTRAT
Devonian	CHRONOSTRAT
,	O
compressive	O
earth	O
movements	O
brought	O
about	O
marked	O
changes	O
in	O
the	O
palaeogeography	O
of	O
central	O
Scotland	O
.	O

The	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
were	O
folded	O
into	O
north-east-trending	O
structures	O
and	O
there	O
were	O
major	O
thrust	O
movements	O
on	O
elements	O
of	O
the	O
Highland	O
Boundary	O
Fault-system	O
.	O

The	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
within	O
the	O
basin	O
was	O
deeply	O
eroded	O
,	O
particularly	O
along	O
anticlinal	O
axes	O
,	O
and	O
continuing	O
uplift	O
prevented	O
the	O
deposition	O
of	O
any	O
Middle	CHRONOSTRAT
Devonian	CHRONOSTRAT
sediments	O
.	O

During	O
most	O
of	O
the	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
period	O
,	O
tectonic	O
activity	O
was	O
subdued	O
.	O

Deposition	O
of	O
the	O
Stratheden	LEXICON
Group	LEXICON
took	O
place	O
under	O
conditions	O
of	O
gentle	O
regional	O
subsidence	O
,	O
with	O
intermittent	O
uplift	O
of	O
the	O
Highlands	O
on	O
fractures	O
within	O
the	O
Highland	O
Boundary	O
Fault-system	O
.	O

Uplift	O
to	O
the	O
west	O
,	O
similar	O
to	O
that	O
which	O
affected	O
the	O
Corloch	O
Fault	O
on	O
north	O
Arran	O
,	O
caused	O
the	O
removal	O
by	O
erosion	O
of	O
any	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
strata	O
.	O

Within	O
the	O
basin	O
,	O
there	O
was	O
upthrow	O
to	O
the	O
west	O
on	O
the	O
Largs	O
Fault-zone	O
,	O
an	O
important	O
north-north-east-trending	O
belt	O
of	O
fractures	O
which	O
was	O
to	O
play	O
a	O
major	O
role	O
in	O
Carboniferous	CHRONOSTRAT
times	O
.	O

The	O
upper-most	O
portion	O
of	O
the	O
Stratheden	LEXICON
Group	LEXICON
in	O
the	O
western	O
part	O
of	O
the	O
district	O
was	O
removed	O
by	O
erosion	O
and	O
the	O
earliest	O
Inverclyde	LEXICON
Group	LEXICON
strata	O
locally	O
succeed	O
unconformably	O
.	O

Deposition	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
in	O
the	O
Midland	O
Valley	O
in	O
early	O
Carboniferous	CHRONOSTRAT
times	O
took	O
place	O
under	O
quiet	O
tectonic	O
conditions	O
.	O

Slow	O
regional	O
subsidence	O
continued	O
and	O
the	O
floodplain	O
deposits	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
were	O
progressively	O
covered	O
by	O
coastal	O
sabkha	O
sediments	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
.	O

Towards	O
the	O
end	O
of	O
Inverclyde	LEXICON
Group	LEXICON
times	O
,	O
the	O
sedimentary	O
sequence	O
within	O
the	O
Greenock	O
district	O
began	O
to	O
be	O
affected	O
by	O
east	O
--	O
west	O
compressive	O
movements	O
.	O

Within	O
the	O
district	O
,	O
the	O
lavas	O
and	O
associated	O
volcaniclastic	O
sediments	O
at	O
the	O
base	O
of	O
the	O
Strathclyde	LEXICON
Group	LEXICON
rest	O
upon	O
an	O
eroded	O
surface	O
of	O
rocks	O
which	O
range	O
from	O
high	O
in	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
to	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

This	O
widespread	O
early	O
Carboniferous	CHRONOSTRAT
volcanicity	O
may	O
relate	O
to	O
a	O
tensional	O
phase	O
initiated	O
as	O
a	O
reaction	O
to	O
the	O
preceding	O
compression	O
.	O

To	O
the	O
east	O
,	O
in	O
the	O
Glasgow	O
district	O
,	O
most	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
can	O
be	O
related	O
to	O
north-east-trending	O
lines	O
such	O
as	O
the	O
Dumbarton	O
--	O
Fintry	O
line	O
.	O

The	O
differences	O
between	O
the	O
lava	O
sequences	O
in	O
the	O
Renfrewshire	O
Hills	O
,	O
the	O
Beith	O
--	O
Barrhead	O
area	O
and	O
the	O
Kilpatrick	O
Hills	O
may	O
be	O
due	O
in	O
part	O
to	O
differential	O
movements	O
of	O
blocks	O
bounded	O
by	O
major	O
crustal	O
fractures	O
,	O
such	O
as	O
the	O
Clyde	O
Fault	O
and	O
the	O
Paisley	LEXICON
Ruck	LEXICON
.	O

Earth	O
movements	O
during	O
the	O
late	O
Carboniferous	CHRONOSTRAT
gave	O
rise	O
to	O
faults	O
,	O
most	O
of	O
which	O
fall	O
within	O
one	O
of	O
four	O
principal	O
trends	O
:	O
north	O
--	O
south	O
,	O
east	O
--	O
west	O
,	O
NE	O
--	O
SW	O
and	O
NW	O
--	O
SE	O
.	O

The	O
North	O
Inchmurrin	O
and	O
Rosneath	O
faults	O
were	O
active	O
,	O
rocks	O
of	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
and	O
early	O
Carboniferous	CHRONOSTRAT
age	O
being	O
let	O
down	O
between	O
them	O
in	O
a	O
graben	O
-	O
like	O
structure	O
.	O

Among	O
other	O
important	O
NE	O
--	O
SW	O
structures	O
of	O
later	O
Carboniferous	CHRONOSTRAT
age	O
are	O
the	O
Camis	O
Eskan	O
Graben	O
,	O
north	O
of	O
the	O
Clyde	O
,	O
the	O
faulted	O
syncline	O
centred	O
on	O
the	O
Spango	O
valley	O
and	O
the	O
complex	O
Paisley	LEXICON
Ruck	LEXICON
.	O

It	O
is	O
probable	O
that	O
most	O
of	O
the	O
east	O
--	O
west	O
faults	O
,	O
some	O
of	O
which	O
are	O
intruded	O
by	O
quartz-dolerite	O
dykes	O
,	O
were	O
in	O
being	O
by	O
the	O
end	O
of	O
the	O
Carboniferous	CHRONOSTRAT
period	O
.	O

At	O
least	O
some	O
of	O
the	O
east	O
--	O
west	O
faults	O
may	O
have	O
been	O
active	O
during	O
Permian	CHRONOSTRAT
or	O
later	O
times	O
as	O
they	O
apparently	O
displace	O
the	O
olivine-dolerite	O
sills	O
of	O
the	O
Kilbarchan	O
area	O
which	O
are	O
considered	O
to	O
be	O
of	O
early	O
Permian	CHRONOSTRAT
age	O
.	O

Members	O
of	O
the	O
group	O
,	O
such	O
as	O
the	O
Kilbarchan	O
Fault	O
,	O
cause	O
major	O
displacements	O
of	O
the	O
upper	O
boundary	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
of	O
the	O
early	O
Permian	CHRONOSTRAT
olivine-dolerite	O
sill-complex	O
.	O

The	O
faults	O
of	O
this	O
group	O
belong	O
to	O
a	O
major	O
fracture	O
system	O
which	O
was	O
probably	O
initiated	O
in	O
the	O
late	O
Carboniferous	CHRONOSTRAT
but	O
which	O
continued	O
to	O
be	O
active	O
during	O
Permian	CHRONOSTRAT
and	O
later	O
times	O
.	O

They	O
may	O
have	O
controlled	O
some	O
of	O
the	O
late	O
Palaeozoic	CHRONOSTRAT
magmatism	O
in	O
the	O
Midland	O
Valley	O
and	O
undoubtedly	O
controlled	O
the	O
siting	O
of	O
important	O
mineral	O
veins	O
,	O
as	O
at	O
Muirshiel	O
,	O
which	O
are	O
possibly	O
of	O
Mesozoic	CHRONOSTRAT
age	O
.	O

The	O
Greenock	O
district	O
was	O
last	O
entirely	O
occupied	O
by	O
ice	O
in	O
late	O
Devensian	CHRONOSTRAT
times	O
,	O
when	O
an	O
ice-sheet	O
,	O
which	O
reached	O
its	O
farthest	O
limits	O
at	O
about	O
18	O
000	O
years	O
Before	O
Present	O
,	O
covered	O
Scotland	O
and	O
northern	O
England	O
.	O

At	O
the	O
start	O
of	O
the	O
climatic	O
amelioration	O
,	O
the	O
margin	O
of	O
the	O
late	O
Devensian	CHRONOSTRAT
ice-sheet	O
still	O
lay	O
south	O
and	O
west	O
of	O
the	O
present	O
district	O
.	O

During	O
the	O
Flandrian	CHRONOSTRAT
,	O
alluvial	O
deposits	O
were	O
laid	O
down	O
by	O
streams	O
and	O
rivers	O
,	O
and	O
were	O
terraced	O
as	O
the	O
drainage	O
adjusted	O
to	O
changes	O
of	O
sea-level	O
.	O

The	O
principle	O
valleys	O
in	O
the	O
district	O
,	O
many	O
of	O
which	O
have	O
a	O
general	O
north-south	O
or	O
NW-SE	O
trend	O
,	O
were	O
doubtless	O
scoured	O
and	O
deepened	O
by	O
ice	O
on	O
more	O
than	O
one	O
occasion	O
during	O
the	O
Quaternary	CHRONOSTRAT
Era	CHRONOSTRAT
.	O

In	O
the	O
Helensburgh	O
--	O
Dumbarton	O
area	O
and	O
along	O
the	O
coast	O
south	O
of	O
the	O
Firth	O
of	O
Clyde	O
,	O
the	O
till	O
is	O
usually	O
clayey	O
,	O
grey-brown	O
in	O
colour	O
,	O
and	O
contains	O
clasts	O
mainly	O
of	O
Dalradian	LEXICON
rock	O
types	O
.	O

Farther	O
east	O
,	O
the	O
till	O
is	O
brown	O
or	O
red-brown	O
in	O
colour	O
and	O
contains	O
angular	O
blocks	O
of	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
sandstones	O
and	O
conglomerates	O
,	O
and	O
lavas	O
and	O
sandstones	O
of	O
Carboniferous	CHRONOSTRAT
age	O
.	O

Examples	O
include	O
small	O
ridges	O
of	O
sand	O
and	O
gravel	O
containing	O
pebbles	O
mainly	O
of	O
Carboniferous	CHRONOSTRAT
lava	O
a	O
little	O
south	O
of	O
Kilmacolm	O
-LSB-	O
NS	O
359	O
679	O
-RSB-	O
and	O
north	O
of	O
Bridge	O
of	O
Weir	O
-LSB-	O
NS	O
394	O
668	O
-RSB-	O
.	O

It	O
has	O
recently	O
been	O
proposed	O
that	O
the	O
younger	O
,	O
colder	O
part	O
of	O
the	O
Clyde	O
Beds	O
should	O
be	O
assigned	O
to	O
the	O
Balloch	LEXICON
Formation	LEXICON
and	O
that	O
the	O
older	O
,	O
less	O
frigid	O
part	O
be	O
subdivided	O
into	O
a	O
lower	O
Paisley	LEXICON
Formation	LEXICON
,	O
consisting	O
of	O
colour-laminated	O
clays	O
and	O
silts	O
,	O
and	O
an	O
upper	O
Linwood	LEXICON
Formation	LEXICON
,	O
composed	O
mainly	O
of	O
grey	O
silts	O
and	O
clays	O
.	O

A	O
thin	O
layer	O
of	O
shelly	O
bouldery	O
gravel	O
intervening	O
between	O
the	O
Linwood	LEXICON
and	O
Balloch	LEXICON
formations	O
has	O
been	O
termed	O
the	O
Inverleven	LEXICON
Formation	LEXICON
.	O

The	O
lower	O
part	O
of	O
the	O
Paisley	LEXICON
Formation	LEXICON
tends	O
to	O
be	O
coarser	O
than	O
the	O
upper	O
part	O
and	O
contains	O
laminae	O
with	O
small	O
angular	O
rock	O
fragments	O
.	O

Larger	O
rock	O
clasts	O
,	O
up	O
to	O
0.1m	O
long	O
,	O
scattered	O
through	O
the	O
deposit	O
,	O
and	O
occurring	O
also	O
in	O
the	O
overlying	O
Linwood	LEXICON
Formation	LEXICON
,	O
were	O
probably	O
dropped	O
in	O
from	O
floating	O
ice-masses	O
.	O

Currently	O
,	O
the	O
Paisley	LEXICON
Formation	LEXICON
is	O
exposed	O
only	O
in	O
the	O
Geilston	O
Burn	O
,	O
Dumbarton	O
-LSB-	O
NS	O
341	O
777	O
-RSB-	O
,	O
where	O
it	O
is	O
about	O
0.6	O
in	O
thick	O
.	O

In	O
the	O
Linwood	O
Borehole	O
,	O
samples	O
of	O
the	O
Paisley	LEXICON
Formation	LEXICON
contained	O
no	O
macrofossils	O
or	O
ostracods	O
.	O

This	O
deposit	O
is	O
immediately	O
overlain	O
,	O
not	O
necessarily	O
conformably	O
,	O
by	O
a	O
freshwater	O
deposit	O
which	O
,	O
although	O
considered	O
to	O
be	O
Flandrian	CHRONOSTRAT
,	O
contains	O
in	O
addition	O
to	O
the	O
gastropods	O
Gyraulus	O
laevis	O
and	O
Lymnaea	O
peregra	O
the	O
cold	O
water	O
bivalve	O
Pisidium	O
obtusale	O
lapponicum	O
.	O

At	O
Geilston	O
Burn	O
,	O
a	O
sequence	O
up	O
to	O
4m	O
thick	O
of	O
fossiliferous	O
grey	O
silts	O
and	O
clays	O
resting	O
upon	O
the	O
Paisley	LEXICON
Formation	LEXICON
is	O
here	O
referred	O
to	O
the	O
Linwood	LEXICON
Formation	LEXICON
.	O

From	O
the	O
radiocarbon	O
dates	O
yielded	O
by	O
shells	O
incorporated	O
in	O
morainic	O
deposits	O
of	O
the	O
Loch	CHRONOSTRAT
Lomond	CHRONOSTRAT
Stadial	CHRONOSTRAT
south	O
of	O
Loch	O
Lomond	O
and	O
at	O
Rhu	O
-LSB-	O
NS	O
265	O
840	O
-RSB-	O
,	O
it	O
may	O
be	O
inferred	O
that	O
the	O
Linwood	LEXICON
Formation	LEXICON
was	O
also	O
laid	O
down	O
in	O
Loch	O
Lomond	O
and	O
the	O
Gare	O
Loch	O
.	O

On	O
the	O
whole	O
,	O
the	O
Linwood	LEXICON
Formation	LEXICON
is	O
much	O
better	O
known	O
in	O
the	O
areas	O
immediately	O
west	O
and	O
east	O
of	O
the	O
present	O
study	O
area	O
where	O
there	O
have	O
been	O
a	O
number	O
of	O
rewarding	O
excavations	O
.	O

The	O
faunas	O
tend	O
to	O
be	O
significantly	O
more	O
diverse	O
than	O
in	O
the	O
Paisley	LEXICON
Formation	LEXICON
,	O
with	O
individual	O
species	O
occurring	O
in	O
greater	O
abundance	O
.	O

When	O
deposition	O
of	O
the	O
Linwood	LEXICON
Formation	LEXICON
commenced	O
,	O
in	O
the	O
period	O
after	O
about	O
12	O
800	O
BP	O
,	O
the	O
sea	O
was	O
still	O
considerably	O
higher	O
than	O
at	O
present	O
but	O
was	O
falling	O
as	O
a	O
result	O
of	O
isostatic	O
uplift	O
.	O

The	O
latter	O
are	O
best	O
developed	O
in	O
the	O
Vale	O
of	O
Leven	O
south	O
of	O
Loch	O
Lomond	O
,	O
where	O
they	O
rest	O
upon	O
a	O
thick	O
series	O
of	O
marine	O
silts	O
and	O
clays	O
,	O
the	O
Balloch	LEXICON
Formation	LEXICON
,	O
which	O
is	O
considered	O
to	O
represent	O
the	O
early	O
,	O
distal	O
outwash	O
from	O
the	O
Loch	O
Lomond	O
glacier	O
.	O

Evidence	O
from	O
boreholes	O
at	O
Balloch	O
and	O
Inverleven	O
in	O
the	O
Leven	O
valley	O
indicates	O
that	O
the	O
sea	O
may	O
have	O
been	O
at	O
a	O
level	O
considerably	O
below	O
OD	O
at	O
the	O
beginning	O
of	O
the	O
period	O
but	O
rose	O
during	O
deposition	O
of	O
the	O
Balloch	LEXICON
Formation	LEXICON
to	O
a	O
position	O
above	O
present	O
sea-level	O
,	O
perhaps	O
by	O
about	O
10300	O
BP	O
.	O

South	O
of	O
Loch	O
Lomond	O
,	O
the	O
till	O
locally	O
contains	O
shells	O
derived	O
from	O
deposits	O
of	O
Linwood	LEXICON
Formation	LEXICON
traversed	O
by	O
the	O
glacier	O
during	O
its	O
passage	O
down	O
the	O
loch	O
.	O

Thus	O
,	O
the	O
discovery	O
in	O
till	O
near	O
Helensburgh	O
on	O
the	O
Gare	O
Loch	O
,	O
of	O
blocks	O
of	O
Linwood	LEXICON
Formation	LEXICON
containing	O
shells	O
,	O
including	O
Arctica	O
islandica	O
,	O
which	O
have	O
yielded	O
radiocarbon	O
dates	O
of	O
11	O
700	O
BP	O
and	O
11	O
000	O
BP	O
,	O
suggests	O
that	O
the	O
maximum	O
position	O
reached	O
by	O
the	O
Gare	O
Loch	O
glacier	O
was	O
some	O
distance	O
beyond	O
the	O
ice-limit	O
marked	O
by	O
the	O
moraine	O
ridges	O
at	O
Rhu	O
.	O

As	O
shown	O
by	O
the	O
Balloch	O
Borehole	O
,	O
the	O
terraced	O
outwash	O
rests	O
upon	O
the	O
marine	O
silts	O
and	O
clays	O
of	O
the	O
Balloch	LEXICON
Formation	LEXICON
.	O

Outwash	O
deposits	O
related	O
to	O
a	O
glacier	O
of	O
this	O
period	O
are	O
present	O
also	O
in	O
the	O
Gare	O
Loch	O
at	O
Rhu	O
,	O
where	O
glacially	O
deformed	O
marine	O
silts	O
and	O
clays	O
are	O
overlain	O
by	O
up	O
to	O
4m	O
of	O
fluvioglacial	O
sand	O
and	O
gravel	O
which	O
is	O
capped	O
by	O
Flandrian	CHRONOSTRAT
beach	O
deposits	O
-LSB-	O
NS	O
265	O
840	O
-RSB-	O
.	O

The	O
former	O
penetrated	O
3g	O
.75m	O
of	O
brown	O
clay	O
and	O
silt	O
to	O
which	O
the	O
name	O
Balloch	LEXICON
Formation	LEXICON
has	O
been	O
given	O
.	O

This	O
rested	O
,	O
at	O
a	O
depth	O
of	O
39m	O
below	O
OD	O
,	O
upon	O
a	O
thin	O
layer	O
of	O
shelly	O
bouldery	O
gravel	O
termed	O
the	O
Inverleven	LEXICON
Formation	LEXICON
.	O

Shell	O
material	O
from	O
the	O
Inverleven	LEXICON
Formation	LEXICON
has	O
yielded	O
radiocarbon	O
dates	O
of	O
11	O
960	O
BP	O
and	O
10	O
350	O
BP	O
at	O
Inverleven	O
and	O
10920	O
BP	O
at	O
Balloch	O
.	O

The	O
oldest	O
of	O
these	O
suggests	O
the	O
possibility	O
that	O
the	O
gravel	O
layer	O
is	O
,	O
in	O
part	O
,	O
a	O
lag	O
deposit	O
produced	O
as	O
tidal	O
currents	O
reworked	O
the	O
Linwood	LEXICON
Formation	LEXICON
which	O
formerly	O
occupied	O
the	O
buried	O
channel	O
of	O
the	O
Leven	O
valley	O
.	O

Advance	O
of	O
a	O
glacier	O
into	O
the	O
loch	O
would	O
have	O
progressively	O
reduced	O
the	O
tidal	O
scour	O
in	O
the	O
Leven	O
valley	O
and	O
eventually	O
allowed	O
deposition	O
of	O
the	O
overlying	O
clay	O
and	O
silt	O
of	O
the	O
Balloch	LEXICON
Formation	LEXICON
seaward	O
of	O
the	O
glacier	O
.	O

Thus	O
,	O
in	O
the	O
western	O
part	O
of	O
the	O
Garvel	O
Park	O
Dock	O
,	O
grey	O
silts	O
and	O
clays	O
contain	O
a	O
boreal	O
fauna	O
of	O
Windermere	CHRONOSTRAT
Interstadial	CHRONOSTRAT
type	O
and	O
are	O
probably	O
Linwood	LEXICON
Formation	LEXICON
.	O

At	O
the	O
eastern	O
end	O
of	O
the	O
dock	O
,	O
grey	O
silts	O
and	O
clays	O
with	O
a	O
gravelly	O
layer	O
at	O
the	O
base	O
reached	O
a	O
depth	O
of	O
about	O
11m	O
below	O
GD	O
;	O
the	O
fauna	O
,	O
which	O
includes	O
P.	O
arctica	O
,	O
indicates	O
that	O
the	O
deposits	O
are	O
probably	O
referable	O
to	O
the	O
Balloch	LEXICON
Formation	LEXICON
.	O

Erosion	O
of	O
a	O
deep	O
channel	O
in	O
response	O
to	O
a	O
lowering	O
of	O
sea-level	O
at	O
,	O
or	O
just	O
before	O
,	O
the	O
start	O
of	O
the	O
Stadial	O
would	O
explain	O
the	O
evidence	O
from	O
the	O
Vale	O
of	O
Leven	O
where	O
the	O
Inverleven	LEXICON
Formation	LEXICON
,	O
with	O
a	O
radiocarbon	O
date	O
of	O
10920	O
BP	O
,	O
occurs	O
to	O
a	O
depth	O
of	O
more	O
than	O
50m	O
below	O
OD	O
in	O
the	O
Inverleven	O
Borehole	O
,	O
whereas	O
the	O
older	O
Linwood	LEXICON
Formation	LEXICON
is	O
apparently	O
present	O
at	O
a	O
much	O
shallower	O
depth	O
in	O
the	O
nearby	O
borehole	O
at	O
Dumbarton	O
Distillery	O
.	O

The	O
sea	O
is	O
considered	O
to	O
have	O
risen	O
during	O
the	O
Stadial	O
,	O
while	O
the	O
Balloch	LEXICON
Formation	LEXICON
was	O
being	O
laid	O
down	O
,	O
to	O
culminate	O
at	O
a	O
position	O
above	O
OD	O
before	O
the	O
end	O
of	O
the	O
period	O
.	O

This	O
continued	O
into	O
early	O
Flandrian	CHRONOSTRAT
times	O
.	O

The	O
rock	O
platform	O
is	O
usually	O
covered	O
by	O
a	O
thin	O
veneer	O
of	O
beach	O
sand	O
and	O
shingle	O
of	O
Flandrian	CHRONOSTRAT
age	O
and	O
in	O
the	O
past	O
has	O
been	O
dated	O
to	O
this	O
period	O
.	O

Several	O
of	O
a	O
series	O
of	O
boreholes	O
drilled	O
recently	O
during	O
site	O
investigations	O
for	O
a	O
proposed	O
outfall	O
sewer	O
east	O
of	O
Gourock	O
Bay	O
-LSB-	O
NS	O
254	O
775	O
-RSB-	O
also	O
proved	O
red-brown	O
till	O
resting	O
upon	O
a	O
rock	O
platform	O
and	O
overlain	O
by	O
Flandrian	CHRONOSTRAT
raised	O
beach	O
deposits	O
.	O

The	O
landscape	O
of	O
the	O
Greenock	O
district	O
has	O
been	O
little	O
modified	O
during	O
the	O
10000	O
years	O
since	O
the	O
start	O
of	O
the	O
Flandrian	CHRONOSTRAT
Stage	O
.	O

From	O
evidence	O
outwith	O
the	O
area	O
,	O
the	O
sea	O
is	O
known	O
to	O
have	O
fallen	O
during	O
the	O
early	O
part	O
of	O
the	O
Flandrian	CHRONOSTRAT
.	O

In	O
the	O
Greenock	O
Outfall	O
Borehole	O
No.	O
20	O
-LSB-	O
NS	O
2624	O
7786	O
-RSB-	O
the	O
fauna	O
appears	O
to	O
be	O
predominantly	O
Flandrian	CHRONOSTRAT
but	O
the	O
presence	O
of	O
the	O
cold	O
water	O
bivalve	O
Yoldiella	O
fraterna	O
confirms	O
that	O
at	O
least	O
some	O
of	O
the	O
material	O
is	O
derived	O
.	O

Within	O
the	O
Greenock	O
district	O
the	O
Flandrian	CHRONOSTRAT
transgression	O
is	O
considered	O
to	O
have	O
reached	O
a	O
height	O
of	O
14m	O
above	O
OD	O
at	O
Rhu	O
and	O
about	O
15m	O
above	O
OD	O
at	O
Loch	O
Lomond	O
.	O

During	O
the	O
period	O
of	O
marine	O
regression	O
in	O
the	O
early	O
part	O
of	O
the	O
Flandrian	CHRONOSTRAT
,	O
peat	O
developed	O
on	O
low	O
ground	O
around	O
Linwood	O
,	O
a	O
little	O
east	O
of	O
the	O
district	O
.	O

Outside	O
the	O
trachytic	O
centre	O
,	O
in	O
the	O
overlying	O
basaltic	O
sequence	O
,	O
baryte	O
veins	O
and	O
irregular	O
pods	O
are	O
closely	O
associated	O
with	O
major	O
ESE-trending	O
faults	O
or	O
with	O
east	O
--	O
west	O
-	O
or	O
ENE-trending	O
late	O
Carboniferous	CHRONOSTRAT
quartz-dolerite	O
dykes	O
.	O

Copper	O
occurred	O
as	O
disseminations	O
of	O
malachite	O
in	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
at	O
two	O
localities	O
south	O
of	O
Gourock	O
,	O
Drumshantie	O
-LSB-	O
NS	O
240	O
766	O
-RSB-	O
and	O
Larkfield	O
-LSB-	O
NS	O
249	O
762	O
-RSB-	O
.	O

Hydrothermal	O
activity	O
was	O
obviously	O
prevalent	O
during	O
eruption	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
may	O
even	O
have	O
occurred	O
earlier	O
,	O
as	O
indicated	O
by	O
the	O
presence	O
of	O
copper	O
in	O
sediments	O
near	O
Gourock	O
.	O

However	O
,	O
many	O
veins	O
follow	O
ENE	O
-	O
to	O
ESE-trending	O
faults	O
and	O
some	O
permeate	O
late	O
Carboniferous	CHRONOSTRAT
quartz-dolerite	O
dykes	O
,	O
as	O
at	O
Kaim	O
.	O

These	O
baryte	O
and	O
copper	O
veins	O
probably	O
relate	O
to	O
an	O
episode	O
of	O
late	O
Carboniferous	CHRONOSTRAT
or	O
early	O
Permian	CHRONOSTRAT
hydrothermal	O
activity	O
which	O
was	O
responsible	O
for	O
the	O
emplacement	O
of	O
many	O
veins	O
of	O
similar	O
type	O
in	O
central	O
and	O
southern	O
Scotland	O
.	O

However	O
,	O
there	O
is	O
little	O
evidence	O
in	O
north-west	O
Europe	O
of	O
hydrothermal	O
activity	O
during	O
this	O
period	O
,	O
and	O
it	O
is	O
possible	O
that	O
the	O
mineral	O
veins	O
and	O
the	O
dykes	O
were	O
injected	O
at	O
different	O
times	O
into	O
a	O
system	O
of	O
fractures	O
which	O
may	O
date	O
from	O
late	O
Carboniferous	CHRONOSTRAT
times	O
.	O

Radiometric	O
,	O
suggest	O
that	O
the	O
main	O
phase	O
of	O
the	O
mineralisation	O
may	O
have	O
occurred	O
during	O
the	O
Triassic	CHRONOSTRAT
period	O
and	O
was	O
approximately	O
contemporaneous	O
with	O
the	O
emplacement	O
of	O
baryte	O
at	O
Strontian	O
,	O
in	O
Glen	O
Sannox	O
and	O
in	O
northern	O
England	O
.	O

The	O
potential	O
resources	O
of	O
crushed	O
rock	O
aggregate	O
in	O
the	O
area	O
are	O
restricted	O
to	O
the	O
metamorphic	O
rocks	O
in	O
the	O
Rosneath	O
peninsula	O
and	O
north-west	O
of	O
Helensburgh	O
,	O
the	O
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
in	O
the	O
Renfrewshire	O
Hills	O
,	O
and	O
dolerite	O
and	O
trachyte	O
intrusions	O
.	O

The	O
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
in	O
the	O
area	O
to	O
the	O
south	O
of	O
the	O
Clyde	O
,	O
are	O
mainly	O
of	O
basic	O
composition	O
and	O
are	O
included	O
in	O
the	O
`	O
Basalt	O
'	O
Group	O
of	O
the	O
British	O
Standard	O
Group	O
Classification	O
for	O
roadstone	O
.	O

,	O
some	O
15	O
--	O
20m	O
thick	O
,	O
intruded	O
in	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sediments	O
,	O
is	O
currently	O
being	O
worked	O
in	O
a	O
large	O
quarry	O
-LSB-	O
NS	O
409	O
635	O
-RSB-	O
near	O
Kilbarchan	O
.	O

In	O
the	O
district	O
,	O
limestone	O
occurs	O
in	O
the	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
and	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
,	O
in	O
the	O
Ballagan	LEXICON
Formation	LEXICON
,	O
and	O
in	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

There	O
are	O
also	O
thin	O
beds	O
of	O
limestone	O
in	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
.	O

The	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
a	O
shaly	O
limestone	O
up	O
to	O
12.7m	O
thick	O
at	O
the	O
base	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
,	O
was	O
worked	O
extensively	O
near	O
Bridge	O
of	O
Weir	O
-LSB-	O
NS	O
399	O
659	O
and	O
NS	O
399	O
654	O
-RSB-	O
and	O
in	O
the	O
Howwood	O
area	O
.	O

Although	O
it	O
is	O
much	O
thinner	O
,	O
the	O
Hollybush	LEXICON
Limestone	LEXICON
in	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
was	O
worked	O
in	O
quarries	O
-LSB-	O
NS	O
412	O
666	O
-RSB-	O
in	O
the	O
same	O
area	O
.	O

Limestone	O
in	O
the	O
Ballagan	LEXICON
Formation	LEXICON
was	O
worked	O
for	O
local	O
agricultural	O
purposes	O
near	O
Camis	O
Eskan	O
-LSB-	O
NS	O
335	O
821	O
-RSB-	O
.	O

Limestone	O
in	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
has	O
been	O
worked	O
near	O
Carman	O
Reservoir	O
-LSB-	O
NS	O
381	O
787	O
-RSB-	O
,	O
at	O
Inverkip	O
-LSB-	O
NS	O
205	O
718	O
-RSB-	O
and	O
in	O
Shielhill	O
Glen	O
-LSB-	O
NS	O
240	O
720	O
-RSB-	O
.	O

There	O
were	O
also	O
small	O
workings	O
in	O
thin	O
limestone	O
bands	O
within	O
the	O
Dunoon	LEXICON
Phyllite	LEXICON
in	O
Glen	O
Fruin	O
.	O

The	O
clays	O
and	O
silts	O
of	O
the	O
Linwood	LEXICON
Formation	LEXICON
in	O
the	O
area	O
to	O
the	O
east	O
of	O
the	O
district	O
have	O
been	O
extensively	O
used	O
in	O
the	O
manufacture	O
of	O
bricks	O
and	O
tiles	O
.	O

Within	O
the	O
district	O
,	O
the	O
Linwood	LEXICON
Formation	LEXICON
and	O
the	O
lithologically	O
similar	O
Balloch	LEXICON
Formation	LEXICON
are	O
mainly	O
confined	O
within	O
the	O
buried	O
channels	O
of	O
the	O
Clyde	O
and	O
Leven	O
.	O

Similar	O
mudstones	O
,	O
but	O
without	O
the	O
dolomitic	O
limestone	O
bands	O
,	O
occur	O
in	O
the	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
and	O
in	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
,	O
near	O
Bridge	O
of	O
Weir	O
.	O

Bright	O
red	O
or	O
carmine	O
sandstone	O
from	O
the	O
Stratheden	LEXICON
Group	LEXICON
near	O
Renton	O
-LSB-	O
NS	O
386	O
791	O
-RSB-	O
,	O
Bonhill	O
-LSB-	O
NS	O
398	O
787	O
-RSB-	O
and	O
Dumbarton	O
-LSB-	O
NS	O
388	O
760	O
-RSB-	O
was	O
used	O
locally	O
for	O
houses	O
and	O
churches	O
.	O

The	O
Kinnesswood	LEXICON
Formation	LEXICON
provided	O
a	O
pale	O
red	O
to	O
grey	O
freestone	O
near	O
Helensburgh	O
-LSB-	O
NS	O
311	O
840	O
,	O
NS	O
313	O
830	O
-RSB-	O
and	O
at	O
Dumbarton	O
-LSB-	O
NS	O
391	O
753	O
-RSB-	O
.	O

White	O
sandstone	O
of	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
was	O
worked	O
for	O
local	O
housing	O
in	O
Gourock	O
,	O
Greenock	O
and	O
Port	O
Glasgow	O
.	O

The	O
Hurlet	LEXICON
Coal	LEXICON
at	O
the	O
top	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
was	O
worked	O
near	O
Bridge	O
of	O
Weir	O
and	O
at	O
Howwood	O
,	O
and	O
the	O
alum	O
shale	O
in	O
the	O
roof	O
of	O
the	O
coal	O
was	O
probably	O
worked	O
at	O
the	O
same	O
time	O
.	O

The	O
Sandholes	LEXICON
Coal	LEXICON
at	O
Sandholes	O
-LSB-	O
NS	O
414	O
644	O
-RSB-	O
and	O
the	O
Quarrelton	LEXICON
Thick	LEXICON
Coal	LEXICON
near	O
Kilbarchan	O
were	O
also	O
exploited	O
to	O
a	O
small	O
extent	O
.	O

The	O
Lillie	LEXICON
's	LEXICON
Shale	LEXICON
Coal	LEXICON
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
,	O
which	O
contains	O
a	O
seam	O
of	O
oil	O
shale	O
as	O
well	O
as	O
coal	O
,	O
was	O
probably	O
mined	O
more	O
than	O
100	O
years	O
ago	O
in	O
the	O
area	O
between	O
Houston	O
and	O
Kilbarchan	O
.	O

The	O
Johnstone	LEXICON
Clayband	LEXICON
Ironstone	LEXICON
was	O
extensively	O
mined	O
over	O
a	O
century	O
ago	O
in	O
the	O
Saudholes	O
basin	O
-LSB-	O
NS	O
40	O
60	O
-RSB-	O
but	O
the	O
clayband	O
ironstones	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
do	O
not	O
appear	O
to	O
have	O
been	O
exploited	O
.	O

The	O
best	O
prospects	O
for	O
groundwater	O
are	O
considered	O
to	O
be	O
the	O
sandstones	O
of	O
the	O
Stratheden	LEXICON
and	O
Inverclyde	LEXICON
groups	O
,	O
from	O
which	O
yields	O
of	O
up	O
to	O
10	O
litres	O
per	O
second	O
might	O
be	O
expected	O
.	O

The	O
36m	O
of	O
strata	O
drilled	O
below	O
the	O
base	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
in	O
the	O
BGS	O
`	O
Tak-ma-doon	O
'	O
Borehole	O
-LSB-	O
NS	O
7291	O
8053	O
-RSB-	O
,	O
Figure	O
3	O
,	O
have	O
been	O
assigned	O
to	O
the	O
Stratheden	LEXICON
Group	LEXICON
and	O
are	O
thought	O
to	O
be	O
of	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
age	O
.	O

There	O
is	O
an	O
abrupt	O
change	O
at	O
the	O
base	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
from	O
red	O
,	O
and	O
grey-purple	O
medium	O
-	O
and	O
coarse-grained	O
sandstones	O
with	O
scattered	O
mudstone	O
clasts	O
and	O
quartz	O
pebbles	O
to	O
fine	O
-	O
and	O
medium-grained	O
whitish	O
,	O
pale	O
green	O
or	O
pink	O
sandstones	O
without	O
clasts	O
or	O
pebbles	O
.	O

These	O
sandstones	O
are	O
very	O
similar	O
in	O
lithology	O
to	O
those	O
assigned	O
to	O
the	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
which	O
occurs	O
at	O
the	O
same	O
stratigraphic	O
horizon	O
along	O
the	O
northern	O
side	O
of	O
the	O
Gargunnock	O
Hills	O
,	O
some	O
6km	O
to	O
the	O
north	O
of	O
the	O
present	O
area	O
.	O

Almost	O
the	O
entire	O
area	O
of	O
the	O
Airdrie	O
District	O
is	O
underlain	O
by	O
strata	O
of	O
Carboniferous	CHRONOSTRAT
age	O
.	O

These	O
strata	O
,	O
which	O
are	O
mainly	O
red	O
and	O
white	O
sandstones	O
with	O
thin	O
beds	O
of	O
concretionary	O
limestone	O
,	O
were	O
deposited	O
in	O
an	O
environment	O
transitional	O
between	O
the	O
arid	O
or	O
semi-arid	O
conditions	O
in	O
which	O
the	O
red	O
fluvial	O
and	O
aeolian	O
sandstones	O
of	O
the	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
were	O
laid	O
down	O
and	O
the	O
humid	O
environment	O
in	O
which	O
the	O
mainly	O
grey	O
fluviodeltaic	O
and	O
marine	O
Carboniferous	CHRONOSTRAT
rocks	O
were	O
deposited	O
.	O

Thus	O
,	O
the	O
name	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
,	O
replaces	O
the	O
term	O
Lower	LEXICON
Limestone	LEXICON
Group	LEXICON
.	O

This	O
part	O
of	O
the	O
succession	O
includes	O
all	O
the	O
strata	O
up	O
to	O
base	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
traditionally	O
taken	O
as	O
the	O
top	O
of	O
the	O
Calciferous	LEXICON
Sandstone	LEXICON
Measures	LEXICON
.	O

This	O
has	O
been	O
renamed	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
and	O
has	O
been	O
placed	O
in	O
the	O
Clackmannan	LEXICON
Group	LEXICON
.	O

Two	O
marine	O
bands	O
and	O
several	O
Lingula	O
bands	O
are	O
present	O
but	O
marine	O
limestones	O
do	O
not	O
occur	O
in	O
these	O
rocks	O
which	O
are	O
referred	O
to	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
.	O

Stratigraphically	O
above	O
is	O
a	O
succession	O
of	O
dominantly	O
arenaceous	O
cyclotherms	O
with	O
mudstones	O
,	O
marine	O
limestones	O
and	O
thin	O
coals	O
forming	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

The	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
,	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
,	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
and	O
the	O
Passage	LEXICON
Formation	LEXICON
have	O
been	O
assigned	O
to	O
the	O
newly	O
erected	O
Clackmannan	LEXICON
Group	LEXICON
.	O

The	O
Lower	LEXICON
,	O
Middle	LEXICON
and	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
considered	O
to	O
be	O
informal	O
units	O
and	O
are	O
placed	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
.	O

The	O
Ballagan	LEXICON
Formation	LEXICON
is	O
placed	O
in	O
the	O
CM	O
miospore	O
zone	O
,	O
the	O
earliest	O
zone	O
which	O
can	O
be	O
recognised	O
in	O
Scotland	O
.	O

At	O
least	O
two	O
lower	O
Carboniferous	CHRONOSTRAT
zones	O
can	O
be	O
recognised	O
elsewhere	O
;	O
in	O
this	O
area	O
these	O
lower	O
zones	O
are	O
thought	O
to	O
be	O
represented	O
by	O
at	O
least	O
the	O
top	O
part	O
of	O
the	O
unfossiliferous	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

This	O
goniatite	O
has	O
not	O
been	O
found	O
in	O
Scotland	O
and	O
the	O
base	O
of	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
has	O
been	O
taken	O
at	O
a	O
suitable	O
arbitrary	O
position	O
which	O
within	O
the	O
present	O
district	O
is	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
strata	O
are	O
assigned	O
to	O
the	O
Inverclyde	LEXICON
Group	LEXICON
comprising	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
the	O
Ballagan	LEXICON
Formation	LEXICON
and	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
;	O
the	O
Strathclyde	LEXICON
Group	LEXICON
consisting	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
the	O
Kirkwood	LEXICON
Formation	LEXICON
,	O
and	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
;	O
and	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
,	O
the	O
lowest	O
of	O
the	O
Clackmannan	LEXICON
Group	LEXICON
.	O

These	O
are	O
assigned	O
to	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
the	O
lowest	O
unit	O
of	O
the	O
Inverclyde	LEXICON
Group	LEXICON
.	O

The	O
only	O
good	O
exposures	O
of	O
Kinnesswood	LEXICON
Formation	LEXICON
strata	O
within	O
the	O
present	O
district	O
occur	O
in	O
the	O
Garrel	O
Burn	O
,	O
about	O
2km	O
north	O
of	O
Kilsyth	O
.	O

The	O
top	O
50m	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
,	O
seen	O
further	O
up	O
stream	O
,	O
comprises	O
medium-grained	O
red-yellow	O
and	O
grey-purple	O
sandstones	O
interbedded	O
with	O
dark	O
red	O
or	O
purplish	O
fine-grained	O
sandstones	O
,	O
siltstones	O
and	O
mudstones	O
.	O

A	O
complete	O
sequence	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
was	O
drilled	O
nearby	O
in	O
the	O
BGS	O
Tak-ma-doon	O
Borehole	O
-LSB-	O
NS	O
7291	O
8053	O
-RSB-	O
where	O
the	O
thickness	O
was	O
found	O
to	O
be	O
146m	O
.	O

The	O
succeeding	O
Ballagan	LEXICON
Formation	LEXICON
,	O
consisting	O
of	O
grey	O
mudstones	O
with	O
thin	O
nodular	O
beds	O
of	O
dolomitic	O
limestone	O
,	O
was	O
deposited	O
in	O
a	O
coastal	O
plain	O
environment	O
subject	O
to	O
fluctuating	O
salinity	O
and	O
periodic	O
dessication	O
.	O

There	O
are	O
no	O
good	O
natural	O
sections	O
of	O
Ballagan	LEXICON
Formation	LEXICON
strata	O
in	O
the	O
present	O
district	O
.	O

The	O
BGS	O
Tak-ma-doon	O
Borehole	O
-LSB-	O
NS	O
7291	O
8053	O
-RSB-	O
proved	O
the	O
Ballagan	LEXICON
Formation	LEXICON
to	O
be	O
only	O
20m	O
thick	O
in	O
that	O
area	O
and	O
2km	O
to	O
the	O
west	O
,	O
in	O
the	O
Balhille	O
Burn	O
-LSB-	O
NS	O
707	O
793	O
-RSB-	O
,	O
the	O
lowest	O
flow	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
appears	O
to	O
lie	O
directly	O
on	O
sediments	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
.	O

The	O
only	O
fossils	O
which	O
have	O
been	O
found	O
in	O
Ballagan	LEXICON
Formation	LEXICON
strata	O
in	O
the	O
present	O
district	O
are	O
ostracods	O
;	O
an	O
isolated	O
fish	O
scale	O
in	O
the	O
Tak-ma-doon	O
Borehole	O
and	O
one	O
occurrence	O
of	O
an	O
algal	O
limestone	O
with	O
?	O

The	O
sandstones	O
are	O
coarser	O
than	O
those	O
of	O
the	O
Kinnesswood	LEXICON
Formation	LEXICON
and	O
though	O
commonly	O
calcareous	O
and	O
concretionary	O
,	O
do	O
not	O
develop	O
true	O
cornstones	O
.	O

The	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
only	O
present	O
in	O
small	O
areas	O
near	O
Fintry	O
and	O
south	O
of	O
the	O
Carron	O
Valley	O
Reservoir	O
.	O

South	O
of	O
the	O
Carron	O
Valley	O
Resevoir	O
-LSB-	O
NS	O
685	O
832	O
-RSB-	O
poor	O
exposures	O
of	O
sandstones	O
with	O
a	O
concretionary	O
limestone	O
have	O
been	O
assigned	O
to	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
but	O
4km	O
to	O
the	O
west	O
they	O
appear	O
to	O
be	O
absent	O
in	O
the	O
Clachie	O
Bridge	O
Borehole	O
.	O

A	O
period	O
of	O
localised	O
uplift	O
and	O
erosion	O
at	O
the	O
beginning	O
of	O
Strathclyde	LEXICON
Group	LEXICON
times	O
was	O
followed	O
by	O
a	O
major	O
volcanic	O
episode	O
which	O
produced	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
of	O
the	O
Kilsyth	O
and	O
Cathkin	O
Hills	O
.	O

The	O
lavas	O
comprising	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
are	O
predominantly	O
olivine-basalt	O
of	O
Markle	O
and	O
Jedburgh	O
types	O
,	O
with	O
subordinate	O
trachybasalt	O
and	O
mugearite	O
,	O
and	O
were	O
erupted	O
from	O
different	O
centres	O
at	O
different	O
times	O
.	O

Elsewhere	O
,	O
at	O
this	O
time	O
,	O
the	O
largely	O
fluvial	O
sandstones	O
,	O
siltstones	O
and	O
mudstones	O
of	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
,	O
were	O
being	O
deposited	O
.	O

The	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
marks	O
the	O
most	O
extensive	O
of	O
a	O
series	O
of	O
volcanic	O
episodes	O
which	O
took	O
place	O
during	O
the	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
in	O
the	O
Midland	O
Valley	O
of	O
Scotland	O
.	O

In	O
contrast	O
,	O
on	O
the	O
north	O
scarp	O
of	O
the	O
Touch	O
-	O
Gargunnock	O
Hills	O
some	O
5km	O
to	O
the	O
north	O
,	O
the	O
volcanic	O
formation	O
apparently	O
overlies	O
the	O
Clyde	LEXICON
Sandstone	LEXICON
Formation	LEXICON
without	O
angular	O
unconformity	O
.	O

These	O
necks	O
are	O
thought	O
to	O
have	O
been	O
active	O
at	O
about	O
the	O
same	O
time	O
as	O
the	O
North	LEXICON
Campsie	LEXICON
Linear	LEXICON
Vent	LEXICON
System	LEXICON
and	O
also	O
to	O
be	O
major	O
sources	O
of	O
the	O
early	O
Jedburgh	O
type	O
lavas	O
.	O

These	O
necks	O
are	O
thought	O
to	O
have	O
produced	O
trachybasalt	O
and	O
Jedburgh	O
type	O
lavas	O
contemporary	O
with	O
the	O
second	O
phase	O
of	O
effusion	O
from	O
the	O
North	LEXICON
Campsie	LEXICON
Linear	LEXICON
Vent	LEXICON
System	LEXICON
.	O

This	O
system	O
lies	O
parallel	O
to	O
and	O
about	O
1km	O
to	O
the	O
south	O
of	O
the	O
Gonachen	LEXICON
Glen	LEXICON
Linear	LEXICON
Vent	LEXICON
System	LEXICON
.	O

The	O
stratigraphic	O
level	O
of	O
this	O
tephra	O
deposit	O
indicates	O
extrusive	O
activity	O
immediately	O
prior	O
to	O
,	O
or	O
contemporaneous	O
with	O
,	O
the	O
earliest	O
flows	O
from	O
the	O
Waterhead	O
Central	O
Volcano	O
.	O

The	O
neck	O
on	O
the	O
eastern	O
slopes	O
of	O
Dungoil	O
-LSB-	O
NS	O
640	O
842	O
-RSB-	O
is	O
not	O
included	O
in	O
the	O
linear	O
vent	O
system	O
but	O
is	O
thought	O
to	O
be	O
related	O
to	O
the	O
younger	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
Complex	LEXICON
.	O

During	O
later	O
stages	O
in	O
the	O
vulcanicity	O
activity	O
became	O
focussed	O
in	O
one	O
central	O
area	O
,	O
the	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
Complex	LEXICON
.	O

The	O
tephra	O
deposits	O
on	O
Meikle	O
Bin	O
-LSB-	O
NS	O
667	O
822	O
-RSB-	O
are	O
part	O
of	O
the	O
Waterhead	O
Complex	O
.	O

Most	O
lie	O
within	O
the	O
linear	O
vent	O
systems	O
with	O
which	O
they	O
share	O
the	O
same	O
trend	O
,	O
or	O
are	O
related	O
to	O
the	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
complex	LEXICON
where	O
they	O
lack	O
any	O
preferred	O
orientation	O
.	O

Some	O
lava	O
may	O
have	O
been	O
extruded	O
by	O
fissures	O
now	O
filled	O
by	O
dykes	O
such	O
as	O
the	O
one	O
in	O
Fin	O
Glen	O
,	O
but	O
the	O
evidence	O
from	O
the	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
Complex	LEXICON
suggests	O
that	O
most	O
of	O
this	O
type	O
of	O
lava	O
was	O
erupted	O
from	O
there	O
,	O
with	O
minor	O
additions	O
from	O
small	O
necks	O
such	O
as	O
the	O
one	O
on	O
the	O
north	O
shore	O
of	O
Loch	O
Carron	O
.	O

In	O
the	O
Forking	O
Burn	O
section	O
,	O
the	O
base	O
of	O
the	O
group	O
rests	O
on	O
a	O
thin	O
tephra	O
horizon	O
which	O
lies	O
on	O
sediments	O
of	O
the	O
Ballagan	LEXICON
Formation	LEXICON
.	O

The	O
group	O
is	O
thought	O
to	O
be	O
derived	O
from	O
the	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
Complex	LEXICON
.	O

The	O
petrography	O
of	O
the	O
basal	O
trachyte	O
is	O
very	O
similar	O
to	O
that	O
of	O
the	O
plug	O
of	O
phonolitic	O
trachyte	O
near	O
Fintry	O
-LSB-	O
NS	O
614	O
863	O
-RSB-	O
which	O
is	O
part	O
of	O
the	O
North	LEXICON
Campsie	LEXICON
Linear	LEXICON
Vent	LEXICON
System	LEXICON
and	O
which	O
may	O
be	O
the	O
source	O
of	O
the	O
lava	O
.	O

The	O
proximal	O
facies	O
sequence	O
exposed	O
to	O
the	O
north-east	O
of	O
Lecket	O
Hill	O
-LSB-	O
NS	O
647	O
813	O
-RSB-	O
suggests	O
derivation	O
from	O
the	O
adjacent	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
Complex	LEXICON
.	O

They	O
occur	O
in	O
geographically	O
isolated	O
areas	O
but	O
are	O
all	O
considered	O
to	O
represent	O
parts	O
of	O
the	O
large	O
central	O
volcano	O
which	O
developed	O
around	O
the	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
Complex	LEXICON
.	O

The	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
is	O
present	O
at	O
outcrop	O
intermittently	O
in	O
a	O
WSW-ENE	O
belt	O
across	O
the	O
northern	O
part	O
of	O
the	O
sheet	O
,	O
from	O
Lennoxtown	O
to	O
the	O
northeast	O
corner	O
.	O

The	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
is	O
much	O
more	O
uniform	O
than	O
the	O
underlying	O
Lawmuir	LEXICON
Formation	LEXICON
.	O

Non-marine	O
limestones	O
with	O
ostracods	O
occur	O
below	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
and	O
were	O
formerly	O
regarded	O
as	O
part	O
of	O
it	O
,	O
but	O
the	O
name	O
is	O
now	O
restricted	O
to	O
the	O
marine	O
limestone	O
only	O
.	O

The	O
lowest	O
cycle	O
starts	O
with	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
a	O
crinoidal	O
bioclastic	O
bed	O
that	O
is	O
visible	O
at	O
Finniescroft	O
-LSB-	O
NS	O
6232	O
7685	O
-RSB-	O
and	O
is	O
usually	O
0.75	O
-	O
1.5m	O
thick	O
,	O
but	O
is	O
up	O
to	O
3.7m	O
thick	O
at	O
Sculliongour	O
-LSB-	O
NS	O
63	O
79	O
-RSB-	O
and	O
up	O
to	O
6.5m	O
at	O
Corrieburn	O
-LSB-	O
NS	O
68	O
79	O
-RSB-	O
.	O

It	O
was	O
quarried	O
and	O
mined	O
,	O
together	O
with	O
the	O
underlying	O
Alum	LEXICON
Shale	LEXICON
and	O
Hurlet	LEXICON
Coal	LEXICON
,	O
at	O
Sculliongour	O
and	O
more	O
extensively	O
north	O
of	O
Milton	O
of	O
Campsie	O
and	O
south	O
of	O
Lennoxtown	O
on	O
the	O
South	O
Brae	O
of	O
Campsie	O
.	O

In	O
the	O
Lennoxtown	O
area	O
10m	O
of	O
mudstones	O
occupy	O
the	O
whole	O
of	O
the	O
interval	O
between	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
and	O
the	O
Shields	O
Bed	O
at	O
the	O
base	O
of	O
the	O
overlying	O
cycle	O
.	O

Indeed	O
,	O
in	O
this	O
area	O
the	O
Shields	LEXICON
Bed	LEXICON
and	O
some	O
clayband	O
ironstones	O
are	O
the	O
only	O
other	O
beds	O
to	O
occur	O
in	O
40m	O
of	O
mudstones	O
between	O
the	O
Hurlet	LEXICON
and	O
Blackhall	LEXICON
Limestones	LEXICON
.	O

The	O
upper	O
one	O
is	O
a	O
shelly	O
bed	O
1.1m	O
thick	O
that	O
weathers	O
to	O
rottenstone	O
-LSB-	O
NS	O
6855	O
7924	O
-RSB-	O
and	O
lies	O
immediately	O
below	O
the	O
Shields	LEXICON
Bed	LEXICON
.	O

The	O
Shields	LEXICON
Bed	LEXICON
is	O
a	O
sandy	O
crinoidal	O
limestone	O
up	O
to	O
1.34m	O
thick	O
which	O
thins	O
westwards	O
and	O
dies	O
out	O
near	O
the	O
western	O
margin	O
of	O
the	O
sheet	O
.	O

This	O
interval	O
also	O
contains	O
the	O
Campsie	LEXICON
Clayband	LEXICON
Ironstones	LEXICON
and	O
,	O
locally	O
,	O
at	O
the	O
top	O
several	O
beds	O
of	O
non-marine	O
limestone	O
with	O
abundant	O
ostracods	O
.	O

This	O
cycle	O
occupies	O
the	O
interval	O
from	O
the	O
base	O
of	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
to	O
the	O
Milngavie	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
Blackhall	LEXICON
Limestone	LEXICON
is	O
a	O
persistent	O
,	O
bioclastic	O
,	O
crinoidal	O
limestone	O
,	O
generally	O
0.45	O
-	O
0.65m	O
thick	O
.	O

The	O
mudstone	O
above	O
the	O
limestone	O
contains	O
the	O
Neilson	LEXICON
Shell	LEXICON
Bed	LEXICON
and	O
a	O
few	O
solitary	O
corals	O
.	O

Two	O
other	O
deep	O
boreholes	O
,	O
Bedlay	O
No.	O
2	O
-LSB-	O
NS	O
7139	O
7064	O
-RSB-	O
and	O
Auchinbee	O
No.	O
1	O
-LSB-	O
NS	O
7323	O
7566	O
-RSB-	O
also	O
reached	O
the	O
Blackhall	LEXICON
Limestone	LEXICON
.	O

In	O
this	O
last	O
area	O
the	O
sandstone	O
may	O
be	O
continuous	O
with	O
the	O
Hosie	LEXICON
Sandstone	LEXICON
in	O
the	O
absence	O
of	O
the	O
Milngavie	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
Milngavie	LEXICON
Marine	LEXICON
Band	LEXICON
shows	O
a	O
very	O
varied	O
development	O
.	O

The	O
correlation	O
suggested	O
therein	O
with	O
the	O
Mill	LEXICON
Hill	LEXICON
Marine	LEXICON
Band	LEXICON
of	O
west	O
Fife	O
is	O
now	O
regarded	O
as	O
correct	O
.	O

A	O
crinoidal	O
limestone	O
0.3m	O
thick	O
in	O
Cardowan	O
No.	O
13	O
Borehole	O
may	O
be	O
the	O
Milngavie	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
but	O
it	O
appears	O
to	O
be	O
rather	O
high	O
in	O
the	O
succession	O
.	O

It	O
passes	O
up	O
through	O
siltstone	O
and	O
silty	O
sandstone	O
into	O
the	O
Hosie	LEXICON
Sandstone	LEXICON
,	O
a	O
mainly	O
medium-grained	O
bed	O
up	O
to	O
13m	O
thick	O
.	O

The	O
latter	O
also	O
has	O
a	O
coal	O
2.5cm	O
thick	O
just	O
below	O
the	O
Main	LEXICON
Hosie	LEXICON
Limestone	LEXICON
.	O

The	O
top	O
three	O
cycles	O
in	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
are	O
much	O
thinner	O
than	O
the	O
preceding	O
four	O
.	O

Each	O
starts	O
with	O
one	O
of	O
the	O
Hosie	LEXICON
Limestones	LEXICON
and	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
completes	O
the	O
group	O
.	O

The	O
Main	LEXICON
Hosie	LEXICON
cycle	O
is	O
6.7	O
to	O
10.6m	O
thick	O
,	O
the	O
Mid	LEXICON
Hosie	LEXICON
cycle	O
12	O
to	O
15m	O
and	O
the	O
Second	LEXICON
Hosie	LEXICON
Cycle	O
2.4	O
to	O
7m	O
.	O

Sandstone	O
does	O
not	O
occur	O
at	O
all	O
between	O
the	O
Second	LEXICON
and	O
Top	LEXICON
Hosie	LEXICON
Limestones	LEXICON
.	O

The	O
Main	LEXICON
,	O
Mid	LEXICON
and	O
Second	LEXICON
Hosie	LEXICON
limestones	O
are	O
all	O
bioclastic	O
and	O
crinoidal	O
.	O

The	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
is	O
of	O
the	O
cementstone	O
type	O
,	O
that	O
is	O
,	O
highly	O
argillaceous	O
,	O
fine-grained	O
and	O
less	O
conspicuously	O
fossiliferous	O
than	O
the	O
other	O
limestones	O
.	O

The	O
Main	LEXICON
Hosie	LEXICON
cycle	O
has	O
the	O
richest	O
fauna	O
and	O
is	O
the	O
only	O
one	O
to	O
include	O
corals	O
and	O
bryozoa	O
.	O

The	O
Main	LEXICON
Hosie	LEXICON
Limestone	LEXICON
is	O
exposed	O
in	O
one	O
of	O
the	O
headwaters	O
of	O
both	O
the	O
Spouthead	O
burn	O
-LSB-	O
NS	O
6549	O
7844	O
-RSB-	O
and	O
the	O
Banton	O
burn	O
-LSB-	O
NS	O
7399	O
8026	O
-RSB-	O
,	O
and	O
in	O
a	O
decalcified	O
state	O
in	O
the	O
River	O
Carron	O
-LSB-	O
NS	O
7918	O
8328	O
-RSB-	O
.	O

The	O
Second	LEXICON
Hosie	LEXICON
Limestone	LEXICON
is	O
visible	O
in	O
the	O
Burniebrae	O
Burn	O
-LSB-	O
NS	O
6605	O
7816	O
-RSB-	O
,	O
the	O
Banton	O
Burn	O
-LSB-	O
NS	O
7403	O
8021	O
-RSB-	O
and	O
the	O
River	O
Carron	O
-LSB-	O
NS	O
7922	O
8325	O
-RSB-	O
.	O

The	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
is	O
the	O
best	O
displayed	O
in	O
Burniebrae	O
Burn	O
-LSB-	O
NS	O
6605	O
7818	O
-RSB-	O
,	O
two	O
unnamed	O
streamlets	O
-LSB-	O
NS	O
6750	O
7778	O
,	O
NS	O
6821	O
7808	O
-RSB-	O
,	O
the	O
eastern	O
burn	O
at	O
Corrieburn	O
-LSB-	O
NS	O
6870	O
7874	O
-RSB-	O
,	O
Banton	O
Burn	O
-LSB-	O
NS	O
7403	O
8017	O
-RSB-	O
and	O
the	O
River	O
Carron	O
-LSB-	O
NS	O
7925	O
8324	O
-RSB-	O
.	O

The	O
section	O
is	O
as	O
follows	O
:	O
metres	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
,	O
with	O
brachiopods	O
and	O
gastropods	O
0.30	O
Calcareous	O
mudstone	O
with	O
productoids	O
0.81	O
Dark	O
mudstone	O
with	O
Posidonia	O
corrugata	O
2.19	O
Second	O
Hosie	O
Limestone	O
,	O
crinoidal	O
0.51	O
Mudstone	O
,	O
shelly	O
and	O
crinoidal	O
at	O
top	O
;	O
rest	O
carbonaceous	O
rooty	O
in	O
places	O
1.19	O
Mudstone	O
,	O
shelly	O
,	O
with	O
Lingula	O
,	O
productoids	O
,	O
and	O
bivalves	O
but	O
the	O
coal	O
and	O
three	O
of	O
the	O
limestones	O
are	O
present	O
,	O
with	O
the	O
fourth	O
represented	O
by	O
a	O
marine	O
band	O
.	O

Northward	O
thinning	O
of	O
units	O
plus	O
changes	O
in	O
facies	O
,	O
for	O
instance	O
of	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
,	O
suggest	O
that	O
the	O
northern	O
part	O
of	O
the	O
sheet	O
may	O
have	O
escaped	O
some	O
of	O
the	O
marine	O
invasions	O
.	O

The	O
Upper	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
strata	O
are	O
assigned	O
to	O
two	O
groups	O
,	O
firstly	O
the	O
upper	O
part	O
of	O
the	O
Clackmannan	LEXICON
Group	LEXICON
comprising	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
,	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
and	O
the	O
Passage	O
Formation	O
,	O
secondly	O
the	O
informal	O
group	O
,	O
the	O
Coal	LEXICON
Measures	LEXICON
which	O
is	O
made	O
up	O
of	O
the	O
Lower	LEXICON
,	O
Middle	LEXICON
and	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

The	O
boundary	O
between	O
the	O
two	O
lithostratigraphic	O
divisions	O
almost	O
coincides	O
with	O
the	O
Namurian	CHRONOSTRAT
and	O
Westphalian	CHRONOSTRAT
boundary	O
.	O

The	O
Silesian	CHRONOSTRAT
part	O
of	O
the	O
Clackmannan	LEXICON
Group	LEXICON
,	O
which	O
consists	O
of	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
,	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
,	O
and	O
the	O
Passage	LEXICON
Formation	LEXICON
,	O
is	O
characterised	O
by	O
the	O
continuation	O
of	O
the	O
deposition	O
of	O
cyclothematic	O
sediments	O
which	O
started	O
in	O
the	O
upper	O
Dinantian	CHRONOSTRAT
.	O

The	O
top	O
of	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
is	O
taken	O
at	O
the	O
base	O
of	O
the	O
Index	LEXICON
Limestone	LEXICON
,	O
the	O
top	O
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
at	O
the	O
top	O
of	O
the	O
Castlecary	LEXICON
Limestone	LEXICON
,	O
and	O
the	O
top	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
at	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
Limestone	CHRONOSTRAT
Coal	CHRONOSTRAT
Formation	CHRONOSTRAT
is	O
the	O
lowest	O
part	O
of	O
the	O
Namurian	CHRONOSTRAT
sequence	O
and	O
belongs	O
entirely	O
to	O
the	O
Pendleian	CHRONOSTRAT
.	O

Exposures	O
are	O
largely	O
confined	O
to	O
streams	O
flowing	O
off	O
the	O
Kilsyth	O
Hills	O
such	O
as	O
Queenzie	O
Burn	O
,	O
where	O
the	O
Black	LEXICON
Metals	LEXICON
are	O
visible	O
at	O
-LSB-	O
NS	O
694	O
786	O
-RSB-	O
,	O
the	O
Garrel	O
Burn	O
,	O
the	O
Banton	O
Burn	O
,	O
where	O
much	O
of	O
the	O
lower	O
part	O
of	O
the	O
group	O
can	O
be	O
seen	O
above	O
Banton	O
-LSB-	O
NS	O
750	O
792	O
-RSB-	O
,	O
and	O
locally	O
along	O
the	O
Castlerankine	O
Burn	O
and	O
the	O
River	O
Carron	O
,	O
both	O
of	O
which	O
traverse	O
the	O
whole	O
of	O
the	O
formation	O
.	O

Coals	O
are	O
largely	O
,	O
but	O
not	O
entirely	O
,	O
confined	O
to	O
that	O
part	O
of	O
the	O
sequence	O
between	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
and	O
the	O
Black	LEXICON
Metals	LEXICON
,	O
and	O
they	O
are	O
generally	O
thicker	O
than	O
in	O
the	O
west	O
.	O

The	O
Kilsyth	LEXICON
Coking	LEXICON
Coal	LEXICON
in	O
particular	O
thickens	O
markedly	O
to	O
1.5m	O
around	O
Kilsyth	O
,	O
a	O
thickness	O
only	O
exceeded	O
in	O
the	O
upper	O
part	O
of	O
the	O
formation	O
by	O
the	O
Bannockburn	LEXICON
Main	LEXICON
Coal	LEXICON
around	O
Dunipace	O
.	O

Clayband	O
ironstones	O
are	O
less	O
abundant	O
than	O
to	O
the	O
west	O
of	O
the	O
district	O
except	O
in	O
the	O
Black	LEXICON
Metals	LEXICON
in	O
the	O
Banton	O
area	O
where	O
nine	O
occur	O
,	O
three	O
of	O
which	O
were	O
formerly	O
worked	O
.	O

The	O
Garibaldi	LEXICON
Clayband	LEXICON
Ironstone	LEXICON
was	O
mined	O
at	O
Banton	O
as	O
the	O
Finestone	O
,	O
but	O
the	O
Johnstone	LEXICON
Clayband	LEXICON
Ironstone	LEXICON
is	O
thin	O
or	O
absent	O
.	O

It	O
is	O
the	O
equivalent	O
of	O
the	O
Lower	LEXICON
Garscadden	LEXICON
Ironstone	LEXICON
of	O
Sheet	O
30E	O
:	O
there	O
is	O
no	O
equivalent	O
of	O
the	O
Upper	LEXICON
Garscadden	LEXICON
Ironstone	LEXICON
in	O
the	O
present	O
district	O
.	O

The	O
cycle	O
that	O
starts	O
with	O
the	O
Kilsyth	LEXICON
Cloven	LEXICON
Coal	LEXICON
is	O
usually	O
the	O
thickest	O
.	O

The	O
most	O
extensively	O
mined	O
of	O
the	O
coals	O
is	O
the	O
Meiklehill	LEXICON
Main	LEXICON
,	O
which	O
is	O
rivalled	O
in	O
thickness	O
only	O
by	O
the	O
Bannockburn	LEXICON
Main	LEXICON
Coal	LEXICON
of	O
Dunipace	O
and	O
the	O
Kilsyth	LEXICON
Coking	LEXICON
Coal	LEXICON
in	O
the	O
lower	O
part	O
of	O
the	O
formation	O
.	O

Other	O
extensively	O
mined	O
seams	O
include	O
the	O
Kilsyth	LEXICON
Cloven	LEXICON
,	O
Dumbreck	LEXICON
Cloven	LEXICON
and	O
Meiklehill	LEXICON
Wee	LEXICON
coals	O
.	O

Nine	O
of	O
the	O
coals	O
pass	O
laterally	O
into	O
blackband	O
ironstones	O
,	O
six	O
of	O
which	O
were	O
mined	O
,	O
the	O
Kilsyth	LEXICON
No.	LEXICON
3	LEXICON
seam	O
quite	O
extensively	O
.	O

The	O
Banton	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
in	O
the	O
lower	O
part	O
of	O
the	O
formation	O
is	O
also	O
of	O
local	O
occurrence	O
.	O

The	O
Cowlairs	LEXICON
Sandstone	LEXICON
at	O
the	O
top	O
of	O
the	O
formation	O
,	O
on	O
the	O
other	O
hand	O
,	O
is	O
generally	O
absent	O
along	O
the	O
northern	O
margin	O
of	O
the	O
outcrop	O
and	O
is	O
best	O
developed	O
at	O
its	O
type	O
locality	O
in	O
northern	O
Glasgow	O
.	O

The	O
most	O
persistent	O
sandstone	O
in	O
the	O
upper	O
part	O
of	O
the	O
formation	O
is	O
the	O
Nitshill	LEXICON
Sandstone	LEXICON
which	O
reaches	O
20m	O
in	O
thickness	O
.	O

It	O
cuts	O
out	O
the	O
underlying	O
Ashfield	LEXICON
Rider	LEXICON
Coal	LEXICON
and	O
at	O
its	O
thickest	O
,	O
its	O
incompactibility	O
prevented	O
the	O
Fourteen-Inch	LEXICON
Under	LEXICON
Coal	LEXICON
,	O
together	O
with	O
its	O
seatearth	O
and	O
overlying	O
mudstone	O
,	O
from	O
developing	O
.	O

Other	O
thicker	O
and	O
coarser	O
sandstones	O
locally	O
cut	O
out	O
the	O
Possil	LEXICON
Wee	LEXICON
and	O
Possil	LEXICON
Rider	LEXICON
coals	O
and	O
the	O
Berryhills	LEXICON
Limestone	LEXICON
,	O
mainly	O
along	O
the	O
northern	O
margin	O
of	O
the	O
outcrop	O
from	O
Torrance	O
-LSB-	O
NS	O
620	O
742	O
-RSB-	O
to	O
Dunipace	O
.	O

The	O
depositional	O
basin	O
continued	O
to	O
subside	O
during	O
the	O
deposition	O
of	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
but	O
marine	O
influences	O
were	O
much	O
weaker	O
than	O
in	O
the	O
underlying	O
formation	O
.	O

Increased	O
subsidence	O
brought	O
about	O
the	O
major	O
marine	O
incursion	O
represented	O
by	O
the	O
Johnstone	LEXICON
Shell	LEXICON
Bed	LEXICON
but	O
only	O
in	O
the	O
southeast	O
corner	O
of	O
the	O
Sheet	O
was	O
the	O
sea	O
clear	O
enough	O
to	O
permit	O
even	O
impure	O
limestone	O
to	O
form	O
.	O

The	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
occurs	O
in	O
most	O
of	O
the	O
central	O
and	O
southern	O
parts	O
of	O
the	O
Sheet	O
,	O
largely	O
at	O
the	O
crop	O
in	O
the	O
central	O
parts	O
,	O
and	O
buried	O
below	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
southern	O
part	O
.	O

The	O
lower	O
part	O
of	O
the	O
group	O
belongs	O
to	O
the	O
Pendleian	CHRONOSTRAT
.	O

The	O
Index	LEXICON
Limestone	LEXICON
is	O
rather	O
poorly	O
exposed	O
in	O
the	O
Castlerankine	O
Burn	O
-LSB-	O
NS	O
7952	O
8228	O
-RSB-	O
and	O
is	O
seen	O
to	O
be	O
baked	O
hard	O
by	O
an	O
underlying	O
sill	O
at	O
Craigroot	O
Quarry	O
-LSB-	O
NS	O
691	O
776	O
-RSB-	O
and	O
beside	O
the	O
adjacent	O
Queenzie	O
Burn	O
.	O

Here	O
,	O
the	O
overlying	O
mudstones	O
are	O
6	O
to	O
8m	O
thick	O
and	O
the	O
Bishopbriggs	LEXICON
Sandstone	LEXICON
has	O
conspicuous	O
laminated	O
burrows	O
.	O

Strata	O
between	O
the	O
Index	LEXICON
and	O
Lyoncross	LEXICON
limestones	O
,	O
including	O
the	O
Huntershill	LEXICON
Cement	LEXICON
Limestone	LEXICON
,	O
are	O
exposed	O
in	O
the	O
headstreams	O
of	O
the	O
Wood	O
Burn	O
-LSB-	O
NS	O
6743	O
7756	O
-	O
NS	O
6790	O
7712	O
;	O
NS	O
6818	O
7779	O
-	O
NS	O
6804	O
7729	O
-RSB-	O
.	O

The	O
mudstones	O
above	O
the	O
Orchard	LEXICON
Limestone	LEXICON
,	O
and	O
the	O
Glenboig	LEXICON
Marine	LEXICON
Band	LEXICON
are	O
exposed	O
in	O
the	O
railway	O
cutting	O
-LSB-	O
NS	O
619	O
707	O
-RSB-	O
.	O

The	O
Calmy	LEXICON
Limestone	LEXICON
was	O
formerly	O
visible	O
in	O
several	O
quarries	O
in	O
northeast	O
Glasgow	O
,	O
around	O
Cumbernauld	O
and	O
elsewhere	O
.	O

The	O
sandstone	O
below	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
and	O
thelimestoneitself	O
are	O
displayed	O
in	O
Drumcavel	O
Quarry	O
-LSB-	O
NS	O
705	O
694	O
-RSB-	O
.	O

The	O
Red	O
Glen	O
at	O
Cumbernauld	O
provides	O
several	O
exposures	O
of	O
the	O
strata	O
associated	O
with	O
the	O
Plean	O
Limestone	O
,	O
including	O
one	O
of	O
Plean	LEXICON
No.	LEXICON
2	LEXICON
Limestone	LEXICON
-LSB-	O
NS	O
7753	O
7520	O
-RSB-	O
,	O
which	O
can	O
also	O
be	O
seen	O
in	O
a	O
quarry	O
-LSB-	O
NS	O
7625	O
7415	O
-RSB-	O
in	O
Glencryan	O
Wood	O
.	O

The	O
Castlecary	LEXICON
Limestone	LEXICON
is	O
no	O
longer	O
visible	O
around	O
Castlecary	O
or	O
Cumbernauld	O
.	O

The	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
in	O
the	O
Sheet	O
area	O
is	O
between	O
225m	O
and	O
300m	O
thick	O
except	O
in	O
two	O
areas	O
.	O

These	O
boreholes	O
lie	O
in	O
a	O
northeast-south-south-west	O
trending	O
positive	O
area	O
marked	O
by	O
reduced	O
sedimentation	O
in	O
Namurian	CHRONOSTRAT
times	O
.	O

The	O
overlying	O
Passage	LEXICON
Formation	LEXICON
rests	O
disconformably	O
on	O
various	O
strata	O
ranging	O
from	O
the	O
Castlecary	LEXICON
Limestone	LEXICON
in	O
the	O
north	O
to	O
just	O
above	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
in	O
the	O
southeast	O
making	O
comparison	O
of	O
differences	O
in	O
the	O
thickness	O
of	O
the	O
formation	O
in	O
different	O
areas	O
largely	O
invalid	O
.	O

The	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
can	O
be	O
divided	O
into	O
two	O
parts	O
reflecting	O
both	O
lithology	O
and	O
chronostratigraphy	O
.	O

The	O
lower	O
part	O
,	O
up	O
to	O
the	O
Orchard	LEXICON
Limestone	LEXICON
,	O
consists	O
mainly	O
of	O
coal-cyclic	O
sequences	O
similar	O
to	O
those	O
in	O
the	O
upper	O
part	O
of	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
except	O
that	O
they	O
are	O
extensively	O
replaced	O
by	O
erosive	O
sandstones	O
.	O

The	O
first	O
started	O
at	O
the	O
Index	LEXICON
Limestone	LEXICON
,	O
a	O
typical	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
bioclastic	O
crinoidal	O
limestone	O
,	O
characteristically	O
containing	O
algal	O
bodies	O
.	O

This	O
is	O
overlain	O
by	O
several	O
metres	O
of	O
mudstone	O
that	O
pass	O
,	O
usually	O
gradually	O
,	O
upwards	O
through	O
siltstone	O
to	O
the	O
generally	O
,	O
fine-grained	O
Bishopbriggs	LEXICON
Sandstone	LEXICON
.	O

The	O
end	O
of	O
this	O
marine	O
phase	O
is	O
marked	O
by	O
the	O
Huntershill	LEXICON
Cement	LEXICON
Limestone	LEXICON
.	O

The	O
Bishopbriggs	LEXICON
Sandstone	LEXICON
locally	O
contains	O
abundant	O
trace-fossils	O
and	O
may	O
be	O
part	O
of	O
the	O
marine	O
episode	O
.	O

The	O
second	O
major	O
marine	O
incursion	O
resulted	O
in	O
the	O
formation	O
of	O
the	O
Lyoncross	LEXICON
Limestone	LEXICON
and	O
a	O
few	O
metres	O
of	O
mudstone	O
.	O

The	O
thickest	O
coal	O
is	O
the	O
Chapelgreen	LEXICON
which	O
was	O
worked	O
to	O
a	O
small	O
extent	O
-LSB-	O
NS	O
6972	O
7750	O
-RSB-	O
near	O
Kilsyth	O
and	O
possibly	O
also	O
,	O
as	O
Gardner	O
's	O
Coal	O
,	O
at	O
Meiklehill	O
-LSB-	O
NS	O
6676	O
7401	O
-RSB-	O
.	O

The	O
Lyoncross	LEXICON
Coal	LEXICON
is	O
not	O
known	O
to	O
have	O
been	O
mined	O
in	O
the	O
Sheet	O
area	O
.	O

The	O
Bishopbriggs	LEXICON
Sandstone	LEXICON
is	O
very	O
variable	O
in	O
thickness	O
and	O
thins	O
markedly	O
eastwards	O
from	O
over	O
30m	O
at	O
its	O
type	O
locality	O
to	O
less	O
than	O
2m	O
over	O
a	O
distance	O
of	O
less	O
than	O
5km	O
.	O

By	O
contrast	O
the	O
sandstones	O
which	O
lie	O
between	O
the	O
Huntershill	LEXICON
Cement	LEXICON
Limestone	LEXICON
and	O
the	O
Lyoncross	LEXICON
Coal	LEXICON
are	O
generally	O
much	O
coarser	O
and	O
have	O
erosive	O
bases	O
.	O

The	O
lowest	O
of	O
these	O
sandstones	O
is	O
the	O
Upper	LEXICON
Dumbreck	LEXICON
Sandstone	LEXICON
which	O
reaches	O
almost	O
40m	O
in	O
thickness	O
and	O
locally	O
cuts	O
out	O
the	O
Huntershill	LEXICON
Cement	LEXICON
Limestone	LEXICON
.	O

The	O
next	O
notable	O
sandstone	O
is	O
the	O
Cadgers	LEXICON
Loan	LEXICON
Sandstone	LEXICON
,	O
which	O
is	O
a	O
very	O
persistent	O
bed	O
up	O
to	O
26m	O
thick	O
that	O
locally	O
replaces	O
one	O
or	O
more	O
of	O
the	O
coals	O
lying	O
both	O
above	O
or	O
below	O
it	O
.	O

Above	O
the	O
Lyoncross	LEXICON
Limestone	LEXICON
the	O
most	O
notable	O
of	O
the	O
coarser	O
,	O
erosive	O
sandstones	O
is	O
the	O
Giffnock	LEXICON
Sandstone	LEXICON
,	O
which	O
is	O
best	O
developed	O
in	O
the	O
present	O
sheet	O
along	O
the	O
northern	O
part	O
of	O
the	O
outcrop	O
,	O
for	O
example	O
in	O
Torrance	O
No.	O
1	O
Borehole	O
-LSB-	O
NS	O
6419	O
7359	O
-RSB-	O
where	O
it	O
is	O
22m	O
thick	O
.	O

The	O
upper	O
part	O
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
starts	O
with	O
two	O
major	O
Yoredale-type	O
cycles	O
.	O

The	O
base	O
of	O
the	O
final	O
cycle	O
is	O
marked	O
by	O
the	O
Orchard	LEXICON
Limestone	LEXICON
.	O

Locally	O
,	O
the	O
overlying	O
sandstone	O
,	O
which	O
reaches	O
37m	O
in	O
thickness	O
in	O
Torrance	O
No.	O
1	O
Borehole	O
,	O
is	O
divided	O
by	O
the	O
Glenboig	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
developed	O
mainly	O
in	O
up	O
to	O
four	O
beds	O
of	O
mudstone	O
,	O
but	O
also	O
as	O
the	O
Glenboig	LEXICON
Limestone	LEXICON
.	O

The	O
Lower	LEXICON
and	O
Upper	LEXICON
Hirst	LEXICON
coals	O
at	O
the	O
top	O
of	O
the	O
cycle	O
are	O
both	O
very	O
variable	O
.	O

The	O
Calmy	LEXICON
Limestone	LEXICON
marking	O
the	O
base	O
of	O
the	O
second	O
cycle	O
is	O
typically	O
in	O
two	O
leaves	O
of	O
`	O
calmy	O
'	O
type	O
-	O
hard	O
,	O
fine-grained	O
,	O
compact	O
,	O
pale-grey	O
,	O
fawn	O
or	O
almost	O
white	O
in	O
colour	O
;	O
conchoidal	O
in	O
fracture	O
and	O
not	O
conspicuously	O
fossiliferous	O
but	O
sufficiently	O
so	O
to	O
establish	O
its	O
fully	O
marine	O
character	O
.	O

It	O
is	O
usually	O
1.3	O
-	O
2m	O
thick	O
,	O
but	O
reaches	O
3m	O
,	O
the	O
maximum	O
for	O
an	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
limestone	O
in	O
the	O
Sheet	O
area	O
.	O

The	O
Calmy	LEXICON
Limestone	LEXICON
was	O
formerly	O
quarried	O
at	O
several	O
widely	O
scattered	O
localities	O
and	O
is	O
known	O
to	O
have	O
been	O
mined	O
around	O
Muirhead	O
-LSB-	O
NS	O
683	O
695	O
-RSB-	O
and	O
Cumbernauld	O
.	O

The	O
mudstone	O
above	O
the	O
Calmy	LEXICON
Limestone	LEXICON
is	O
also	O
thick	O
and	O
grades	O
up	O
through	O
siltstone	O
into	O
sandstone	O
;	O
the	O
proportions	O
of	O
the	O
three	O
lithologies	O
vary	O
a	O
great	O
deal	O
.	O

Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
is	O
shelly	O
and	O
crinoidal	O
over	O
much	O
of	O
the	O
Sheet	O
area	O
but	O
locally	O
develops	O
a	O
coralline	O
phase	O
.	O

It	O
usually	O
has	O
little	O
or	O
no	O
coal	O
below	O
it	O
,	O
except	O
in	O
the	O
northeast	O
,	O
where	O
a	O
seam	O
which	O
was	O
mined	O
to	O
a	O
small	O
extent	O
as	O
the	O
Navigation	LEXICON
Coal	LEXICON
,	O
may	O
lie	O
at	O
this	O
horizon	O
.	O

Above	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
there	O
is	O
a	O
sequence	O
,	O
known	O
as	O
the	O
strata	O
associated	O
with	O
the	O
Plean	LEXICON
Limestones	LEXICON
,	O
that	O
is	O
25m	O
to	O
40m	O
thick	O
and	O
includes	O
up	O
to	O
6	O
cycles	O
,	O
three	O
of	O
which	O
locally	O
include	O
a	O
thin	O
coal	O
.	O

Near	O
the	O
top	O
of	O
the	O
sequence	O
is	O
Plean	O
No.	LEXICON
2	LEXICON
Limestone	LEXICON
which	O
,	O
although	O
generally	O
persistent	O
,	O
is	O
locally	O
cut	O
out	O
.	O

Plean	LEXICON
No.	LEXICON
3	LEXICON
Limestone	LEXICON
is	O
not	O
known	O
in	O
the	O
Sheet	O
area	O
.	O

The	O
highest	O
part	O
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
is	O
known	O
only	O
in	O
the	O
north	O
where	O
it	O
is	O
up	O
to	O
35m	O
thick	O
and	O
consists	O
mainly	O
of	O
a	O
coarse-grained	O
sandstone	O
up	O
to	O
18m	O
thick	O
with	O
an	O
erosive	O
base	O
.	O

The	O
Castlecary	LEXICON
Limestone	LEXICON
at	O
the	O
top	O
of	O
the	O
group	O
is	O
also	O
known	O
only	O
in	O
the	O
north	O
,	O
where	O
it	O
is	O
1.5	O
-	O
2.0m	O
thick	O
,	O
dolomitic	O
and	O
locally	O
affected	O
by	O
contemporaneous	O
leaching	O
that	O
reduced	O
it	O
to	O
nodules	O
in	O
a	O
clay	O
matrix	O
as	O
seen	O
in	O
the	O
Coneypark	O
Borehole	O
-LSB-	O
NS	O
7754	O
7888	O
-RSB-	O
.	O

The	O
Orchard	LEXICON
Limestone	LEXICON
has	O
a	O
thickness	O
within	O
its	O
normal	O
range	O
.	O

The	O
Calmy	LEXICON
Limestone	LEXICON
are	O
actually	O
thicker	O
.	O

The	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
shows	O
marked	O
contrasts	O
in	O
palaegeography	O
.	O

Their	O
duration	O
is	O
uncertain	O
because	O
the	O
absence	O
of	O
marine	O
fossils	O
in	O
silty	O
or	O
sandy	O
sediments	O
does	O
not	O
preclude	O
marine	O
conditions	O
;	O
for	O
example	O
,	O
in	O
the	O
interval	O
between	O
the	O
formation	O
of	O
the	O
Index	LEXICON
and	O
Huntershill	LEXICON
Cement	LEXICON
limestones	O
.	O

The	O
Castlecary	LEXICON
Limestone	LEXICON
,	O
produced	O
in	O
this	O
event	O
,	O
was	O
probably	O
formed	O
all	O
over	O
the	O
district	O
but	O
was	O
speedily	O
removed	O
from	O
much	O
of	O
it	O
by	O
penecontemporaneous	O
erosion	O
.	O

Towards	O
the	O
end	O
of	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
times	O
more	O
widespread	O
erosion	O
resumed	O
in	O
the	O
southern	O
part	O
of	O
the	O
district	O
heralding	O
the	O
more	O
powerful	O
downcutting	O
processes	O
in	O
Passage	LEXICON
Formation	LEXICON
times	O
which	O
removed	O
variable	O
amounts	O
of	O
the	O
highest	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
strata	O
.	O

The	O
term	O
`	O
Passage	LEXICON
Group	LEXICON
'	O
Millstone	LEXICON
Grit	LEXICON
,	O
because	O
the	O
strata	O
concerned	O
are	O
equivalent	O
to	O
only	O
the	O
top	O
part	O
of	O
the	O
English	O
Millstone	LEXICON
Grit	LEXICON
,	O
plus	O
some	O
of	O
the	O
English	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

In	O
the	O
Central	O
Coalfield	O
the	O
Passage	LEXICON
Group	LEXICON
originally	O
included	O
the	O
strata	O
between	O
the	O
Castlecary	LEXICON
Limestone	LEXICON
and	O
the	O
Crofthead	LEXICON
Slatyband	LEXICON
Ironstone	LEXICON
but	O
Francis	O
and	O
others	O
extended	O
the	O
group	O
in	O
the	O
adjacent	O
Stirling	O
and	O
Clackmannan	O
Coalfield	O
upwards	O
to	O
the	O
base	O
of	O
the	O
more	O
persistent	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
presence	O
of	O
both	O
Marsdenian	CHRONOSTRAT
and	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
strata	O
is	O
indicated	O
with	O
some	O
certainty	O
by	O
miospore	O
evidence	O
.	O

It	O
has	O
not	O
,	O
however	O
,	O
proved	O
possible	O
to	O
identify	O
the	O
Gastrioceras	O
subcrenatum	O
marine	O
band	O
at	O
the	O
Namurian-Westphalian	O
boundary	O
,	O
although	O
it	O
is	O
thought	O
to	O
be	O
one	O
of	O
the	O
bands	O
in	O
the	O
No.	LEXICON
6	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
.	O

It	O
follows	O
that	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
together	O
with	O
the	O
topmost	O
beds	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
is	O
regarded	O
as	O
lying	O
within	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
.	O

Numbers	O
0	O
,	O
1	O
and	O
2	O
occur	O
as	O
single	O
bands	O
,	O
usually	O
with	O
limestones	O
:	O
No.	O
0	O
is	O
local	O
,	O
the	O
other	O
two	O
are	O
widespread	O
except	O
in	O
the	O
southeast	O
part	O
of	O
the	O
Sheet	O
.	O

In	O
the	O
Alexandra	O
Parade	O
Borehole	O
three	O
bands	O
occur	O
close	O
together	O
and	O
contain	O
a	O
fauna	O
that	O
suggests	O
identification	O
as	O
No.	LEXICON
3	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
though	O
the	O
borehole	O
is	O
more	O
than	O
25km	O
southwest	O
of	O
the	O
nearest	O
known	O
occurrences	O
.	O

A	O
single	O
marine	O
band	O
occurs	O
in	O
the	O
Castlecary	O
-	O
Bonnybridge	O
area	O
,	O
on	O
both	O
sides	O
of	O
the	O
Sheet	O
31W	O
-	O
Sheet	O
31E	O
boundary	O
,	O
between	O
No.	LEXICON
3	LEXICON
Marine	LEXICON
Band	LEXICON
and	O
No.	LEXICON
5	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
.	O

It	O
is	O
suggested	O
that	O
the	O
term	O
No.	LEXICON
4	LEXICON
Marine	LEXICON
Band	LEXICON
be	O
resurrected	O
for	O
this	O
band	O
,	O
which	O
is	O
represented	O
at	O
Castlecary	O
by	O
a	O
Lingula	O
band	O
but	O
is	O
not	O
known	O
elsewhere	O
in	O
the	O
district	O
.	O

No.	LEXICON
5	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
includes	O
four	O
marine	O
or	O
Lingula	O
bands	O
at	O
Castlecary	O
,	O
one	O
more	O
than	O
Francis	O
and	O
others	O
could	O
confirm	O
in	O
the	O
Kincardine	O
Basin	O
.	O

No.	LEXICON
6	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
is	O
represented	O
in	O
Sheet	O
31W	O
by	O
a	O
single	O
Lingula	O
band	O
,	O
known	O
only	O
at	O
Castlecary	O
.	O

The	O
Passage	LEXICON
Formation	LEXICON
crops	O
out	O
in	O
an	O
irregular	O
northeast-trending	O
belt	O
across	O
the	O
middle	O
of	O
Sheet	O
31W	O
extending	O
below	O
Coal	LEXICON
Measures	LEXICON
to	O
the	O
south	O
.	O

This	O
erosive	O
process	O
was	O
most	O
notable	O
in	O
the	O
upper	O
part	O
of	O
the	O
formation	O
,	O
although	O
a	O
widespread	O
break	O
prior	O
to	O
the	O
deposition	O
of	O
No.	LEXICON
0	LEXICON
Marine	LEXICON
Band	LEXICON
occurs	O
over	O
most	O
of	O
the	O
Sheet	O
area	O
.	O

This	O
erosive	O
event	O
removed	O
the	O
Castlecary	LEXICON
Limestone	LEXICON
over	O
the	O
central	O
and	O
southern	O
parts	O
of	O
the	O
Sheet	O
and	O
locally	O
cut	O
down	O
as	O
far	O
as	O
Plean	LEXICON
No.	LEXICON
2	LEXICON
Limestone	LEXICON
.	O

The	O
Bowhousebog	LEXICON
Coal	LEXICON
is	O
absent	O
but	O
the	O
Bonnybridge	LEXICON
Upper	LEXICON
Fireclay	LEXICON
can	O
be	O
recognised	O
.	O

The	O
Goodockhill	LEXICON
Slatyband	LEXICON
Ironstone	LEXICON
is	O
represented	O
by	O
a	O
coal	O
but	O
the	O
last	O
surviving	O
band	O
in	O
No.	LEXICON
6	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
has	O
disappeared	O
.	O

An	O
assemblage	O
of	O
mudstones	O
,	O
fireclays	O
and	O
a	O
thin	O
coal	O
includes	O
a	O
Lingula	O
band	O
as	O
a	O
representative	O
of	O
No.	LEXICON
5	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
,	O
to	O
which	O
a	O
marine	O
band	O
9m	O
below	O
it	O
may	O
also	O
belong	O
.	O

Below	O
a	O
coarse	O
,	O
pebbly	O
sandstone	O
,	O
with	O
a	O
clearly	O
erosive	O
base	O
,	O
there	O
is	O
a	O
thin	O
crinoidal	O
limestone	O
that	O
is	O
tentatively	O
identified	O
as	O
Plean	LEXICON
No.	LEXICON
1	LEXICON
Limestone	LEXICON
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

If	O
this	O
correlation	O
is	O
correct	O
the	O
Passage	LEXICON
Formation	LEXICON
is	O
80m	O
thick	O
and	O
the	O
lower	O
part	O
is	O
entirely	O
missing	O
.	O

The	O
Passage	LEXICON
Formation	LEXICON
consists	O
mainly	O
of	O
sandstones	O
with	O
subordinate	O
poorly-bedded	O
mudstones	O
that	O
are	O
commonly	O
termed	O
fireclays	O
regardless	O
of	O
their	O
refractory	O
properties	O
.	O

Bedded	O
mudstones	O
,	O
siltstones	O
,	O
coals	O
and	O
limestones	O
all	O
occur	O
but	O
are	O
very	O
thin	O
except	O
from	O
the	O
base	O
to	O
the	O
top	O
of	O
No	LEXICON
2	LEXICON
Marine	LEXICON
Band	LEXICON
and	O
within	O
Nos	LEXICON
3	LEXICON
and	O
5	LEXICON
Marine	LEXICON
Band	LEXICON
groups	O
where	O
the	O
succession	O
is	O
clearly	O
coal-cyclic	O
with	O
all	O
the	O
lithologies	O
forming	O
significant	O
parts	O
.	O

Most	O
of	O
the	O
seams	O
used	O
lie	O
in	O
the	O
Passage	LEXICON
Formation	LEXICON
,	O
including	O
the	O
one	O
which	O
was	O
most	O
extensively	O
exploited	O
,	O
now	O
named	O
the	O
Glenboig	LEXICON
Lower	LEXICON
Fireclay	LEXICON
but	O
widely	O
known	O
as	O
the	O
Lower	LEXICON
Fireclay	LEXICON
.	O

It	O
lies	O
between	O
the	O
Roman	LEXICON
Cement	LEXICON
and	O
the	O
Netherwood	LEXICON
Coal	LEXICON
.	O

The	O
Glenboig	LEXICON
Lower	LEXICON
Fireclay	LEXICON
yields	O
material	O
with	O
over	O
40%	O
alumina	O
and	O
was	O
quarried	O
or	O
mined	O
almost	O
throughtout	O
its	O
outcrop	O
from	O
Heathfield	O
to	O
Castlecary	O
.	O

It	O
may	O
therefore	O
be	O
largely	O
the	O
product	O
of	O
intense	O
bauxitic	O
weathering	O
of	O
basaltic	O
lavas	O
,	O
possibly	O
being	O
derived	O
from	O
exhumed	O
parts	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

The	O
latter	O
must	O
not	O
be	O
confused	O
with	O
the	O
much	O
higher	O
Bonnybridge	LEXICON
Upper	LEXICON
Fireclay	LEXICON
to	O
the	O
east	O
.	O

Some	O
,	O
such	O
as	O
the	O
Captain	LEXICON
's	LEXICON
Fireclay	LEXICON
at	O
Glenboig	O
,	O
are	O
probably	O
in	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

The	O
very	O
shaly	O
or	O
cannely	O
mudstone	O
immediately	O
above	O
the	O
Castlecary	LEXICON
Limestone	LEXICON
at	O
Castlecary	O
and	O
Cumbernauld	O
contains	O
Curvirimula	O
,	O
fish	O
debris	O
and	O
ostracods	O
.	O

There	O
are	O
up	O
to	O
three	O
thin	O
impersistent	O
limestones	O
near	O
the	O
base	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
.	O

The	O
lowest	O
is	O
No.	LEXICON
0	LEXICON
Marine	LEXICON
Band	LEXICON
Limestone	LEXICON
.	O

Nos	LEXICON
0	LEXICON
and	O
1	LEXICON
Marine	LEXICON
Band	LEXICON
Limestones	LEXICON
are	O
both	O
argillaceous	O
,	O
bioclastic	O
and	O
crinoidal	O
,	O
in	O
contrast	O
to	O
the	O
Roman	LEXICON
Cement	LEXICON
or	O
No.	LEXICON
2	LEXICON
Marine	LEXICON
Band	LEXICON
Limestone	LEXICON
,	O
which	O
consists	O
largely	O
of	O
a	O
`	O
lumachelle	O
'	O
of	O
crushed	O
orthotetoid	O
and	O
Schizophoria	O
valves	O
.	O

The	O
Netherwood	LEXICON
Coal	LEXICON
takes	O
its	O
name	O
from	O
Netherwood	O
Farm	O
-LSB-	O
NS	O
775	O
784	O
-RSB-	O
.	O

The	O
Skipperton	LEXICON
Coal	LEXICON
is	O
0.5m	O
thick	O
at	O
Castlecary	O
but	O
elsewhere	O
is	O
not	O
identifiable	O
.	O

The	O
Bowhousebog	LEXICON
Coal	LEXICON
is	O
known	O
at	O
Bonnybridge	O
,	O
just	O
east	O
of	O
the	O
sheet	O
margin	O
,	O
but	O
its	O
presence	O
has	O
not	O
been	O
established	O
within	O
the	O
sheet	O
,	O
even	O
in	O
the	O
Banknock-Castlecary	O
area	O
.	O

It	O
is	O
probably	O
a	O
correlative	O
of	O
the	O
better	O
known	O
Crofthead	LEXICON
Slatyband	LEXICON
Ironstone	LEXICON
of	O
Sheet	O
31E	O
,	O
as	O
is	O
the	O
Earlshill	O
Upper	LEXICON
Slatyband	LEXICON
Ironstone	LEXICON
,	O
whose	O
workings	O
,	O
at	O
depths	O
of	O
over	O
150m	O
,	O
extend	O
westwards	O
onto	O
Sheet	O
31W	O
at	O
Stepends	O
-LSB-	O
NS	O
804	O
671	O
-RSB-	O
and	O
Easter	O
Moffat	O
-LSB-	O
NS	O
802	O
663	O
-RSB-	O
.	O

The	O
Goodockhill	LEXICON
Slatyband	LEXICON
Ironstone	LEXICON
of	O
Sheet	O
31E	O
is	O
represented	O
by	O
a	O
coal	O
in	O
the	O
Chapelhall	O
area	O
;	O
its	O
horizon	O
is	O
not	O
recognisable	O
elsewhere	O
.	O

Read	O
indicated	O
that	O
with	O
the	O
onset	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
the	O
paralic	O
,	O
probably	O
mainly	O
deltaic	O
conditions	O
that	O
had	O
prevailed	O
in	O
the	O
Central	O
Coalfield	O
tended	O
to	O
retreat	O
before	O
a	O
great	O
influx	O
of	O
coarse-grained	O
clastic	O
sediments	O
.	O

The	O
depositional	O
basin	O
probably	O
contracted	O
,	O
some	O
of	O
the	O
Dinantian	LEXICON
lavas	O
to	O
the	O
north	O
and	O
west	O
may	O
have	O
been	O
exhumed	O
and	O
fluviatile	O
conditions	O
prevailed	O
.	O

The	O
marine	O
strata	O
mostly	O
die	O
out	O
to	O
the	O
west	O
and	O
south	O
,	O
the	O
directions	O
in	O
which	O
the	O
Passage	LEXICON
Formation	LEXICON
thins	O
markedly	O
.	O

Here	O
,	O
the	O
lower	O
part	O
of	O
the	O
formation	O
,	O
plus	O
the	O
top	O
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
,	O
appears	O
to	O
be	O
missing	O
.	O

The	O
coal-bearing	O
,	O
cyclic	O
,	O
fluviodeltaic	O
sediments	O
which	O
overlie	O
the	O
Passage	LEXICON
Formation	LEXICON
have	O
long	O
been	O
known	O
as	O
coal	O
measures	O
''	O
.	O

He	O
split	O
the	O
latter	O
into	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
and	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

The	O
top	O
of	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
was	O
defined	O
by	O
Skipsey	LEXICON
's	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

The	O
term	O
Coal	LEXICON
Measures	LEXICON
reflects	O
the	O
different	O
usage	O
in	O
Scotland	O
and	O
because	O
the	O
top	O
and	O
bottom	O
are	O
not	O
formally	O
defined	O
it	O
is	O
considered	O
to	O
be	O
an	O
informal	O
unit	O
of	O
group	O
status	O
.	O

The	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
falls	O
entirely	O
within	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
,	O
ending	O
at	O
the	O
top	O
of	O
the	O
latter	O
.	O

The	O
base	O
is	O
now	O
drawn	O
at	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
which	O
lies	O
about	O
70m	O
above	O
the	O
base	O
of	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
at	O
Castlecary	O
and	O
less	O
than	O
that	O
elsewhere	O
in	O
the	O
district	O
.	O

The	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
occur	O
,	O
either	O
at	O
the	O
surface	O
or	O
at	O
depth	O
,	O
over	O
most	O
of	O
the	O
southern	O
half	O
of	O
the	O
Sheet	O
and	O
also	O
in	O
the	O
Banknock	O
Coalfield	O
.	O

The	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
thickest	O
,	O
the	O
thinning	O
being	O
most	O
marked	O
in	O
the	O
lower	O
part	O
of	O
the	O
sequence	O
.	O

The	O
mudstones	O
and	O
siltstones	O
between	O
the	O
Ladygrange	LEXICON
and	O
Airdrie	LEXICON
Virtuewell	LEXICON
coals	O
are	O
commonly	O
unusually	O
pale-grey	O
in	O
colour	O
,	O
in	O
places	O
with	O
a	O
greenish	O
tinge	O
.	O

The	O
only	O
carbonate	O
rock	O
calcareous	O
enough	O
to	O
be	O
locally	O
called	O
limestone	O
is	O
at	O
the	O
top	O
of	O
the	O
sequence	O
and	O
is	O
more	O
usually	O
known	O
as	O
the	O
Roughband	LEXICON
Ironstone	LEXICON
.	O

It	O
occurs	O
in	O
the	O
seatclay	O
below	O
the	O
Vanderbeckei	LEXICON
Marine	LEXICON
Band	LEXICON
and	O
is	O
best	O
developed	O
in	O
the	O
southeast	O
part	O
of	O
the	O
Sheet	O
,	O
where	O
it	O
was	O
mined	O
.	O

Two	O
were	O
mined	O
as	O
the	O
Chapelhall	LEXICON
Lower	LEXICON
and	O
Upper	LEXICON
Fireclays	O
.	O

The	O
coals	O
in	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
mostly	O
less	O
than	O
1m	O
thick	O
.	O

However	O
,	O
the	O
Lime	LEXICON
Coal	LEXICON
of	LEXICON
Greengairs	LEXICON
dies	O
out	O
completely	O
north	O
of	O
Airdrie	O
;	O
the	O
two	O
leaves	O
of	O
the	O
Mid	LEXICON
Drumgray	LEXICON
Coal	LEXICON
coalesce	O
in	O
the	O
east	O
and	O
south-east	O
and	O
the	O
Bonnyhill	LEXICON
Craw	LEXICON
Coal	LEXICON
is	O
absent	O
over	O
wide	O
areas	O
.	O

One	O
is	O
named	O
after	O
the	O
Auldshields	LEXICON
Musselband	LEXICON
,	O
which	O
is	O
only	O
found	O
in	O
the	O
Sheet	O
area	O
around	O
the	O
type	O
locality	O
-LSB-	O
NS	O
770	O
715	O
-RSB-	O
.	O

The	O
other	O
lies	O
between	O
the	O
Kiltongue	LEXICON
Musselband	LEXICON
and	O
the	O
Ladygrange	LEXICON
Coal	LEXICON
.	O

The	O
four	O
most	O
extensively	O
mined	O
were	O
:	O
1	O
-RRB-	O
the	O
Lower	LEXICON
Drumgray	LEXICON
.	O

The	O
seams	O
are	O
generally	O
thinner	O
than	O
those	O
in	O
the	O
overlying	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
and	O
dewatering	O
was	O
a	O
considerable	O
problem	O
.	O

Blackband	O
ironstones	O
are	O
rare	O
in	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
of	O
the	O
Sheet	O
area	O
.	O

The	O
Colinburn	LEXICON
Coal	LEXICON
in	O
its	O
Duntilland	O
Parrot	O
phase	O
around	O
Chapelhall	O
includes	O
blackband	O
ironstone	O
.	O

The	O
Auldshields	LEXICON
Musselband	LEXICON
Ironstone	LEXICON
is	O
sufficiently	O
carbonaceous	O
at	O
Auldshields	O
-LSB-	O
NS	O
7710	O
715	O
-RSB-	O
to	O
be	O
included	O
but	O
the	O
only	O
seam	O
known	O
to	O
have	O
been	O
mined	O
for	O
blackband	O
ironstone	O
alone	O
is	O
the	O
Bellside	LEXICON
Ironstone	LEXICON
,	O
a	O
local	O
development	O
up	O
to	O
0.2m	O
thick	O
of	O
the	O
Bellside	LEXICON
Coal	LEXICON
in	O
the	O
Newarthill	O
-	O
Cleland	O
area	O
.	O

The	O
upper	O
part	O
of	O
the	O
Kiltongue	LEXICON
Coal	LEXICON
passes	O
locally	O
into	O
cannel	O
,	O
oil-shale	O
and	O
ironstone	O
in	O
the	O
Chapelhall	O
area	O
and	O
was	O
worked	O
as	O
the	O
Calderbraes	O
or	O
Kennelburn	LEXICON
Ironstone	LEXICON
.	O

The	O
Kiltongue	LEXICON
Musselband	LEXICON
Ironstone	LEXICON
is	O
part	O
of	O
a	O
complex	O
seam	O
which	O
locally	O
includes	O
a	O
coal	O
up	O
to	O
0.6m	O
thick	O
,	O
that	O
was	O
mined	O
at	O
Banknock	O
as	O
the	O
Shale	LEXICON
Coal	LEXICON
.	O

Oil-shale	O
up	O
to	O
0.35m	O
thick	O
also	O
occurs	O
in	O
places	O
above	O
the	O
Airdrie	LEXICON
Virtuewell	LEXICON
Coal	LEXICON
and	O
was	O
formerly	O
exploited	O
in	O
northern	O
Airdrie	O
.	O

The	O
dominantly	O
fluviatile	O
conditions	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
gradually	O
gave	O
way	O
to	O
a	O
broad	O
flat	O
deltaic	O
plain	O
.	O

The	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
coincide	O
exactly	O
with	O
the	O
Westphalian	CHRONOSTRAT
B	CHRONOSTRAT
stage	O
.	O

They	O
are	O
covered	O
by	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
in	O
the	O
Lanarkshire	O
Basin	O
,	O
at	O
Rutherglen	O
,	O
in	O
a	O
west-east	O
belt	O
from	O
Glasgow	O
almost	O
to	O
Holytown	O
and	O
in	O
a	O
small	O
area	O
in	O
Coatbridge	O
.	O

The	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
almost	O
200m	O
thick	O
in	O
the	O
east	O
,	O
decreasing	O
westwards	O
to	O
160m	O
.	O

Coarser	O
and	O
usually	O
thicker	O
sandstones	O
are	O
largely	O
confined	O
to	O
the	O
strata	O
above	O
the	O
Glasgow	LEXICON
Upper	LEXICON
Coal	LEXICON
,	O
where	O
they	O
locally	O
cut	O
out	O
parts	O
of	O
the	O
cyclic	O
sequence	O
.	O

Examples	O
include	O
the	O
Shettleston	LEXICON
Sandstone	LEXICON
.	O

Examples	O
include	O
the	O
effect	O
of	O
the	O
Auchinlea	LEXICON
Sandstone	LEXICON
on	O
the	O
Airdrie	LEXICON
Blackband	LEXICON
Coal	LEXICON
southeast	O
of	O
Newarthill	O
and	O
the	O
thinness	O
of	O
the	O
Humph	LEXICON
Coal	LEXICON
in	O
eastern	O
Glasgow	O
.	O

The	O
very	O
variable	O
sandstone	O
between	O
the	O
Glasgow	LEXICON
Main	LEXICON
and	O
Pyotshaw	LEXICON
coals	O
has	O
little	O
effect	O
on	O
either	O
seam	O
.	O

The	O
Airdrie	LEXICON
Blackband	LEXICON
Coal	LEXICON
was	O
mined	O
extensively	O
except	O
in	O
Glasgow	O
,	O
where	O
it	O
is	O
thin	O
,	O
and	O
in	O
Coatbridge	O
and	O
Airdrie	O
,	O
where	O
the	O
lower	O
leaf	O
is	O
thin	O
or	O
absent	O
and	O
the	O
upper	O
leaf	O
passes	O
laterally	O
into	O
the	O
Airdrie	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
.	O

The	O
Coatbridge	LEXICON
Musselband	LEXICON
Coal	LEXICON
was	O
mined	O
to	O
a	O
small	O
extent	O
in	O
the	O
Airdrie	O
area	O
,	O
where	O
it	O
reaches	O
its	O
maximum	O
thickness	O
.	O

The	O
Virgin	LEXICON
Coal	LEXICON
is	O
one	O
of	O
the	O
most	O
variable	O
seams	O
in	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
thinning	O
eastwards	O
and	O
more	O
markedly	O
southwards	O
.	O

The	O
Glasgow	LEXICON
Splint	LEXICON
Coal	LEXICON
was	O
very	O
much	O
in	O
demand	O
,	O
especially	O
for	O
furnaces	O
,	O
because	O
the	O
hard	O
splinty	O
character	O
of	O
bands	O
in	O
the	O
seam	O
although	O
locally	O
in	O
southeast	O
Glasgow	O
the	O
coal	O
was	O
`	O
burnt	O
'	O
,	O
that	O
is	O
,	O
oxidised	O
by	O
fluids	O
percolating	O
down	O
from	O
thick	O
,	O
locally	O
red-stained	O
sandstones	O
.	O

The	O
Humph	LEXICON
Coal	LEXICON
is	O
also	O
variable	O
being	O
thin	O
or	O
absent	O
in	O
eastern	O
Glasgow	O
and	O
generally	O
in	O
two-leaves	O
in	O
the	O
Coatbridge-Airdrie	O
area	O
,	O
where	O
mining	O
was	O
largely	O
confined	O
to	O
the	O
southern	O
part	O
of	O
the	O
district	O
.	O

The	O
Humph	LEXICON
Rider	LEXICON
and	O
Glasgow	LEXICON
Main	LEXICON
Under	LEXICON
both	O
pass	O
locally	O
into	O
blackband	O
ironstone	O
in	O
Glasgow	O
.	O

It	O
forms	O
a	O
single	O
seam	O
,	O
up	O
to	O
3m	O
thick	O
,	O
with	O
the	O
Pyotshaw	LEXICON
Coal	LEXICON
in	O
Glasgow	O
and	O
locally	O
elsewhere	O
,	O
for	O
instance	O
around	O
Newarthill	O
.	O

The	O
Glasgow	LEXICON
Ell	LEXICON
Coal	LEXICON
is	O
thickest	O
in	O
the	O
south	O
,	O
where	O
it	O
locally	O
exceeds	O
3m	O
and	O
was	O
much	O
sought	O
after	O
.	O

The	O
Maggie	LEXICON
Coal	LEXICON
is	O
a	O
local	O
development	O
in	O
the	O
Holytown	O
-	O
Newarthill	O
area	O
.	O

The	O
Glasgow	LEXICON
Upper	LEXICON
Coal	LEXICON
,	O
which	O
has	O
been	O
mined	O
between	O
Glasgow	O
and	O
Bothwell	O
,	O
is	O
the	O
highest	O
of	O
the	O
important	O
seams	O
.	O

Like	O
the	O
Virgin	LEXICON
Coal	LEXICON
it	O
is	O
thickest	O
in	O
the	O
west	O
,	O
where	O
it	O
locally	O
exceeds	O
2m	O
,	O
but	O
thins	O
markedly	O
south-eastwards	O
and	O
less	O
so	O
eastwards	O
.	O

The	O
variable	O
Palacecraig	LEXICON
Coal	LEXICON
is	O
up	O
to	O
0.9m	O
thick	O
and	O
passes	O
into	O
the	O
0.3m	O
Palacecraig	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
south	O
of	O
Airdrie	O
.	O

Seams	O
in	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
in	O
the	O
Banknock	O
Coalfield	O
have	O
been	O
mined	O
using	O
Central	O
Coalfield	O
names	O
such	O
as	O
Virgin	O
,	O
Splint	O
,	O
Humph	O
,	O
Main	O
and	O
Pyotshaw	O
.	O

Sedimentation	O
on	O
the	O
delta	O
plain	O
which	O
prevailed	O
during	O
most	O
of	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
was	O
interrupted	O
by	O
the	O
major	O
marine	O
incursion	O
that	O
formed	O
the	O
Vanderbeckei	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
but	O
thereafter	O
became	O
reestablished	O
during	O
Westphalian	CHRONOSTRAT
B	CHRONOSTRAT
.	O

These	O
incursions	O
allowed	O
marine	O
or	O
quasi-marine	O
rather	O
than	O
non-marine	O
faunas	O
to	O
become	O
established	O
at	O
regular	O
intervals	O
towards	O
the	O
end	O
of	O
Westphalian	CHRONOSTRAT
B	CHRONOSTRAT
.	O

The	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
the	O
youngest	O
Carboniferous	CHRONOSTRAT
strata	O
preserved	O
in	O
the	O
district	O
and	O
belong	O
mainly	O
to	O
the	O
Westphalian	CHRONOSTRAT
C	CHRONOSTRAT
stage	O
but	O
may	O
include	O
some	O
Westphalian	CHRONOSTRAT
D	CHRONOSTRAT
strata	O
at	O
the	O
top	O
.	O

The	O
Aegiranum	LEXICON
Marine	LEXICON
Band	LEXICON
at	O
the	O
base	O
is	O
known	O
in	O
Scotland	O
as	O
Skipsey	LEXICON
's	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
although	O
it	O
is	O
now	O
believed	O
.	O

The	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
up	O
to	O
270m	O
thick	O
and	O
are	O
confined	O
to	O
the	O
southern	O
part	O
of	O
the	O
Sheet	O
where	O
the	O
main	O
outcrop	O
is	O
in	O
the	O
middle	O
of	O
the	O
Lanarkshire	O
Basin	O
.	O

Skipsey	LEXICON
's	LEXICON
Marine	LEXICON
Band	LEXICON
is	O
visible	O
in	O
the	O
North	O
Calder	O
Water	O
-LSB-	O
NS	O
7519	O
6324	O
-RSB-	O
.	O

The	O
Bothwell	LEXICON
Bridge	LEXICON
Marine	LEXICON
Band	LEXICON
is	O
exposed	O
in	O
the	O
Clyde	O
at	O
its	O
type	O
locality	O
-LSB-	O
NS	O
7069	O
5773	O
-RSB-	O
.	O

No	O
coal	O
in	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
is	O
known	O
to	O
have	O
been	O
mined	O
but	O
a	O
terra-cotta	O
clay	O
2.6m	O
thick	O
which	O
occurs	O
almost	O
50m	O
above	O
the	O
base	O
was	O
mined	O
from	O
1955-65	O
at	O
Blantyreferme	O
Nos.	O
4	O
and	O
5	O
mines	O
-LSB-	O
NS	O
682	O
610	O
-RSB-	O
.	O

The	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
were	O
deposited	O
as	O
coal-cyclic	O
sequences	O
but	O
subsequent	O
oxidation	O
has	O
reddened	O
all	O
but	O
the	O
lowest	O
strata	O
and	O
the	O
coals	O
have	O
mostly	O
been	O
destroyed	O
or	O
replaced	O
by	O
limestone	O
.	O

Deposition	O
of	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
was	O
intially	O
controlled	O
by	O
a	O
marine	O
incursion	O
which	O
formed	O
the	O
Aegiranum	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

Thereafter	O
conditions	O
returned	O
to	O
these	O
characteristic	O
of	O
Late	CHRONOSTRAT
Westphalian	CHRONOSTRAT
B	CHRONOSTRAT
times	O
,	O
with	O
delta	O
plain	O
sedimentation	O
locally	O
interrupted	O
by	O
sand-filled	O
distributary	O
channels	O
.	O

General	O
discussions	O
of	O
the	O
nature	O
and	O
palaeoecological	O
significance	O
of	O
the	O
marine	O
faunas	O
of	O
the	O
Dinantian	CHRONOSTRAT
and	O
Namurian	CHRONOSTRAT
have	O
been	O
published	O
by	O
Wilson	O
,	O
and	O
some	O
details	O
from	O
these	O
accounts	O
have	O
been	O
included	O
here	O
.	O

Selected	O
Dinantian	CHRONOSTRAT
and	O
Namurian	CHRONOSTRAT
fossils	O
are	O
illustrated	O
in	O
Plate	O
5	O
.	O

Lawmuir	LEXICON
Formation	LEXICON
.	O

On	O
this	O
sheet	O
the	O
formation	O
includes	O
strata	O
which	O
are	O
mainly	O
of	O
Brigantian	CHRONOSTRAT
age	O
.	O

As	O
already	O
noted	O
Latiproductus	O
cf.	O
latissimus	O
is	O
common	O
at	O
the	O
horizon	O
of	O
the	O
Hollybush	LEXICON
Limestone	LEXICON
over	O
most	O
of	O
the	O
area	O
,	O
but	O
otherwise	O
is	O
rarely	O
present	O
.	O

Miospores	O
from	O
this	O
formation	O
in	O
the	O
Lawmuir	O
Borehole	O
,	O
drilled	O
in	O
the	O
adjacent	O
30E	O
sheet	O
are	O
characteristic	O
of	O
the	O
VF	O
Miospore	O
Zone	O
and	O
may	O
thus	O
be	O
regarded	O
as	O
of	O
Brigantian	CHRONOSTRAT
age	O
.	O

Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

The	O
marine	O
fauna	O
from	O
this	O
formation	O
is	O
more	O
varied	O
than	O
that	O
from	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
and	O
the	O
individual	O
marine	O
episodes	O
also	O
show	O
greater	O
differences	O
between	O
each	O
other	O
.	O

In	O
general	O
the	O
Hurlet	LEXICON
Limestone	LEXICON
is	O
not	O
very	O
fossiliferous	O
,	O
although	O
in	O
the	O
Corrieburn	O
area	O
the	O
mud	O
fraction	O
is	O
reduced	O
,	O
with	O
the	O
result	O
that	O
the	O
fauna	O
changes	O
and	O
a	O
wider	O
variety	O
of	O
corals	O
and	O
brachiopods	O
,	O
together	O
with	O
Limipecten	O
dissimilis	O
,	O
is	O
present	O
.	O

The	O
Blackhall	LEXICON
Limestone	LEXICON
,	O
with	O
the	O
Neilson	LEXICON
Shell	LEXICON
Bed	LEXICON
in	O
the	O
mudstones	O
above	O
it	O
,	O
carries	O
one	O
of	O
the	O
most	O
varied	O
faunas	O
in	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

In	O
localities	O
along	O
the	O
southern	O
margin	O
of	O
the	O
Campsie	O
Fells	O
the	O
lower	O
two	O
of	O
the	O
Hosie	LEXICON
Limestones	LEXICON
contain	O
isolated	O
specimens	O
of	O
Caneyella	O
membranacea	O
,	O
a	O
bivalve	O
common	O
in	O
the	O
higher	O
beds	O
of	O
P2	O
Zone	O
in	O
the	O
Pennine	O
region	O
of	O
England	O
.	O

There	O
are	O
marked	O
differences	O
between	O
the	O
faunas	O
which	O
occur	O
in	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
in	O
the	O
north	O
of	O
the	O
Airdrie	O
Sheet	O
and	O
those	O
from	O
the	O
adjacent	O
Hamilton	O
Sheet	O
to	O
the	O
south	O
.	O

However	O
,	O
little	O
is	O
known	O
of	O
the	O
faunas	O
of	O
the	O
formation	O
in	O
the	O
intervening	O
area	O
below	O
the	O
wide	O
outcrop	O
of	O
Coal	LEXICON
Measures	LEXICON
strata	O
.	O

Miospore	O
evidence	O
from	O
various	O
sources	O
suggests	O
that	O
rocks	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
contain	O
assemblages	O
typical	O
of	O
the	O
VF	O
Miospore	O
Zone	O
and	O
that	O
this	O
zone	O
is	O
represented	O
in	O
the	O
Hosie	LEXICON
Limestones	LEXICON
.	O

Conodonts	O
described	O
by	O
Clarke	O
from	O
just	O
below	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
indicate	O
the	O
presence	O
of	O
the	O
upper	O
part	O
of	O
P2	O
Zone	O
,	O
that	O
is	O
,	O
a	O
late	O
Brigantian	CHRONOSTRAT
age	O
.	O

The	O
discovery	O
of	O
Cravenoceras	O
scoticum	O
in	O
shales	O
below	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
at	O
East	O
Kilbride	O
to	O
take	O
the	O
base	O
of	O
the	O
Pendleian	CHRONOSTRAT
stage	O
below	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
.	O

Thus	O
the	O
Visean	CHRONOSTRAT
-	O
Namurian	CHRONOSTRAT
boundary	O
has	O
been	O
taken	O
for	O
convenience	O
at	O
the	O
base	O
of	O
the	O
Top	LEXICON
Hosie	LEXICON
Limestone	LEXICON
.	O

There	O
have	O
been	O
no	O
records	O
of	O
the	O
goniatites	O
which	O
characterise	O
the	O
principal	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
marine	O
bands	O
in	O
Lancashire	O
and	O
the	O
base	O
of	O
the	O
Westphalian	CHRONOSTRAT
is	O
thought	O
to	O
occur	O
within	O
No.	LEXICON
6	LEXICON
Marine	LEXICON
Band	LEXICON
group	O
,	O
where	O
miospores	O
indicative	O
of	O
a	O
basal	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
age	O
have	O
been	O
found	O
in	O
adjacent	O
areas	O
.	O

Above	O
this	O
level	O
only	O
the	O
Lowstone	LEXICON
Marine	LEXICON
Band	LEXICON
is	O
well	O
represented	O
on	O
this	O
sheet	O
and	O
that	O
only	O
in	O
the	O
east	O
.	O

The	O
faunas	O
in	O
the	O
Duntilland	O
Parrot	O
phase	O
of	O
the	O
Colinburn	LEXICON
Coal	LEXICON
include	O
Carbonicola	O
crispa	O
,	O
and	O
in	O
the	O
Auldshields	LEXICON
Musselband	LEXICON
Carbonicola	O
extenuata	O
is	O
present	O
,	O
thus	O
enabling	O
the	O
recognition	O
of	O
the	O
Lenisulcata	BIOZONE
Biozone	BIOZONE
in	O
the	O
eastern	O
part	O
of	O
the	O
sheet	O
.	O

The	O
non-marine	O
bivalves	O
become	O
more	O
abundant	O
above	O
the	O
Coatbridge	LEXICON
Balmoral	LEXICON
Coal	LEXICON
and	O
scarcer	O
again	O
above	O
the	O
Kiltongue	LEXICON
Musselband	LEXICON
.	O

Westwards	O
the	O
faunas	O
deteriorate	O
and	O
even	O
the	O
normally	O
persistent	O
bands	O
such	O
as	O
those	O
above	O
the	O
Shiels	LEXICON
,	O
Shotts	LEXICON
Gas	LEXICON
and	O
Upper	LEXICON
Drumgray	LEXICON
coals	O
become	O
,	O
at	O
best	O
,	O
intermittent	O
in	O
occurrence	O
.	O

In	O
the	O
Glasgow	O
area	O
Curvirimula	O
is	O
found	O
in	O
association	O
with	O
Euestheria	O
and	O
Leaia	O
in	O
strata	O
between	O
the	O
Shotts	LEXICON
Gas	LEXICON
and	O
Upper	LEXICON
Drumgray	LEXICON
coals	O
.	O

Near	O
the	O
base	O
of	O
the	O
zone	O
,	O
above	O
the	O
Mill	LEXICON
Coal	LEXICON
,	O
the	O
trace	O
fossil	O
Planolites	O
aff	O
.	O

The	O
Kiltongue	LEXICON
Musselband	LEXICON
contains	O
Anthraconaia	O
modiolaris	O
,	O
Anthracosia	O
regularis	O
and	O
Carbonicola	O
oslancis	O
and	O
has	O
been	O
taken	O
to	O
mark	O
the	O
base	O
of	O
the	O
Modiolaris	BIOZONE
Biozone	BIOZONE
.	O

The	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
may	O
be	O
divided	O
into	O
three	O
sections	O
on	O
the	O
basis	O
of	O
the	O
contained	O
faunas	O
.	O

The	O
lower	O
part	O
,	O
up	O
to	O
the	O
Pyotshaw	LEXICON
Coal	LEXICON
at	O
the	O
top	O
of	O
the	O
Modiolaris	BIOZONE
Biozone	BIOZONE
,	O
is	O
dominated	O
by	O
several	O
rich	O
non-marine	O
bivalve	O
bands	O
.	O

The	O
only	O
marine	O
band	O
is	O
the	O
Vanderbeckei	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
originally	O
described	O
as	O
the	O
Queenslie	LEXICON
Marine	LEXICON
Band	LEXICON
.	O

Non-marine	O
faunas	O
deteriorate	O
southwards	O
to	O
some	O
extent	O
,	O
and	O
at	O
the	O
horizon	O
of	O
the	O
Coatbridge	LEXICON
Musselband	LEXICON
they	O
also	O
deteriorate	O
westwards	O
.	O

The	O
middle	O
part	O
extends	O
to	O
just	O
above	O
the	O
Palacecraig	LEXICON
Coal	LEXICON
and	O
is	O
entirely	O
within	O
the	O
Lower	O
Similis-Pulchra	BIOZONE
Biozone	BIOZONE
.	O

Euestheria	O
is	O
widespread	O
in	O
horizons	O
above	O
the	O
Glasgow	LEXICON
Upper	LEXICON
Coal	LEXICON
and	O
the	O
lowest	O
of	O
the	O
Lower	BIOZONE
Similis-Pulchra	BIOZONE
Biozone	BIOZONE
marine	O
bands	O
also	O
occurs	O
in	O
this	O
part	O
of	O
the	O
sequence	O
.	O

In	O
general	O
the	O
non-marine	O
bivalve	O
faunas	O
below	O
the	O
Glasgow	LEXICON
Upper	LEXICON
Coal	LEXICON
are	O
best	O
developed	O
in	O
eastern	O
Glasgow	O
,	O
those	O
above	O
it	O
,	O
in	O
Coatbridge	O
and	O
Airdrie	O
.	O

The	O
highest	O
part	O
starts	O
with	O
the	O
Carnbroe	LEXICON
Marine	LEXICON
Band	LEXICON
and	O
includes	O
the	O
Drumpark	LEXICON
Marine	LEXICON
Band	LEXICON
and	O
the	O
recently	O
discovered	O
Dalziel	LEXICON
Works	LEXICON
Lingula	LEXICON
Band	LEXICON
near	O
the	O
top	O
.	O

The	O
Drumpark	LEXICON
Marine	LEXICON
Band	LEXICON
is	O
now	O
thought	O
to	O
be	O
the	O
marine	O
band	O
originally	O
described	O
by	O
Skipsey	O
.	O

The	O
Aegiranum	LEXICON
Marine	LEXICON
Band	LEXICON
exhibits	O
three	O
different	O
facies	O
within	O
the	O
area	O
of	O
this	O
sheet	O
.	O

In	O
the	O
east	O
it	O
occurs	O
in	O
shale	O
with	O
a	O
black	LEXICON
limestone	LEXICON
near	O
the	O
base	O
,	O
reminiscent	O
of	O
the	O
development	O
of	O
the	O
band	O
in	O
much	O
of	O
the	O
Pennine	O
area	O
of	O
England	O
,	O
but	O
with	O
a	O
less	O
varied	O
fauna	O
.	O

The	O
only	O
other	O
marine	O
horizon	O
recognised	O
in	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
is	O
the	O
Bothwell	LEXICON
Bridge	LEXICON
Marine	LEXICON
Band	LEXICON
,	O
now	O
known	O
to	O
extend	O
from	O
the	O
type	O
locality	O
westwards	O
to	O
the	O
Prospecthill	O
borehole	O
on	O
sheet	O
30E	O
.	O

The	O
association	O
has	O
led	O
to	O
this	O
band	O
being	O
correlated	O
with	O
the	O
Shafton	LEXICON
Marine	LEXICON
Band	LEXICON
of	O
the	O
Pennine	O
coalfields	O
of	O
northern	O
England	O
.	O

The	O
horizon	O
of	O
intrusion	O
rises	O
eastwards	O
from	O
low	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
to	O
above	O
the	O
Glasgow	LEXICON
Main	LEXICON
Coal	LEXICON
in	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

Three	O
members	O
of	O
the	O
sill-complex	O
in	O
the	O
adjacent	O
Sheet	O
30E	O
have	O
been	O
radiometrically	O
dated	O
at	O
270-273	O
Ma	O
suggesting	O
that	O
the	O
complex	O
is	O
early	O
to	O
mid	O
-	O
Permian	CHRONOSTRAT
in	O
age	O
.	O

They	O
cut	O
strata	O
up	O
to	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
in	O
age	O
.	O

Their	O
age	O
is	O
assumed	O
to	O
be	O
the	O
same	O
as	O
that	O
of	O
the	O
sills	O
,	O
namely	O
290-295	O
Ma	O
,	O
that	O
is	O
late	O
-	O
Westphalian	CHRONOSTRAT
or	O
early	O
Stephanian	CHRONOSTRAT
.	O

East	O
of	O
there	O
a	O
continuation	O
cuts	O
Namurian	CHRONOSTRAT
strata	O
and	O
extends	O
on	O
to	O
Sheet	O
31E	O
.	O

The	O
Midland	O
Valley	O
quartz-dolerite	O
sill-complex	O
is	O
regarded	O
as	O
late	O
-	O
Westphalian	CHRONOSTRAT
or	O
early	O
Stephenian	CHRONOSTRAT
,	O
with	O
a	O
radiometric	O
age	O
of	O
290-295	O
Ma	O
.	O

In	O
the	O
north	O
the	O
main	O
part	O
of	O
the	O
sill-complex	O
is	O
intruded	O
into	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
strata	O
.	O

Southwards	O
it	O
rises	O
stratigraphically	O
through	O
the	O
Limestone	LEXICON
Coal	LEXICON
Group	LEXICON
at	O
Kilsyth	O
,	O
the	O
Upper	LEXICON
Limestone	LEXICON
Group	LEXICON
at	O
Cumbernauld	O
,	O
the	O
Passage	O
Group	O
at	O
Glenboig	O
reaching	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
at	O
Airdrie	O
.	O

The	O
more	O
northerly	O
one	O
is	O
within	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
the	O
other	O
,	O
separated	O
from	O
it	O
by	O
the	O
Campsie	O
Fault	O
,	O
straddles	O
a	O
NE-SW	O
fault	O
between	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

Biotite	O
crystals	O
from	O
the	O
Lennoxtown	O
essexite	O
have	O
been	O
dated	O
radiometrically	O
at	O
270	O
Ma	O
suggesting	O
an	O
early	O
or	O
mid	O
-	O
Permian	CHRONOSTRAT
age	O
,	O
the	O
same	O
as	O
the	O
alkali-dolerite	O
sills	O
.	O

The	O
inclusions	O
are	O
notably	O
similar	O
to	O
those	O
found	O
in	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
conglomerates	O
along	O
the	O
Highland	O
Boundary	O
Fault	O
.	O

Olivine-dolerite	O
dykes	O
with	O
WNW-ESE	O
trend	O
occur	O
in	O
late	O
-	O
Dinantian	CHRONOSTRAT
and	O
Namurian	CHRONOSTRAT
strata	O
at	O
the	O
surface	O
in	O
the	O
Lennoxtown	O
area	O
,	O
underground	O
near	O
Torrance	O
-LSB-	O
NS	O
620	O
742	O
-RSB-	O
and	O
both	O
above	O
and	O
below	O
ground	O
between	O
Glasgow	O
and	O
Coatbridge	O
.	O

The	O
graben	O
structure	O
was	O
developed	O
in	O
the	O
early	O
Devonian	CHRONOSTRAT
in	O
a	O
zone	O
of	O
crustal	O
weakness	O
inherited	O
from	O
the	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
.	O

Analyses	O
of	O
plate	O
movements	O
,	O
structural	O
patterns	O
,	O
facies	O
distribution	O
of	O
the	O
sediments	O
,	O
and	O
the	O
presence	O
of	O
volcanism	O
,	O
have	O
led	O
to	O
the	O
proposal	O
of	O
a	O
wide	O
variety	O
of	O
stress	O
systems	O
and	O
their	O
origins	O
,	O
which	O
are	O
thought	O
to	O
have	O
affected	O
the	O
Devonian	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
of	O
the	O
Midland	O
Valley	O
.	O

However	O
several	O
authors	O
,	O
such	O
as	O
Kennedy	O
,	O
have	O
pointed	O
out	O
that	O
different	O
stress	O
systems	O
appear	O
to	O
have	O
been	O
operative	O
at	O
different	O
times	O
during	O
the	O
late	O
Devonian	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
.	O

The	O
oldest	O
sediments	O
seen	O
at	O
the	O
surface	O
in	O
the	O
Airdrie	O
district	O
,	O
the	O
Inverclyde	LEXICON
Group	LEXICON
of	O
late	O
Devonian	CHRONOSTRAT
-	O
early	O
Carboniferous	CHRONOSTRAT
age	O
,	O
were	O
deposited	O
under	O
quiet	O
tectonic	O
conditions	O
on	O
an	O
alluvial	O
plain	O
which	O
became	O
marginally	O
marine	O
and	O
subject	O
to	O
fluctuating	O
salinity	O
and	O
periodic	O
dessication	O
.	O

Shortly	O
after	O
,	O
during	O
the	O
mid	O
-	O
Dinantian	CHRONOSTRAT
,	O
a	O
major	O
unconformity	O
occurred	O
along	O
the	O
south	O
margin	O
of	O
the	O
Kilsyth	O
Hills	O
,	O
just	O
to	O
the	O
south	O
of	O
the	O
South	LEXICON
Campsie	LEXICON
Linear	LEXICON
Vent	LEXICON
System	LEXICON
.	O

This	O
implies	O
that	O
the	O
break	O
may	O
be	O
due	O
to	O
magmatic	O
updoming	O
prior	O
to	O
eruption	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
lavas	O
.	O

The	O
absence	O
of	O
volcanics	O
in	O
a	O
very	O
attenuated	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sequence	O
in	O
this	O
area	O
does	O
not	O
preclude	O
magmatic	O
updoming	O
as	O
a	O
controlling	O
mechanism	O
.	O

In	O
the	O
western	O
part	O
of	O
the	O
Midland	O
Valley	O
the	O
unconformity	O
was	O
followed	O
by	O
the	O
eruption	O
of	O
several	O
hundred	O
metres	O
of	O
lavas	O
belonging	O
to	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

Cyclic	O
sedimentation	O
became	O
established	O
and	O
continued	O
throughout	O
the	O
late	O
Dinantian	CHRONOSTRAT
and	O
Silesian	CHRONOSTRAT
.	O

During	O
the	O
late	O
Dinantian	CHRONOSTRAT
the	O
cyclic	O
sediments	O
of	O
the	O
Lower	LEXICON
Limestone	LEXICON
Formation	LEXICON
indicate	O
repeated	O
subsidence	O
of	O
a	O
fluvio-deltaic	O
environment	O
below	O
a	O
shallow	O
sea	O
.	O

During	O
the	O
Namurian	CHRONOSTRAT
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
sediments	O
of	O
the	O
present	O
district	O
were	O
deposited	O
in	O
a	O
similar	O
pattern	O
in	O
river-dominated	O
deltas	O
with	O
occasional	O
marine	O
influxes	O
.	O

On	O
the	O
bases	O
of	O
facies	O
and	O
thickness	O
distribution	O
of	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
sediments	O
Stedman	O
suggests	O
that	O
the	O
stress	O
regime	O
was	O
one	O
of	O
E-W	O
tension	O
which	O
in	O
the	O
SW	O
of	O
the	O
Midland	O
Valley	O
reactivated	O
a	O
Caledonoid	O
grain	O
.	O

In	O
the	O
present	O
district	O
the	O
succeeding	O
fluviodeltaic	O
and	O
marine	O
sediments	O
of	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
are	O
thickest	O
in	O
an	O
ENE-WSW	O
basin	O
which	O
developed	O
under	O
what	O
is	O
thought	O
to	O
be	O
transtensional	O
conditions	O
near	O
the	O
centre	O
of	O
the	O
area	O
.	O

The	O
dominantly	O
fluvial	O
conditions	O
with	O
short-lived	O
marine	O
incursions	O
which	O
followed	O
during	O
the	O
deposition	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
show	O
a	O
marked	O
change	O
in	O
facies	O
and	O
sediment	O
thickness	O
.	O

The	O
overlying	O
fluviodeltaic	O
Lower	LEXICON
and	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
of	O
Westphalian	CHRONOSTRAT
age	O
are	O
thickest	O
in	O
the	O
east	O
of	O
the	O
present	O
district	O
and	O
thin	O
gradually	O
westwards	O
reflecting	O
a	O
continuing	O
N-S	O
control	O
.	O

The	O
E-W	O
trending	O
quartz-dolerite	O
dykes	O
are	O
now	O
generally	O
accepted	O
to	O
be	O
of	O
late	O
Westphalian	CHRONOSTRAT
-	O
early	O
Stephanian	CHRONOSTRAT
in	O
age	O
.	O

This	O
is	O
thought	O
to	O
indicate	O
an	O
apparent	O
N-S	O
tensional	O
or	O
transtensional	O
phase	O
during	O
the	O
late	O
Carboniferous	CHRONOSTRAT
.	O

He	O
concluded	O
that	O
all	O
these	O
Silesian	CHRONOSTRAT
structural	O
features	O
are	O
compatable	O
with	O
right-lateral	O
strike	O
slip	O
superimposed	O
on	O
thermal	O
subsidence	O
.	O

Though	O
the	O
amount	O
of	O
lateral	O
movement	O
may	O
be	O
relatively	O
small	O
up	O
to	O
the	O
end	O
of	O
the	O
Namurian	CHRONOSTRAT
,	O
it	O
may	O
have	O
been	O
greater	O
at	O
the	O
end	O
of	O
the	O
Carboniferous	CHRONOSTRAT
.	O

In	O
this	O
context	O
,	O
transtension	O
appears	O
to	O
have	O
dominated	O
with	O
brief	O
intervals	O
of	O
transpression	O
during	O
deposition	O
of	O
the	O
early	O
part	O
of	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
,	O
Passage	LEXICON
Formation	LEXICON
and	O
towards	O
the	O
end	O
of	O
the	O
Silesian	CHRONOSTRAT
.	O

The	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
north	O
of	O
the	O
Campsie	O
Fault	O
is	O
very	O
gently	O
tilted	O
to	O
the	O
east	O
but	O
shows	O
no	O
sign	O
of	O
folding	O
.	O

Towards	O
the	O
north	O
,	O
where	O
it	O
becomes	O
a	O
very	O
shallow	O
,	O
open	O
fold	O
,	O
an	O
ill-defined	O
anticline	O
separates	O
it	O
from	O
a	O
NNE-SSW	O
syncline	O
that	O
runs	O
from	O
Balmalloch	O
-LSB-	O
NS	O
704	O
782	O
-RSB-	O
to	O
Shirva	O
-LSB-	O
NS	O
691	O
755	O
-RSB-	O
,	O
where	O
it	O
ends	O
in	O
the	O
basin	O
with	O
Passage	LEXICON
Formation	LEXICON
strata	O
on	O
the	O
north	O
side	O
of	O
the	O
Hilton-St	O
Flanans	O
Fault	O
.	O

From	O
the	O
half-dome	O
with	O
Limestone	LEXICON
Coal	LEXICON
Group	LEXICON
strata	O
south	O
of	O
the	O
fault	O
,	O
a	O
diffuse	O
,	O
ill-defined	O
NNE-SSW	O
anticline	O
can	O
be	O
traced	O
as	O
far	O
south	O
as	O
Gartcosh	O
-LSB-	O
NS	O
699	O
681	O
-RSB-	O
.	O

The	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
Banknock	O
Coalfield	O
are	O
bounded	O
by	O
two	O
large	O
faults	O
and	O
quite	O
steeply	O
folded	O
into	O
a	O
W-E	O
syncline	O
with	O
a	O
small	O
deep	O
basin	O
at	O
each	O
end	O
,	O
in	O
which	O
are	O
found	O
the	O
youngest	O
strata	O
preserved	O
.	O

The	O
southern	O
part	O
of	O
the	O
sheet	O
is	O
dominated	O
by	O
the	O
northern	O
part	O
of	O
the	O
Lanarkshire	O
Basin	O
,	O
a	O
broad	O
,	O
open	O
structure	O
largely	O
free	O
of	O
faults	O
,	O
and	O
occupied	O
by	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

To	O
the	O
southwest	O
the	O
northerly	O
dipping	O
southern	O
limb	O
of	O
the	O
basin	O
is	O
cut	O
off	O
to	O
the	O
south	O
by	O
the	O
major	O
lineament	O
,	O
the	O
Dechmont	O
Fault	O
,	O
south	O
of	O
which	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
lies	O
almost	O
flat	O
.	O

In	O
general	O
it	O
separates	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
to	O
the	O
north	O
from	O
younger	O
rocks	O
to	O
the	O
south	O
.	O

North	O
of	O
the	O
Campsie	O
Fault	O
,	O
fractures	O
are	O
numerous	O
in	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
can	O
mostly	O
be	O
divided	O
into	O
three	O
types	O
.	O

Secondly	O
,	O
there	O
are	O
several	O
that	O
radiate	O
out	O
from	O
the	O
Waterhead	LEXICON
Central	LEXICON
Volcanic	LEXICON
Complex	LEXICON
and	O
thirdly	O
there	O
is	O
the	O
Waterhead	O
Ring	O
Fault	O
that	O
bounds	O
the	O
complex	O
itself	O
.	O

Associated	O
marine	O
clays	O
of	O
the	O
Paisley	LEXICON
and	O
Linwood	LEXICON
Formation	LEXICON
,	O
are	O
preserved	O
in	O
parts	O
of	O
the	O
Clyde	O
valley	O
.	O

By	O
11	O
000	O
years	O
BP	O
local	O
sea-level	O
in	O
the	O
Clyde	O
valley	O
had	O
probably	O
fallen	O
from	O
the	O
late	O
-	O
Devensian	CHRONOSTRAT
maximum	O
to	O
present	O
OD	O
or	O
lower	O
.	O

The	O
following	O
account	O
of	O
the	O
Quaternary	O
sediments	O
and	O
associated	O
landforms	O
is	O
structured	O
to	O
reflect	O
their	O
relative	O
ages	O
and	O
utilises	O
the	O
stratigraphical	O
framework	O
established	O
by	O
Browne	O
and	O
McMillan	O
for	O
the	O
Clyde	O
valley	O
area	O
with	O
the	O
addition	O
of	O
one	O
newly	O
defined	O
unit	O
,	O
the	O
Kelvin	LEXICON
Formation	LEXICON
.	O

Whatever	O
the	O
sequence	O
of	O
events	O
,	O
it	O
seems	O
likely	O
that	O
erosive	O
processes	O
at	O
work	O
beneath	O
ice	O
sheets	O
during	O
the	O
Quaternary	CHRONOSTRAT
have	O
overdeepened	O
these	O
drainage	O
systems	O
.	O

During	O
late	O
-	O
Devensian	CHRONOSTRAT
and	O
Flandrian	CHRONOSTRAT
times	O
the	O
bedrock	O
depressions	O
have	O
been	O
filled	O
principally	O
with	O
water-laid	O
sediments	O
.	O

Pre	O
-	O
Dimlington	CHRONOSTRAT
Stade	CHRONOSTRAT
sand	O
and	O
gravel	O
of	O
the	O
Cadder	LEXICON
Formation	LEXICON
is	O
also	O
present	O
locally	O
,	O
underlying	O
the	O
Dimlington	O
till	O
of	O
the	O
Wilderness	LEXICON
Formation	LEXICON
.	O

In	O
the	O
Airdrie	O
Sheet	O
,	O
borehole	O
records	O
indicate	O
thicknesses	O
of	O
the	O
infilling	O
sediments	O
to	O
range	O
from	O
about	O
30m	O
west	O
of	O
Kilsyth	O
-LSB-	O
NS	O
700	O
770	O
-RSB-	O
to	O
87m	O
at	O
Torrance	O
-LSB-	O
NS	O
620	O
735	O
-RSB-	O
.	O

Between	O
Bothwell	O
-LSB-	O
NS	O
700	O
580	O
-RSB-	O
and	O
Cambuslang	O
-LSB-	O
NS	O
640	O
600	O
-RSB-	O
the	O
river	O
bed	O
is	O
cut	O
mainly	O
in	O
rock	O
and	O
is	O
therefore	O
likely	O
to	O
be	O
mainly	O
of	O
Flandrian	CHRONOSTRAT
age	O
.	O

On	O
the	O
high	O
ground	O
of	O
the	O
Airdrie	O
district	O
,	O
the	O
Devensian	CHRONOSTRAT
topography	O
was	O
probably	O
similar	O
to	O
that	O
of	O
today	O
.	O

On	O
high	O
ground	O
north	O
of	O
Airdrie	O
-LSB-	O
NS	O
760	O
650	O
-RSB-	O
and	O
around	O
Cumbernauld	O
-LSB-	O
NS	O
770	O
745	O
-RSB-	O
,	O
where	O
drift	O
thicknesses	O
generally	O
do	O
not	O
exceed	O
a	O
few	O
metres	O
,	O
easterly	O
aligned	O
crag	O
and	O
tail	O
landforms	O
are	O
developed	O
on	O
resistant	O
bedrock	O
including	O
Upper	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sandstones	O
and	O
Permo	CHRONOSTRAT
-	O
Carboniferous	CHRONOSTRAT
dolerite	O
sills	O
and	O
dykes	O
.	O

These	O
deposits	O
,	O
which	O
are	O
preserved	O
only	O
in	O
a	O
limited	O
area	O
around	O
Baillieston	O
-LSB-	O
NS	O
670	O
640	O
-RSB-	O
in	O
eastern	O
Glasgow	O
,	O
are	O
overlain	O
by	O
the	O
Baillieston	LEXICON
Till	LEXICON
Formation	LEXICON
.	O

The	O
till	O
lies	O
stratigraphically	O
below	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
and	O
,	O
despite	O
the	O
absence	O
of	O
definitive	O
age	O
data	O
,	O
is	O
considered	O
to	O
be	O
the	O
product	O
of	O
a	O
glacial	O
event	O
earlier	O
than	O
the	O
late	O
-	O
Devensian	CHRONOSTRAT
.	O

In	O
general	O
the	O
colour	O
of	O
the	O
clay	O
matrix	O
is	O
greyish	O
brown	O
reflecting	O
that	O
of	O
the	O
local	O
Coal	LEXICON
Measures	LEXICON
bedrock	O
.	O

Possible	O
ancient	O
surface	O
weathering	O
,	O
in	O
the	O
form	O
of	O
oxidation	O
,	O
results	O
in	O
a	O
reddish	O
brown	O
hue	O
to	O
the	O
upper	O
surface	O
of	O
the	O
Baillieston	LEXICON
Till	LEXICON
as	O
seen	O
in	O
the	O
M8	O
sections	O
.	O

Here	O
sand	O
and	O
gravel	O
of	O
the	O
Cadder	LEXICON
Formation	LEXICON
rests	O
on	O
the	O
Baillieston	LEXICON
Till	LEXICON
Formation	LEXICON
and	O
is	O
in	O
turn	O
overlain	O
by	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
.	O

Between	O
Torrance	O
-LSB-	O
NS	O
620	O
740	O
-RSB-	O
and	O
Kirkintilloch	O
-LSB-	O
NS	O
655	O
740	O
-RSB-	O
most	O
available	O
borehole	O
logs	O
record	O
only	O
the	O
top	O
part	O
of	O
the	O
Quaternary	CHRONOSTRAT
sequence	O
through	O
the	O
Flandrian	CHRONOSTRAT
and	O
late	O
-	O
Devensian	CHRONOSTRAT
sediments	O
.	O

However	O
records	O
of	O
boreholes	O
south	O
of	O
Redbog	O
Farm	O
at	O
Torrance	O
-LSB-	O
NS	O
6153	O
7361	O
-RSB-	O
and	O
Crofthead	O
-LSB-	O
NS	O
6228	O
7264	O
-RSB-	O
penetrated	O
the	O
top	O
few	O
metres	O
of	O
sand	O
and	O
silt	O
lying	O
below	O
the	O
Wilderness	LEXICON
Till	LEXICON
.	O

Broomhill	LEXICON
Formation	LEXICON
,	O
see	O
below	O
-RRB-	O
lies	O
between	O
the	O
sand	O
and	O
gravel	O
and	O
the	O
Baillieston	LEXICON
Till	LEXICON
.	O

Observed	O
faulting	O
of	O
the	O
sediments	O
may	O
be	O
due	O
in	O
part	O
to	O
glacial	O
overriding	O
by	O
the	O
ice-sheet	O
that	O
deposited	O
the	O
overlying	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
.	O

The	O
outwash	O
deposits	O
were	O
subsequently	O
overridden	O
by	O
the	O
ice	O
which	O
deposited	O
the	O
overlying	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
.	O

Subsurface	O
data	O
and	O
temporary	O
sections	O
reveal	O
laminated	O
muds	O
resting	O
discontinuously	O
upon	O
the	O
Baillieston	LEXICON
Till	LEXICON
.	O

The	O
clay	O
was	O
observed	O
to	O
be	O
in	O
thrust	O
contact	O
with	O
the	O
underlying	O
Baillieston	LEXICON
Till	LEXICON
and	O
overlying	O
Wilderness	LEXICON
Till	LEXICON
.	O

The	O
principal	O
deposit	O
of	O
the	O
Dimlington	O
ice	O
sheet	O
is	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
.	O

The	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
was	O
proved	O
,	O
amongst	O
others	O
,	O
in	O
the	O
BGS	O
Bellshill	O
-LSB-	O
NS	O
7304	O
6161	O
-RSB-	O
and	O
Bothwell	O
Park	O
-LSB-	O
NS	O
7159	O
5956	O
-RSB-	O
boreholes	O
.	O

The	O
colour	O
of	O
the	O
matrix	O
varies	O
,	O
depending	O
upon	O
that	O
of	O
the	O
local	O
bedrock	O
and	O
can	O
be	O
reddish	O
brown	O
from	O
Devonian	CHRONOSTRAT
and	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
sources	O
,	O
brownish	O
grey	O
or	O
black	O
from	O
Lower	LEXICON
and	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
and	O
Namurian	CHRONOSTRAT
strata	O
and	O
greenish	O
grey	O
from	O
Highland	O
metamorphic	O
rocks	O
.	O

Minor	O
features	O
noted	O
in	O
the	O
Wilderness	LEXICON
Till	LEXICON
include	O
pockets	O
and	O
bands	O
of	O
medium-grained	O
sand	O
and	O
thin	O
bands	O
of	O
laminated	O
clay	O
.	O

In	O
the	O
Cadder	O
area	O
,	O
temporary	O
sections	O
in	O
the	O
Wilderness	LEXICON
Till	LEXICON
revealed	O
that	O
locally	O
the	O
diamicton	O
is	O
graded	O
,	O
displaying	O
both	O
upward	O
and	O
downward	O
coarsening	O
of	O
the	O
dispersed	O
pebble	O
to	O
boulder	O
sized	O
clasts	O
.	O

In	O
the	O
easternmost	O
of	O
the	O
sections	O
the	O
clays	O
and	O
silts	O
are	O
sheared	O
out	O
so	O
that	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
rests	O
directly	O
upon	O
the	O
Baillieston	LEXICON
Till	LEXICON
.	O

The	O
overlying	O
till	O
,	O
which	O
is	O
considered	O
to	O
be	O
the	O
Wilderness	LEXICON
Till	LEXICON
,	O
is	O
a	O
red-brown	O
,	O
sandy	O
,	O
clayey	O
diamicton	O
.	O

The	O
observed	O
faulted	O
blocks	O
may	O
represent	O
a	O
disturbed	O
floor	O
of	O
the	O
Baillieston	LEXICON
Till	LEXICON
Formation	LEXICON
or	O
may	O
alternatively	O
be	O
isolated	O
slices	O
of	O
the	O
Wilderness	LEXICON
Till	LEXICON
broken	O
off	O
and	O
incorporated	O
into	O
the	O
bedded	O
sediments	O
by	O
glacitectonic	O
processes	O
.	O

At	O
Cadder	O
,	O
glacitectonic	O
disturbance	O
in	O
the	O
Cadder	LEXICON
Formation	LEXICON
,	O
which	O
underlies	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
,	O
is	O
restricted	O
to	O
minor	O
faulting	O
and	O
small-scale	O
folding	O
.	O

Early	O
references	O
to	O
organic	O
remains	O
either	O
caught	O
up	O
within	O
or	O
underlying	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
provide	O
indications	O
of	O
boreal	O
and	O
sub-arctic	O
climatic	O
conditions	O
before	O
and	O
during	O
the	O
build-up	O
of	O
the	O
ice	O
sheet	O
.	O

Although	O
all	O
of	O
the	O
species	O
recorded	O
from	O
Airdrie	O
occur	O
in	O
Devensian	CHRONOSTRAT
interstadial	O
faunas	O
,	O
no	O
specific	O
interstadial	O
has	O
been	O
found	O
to	O
contain	O
all	O
five	O
of	O
the	O
Airdrie	O
taxa	O
.	O

Sand	O
and	O
gravel	O
transported	O
and	O
deposited	O
by	O
meltwaters	O
in	O
both	O
valleys	O
are	O
referred	O
to	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
,	O
named	O
after	O
the	O
Broomhouse	O
area	O
of	O
eastern	O
Glasgow	O
,	O
where	O
the	O
deposits	O
directly	O
overlie	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
.	O

The	O
landforms	O
associated	O
with	O
deposits	O
of	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
indicate	O
an	O
ice	O
contact	O
environment	O
.	O

The	O
sedimentological	O
features	O
of	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
point	O
to	O
the	O
operation	O
of	O
fluvial	O
and	O
deltaic	O
processes	O
.	O

The	O
Bellshill	LEXICON
Formation	LEXICON
is	O
named	O
from	O
the	O
Bellshill	O
area	O
where	O
the	O
unit	O
is	O
widely	O
distributed	O
at	O
surface	O
and	O
is	O
usually	O
underlain	O
by	O
the	O
Wilderness	LEXICON
Till	LEXICON
.	O

The	O
presence	O
of	O
deltas	O
building	O
out	O
laterally	O
into	O
the	O
lake	O
from	O
tributary	O
valleys	O
of	O
the	O
Clyde	O
is	O
indicated	O
by	O
the	O
occurrence	O
of	O
the	O
sand	O
and	O
gravel	O
bodies	O
which	O
have	O
been	O
assigned	O
to	O
the	O
Ross	LEXICON
Formation	LEXICON
.	O

Sediments	O
deposited	O
in	O
a	O
proximal	O
position	O
to	O
the	O
ice	O
dam	O
at	O
the	O
the	O
northwest	O
end	O
of	O
the	O
proglacial	O
lake	O
are	O
interpreted	O
as	O
a	O
complex	O
of	O
ice-contact	O
and	O
deltaic	O
sands	O
and	O
gravels	O
,	O
assigned	O
respectively	O
to	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
and	O
Ross	LEXICON
Formations	LEXICON
.	O

Although	O
the	O
transport	O
direction	O
of	O
the	O
Ross	LEXICON
Formation	LEXICON
is	O
ambivalent	O
in	O
temporary	O
sections	O
exposed	O
at	O
Bothwell	O
-LSB-	O
NS	O
708	O
589	O
-RSB-	O
,	O
there	O
are	O
clear	O
indications	O
of	O
easterly	O
current	O
directions	O
in	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
at	O
Greenoakhill	O
Gravel	O
Pit	O
-LSB-	O
NS	O
675	O
625	O
-RSB-	O
.	O

Similar	O
structures	O
also	O
affect	O
the	O
overlying	O
marine	O
Paisley	LEXICON
Formation	LEXICON
clays	O
.	O

Moundy	O
deposits	O
of	O
sand	O
and	O
gravel	O
,	O
assigned	O
to	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
,	O
occupy	O
mainly	O
the	O
northern	O
slopes	O
of	O
the	O
Kelvin	O
and	O
Bonny	O
Water	O
valley	O
,	O
between	O
Kilsyth	O
-LSB-	O
NS	O
720	O
780	O
-RSB-	O
and	O
Bonnybridge	O
-LSB-	O
NS	O
824	O
800	O
-RSB-	O
.	O

Boreholes	O
put	O
down	O
on	O
the	O
northern	O
valley	O
side	O
show	O
deposits	O
to	O
range	O
from	O
2	O
to	O
4m	O
in	O
thickness	O
and	O
to	O
rest	O
on	O
Wilderness	LEXICON
Till	LEXICON
.	O

On	O
the	O
south	O
side	O
of	O
the	O
valley	O
at	O
Easter	O
Dullatur	O
-LSB-	O
NS	O
747	O
772	O
-RSB-	O
boreholes	O
sited	O
on	O
the	O
moundy	O
terrain	O
proved	O
between	O
1	O
and	O
6m	O
of	O
sand	O
and	O
gravel	O
assigned	O
to	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
.	O

On	O
the	O
north	O
side	O
boreholes	O
prove	O
between	O
3	O
and	O
26m	O
of	O
sand	O
and	O
gravel	O
usually	O
resting	O
on	O
Wilderness	LEXICON
Till	LEXICON
.	O

Boreholes	O
sited	O
on	O
the	O
floodplain	O
at	O
Birdston	O
Farm	O
-LSB-	O
NS	O
6572	O
7563	O
-RSB-	O
,	O
Springfield	O
-LSB-	O
NS	O
6490	O
7443	O
-RSB-	O
and	O
Sandy	O
Knowes	O
-LSB-	O
NS	O
6318	O
7357	O
-RSB-	O
all	O
prove	O
deposits	O
of	O
sand	O
and	O
gravel	O
,	O
assigned	O
to	O
the	O
Ross	LEXICON
Formation	LEXICON
,	O
beneath	O
alluvial	O
silt	O
of	O
the	O
Kelvin	LEXICON
Formation	LEXICON
.	O

The	O
Bellshill	O
deposits	O
rest	O
on	O
some	O
28m	O
of	O
sand	O
and	O
gravel	O
,	O
presumed	O
to	O
be	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
,	O
which	O
in	O
turn	O
overlie	O
about	O
10m	O
of	O
Wilderness	LEXICON
Till	LEXICON
.	O

In	O
central	O
and	O
western	O
Glasgow	O
outwash	O
deposits	O
which	O
formed	O
in	O
a	O
sub-marine	O
environment	O
have	O
been	O
defined	O
as	O
the	O
Bridgeton	LEXICON
Formation	LEXICON
.	O

They	O
are	O
interpreted	O
as	O
being	O
material	O
which	O
was	O
eroded	O
from	O
the	O
sand	O
and	O
gravel	O
of	O
the	O
Broomhouse	LEXICON
and	O
Ross	LEXICON
formations	O
and	O
redeposited	O
farther	O
downstream	O
.	O

Dead	O
ice	O
must	O
also	O
have	O
remained	O
to	O
cap	O
some	O
of	O
the	O
remnant	O
mounds	O
of	O
sand	O
and	O
gravel	O
of	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
.	O

Locally	O
the	O
mounds	O
were	O
situated	O
at	O
elevations	O
low	O
enough	O
to	O
allow	O
burial	O
by	O
the	O
marine	O
clays	O
and	O
silts	O
of	O
the	O
Paisley	LEXICON
Formation	LEXICON
.	O

As	O
at	O
Shieldhall	O
,	O
the	O
Greenoakhill	O
sections	O
reveal	O
evidence	O
for	O
burial	O
of	O
ice	O
which	O
survived	O
perhaps	O
for	O
many	O
hundreds	O
of	O
years	O
in	O
or	O
under	O
deposits	O
of	O
sand	O
and	O
gravel	O
sealed	O
under	O
a	O
thick	O
cap	O
of	O
marine	O
clay	O
and	O
silt	O
of	O
the	O
Paisley	LEXICON
Formation	LEXICON
.	O

Initially	O
,	O
meltwater	O
plumes	O
dominated	O
and	O
the	O
Paisley	LEXICON
Formation	LEXICON
clay	O
and	O
silt	O
reflects	O
this	O
influence	O
.	O

The	O
stratigraphical	O
relationships	O
of	O
the	O
Paisley	LEXICON
Formation	LEXICON
to	O
the	O
late	O
-	O
Devensian	CHRONOSTRAT
glacial	O
and	O
glacilacustrine	O
deposits	O
at	O
Bothwell	O
are	O
shown	O
on	O
Figure	O
22	O
.	O

The	O
presence	O
in	O
the	O
Paisley	LEXICON
Formation	LEXICON
sediments	O
of	O
primary	O
current	O
lineation	O
suggests	O
relatively	O
high	O
energy	O
depositional	O
conditions	O
.	O

The	O
maximum	O
altitudes	O
to	O
which	O
clays	O
assigned	O
to	O
the	O
Paisley	LEXICON
Formation	LEXICON
are	O
known	O
to	O
occur	O
are	O
generally	O
over	O
40m	O
above	O
OD	O
in	O
eastern	O
Glasgow	O
and	O
45m	O
above	O
OD	O
at	O
Ross	O
House	O
,	O
Hamilton	O
.	O

In	O
the	O
Glasgow	O
and	O
Paisley	O
areas	O
the	O
Paisley	LEXICON
Formation	LEXICON
is	O
commonly	O
overlain	O
by	O
thickly	O
bedded	O
muds	O
of	O
the	O
Linwood	LEXICON
Formation	LEXICON
which	O
contain	O
a	O
rich	O
mid	O
-	O
to	O
high-boreal	O
fauna	O
.	O

There	O
is	O
no	O
definitive	O
evidence	O
for	O
the	O
existence	O
of	O
the	O
Linwood	LEXICON
Formation	LEXICON
in	O
the	O
Airdrie	O
district	O
although	O
an	O
occurrence	O
of	O
shells	O
was	O
recorded	O
in	O
`	O
blue	O
'	O
clays	O
in	O
the	O
former	O
Polmadie	O
Brick	O
Pit	O
-LSB-	O
NS	O
600	O
628	O
-RSB-	O
,	O
just	O
to	O
the	O
west	O
of	O
the	O
Airdrie	O
sheet	O
,	O
at	O
a	O
depth	O
of	O
8	O
m.	O

Such	O
evidence	O
may	O
indicate	O
the	O
presence	O
locally	O
of	O
small	O
outliers	O
of	O
marine	O
clays	O
of	O
the	O
Linwood	LEXICON
Formation	LEXICON
farther	O
east	O
.	O

In	O
the	O
Fullarton	O
-LSB-	O
NS	O
640	O
630	O
-RSB-	O
,	O
Mount	O
Vernon	O
-LSB-	O
NS	O
650	O
630	O
-RSB-	O
and	O
Carmyle	O
-LSB-	O
NS	O
640	O
620	O
-RSB-	O
areas	O
,	O
deltaic	O
sand	O
and	O
gravel	O
deposits	O
of	O
the	O
Killearn	LEXICON
Formation	LEXICON
occur	O
.	O

However	O
,	O
dating	O
of	O
the	O
supposed	O
incision	O
is	O
open	O
to	O
doubt	O
because	O
of	O
the	O
problem	O
of	O
correlating	O
largely	O
unfossiliferous	O
superimposed	O
successions	O
of	O
sands	O
and	O
gravels	O
which	O
could	O
include	O
the	O
late	O
-	O
Devensian	CHRONOSTRAT
Broomhouse	LEXICON
and	O
Bridgeton	LEXICON
formations	O
.	O

Here	O
the	O
till	O
is	O
overlain	O
by	O
a	O
thin	O
Flandrian	CHRONOSTRAT
peat	O
dated	O
at	O
5994	O
~	O
50	O
years	O
BP	O
.	O

Other	O
examples	O
occur	O
in	O
the	O
sheet	O
area	O
of	O
late	O
-	O
Devensian	CHRONOSTRAT
peat	O
and	O
associated	O
fine-grained	O
lake	O
sediments	O
which	O
formed	O
immediately	O
prior	O
to	O
the	O
cold	O
episode	O
of	O
the	O
Loch	CHRONOSTRAT
Lomond	CHRONOSTRAT
Stade	CHRONOSTRAT
.	O

The	O
succeeding	O
warm	O
phase	O
,	O
the	O
Flandrian	CHRONOSTRAT
Stage	O
,	O
is	O
marked	O
by	O
marine	O
and	O
non-marine	O
deposits	O
and	O
landforms	O
in	O
the	O
Clyde	O
area	O
but	O
,	O
despite	O
their	O
wide	O
geographical	O
distribution	O
,	O
these	O
are	O
not	O
well	O
understood	O
.	O

Between	O
about	O
8	O
400	O
and	O
5	O
000	O
years	O
BP	O
,	O
the	O
main	O
Flandrian	CHRONOSTRAT
marine	O
transgression	O
led	O
to	O
the	O
inundation	O
of	O
ground	O
on	O
either	O
side	O
of	O
the	O
River	O
Clyde	O
as	O
far	O
upstream	O
as	O
Cambuslang	O
.	O

Evidence	O
for	O
changes	O
in	O
sea-level	O
is	O
seen	O
in	O
the	O
presence	O
of	O
three	O
series	O
of	O
Flandrian	CHRONOSTRAT
to	O
Recent	O
levels	O
in	O
the	O
lower	O
Clyde	O
valley	O
.	O

In	O
east	O
Glasgow	O
two	O
of	O
these	O
series	O
are	O
recognised	O
:	O
early	O
to	O
mid	O
-	O
Flandrian	CHRONOSTRAT
levels	O
of	O
up	O
to	O
12m	O
above	O
OD	O
,	O
and	O
late	O
-	O
Flandrian	CHRONOSTRAT
to	O
Recent	O
surfaces	O
of	O
3	O
to	O
6	O
m.	O
Associated	O
with	O
these	O
surfaces	O
in	O
the	O
Clyde	O
valley	O
are	O
estuarine	O
sediments	O
of	O
the	O
Erskine	LEXICON
and	O
Gourock	LEXICON
formations	O
.	O

Although	O
some	O
late	O
-	O
Devensian	CHRONOSTRAT
peat	O
beds	O
occur	O
in	O
the	O
sheet	O
area	O
the	O
principal	O
deposits	O
of	O
peat	O
found	O
in	O
the	O
district	O
are	O
of	O
Flandrian	CHRONOSTRAT
age	O
.	O

During	O
the	O
early	O
Flandrian	CHRONOSTRAT
,	O
as	O
the	O
Scottish	O
climate	O
became	O
warmer	O
and	O
wetter	O
Sphagnum	O
peat	O
began	O
to	O
develop	O
in	O
hollows	O
on	O
former	O
lake	O
floors	O
and	O
on	O
poorly	O
drained	O
flat	O
areas	O
.	O

Peat	O
,	O
which	O
in	O
the	O
Glasgow	O
area	O
has	O
been	O
assigned	O
to	O
the	O
Clippens	LEXICON
Peat	LEXICON
Formation	LEXICON
,	O
formed	O
in	O
low	O
lying	O
ground	O
particularly	O
to	O
the	O
north	O
of	O
Coatbridge	O
.	O

The	O
peat	O
rests	O
on	O
earlier	O
Flandrian	CHRONOSTRAT
alluvial	O
sediments	O
.	O

This	O
record	O
serves	O
to	O
indicate	O
that	O
peat	O
accumulated	O
intermittently	O
on	O
the	O
valley	O
floor	O
during	O
the	O
Flandrian	CHRONOSTRAT
.	O

Coarse-grained	O
Flandrian	CHRONOSTRAT
sediments	O
deposited	O
in	O
fluvial	O
environments	O
,	O
including	O
present-day	O
river	O
courses	O
were	O
assigned	O
by	O
Browne	O
and	O
McMillan	O
to	O
the	O
Law	LEXICON
Formation	LEXICON
.	O

Older	O
Flandrian	CHRONOSTRAT
sand	O
and	O
gravel	O
which	O
may	O
have	O
been	O
partly	O
associated	O
with	O
deltaic	O
and	O
lacustrine	O
environments	O
were	O
referred	O
to	O
the	O
Endrick	LEXICON
Formation	LEXICON
.	O

The	O
Law	LEXICON
Formation	LEXICON
is	O
named	O
from	O
the	O
Law	O
Borehole	O
,	O
which	O
contains	O
the	O
standard	O
section	O
.	O

Up	O
to	O
6m	O
of	O
Law	LEXICON
Formation	LEXICON
sand	O
and	O
gravel	O
is	O
proved	O
in	O
records	O
of	O
boreholes	O
on	O
the	O
alluvial	O
plain	O
of	O
the	O
River	O
Clyde	O
south-east	O
of	O
Bothwell	O
-LSB-	O
NS	O
700	O
580	O
-RSB-	O
.	O

In	O
the	O
northern	O
part	O
of	O
the	O
district	O
,	O
alluvial	O
gravels	O
of	O
the	O
Law	LEXICON
Formation	LEXICON
are	O
present	O
in	O
the	O
valleys	O
of	O
the	O
River	O
Kelvin	O
,	O
Bonny	O
Water	O
,	O
Luggie	O
Water	O
,	O
River	O
Carron	O
and	O
Glazert	O
Water	O
.	O

East	O
of	O
Kilsyth	O
,	O
at	O
Craigmarloch	O
Drawbridge	O
,	O
-LSB-	O
NS	O
7332	O
7745	O
-RSB-	O
some	O
2.5m	O
of	O
sand	O
and	O
gravel	O
ascribed	O
to	O
the	O
Law	LEXICON
Formation	LEXICON
rests	O
on	O
late	O
-	O
Devensian	CHRONOSTRAT
gravels	O
.	O

Between	O
Kilsyth	O
and	O
Kirkintilloch	O
up	O
to	O
5m	O
of	O
sand	O
and	O
gravel	O
,	O
commonly	O
overlain	O
by	O
fine-grained	O
deposits	O
of	O
the	O
Kelvin	LEXICON
Formation	LEXICON
.	O

The	O
whole	O
sequence	O
has	O
been	O
ascribed	O
to	O
the	O
Law	LEXICON
Formation	LEXICON
but	O
the	O
basal	O
part	O
could	O
have	O
been	O
deposited	O
by	O
glacial	O
meltwaters	O
during	O
either	O
of	O
the	O
late	O
-	O
Devensian	CHRONOSTRAT
glaciations	O
.	O

Deposits	O
of	O
the	O
deltaic	O
Endrick	LEXICON
Formation	LEXICON
may	O
be	O
present	O
under	O
`	O
alluvial	O
'	O
terraces	O
of	O
the	O
Kelvin	O
lying	O
above	O
the	O
general	O
level	O
of	O
the	O
floodplain	O
at	O
elevations	O
of	O
35	O
to	O
50m	O
OD	O
.	O

At	O
Longcroft	O
,	O
about	O
4m	O
of	O
gravels	O
of	O
the	O
Endrick	LEXICON
Formation	LEXICON
overlie	O
late	O
-	O
Devensian	CHRONOSTRAT
glacifluvial	O
gravels	O
of	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
,	O
the	O
latter	O
probably	O
having	O
been	O
transported	O
along	O
the	O
Red	O
Glen	O
-LSB-	O
NS	O
776	O
760	O
-RSB-	O
.	O

The	O
glacifluvial	O
gravels	O
overlie	O
Wilderness	LEXICON
Till	LEXICON
.	O

At	O
Hirst	O
2.2m	O
of	O
sandy	O
gravel	O
,	O
of	O
possible	O
deltaic	O
origin	O
,	O
rests	O
directly	O
on	O
Wilderness	LEXICON
Till	LEXICON
.	O

These	O
sands	O
may	O
be	O
early	O
Flandrian	CHRONOSTRAT
fluvial	O
deposits	O
and	O
as	O
such	O
are	O
best	O
referred	O
to	O
the	O
Endrick	LEXICON
Formation	LEXICON
.	O

The	O
Kelvin	LEXICON
Formation	LEXICON
includes	O
the	O
recent	O
fine-grained	O
sediments	O
of	O
the	O
valley	O
floor	O
of	O
the	O
River	O
Kelvin	O
,	O
Bonny	O
Water	O
and	O
other	O
rivers	O
and	O
streams	O
.	O

Lake	O
alluvium	O
of	O
Flandrian	CHRONOSTRAT
age	O
present	O
north-east	O
of	O
Glasgow	O
and	O
east	O
of	O
Bisphopbriggs	O
at	O
elevations	O
between	O
about	O
60	O
and	O
90m	O
above	O
OD	O
is	O
also	O
referred	O
to	O
this	O
formation	O
.	O

Clay	O
and	O
silt	O
of	O
the	O
Kelvin	LEXICON
Formation	LEXICON
forms	O
much	O
of	O
the	O
valley	O
floor	O
of	O
the	O
River	O
Kelvin	O
.	O

In	O
the	O
Kelvin	O
valley	O
lacustrine	O
clay	O
and	O
silt	O
deposits	O
concealed	O
by	O
younger	O
Flandrian	CHRONOSTRAT
sediments	O
are	O
locally	O
present	O
.	O

These	O
deposits	O
probably	O
belong	O
to	O
the	O
Kilmaronock	LEXICON
Formation	LEXICON
defined	O
by	O
Browne	O
and	O
McMillan	O
from	O
the	O
Mains	O
of	O
Kilmaronock	O
Borehole	O
by	O
Loch	O
Lomond	O
.	O

At	O
Strone	O
-LSB-	O
NS	O
7033	O
7665	O
-RSB-	O
a	O
borehole	O
record	O
proved	O
2.8m	O
of	O
dark	O
grey	O
clayey	O
silt	O
below	O
sand	O
of	O
the	O
Endrick	LEXICON
Formation	LEXICON
.	O

Many	O
former	O
excavations	O
are	O
infilled	O
or	O
partially	O
infilled	O
with	O
variably	O
compacted	O
materials	O
and	O
these	O
deposits	O
,	O
classified	O
as	O
Fill	O
or	O
Disturbed	LEXICON
Ground	LEXICON
on	O
the	O
Airdrie	O
Sheet	O
,	O
are	O
generally	O
thicker	O
than	O
other	O
made	O
ground	O
and	O
may	O
be	O
in	O
the	O
order	O
of	O
tens	O
of	O
metres	O
.	O

The	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
and	O
the	O
Coal	LEXICON
Measures	LEXICON
contain	O
most	O
of	O
the	O
economic	O
coals	O
.	O

The	O
Hurlet	LEXICON
Coal	LEXICON
in	O
the	O
Lawmuir	LEXICON
Formation	LEXICON
and	O
the	O
Chapelgreen	LEXICON
and	O
Upper	LEXICON
Hirst	LEXICON
coals	O
in	O
the	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
have	O
also	O
been	O
worked	O
,	O
plus	O
one	O
or	O
two	O
minor	O
seams	O
in	O
the	O
latter	O
.	O

The	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
was	O
the	O
main	O
source	O
of	O
both	O
blackband	O
and	O
clayband	O
ironstones	O
in	O
Sheet	O
31W	O
:	O
at	O
least	O
6	O
seams	O
of	O
the	O
former	O
and	O
four	O
of	O
the	O
latter	O
were	O
exploited	O
.	O

In	O
the	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
the	O
Airdrie	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
was	O
mined	O
extensively	O
,	O
and	O
the	O
Palacecraig	LEXICON
Blackband	LEXICON
Ironstone	LEXICON
was	O
worked	O
to	O
some	O
extent	O
.	O

The	O
Cambuslang	LEXICON
Marble	LEXICON
,	O
a	O
limy	O
ironstone	O
packed	O
with	O
non-marine	O
shells	O
,	O
was	O
worked	O
at	O
Cambuslang	O
-LSB-	O
NS	O
646	O
597	O
-RSB-	O
as	O
an	O
ornamental	O
stone	O
.	O

The	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
deficient	O
in	O
ironstone	O
,	O
but	O
four	O
seams	O
were	O
locally	O
extracted	O
.	O

The	O
Hurlet	LEXICON
limestone	LEXICON
was	O
extracted	O
together	O
with	O
the	O
Alum	LEXICON
Shale	LEXICON
and	O
the	O
Hurlet	LEXICON
Coal	LEXICON
.	O

Mining	O
of	O
fireclays	O
,	O
mostly	O
from	O
the	O
Passage	LEXICON
Formation	LEXICON
,	O
began	O
in	O
the	O
Garnkirk	O
and	O
Glenboig	O
areas	O
over	O
100	O
years	O
ago	O
and	O
later	O
spread	O
along	O
the	O
outcrop	O
of	O
the	O
formation	O
westwards	O
to	O
Glasgow	O
and	O
north-eastwards	O
to	O
Castlecary	O
.	O

At	O
Chapelhall	O
,	O
two	O
seams	O
in	O
the	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
were	O
extracted	O
.	O

The	O
Glenboig	LEXICON
Lower	LEXICON
Fireclay	LEXICON
provided	O
the	O
bulk	O
of	O
the	O
material	O
.	O

The	O
mudstones	O
above	O
the	O
Calmy	LEXICON
Limestone	LEXICON
have	O
been	O
quarried	O
quite	O
extensively	O
for	O
brick	O
manufacture	O
,	O
mainly	O
around	O
Cumbernauld	O
,	O
but	O
operations	O
have	O
ceased	O
for	O
the	O
present	O
.	O

The	O
National	O
Coal	O
Board	O
used	O
Blantyreferme	O
Nos.	O
4	O
and	O
5	O
mines	O
for	O
about	O
10	O
years	O
to	O
obtain	O
a	O
terracotta	O
clay	O
from	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
but	O
this	O
operation	O
ceased	O
20	O
years	O
ago	O
.	O

Lavas	O
in	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
at	O
Cathkin	O
Quarry	O
-LSB-	O
NS	O
622	O
583	O
-RSB-	O
,	O
alkaki	O
olivine-dolerite	O
sills	O
in	O
eastern	O
Glasgow	O
,	O
quartz-dolerite	O
dykes	O
in	O
several	O
places	O
and	O
quartz-dolerite	O
sills	O
almost	O
wherever	O
they	O
occur	O
,	O
have	O
all	O
been	O
used	O
for	O
concrete	O
aggregate	O
,	O
roadstone	O
,	O
kerbstones	O
etc.	O
.	O

In	O
Strathkelvin	O
,	O
sandstone	O
of	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
was	O
worked	O
at	O
Queenzieburn	O
-LSB-	O
NS	O
691	O
775	O
-RSB-	O
NE	O
of	O
Kirkintilloch	O
.	O

For	O
example	O
,	O
Deer	O
Park	O
Quarry	O
-LSB-	O
NS	O
735	O
539	O
-RSB-	O
in	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
was	O
re-opened	O
to	O
provide	O
a	O
source	O
of	O
stone	O
for	O
the	O
renovation	O
of	O
Chatelheraut	O
Hunting	O
Lodge	O
-LRB-	O
Stone	O
Industries	O
,	O
9	O
,	O
1987	O
,	O
p.	O
23	O
.	O

The	O
Carboniferous	CHRONOSTRAT
strata	O
which	O
appear	O
at	O
or	O
near	O
surface	O
in	O
this	O
district	O
offer	O
a	O
wide	O
range	O
of	O
hydraulic	O
properties	O
.	O

There	O
are	O
also	O
mudrocks	O
,	O
particularly	O
in	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
which	O
are	O
weakly	O
permeable	O
and	O
act	O
as	O
barriers	O
to	O
vertical	O
groundwater	O
movement	O
.	O

Nevertheless	O
,	O
groundwater	O
has	O
been	O
a	O
valuable	O
resource	O
for	O
industry	O
in	O
the	O
past	O
,	O
with	O
abstraction	O
notably	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
,	O
Passage	LEXICON
Formation	LEXICON
and	O
Upper	LEXICON
Limestone	LEXICON
Formation	LEXICON
.	O

Mine	O
drainage	O
records	O
in	O
the	O
Limestone	LEXICON
Coal	LEXICON
Formation	LEXICON
and	O
the	O
Coal	LEXICON
Measures	LEXICON
bear	O
this	O
out	O
.	O

Borehole	O
yields	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
and	O
the	O
older	O
strata	O
are	O
,	O
for	O
the	O
most	O
part	O
,	O
relatively	O
modest	O
.	O

This	O
contrasts	O
with	O
the	O
situation	O
in	O
Lothian	O
District	O
where	O
,	O
for	O
example	O
,	O
the	O
Passage	LEXICON
Formation	LEXICON
would	O
normally	O
offer	O
the	O
highest	O
groundwater	O
potential	O
.	O

There	O
are	O
no	O
local	O
exposures	O
of	O
crystalline	O
basement	O
from	O
which	O
its	O
properties	O
can	O
be	O
determined	O
,	O
but	O
it	O
can	O
be	O
expected	O
to	O
have	O
significant	O
contrasts	O
with	O
the	O
overlying	O
Palaeozoic	CHRONOSTRAT
sequence	O
.	O

Above	O
the	O
basement	O
the	O
first	O
principal	O
density	O
contrast	O
is	O
between	O
cleaved	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
and	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
.	O

The	O
second	O
is	O
between	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
rocks	O
and	O
the	O
overlying	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
and	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sedimentary	O
rocks	O
taken	O
together	O
.	O

The	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
also	O
have	O
a	O
marked	O
contrast	O
with	O
the	O
underlying	O
and	O
overlying	O
sedimentary	O
sequences	O
.	O

However	O
,	O
average	O
values	O
for	O
the	O
Devonian	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
successions	O
are	O
variable	O
,	O
depending	O
particularly	O
upon	O
the	O
poorly	O
known	O
proportions	O
of	O
igneous	O
material	O
present	O
in	O
the	O
sequences	O
,	O
and	O
also	O
on	O
the	O
sandstone	O
to	O
mudstone	O
ratios	O
.	O

The	O
magnetic	O
properties	O
and	O
the	O
palaeomagnetic	O
significance	O
of	O
igneous	O
rocks	O
in	O
the	O
district	O
and	O
elsewhere	O
in	O
the	O
Midland	O
Valley	O
have	O
been	O
the	O
subject	O
of	O
many	O
studies	O
,	O
which	O
have	O
concentrated	O
on	O
the	O
Carboniferous	CHRONOSTRAT
and	O
Permian	CHRONOSTRAT
igneous	O
rocks	O
.	O

These	O
inclinations	O
are	O
consistent	O
with	O
movement	O
of	O
the	O
Midland	O
Valley	O
Terrane	O
during	O
Carboniferous	CHRONOSTRAT
times	O
from	O
low	O
southerly	O
latitudes	O
to	O
the	O
equator	O
.	O

The	O
Hamilton	O
Low	O
corresponds	O
to	O
an	O
area	O
of	O
Westphalian	CHRONOSTRAT
and	O
older	O
Carboniferous	CHRONOSTRAT
sedimentary	O
rocks	O
.	O

Although	O
the	O
Waterhead	O
Farm	O
anomaly	O
occurs	O
over	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
the	O
thickness	O
of	O
the	O
lavas	O
in	O
this	O
area	O
is	O
insufficient	O
to	O
explain	O
its	O
amplitude	O
.	O

The	O
latter	O
interpret	O
the	O
Waterhead	O
Farm	O
feature	O
as	O
being	O
due	O
to	O
about	O
600m	O
of	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

Cotton	O
inferred	O
from	O
the	O
gradient	O
that	O
it	O
marks	O
a	O
fault	O
downthrowing	O
the	O
top	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
overlying	O
sedimentary	O
rocks	O
about	O
140m	O
to	O
the	O
NW	O
.	O

Rollin	O
attribute	O
this	O
low	O
to	O
a	O
2.5km	O
thick	O
sequence	O
of	O
upper	O
Palaeozoic	CHRONOSTRAT
rocks	O
.	O

An	O
alternative	O
interpretation	O
by	O
Alomari	O
,	O
ascribes	O
the	O
Hamilton	O
Low	O
to	O
a	O
concealed	O
granite	O
or	O
a	O
8km	O
thick	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
basin	O
.	O

The	O
exposed	O
Carboniferous	CHRONOSTRAT
igneous	O
rocks	O
in	O
the	O
area	O
can	O
not	O
account	O
for	O
the	O
anomalies	O
and	O
therefore	O
the	O
source	O
must	O
underlie	O
these	O
rocks	O
.	O

There	O
are	O
two	O
main	O
geophysical	O
current	O
interpretations	O
:	O
1	O
-RRB-	O
a	O
shallow	O
body	O
with	O
properties	O
similar	O
to	O
those	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
extending	O
from	O
their	O
base	O
.	O

The	O
bodies	O
in	O
these	O
interpretations	O
are	O
generally	O
regarded	O
as	O
intrusions	O
of	O
Carboniferous	CHRONOSTRAT
and	O
,	O
or	O
Devonian	CHRONOSTRAT
age	O
.	O

The	O
anomaly	O
pattern	O
comprises	O
high	O
frequency	O
,	O
high	O
amplitude	O
anomalies	O
over	O
the	O
outcrop	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
and	O
lower	O
frequency	O
,	O
low	O
amplitude	O
anomalies	O
over	O
the	O
areas	O
of	O
sedimentary	O
rocks	O
.	O

The	O
lavas	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
are	O
associated	O
with	O
a	O
dipolar	O
anomaly	O
at	O
their	O
boundary	O
with	O
the	O
sedimentary	O
rocks	O
,	O
with	O
a	O
trough	O
to	O
the	O
north	O
and	O
peak	O
to	O
the	O
south	O
.	O

This	O
indicates	O
that	O
in	O
bulk	O
the	O
lavas	O
have	O
a	O
normal	O
total	O
magnetisation	O
and	O
suggest	O
that	O
the	O
NRM	O
directions	O
are	O
highly	O
scattered	O
and	O
consequently	O
are	O
probably	O
less	O
reliable	O
than	O
Carboniferous	CHRONOSTRAT
intrusions	O
for	O
making	O
palaeogeographical	O
deductions	O
.	O

This	O
suggests	O
that	O
the	O
sedimentary	O
rocks	O
may	O
be	O
underlain	O
by	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
.	O

The	O
sonic	O
velocity	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
is	O
generally	O
so	O
much	O
higher	O
than	O
that	O
of	O
the	O
sedimentary	O
rocks	O
that	O
its	O
boundaries	O
have	O
high	O
reflection	O
coefficients	O
,	O
which	O
prevents	O
much	O
energy	O
from	O
penetrating	O
to	O
greater	O
depths	O
.	O

The	O
800m	O
deep	O
top	O
of	O
the	O
underlying	O
Dinantian	CHRONOSTRAT
lavas	O
was	O
also	O
detected	O
.	O

Hall	O
suggested	O
that	O
a	O
reflector	O
occurring	O
at	O
1.26km	O
was	O
due	O
to	O
the	O
base	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
and	O
that	O
the	O
lavas	O
thin	O
to	O
the	O
east	O
.	O

Among	O
the	O
reflectors	O
were	O
the	O
top	O
and	O
bottom	O
of	O
about	O
600m	O
of	O
the	O
Clyde	LEXICON
Plateau	LEXICON
Volcanic	LEXICON
Formation	LEXICON
,	O
showing	O
an	O
interval	O
velocity	O
of	O
4.2	O
km	O
s-1	O
and	O
horizons	O
in	O
the	O
Inverclyde	LEXICON
Group	LEXICON
and	O
the	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
.	O

The	O
deepest	O
identifiable	O
reflector	O
,	O
at	O
1s	O
two-way	O
time	O
,	O
was	O
interpreted	O
as	O
the	O
top	O
of	O
Lower	CHRONOSTRAT
Devonian	CHRONOSTRAT
and	O
possibly	O
older	O
rocks	O
.	O

Andrew	O
reported	O
reflection	O
lines	O
,	O
north	O
of	O
the	O
district	O
,	O
made	O
to	O
test	O
penetration	O
of	O
Devonian	CHRONOSTRAT
lavas	O
.	O

Four	O
main	O
refractors	O
are	O
generally	O
recognised	O
in	O
the	O
Midland	O
Valley	O
:	O
1	O
-RRB-	O
0.5	O
-	O
3.0km	O
thick	O
Carboniferous	CHRONOSTRAT
and	O
Upper	CHRONOSTRAT
Devonian	CHRONOSTRAT
strata	O
,	O
LISPB	O
layer	O
a1	O
,	O
top	O
7-9km	O
deep	O
.	O

South	LEXICON
Quarry	LEXICON
Breccia	LEXICON
Member	LEXICON
,	O
about	O
30m	O
thick	O
.	O

The	O
lowest	O
unit	O
is	O
the	O
Benscliffe	LEXICON
Breccia	LEXICON
Member	LEXICON
20	O
to	O
100m	O
thick	O
.	O

The	O
overlying	O
Beacon	LEXICON
Tuff	LEXICON
Member	LEXICON
is	O
about	O
875m	O
thick	O
.	O

At	O
the	O
top	O
of	O
the	O
formation	O
are	O
predominantly	O
volcaniclastic	O
units	O
commencing	O
with	O
the	O
Sandhills	LEXICON
Lodge	LEXICON
Member	LEXICON
,	O
exposed	O
south	O
of	O
Home	O
Farm	O
-LSB-	O
5037	O
1617	O
-RSB-	O
.	O

The	O
overlying	O
Buck	LEXICON
Hills	LEXICON
Member	LEXICON
is	O
a	O
fining-upwards	O
sequence	O
,	O
consisting	O
of	O
alternations	O
between	O
blue-grey	O
,	O
parallel-laminated	O
,	O
graded	O
volcaniclastic	O
mudstones	O
,	O
siltstones	O
and	O
sandstones	O
.	O

The	O
Swannymote	LEXICON
Breccia	LEXICON
Member	LEXICON
,	O
some	O
120m	O
thick	O
,	O
forms	O
isolated	O
outcrops	O
in	O
close	O
association	O
with	O
Sharpley	LEXICON
Porphyritic	LEXICON
Dacite	LEXICON
of	O
the	O
Whitwick	LEXICON
Volcanic	LEXICON
Complex	LEXICON
.	O

The	O
Cademan	LEXICON
Volcanic	LEXICON
Breccia	LEXICON
,	O
up	O
to	O
about	O
450m	O
thick	O
,	O
is	O
most	O
typically	O
developed	O
around	O
Calvary	O
Rock	O
.	O

To	O
the	O
south	O
,	O
beds	O
of	O
the	O
overlying	O
Swithland	LEXICON
Formation	LEXICON
contain	O
the	O
trace	O
fossil	O
Teichichnus	O
which	O
is	O
considered	O
to	O
be	O
no	O
older	O
than	O
Lower	CHRONOSTRAT
Cambrian	CHRONOSTRAT
.	O

The	O
North	LEXICON
Charnwood	LEXICON
Diorites	LEXICON
is	O
represented	O
by	O
near-vertical	O
to	O
inclined	O
andesitic	O
sheets	O
,	O
up	O
to	O
60m	O
wide	O
.	O

A	O
second	O
intrusive	O
type	O
,	O
the	O
Lubcloud	LEXICON
Microgranite	LEXICON
,	O
is	O
exposed	O
south	O
of	O
Ives	O
Head	O
summit	O
where	O
it	O
occurs	O
as	O
a	O
9	O
m-wide	O
north-west-trending	O
dyke	O
.	O

Stockingford	LEXICON
Shale	LEXICON
Group	LEXICON
.	O

Small	O
outliers	O
of	O
Lower	LEXICON
Coal	LEXICON
Measures	LEXICON
were	O
proved	O
to	O
the	O
north-east	O
of	O
the	O
Thringstone	O
Fault	O
,	O
as	O
shown	O
on	O
Sheet	O
141	O
Loughborough	O
.	O

The	O
overlying	O
sequence	O
includes	O
the	O
Wingfield	LEXICON
Flags	LEXICON
.	O

In	O
this	O
district	O
,	O
these	O
beds	O
are	O
proved	O
only	O
in	O
the	O
Caldwell	O
No.	O
2	O
Borehole	O
,	O
where	O
44.7m	O
of	O
strata	O
beneath	O
the	O
Trias	O
is	O
correlated	O
with	O
the	O
Etruria	LEXICON
Formation	LEXICON
.	O

Permian	CHRONOSTRAT
strata	O
were	O
proved	O
only	O
at	O
depth	O
,	O
in	O
the	O
north-eastern	O
corner	O
of	O
the	O
district	O
,	O
where	O
the	O
Chilwell	O
Borehole	O
and	O
Central	O
Ordnance	O
Borehole	O
showed	O
,	O
respectively	O
,	O
1.6m	O
and	O
14.3m	O
of	O
red	O
mudstone	O
or	O
marl	O
which	O
was	O
assigned	O
to	O
the	O
Edlington	LEXICON
Formation	LEXICON
.	O

In	O
the	O
Chilwell	O
Borehole	O
,	O
the	O
mudstone	O
is	O
overlain	O
by	O
37.9m	O
of	O
sandstone	O
and	O
pebbly	O
sandstone	O
,	O
of	O
which	O
the	O
lowermost	O
20.3m	O
may	O
be	O
Lenton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
Shepshed	LEXICON
Sandstone	LEXICON
Member	LEXICON
is	O
a	O
distinctive	O
mappable	O
subdivision	O
confined	O
to	O
the	O
area	O
within	O
and	O
around	O
Charnwood	O
Forest	O
.	O

The	O
Hollygate	LEXICON
Sandstone	LEXICON
Member	LEXICON
.	O

The	O
principal	O
massive	O
gypsum	O
bed	O
,	O
the	O
Tutbury	LEXICON
Gypsum	LEXICON
,	O
commonly	O
ranges	O
between	O
3	O
and	O
5m	O
thick	O
.	O

The	O
stratigraphically	O
higher	O
Newark	LEXICON
Gypsum	LEXICON
.	O

Only	O
the	O
Cotham	LEXICON
Member	LEXICON
at	O
mapping	O
scale	O
represents	O
this	O
formation	O
.	O

The	O
overlying	O
Langport	LEXICON
Member	LEXICON
,	O
0.25m	O
thick	O
,	O
is	O
represented	O
by	O
a	O
hard	O
,	O
pale	O
grey	O
micrite	O
,	O
which	O
has	O
only	O
been	O
recognised	O
in	O
the	O
Normanton	O
Hills	O
railway	O
cutting	O
.	O

The	O
Elvaston	O
Palaeochannel	O
is	O
largely	O
filled	O
with	O
the	O
Findern	LEXICON
Clay	LEXICON
,	O
a	O
grey	O
to	O
brown	O
,	O
horizontally	O
laminated	O
glaciolacustrine	O
clay	O
with	O
dropstones	O
and	O
flow	O
tills	O
of	O
Oadby	LEXICON
Till	LEXICON
derivation	O
.	O

The	O
Hathern	LEXICON
Gravel	LEXICON
from	O
the	O
Peak	O
District	O
.	O

The	O
highest	O
and	O
most	O
scattered	O
terrace	O
patches	O
,	O
named	O
the	O
Eagle	LEXICON
Moor	LEXICON
Sand	LEXICON
And	LEXICON
Gravel	LEXICON
although	O
deposits	O
reworked	O
during	O
o.i.	O
Stage	O
10	O
can	O
not	O
be	O
excluded	O
.	O

The	O
Cheshire	O
Basin	O
was	O
selected	O
as	O
being	O
representative	O
of	O
the	O
basins	O
formed	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rift	O
systems	O
which	O
cut	O
north	O
south	O
across	O
the	O
British	O
Isles	O
and	O
the	O
continental	O
shelf	O
and	O
which	O
host	O
important	O
resources	O
onshore	O
and	O
offshore	O
.	O

It	O
is	O
hoped	O
that	O
this	O
report	O
will	O
not	O
only	O
provide	O
new	O
methods	O
for	O
assessing	O
the	O
resources	O
of	O
red-bed	O
sedimentary	O
basins	O
,	O
but	O
also	O
stimulate	O
fresh	O
discussion	O
on	O
all	O
aspects	O
of	O
the	O
geology	O
of	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rift	O
system	O
basins	O
in	O
Britain	O
and	O
elsewhere	O
.	O

The	O
Cheshire	O
Basin	O
is	O
a	O
major	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
extensional	O
basin	O
within	O
a	O
complex	O
north	O
south-trending	O
rift	O
system	O
which	O
stretches	O
for	O
about	O
400km	O
from	O
the	O
English	O
Channel	O
Basin	O
in	O
the	O
south	O
to	O
the	O
East	O
Irish	O
Sea	O
Basin	O
and	O
beyond	O
in	O
the	O
north	O
.	O

Offshore	O
,	O
similar	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rift	O
systems	O
underlie	O
the	O
North	O
Sea	O
.	O

In	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
times	O
the	O
Cheshire	O
Basin	O
marked	O
a	O
particularly	O
rapidly	O
subsiding	O
segment	O
of	O
the	O
rift	O
system	O
,	O
and	O
has	O
a	O
preserved	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sediment	O
thickness	O
of	O
almost	O
4000m	O
.	O

The	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
of	O
the	O
basin	O
,	O
particularly	O
the	O
Sherwood	LEXICON
Sandstone	LEXICON
Group	LEXICON
,	O
have	O
been	O
the	O
focus	O
of	O
detailed	O
investigation	O
because	O
of	O
their	O
importance	O
as	O
reservoirs	O
for	O
hydrocarbons	O
,	O
water	O
and	O
geothermal	O
resources	O
.	O

The	O
Cheshire	O
Basin	O
was	O
selected	O
for	O
detailed	O
study	O
because	O
it	O
is	O
one	O
of	O
the	O
few	O
onshore	O
basins	O
with	O
some	O
unexplored	O
potential	O
for	O
hydrocarbons	O
,	O
it	O
contains	O
important	O
water	O
and	O
halite	O
resources	O
,	O
and	O
,	O
unlike	O
many	O
British	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
,	O
it	O
contains	O
Cu-Pb-Zn	O
mineralisation	O
.	O

Modelling	O
the	O
formation	O
of	O
the	O
ore	O
deposits	O
can	O
provide	O
considerable	O
information	O
on	O
palaeo	O
-	O
and	O
present-day	O
fluid	O
flow	O
of	O
importance	O
for	O
resource	O
analysis	O
of	O
British	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
generally	O
.	O

The	O
most	O
important	O
occurrence	O
is	O
at	O
Alderley	O
Edge	O
,	O
where	O
Cu	O
,	O
Pb	O
,	O
and	O
Zn	O
,	O
with	O
minor	O
amounts	O
of	O
Ag	O
,	O
Co	O
,	O
V	O
,	O
Ni	O
and	O
Mn	O
,	O
occur	O
as	O
disseminations	O
or	O
in	O
fault	O
breccias	O
,	O
mainly	O
in	O
three	O
conglomerate	O
and	O
sandstone	O
units	O
near	O
the	O
top	O
of	O
the	O
Lower	CHRONOSTRAT
Triassic	CHRONOSTRAT
Sherwood	LEXICON
Sandstone	LEXICON
Group	LEXICON
.	O

The	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
red	O
beds	O
of	O
the	O
UK	O
are	O
host	O
to	O
commercially	O
valuable	O
evaporites	O
,	O
including	O
sylvite	O
.	O

Brine	O
extraction	O
,	O
presently	O
by	O
controlled	O
pumping	O
in	O
the	O
Holford	O
and	O
Warmingham	O
Brinefields	O
,	O
is	O
from	O
the	O
Northwich	LEXICON
Halite	LEXICON
Formation	LEXICON
;	O
salt	O
is	O
also	O
mined	O
from	O
the	O
Bottom	O
Bed	O
of	O
this	O
formation	O
.	O

Red	LEXICON
beds	LEXICON
are	O
important	O
hydrocarbon	O
reservoirs	O
in	O
many	O
parts	O
of	O
the	O
world	O
.	O

In	O
the	O
UK	O
,	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
are	O
important	O
hydrocarbon	O
reservoirs	O
in	O
the	O
North	O
Sea	O
and	O
the	O
Wessex	O
and	O
East	O
Irish	O
Sea	O
basins	O
.	O

Producing	O
fields	O
from	O
Triassic	CHRONOSTRAT
reservoirs	O
in	O
basins	O
adjacent	O
to	O
Cheshire	O
,	O
at	O
Formby	O
and	O
in	O
the	O
East	O
Irish	O
Sea	O
,	O
together	O
with	O
oil	O
shows	O
in	O
the	O
Needwood	O
Basin	O
in	O
the	O
Midlands	O
,	O
indicate	O
that	O
both	O
oil	O
and	O
gas	O
have	O
been	O
generated	O
over	O
a	O
wide	O
area	O
.	O

In	O
the	O
East	O
Midlands	O
oilfields	O
the	O
source	O
and	O
the	O
reservoirs	O
are	O
of	O
Carboniferous	CHRONOSTRAT
age	O
,	O
and	O
in	O
this	O
study	O
we	O
consider	O
not	O
only	O
the	O
prospectivity	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
but	O
also	O
that	O
of	O
the	O
Upper	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
rocks	O
beneath	O
the	O
Cheshire	O
Basin	O
.	O

Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
red	O
beds	O
are	O
major	O
sources	O
of	O
potable	O
water	O
in	O
Cheshire	O
,	O
Lancashire	O
and	O
Nottinghamshire	O
,	O
and	O
are	O
exploited	O
as	O
geothermal	O
reservoirs	O
in	O
the	O
Wessex	O
Basin	O
.	O

The	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sandstones	O
are	O
prolific	O
aquifers	O
,	O
exploited	O
largely	O
where	O
they	O
are	O
not	O
confined	O
by	O
the	O
overlying	O
Mercia	LEXICON
Mudstone	LEXICON
Group	LEXICON
and	O
younger	O
formations	O
.	O

Chapter	O
2	O
of	O
the	O
volume	O
gives	O
an	O
account	O
of	O
the	O
stratigraphy	O
of	O
the	O
Permian	CHRONOSTRAT
to	O
Lower	CHRONOSTRAT
Jurassic	CHRONOSTRAT
basin	O
fill	O
,	O
including	O
sections	O
on	O
the	O
regional	O
setting	O
,	O
biostratigraphy	O
and	O
sedimentology	O
.	O

Because	O
groundwater	O
abstraction	O
or	O
monitoring	O
boreholes	O
are	O
heavily	O
represented	O
,	O
there	O
is	O
a	O
bias	O
towards	O
the	O
permeable	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sandstone	O
aquifer	O
rocks	O
around	O
the	O
margins	O
of	O
the	O
Cheshire	O
Basin	O
.	O

Less	O
borehole	O
core	O
was	O
available	O
from	O
the	O
Mercia	LEXICON
Mudstone	LEXICON
Group	LEXICON
and	O
other	O
formations	O
in	O
the	O
centre	O
of	O
the	O
basin	O
,	O
but	O
MMG	O
strata	O
were	O
sampled	O
from	O
BGS	O
boreholes	O
,	O
such	O
as	O
Wilkesley	O
and	O
Crewe	O
,	O
and	O
from	O
exploration	O
for	O
evaporites	O
and	O
site-investigation	O
boreholes	O
.	O

In	O
addition	O
to	O
borehole	O
material	O
,	O
the	O
MMG	O
was	O
sampled	O
underground	O
at	O
the	O
Meadowbank	O
Rock	O
Salt	O
Mine	O
,	O
Winsford	O
.	O

Due	O
to	O
the	O
lack	O
of	O
available	O
material	O
only	O
a	O
limited	O
study	O
was	O
made	O
of	O
pre	O
-	O
SSG	O
strata	O
.	O

The	O
Collyhurst	LEXICON
Sandstone	LEXICON
,	O
Manchester	LEXICON
Marl	LEXICON
and	O
earlier	O
strata	O
were	O
sampled	O
from	O
a	O
small	O
number	O
of	O
boreholes	O
.	O

In	O
total	O
more	O
than	O
850	O
samples	O
were	O
collected	O
during	O
the	O
project	O
,	O
of	O
which	O
more	O
than	O
450	O
were	O
from	O
the	O
SSG	O
and	O
over	O
300	O
from	O
the	O
MMG	O
.	O

Overviews	O
of	O
the	O
tectonic	O
development	O
of	O
Britain	O
and	O
neighbouring	O
regions	O
before	O
and	O
during	O
the	O
deposition	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sediments	O
of	O
the	O
Cheshire	O
Basin	O
are	O
given	O
by	O
,	O
among	O
others	O
,	O
Anderton	O
et	O
al.	O
.	O

During	O
Precambrian	CHRONOSTRAT
and	O
Palaeozoic	CHRONOSTRAT
times	O
,	O
the	O
tectonics	O
of	O
north-west	O
Europe	O
were	O
dominated	O
by	O
the	O
sequential	O
accretion	O
of	O
magmatic	O
arcs	O
and	O
older	O
continental	O
fragments	O
against	O
and	O
onto	O
the	O
stable	O
North	O
American	O
craton	O
.	O

In	O
early	O
to	O
middle	CHRONOSTRAT
Devonian	CHRONOSTRAT
times	O
,	O
oblique	O
collision	O
between	O
the	O
Laurentian	CHRONOSTRAT
and	O
Avalonian	CHRONOSTRAT
land	O
masses	O
produced	O
regional	O
compressional	O
deformation	O
over	O
much	O
of	O
Britain	O
,	O
with	O
widespread	O
uplift	O
,	O
folding	O
and	O
basin	O
inversion	O
.	O

Closure	O
of	O
this	O
ocean	O
,	O
combined	O
with	O
the	O
buffering	O
effects	O
of	O
various	O
small	O
terranes	O
,	O
had	O
,	O
by	O
end	O
-	O
Carboniferous	CHRONOSTRAT
times	O
,	O
created	O
the	O
Variscides	O
as	O
a	O
collision	O
orogenic	O
belt	O
.	O

The	O
Devonian	CHRONOSTRAT
and	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sedimentary	O
sequence	O
in	O
south-west	O
England	O
reflects	O
a	O
marine	O
transgression	O
from	O
the	O
south	O
.	O

During	O
Namurian	CHRONOSTRAT
and	O
Westphalian	CHRONOSTRAT
times	O
the	O
Variscan	O
thrust	O
front	O
advanced	O
from	O
the	O
south	O
while	O
the	O
flysch-like	O
sediments	O
of	O
the	O
Culm	O
were	O
deposited	O
in	O
north	O
Devon	O
and	O
Cornwall	O
.	O

To	O
the	O
north	O
of	O
the	O
developing	O
Variscan	O
fold	O
belt	O
in	O
southern	O
Britain	O
lay	O
a	O
foreland	O
on	O
which	O
extensional	O
basins	O
developed	O
in	O
Carboniferous	CHRONOSTRAT
times	O
on	O
the	O
northern	O
side	O
of	O
a	O
persistent	O
Wales-London-Brabant	O
high	O
.	O

Extension	O
in	O
latest	O
Devonian	CHRONOSTRAT
and	O
early	O
Carboniferous	CHRONOSTRAT
times	O
produced	O
a	O
series	O
of	O
grabens	O
and	O
half-grabens	O
in	O
the	O
Caledonian	O
basement	O
,	O
which	O
exerted	O
the	O
dominant	O
control	O
on	O
early	O
Carboniferous	CHRONOSTRAT
sedimentation	O
to	O
the	O
north	O
of	O
the	O
high	O
.	O

In	O
Namurian	CHRONOSTRAT
times	O
,	O
crustal	O
extension	O
progressively	O
gave	O
way	O
to	O
regional	O
post-extensional	O
subsidence	O
,	O
the	O
early	O
Carboniferous	CHRONOSTRAT
deposition	O
of	O
carbonate	O
and	O
detrital	O
sediments	O
on	O
a	O
block-and-basin	O
topography	O
being	O
followed	O
by	O
the	O
accumulation	O
of	O
thick	O
,	O
more	O
uniform	O
sequences	O
of	O
deltaic	O
strata	O
.	O

Later	O
in	O
the	O
Carboniferous	CHRONOSTRAT
,	O
subsidence	O
was	O
replaced	O
by	O
uplift	O
,	O
as	O
Variscan	O
compressive	O
forces	O
became	O
progressively	O
more	O
dominant	O
.	O

The	O
main	O
effects	O
of	O
this	O
regional	O
Variscan	O
compression	O
were	O
the	O
reversal	O
of	O
Caledonian	O
lines	O
of	O
weakness	O
and	O
structural	O
inversion	O
of	O
the	O
Carboniferous	CHRONOSTRAT
basins	O
.	O

Minor	O
inversion	O
occurred	O
sporadically	O
in	O
latest	O
Dinantian	CHRONOSTRAT
and	O
Namurian	CHRONOSTRAT
times	O
,	O
but	O
the	O
main	O
period	O
of	O
basin	O
inversion	O
,	O
roughly	O
coeval	O
with	O
emplacement	O
of	O
the	O
Variscan	O
thrust	O
front	O
,	O
took	O
place	O
in	O
Westphalian	CHRONOSTRAT
and	O
Stephanian	CHRONOSTRAT
times	O
.	O

During	O
Devonian	CHRONOSTRAT
times	O
,	O
a	O
hot	O
semi-arid	O
climate	O
prevailed	O
over	O
much	O
of	O
the	O
North	O
Atlantic	O
area	O
,	O
Britain	O
lying	O
close	O
to	O
the	O
equator	O
.	O

Though	O
Britain	O
remained	O
near	O
the	O
equator	O
throughout	O
the	O
Carboniferous	CHRONOSTRAT
and	O
early	O
Permian	CHRONOSTRAT
,	O
the	O
climate	O
changed	O
from	O
arid	O
in	O
the	O
earliest	O
Dinantian	CHRONOSTRAT
to	O
semi-arid	O
and	O
then	O
monsoonal	O
in	O
later	O
Dinantian	CHRONOSTRAT
times	O
.	O

Later	O
in	O
the	O
Carboniferous	CHRONOSTRAT
,	O
an	O
increasingly	O
humid	O
tropical	O
climate	O
prevailed	O
over	O
much	O
of	O
north-west	O
Europe	O
,	O
which	O
ended	O
in	O
latest	O
Westphalian	CHRONOSTRAT
to	O
Stephanian	CHRONOSTRAT
times	O
when	O
the	O
evidence	O
of	O
red	O
beds	O
and	O
oxidised	O
coal	O
seams	O
indicates	O
the	O
onset	O
of	O
the	O
lengthy	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
arid	O
period	O
.	O

During	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
times	O
,	O
northern	O
Europe	O
lay	O
within	O
the	O
arid	O
hinterland	O
of	O
the	O
Pangaean	O
supercontinent	O
,	O
newly	O
formed	O
by	O
the	O
collision	O
of	O
Laurasia	O
and	O
Gondwana	O
.	O

Marine	O
incursions	O
entered	O
from	O
the	O
north-west	O
in	O
Late	CHRONOSTRAT
Permian	CHRONOSTRAT
and	O
Mid	CHRONOSTRAT
and	O
Late	CHRONOSTRAT
Triassic	CHRONOSTRAT
times	O
,	O
and	O
from	O
the	O
south	O
and	O
west	O
at	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
.	O

The	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
fill	O
rests	O
unconformably	O
on	O
,	O
or	O
is	O
in	O
faulted	O
contact	O
with	O
,	O
folded	O
Carboniferous	CHRONOSTRAT
and	O
older	O
rocks	O
and	O
is	O
contiguous	O
with	O
the	O
fill	O
of	O
the	O
East	O
Irish	O
Sea	O
Basin	O
to	O
the	O
north-west	O
,	O
and	O
the	O
Stafford	O
,	O
Needwood	O
and	O
Worcester	O
basins	O
to	O
the	O
south-east	O
and	O
south	O
.	O

The	O
basin	O
fill	O
comprises	O
formations	O
assigned	O
to	O
the	O
Appleby	LEXICON
,	O
Cumbrian	LEXICON
Coast	LEXICON
,	O
Sherwood	LEXICON
Sandstone	LEXICON
,	O
Mercia	LEXICON
Mudstone	LEXICON
,	O
Penarth	LEXICON
and	O
Lias	LEXICON
groups	O
.	O

Around	O
the	O
northern	O
,	O
western	O
and	O
southern	O
margins	O
of	O
the	O
basin	O
the	O
fill	O
rests	O
on	O
folded	O
and	O
faulted	O
pre	O
-	O
Permian	CHRONOSTRAT
rocks	O
in	O
age	O
though	O
Ordovician	CHRONOSTRAT
rocks	O
occur	O
at	O
the	O
south-western	O
margin	O
,	O
south	O
of	O
Oswestry	O
.	O

Nearly	O
50km	O
to	O
the	O
north-north-east	O
,	O
Carboniferous	CHRONOSTRAT
shales	O
,	O
sandstones	O
and	O
coals	O
of	O
Westphalian	CHRONOSTRAT
age	O
were	O
proved	O
from	O
c.	O
2820mKB	O
to	O
TD	O
.	O

A	O
small	O
inlier	O
of	O
Carboniferous	CHRONOSTRAT
rocks	O
has	O
been	O
proved	O
near	O
Chester	O
.	O

A	O
summary	O
account	O
of	O
the	O
distribution	O
and	O
structures	O
of	O
the	O
pre	O
-	O
Permian	CHRONOSTRAT
rocks	O
of	O
the	O
basin	O
floor	O
and	O
in	O
the	O
surrounding	O
area	O
is	O
given	O
on	O
pp.55-67	O
.	O

At	O
the	O
beginning	O
of	O
the	O
Permian	CHRONOSTRAT
,	O
Britain	O
lay	O
deep	O
within	O
the	O
Pangaean	O
supercontinent	O
,	O
in	O
a	O
belt	O
of	O
easterly	O
winds	O
and	O
situated	O
within	O
a	O
few	O
degrees	O
of	O
the	O
equator	O
.	O

The	O
sands	O
were	O
deposited	O
on	O
an	O
uneven	O
erosional	O
surface	O
of	O
mainly	O
Carboniferous	CHRONOSTRAT
rocks	O
,	O
and	O
this	O
surface	O
was	O
further	O
modified	O
by	O
syndepositional	O
faulting	O
.	O

Early	O
in	O
the	O
Late	CHRONOSTRAT
Permian	CHRONOSTRAT
,	O
a	O
marine	O
incursion	O
from	O
the	O
north-west	O
into	O
the	O
northern	O
part	O
of	O
the	O
Cheshire	O
Basin	O
led	O
to	O
the	O
deposition	O
of	O
the	O
dolomitic	O
and	O
gypsiferous	O
mudstones	O
of	O
the	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
.	O

In	O
the	O
southern	O
part	O
of	O
the	O
basin	O
at	O
this	O
time	O
,	O
the	O
Bold	LEXICON
Formation	LEXICON
represents	O
a	O
continuation	O
of	O
the	O
conditions	O
that	O
obtained	O
during	O
the	O
deposition	O
of	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
.	O

Towards	O
the	O
end	O
of	O
the	O
Permian	CHRONOSTRAT
,	O
the	O
sea	O
retreated	O
and	O
the	O
Bold	LEXICON
and	O
Manchester	LEXICON
Marls	LEXICON
formations	O
were	O
succeeded	O
by	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
.	O

Marine	O
conditions	O
persisted	O
for	O
longer	O
in	O
the	O
area	O
of	O
the	O
East	O
Irish	O
Sea	O
,	O
with	O
the	O
deposition	O
of	O
the	O
St	LEXICON
Bees	LEXICON
Shales	LEXICON
and	O
Evaporites	LEXICON
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
consists	O
dominantly	O
of	O
aeolian	O
sands	O
,	O
though	O
evidence	O
of	O
fluvial	O
action	O
suggests	O
the	O
presence	O
of	O
rivers	O
in	O
the	O
interdune	O
areas	O
.	O

Similar	O
conditions	O
continued	O
into	O
the	O
Triassic	CHRONOSTRAT
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
was	O
succeeded	O
by	O
conglomerates	O
and	O
sandstones	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
.	O

The	O
abundance	O
of	O
pebbles	O
decreases	O
northwards	O
;	O
pebble	O
beds	O
extend	O
into	O
the	O
south-eastern	O
extremity	O
of	O
the	O
EISB	O
,	O
beyond	O
which	O
lie	O
fluvial	O
sandstones	O
similar	O
to	O
the	O
Wilmslow	LEXICON
Sandstones	LEXICON
which	O
,	O
in	O
the	O
Cheshire	O
Basin	O
,	O
overlie	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
consists	O
of	O
sandstones	O
,	O
with	O
some	O
siltstones	O
and	O
mudstones	O
,	O
deposited	O
from	O
the	O
north-west-flowing	O
river	O
system	O
,	O
and	O
also	O
features	O
dunes	O
formed	O
by	O
easterly	O
winds	O
.	O

The	O
succeeding	O
beds	O
of	O
the	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
Formation	LEXICON
are	O
only	O
locally	O
present	O
,	O
and	O
their	O
deposition	O
was	O
followed	O
by	O
a	O
period	O
of	O
faulting	O
and	O
erosion	O
,	O
now	O
marked	O
by	O
the	O
Hardegsen	O
disconformity	O
.	O

The	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
its	O
correlative	O
in	O
the	O
EISB	O
,	O
the	O
Ormskirk	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
were	O
deposited	O
on	O
the	O
Hardegsen	O
erosion	O
surface	O
,	O
under	O
the	O
influence	O
of	O
easterly	O
winds	O
and	O
rivers	O
from	O
the	O
south-east	O
.	O

The	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
,	O
the	O
lowest	O
formation	O
of	O
the	O
MMG	O
,	O
was	O
laid	O
down	O
in	O
intertidal	O
and	O
playa	O
environments	O
and	O
marks	O
a	O
transition	O
to	O
less	O
sandy	O
deposits	O
.	O

Subsidence	O
accompanied	O
by	O
movement	O
along	O
contemporary	O
faults	O
continued	O
until	O
Carnian	CHRONOSTRAT
times	O
.	O

The	O
MMG	O
in	O
the	O
EISB	O
is	O
broadly	O
similar	O
to	O
that	O
in	O
the	O
Cheshire	O
Basin	O
.	O

The	O
Blue	LEXICON
Anchor	LEXICON
Formation	LEXICON
,	O
at	O
the	O
top	O
of	O
the	O
MMG	O
,	O
closely	O
resembles	O
the	O
laminated	O
facies	O
of	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
,	O
being	O
composed	O
of	O
wind-blown	O
detritus	O
deposited	O
in	O
shallow	O
water	O
,	O
except	O
that	O
it	O
consists	O
almost	O
entirely	O
of	O
reduced	O
facies	O
;	O
terrestrial	O
and/or	O
freshwater	O
life	O
may	O
have	O
been	O
more	O
prolific	O
,	O
perhaps	O
because	O
of	O
a	O
more	O
reliable	O
rainfall	O
.	O

The	O
Penarth	LEXICON
Group	LEXICON
consists	O
of	O
mudstones	O
,	O
fine	O
sandstones	O
and	O
limestones	O
with	O
marine	O
fossils	O
,	O
and	O
this	O
fauna	O
became	O
more	O
diverse	O
in	O
the	O
overlying	O
Lias	LEXICON
Group	LEXICON
.	O

In	O
its	O
most	O
complete	O
form	O
,	O
in	O
the	O
northern	O
part	O
of	O
the	O
basin	O
,	O
the	O
fill	O
comprises	O
the	O
Appleby	LEXICON
,	O
Cumbrian	LEXICON
Coast	LEXICON
,	O
Sherwood	LEXICON
Sandstone	LEXICON
and	O
Mercia	LEXICON
Mudstone	LEXICON
groups	O
;	O
to	O
the	O
south	O
,	O
younger	O
deposits	O
of	O
the	O
Penarth	LEXICON
Group	LEXICON
and	O
the	O
lower	O
part	O
of	O
the	O
Lias	LEXICON
Group	LEXICON
are	O
also	O
present	O
.	O

The	O
Collyhurst	LEXICON
Sandstone	LEXICON
Formation	LEXICON
where	O
it	O
rests	O
unconformably	O
upon	O
Carboniferous	CHRONOSTRAT
rocks	O
and	O
is	O
overlain	O
conformably	O
by	O
the	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
.	O

Further	O
south	O
in	O
the	O
basin	O
the	O
formation	O
becomes	O
almost	O
indistinguishable	O
from	O
the	O
overlying	O
Manchester	LEXICON
Marls	LEXICON
where	O
the	O
latter	O
pass	O
laterally	O
into	O
a	O
more	O
silty	O
or	O
arenaceous	O
facies	O
,	O
as	O
recognised	O
in	O
the	O
Prees	O
Borehole	O
.	O

Where	O
these	O
formations	O
become	O
indistinguishable	O
,	O
their	O
correlatives	O
are	O
regarded	O
as	O
forming	O
the	O
lower	O
part	O
of	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
of	O
the	O
Sherwood	LEXICON
Sandstone	LEXICON
Group	LEXICON
.	O

The	O
Collyhurst	LEXICON
Sandstone	LEXICON
is	O
of	O
continental	O
,	O
aeolian	O
,	O
origin	O
.	O

Further	O
south	O
,	O
in	O
the	O
Stafford	O
and	O
Worcester	O
basins	O
,	O
the	O
lower	O
part	O
of	O
the	O
aeolian	O
Bridgnorth	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
equivalent	O
to	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
.	O

The	O
Bridgnorth	LEXICON
Sandstone	LEXICON
is	O
interpreted	O
as	O
having	O
accumulated	O
in	O
a	O
combination	O
of	O
transverse	O
and	O
barchanoid	O
draas	O
,	O
with	O
superimposed	O
oblique	O
crescentic	O
and	O
linear	O
dunes	O
,	O
under	O
the	O
influence	O
of	O
fluctuating	O
winds	O
from	O
a	O
predominantly	O
easterly	O
direction	O
.	O

To	O
the	O
north-west	O
,	O
in	O
the	O
EISB	O
,	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
comprises	O
mainly	O
aeolian	O
deposits	O
.	O

There	O
is	O
no	O
direct	O
evidence	O
for	O
the	O
age	O
of	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
,	O
but	O
the	O
youngest	O
underlying	O
beds	O
are	O
Late	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
.	O

The	O
Collyhurst	LEXICON
Sandstone	LEXICON
is	O
thus	O
constrained	O
only	O
within	O
the	O
post	O
-	O
Westphalian	CHRONOSTRAT
to	O
pre	O
-	O
Kazanian	CHRONOSTRAT
interval	O
.	O

The	O
Manchester	LEXICON
Marls	LEXICON
rest	O
on	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
or	O
locally	O
overlap	O
that	O
formation	O
and	O
rest	O
unconformably	O
on	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

The	O
Manchester	LEXICON
Marls	LEXICON
comprise	O
red	O
,	O
rarely	O
green	O
,	O
dolomitic	O
and	O
gypsiferous	O
mudstones	O
.	O

Upwards	O
,	O
the	O
formation	O
becomes	O
more	O
arenaceous	O
and	O
passes	O
into	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
of	O
the	O
SSG	O
.	O

A	O
concealed	O
development	O
of	O
the	O
Manchester	LEXICON
Marls	LEXICON
extends	O
south	O
for	O
at	O
least	O
40km	O
from	O
the	O
outcrops	O
at	O
the	O
northern	O
end	O
of	O
the	O
basin	O
.	O

Elsewhere	O
the	O
formation	O
is	O
indistinguishable	O
from	O
the	O
underlying	O
Collyhurst	LEXICON
Sandstone	LEXICON
and	O
merges	O
with	O
the	O
equivalent	O
of	O
that	O
formation	O
to	O
form	O
the	O
lower	O
part	O
of	O
an	O
arenaceous	O
sequence	O
assigned	O
to	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

An	O
interbedded	O
succession	O
of	O
aeolian	O
sandsheet	O
deposits	O
and	O
fluvial	O
sheetflood	O
facies	O
in	O
the	O
Speke	O
Reservoir	O
Borehole	O
is	O
attributed	O
to	O
the	O
Bold	LEXICON
Formation	LEXICON
.	O

Regional	O
studies	O
show	O
that	O
the	O
Manchester	LEXICON
Marls	LEXICON
accumulated	O
marginally	O
to	O
a	O
depocentre	O
sited	O
to	O
the	O
north-west	O
,	O
in	O
the	O
EISB	O
.	O

The	O
age	O
of	O
the	O
Manchester	LEXICON
Marls	LEXICON
is	O
,	O
on	O
biostratigraphic	O
evidence	O
,	O
Late	CHRONOSTRAT
Permian	CHRONOSTRAT
.	O

The	O
formations	O
of	O
this	O
group	O
have	O
an	O
extensive	O
outcrop	O
in	O
the	O
Cheshire	O
Basin	O
,	O
almost	O
surrounding	O
that	O
of	O
the	O
Mercia	LEXICON
Mudstone	LEXICON
Group	LEXICON
and	O
younger	O
deposits	O
.	O

The	O
upward	O
increase	O
in	O
sand	O
content	O
in	O
the	O
Manchester	LEXICON
Marls	LEXICON
and	O
the	O
transition	O
into	O
the	O
sandstones	O
of	O
the	O
SSG	O
reflect	O
palaeogeographical	O
changes	O
that	O
resulted	O
in	O
the	O
exclusion	O
of	O
marine	O
influences	O
from	O
the	O
northern	O
part	O
of	O
the	O
Cheshire	O
Basin	O
and	O
the	O
neighbouring	O
EISB	O
.	O

The	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
,	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
were	O
deposited	O
under	O
continental	O
conditions	O
as	O
parts	O
of	O
a	O
dominantly	O
fluvial	O
facies	O
association	O
that	O
spread	O
northwards	O
from	O
southern	O
England	O
,	O
through	O
the	O
Worcester	O
,	O
Stafford	O
and	O
Cheshire	O
basins	O
,	O
into	O
the	O
EISB	O
in	O
Early	CHRONOSTRAT
Triassic	CHRONOSTRAT
times	O
.	O

The	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
and	O
Wilmslow	LEXICON
Sandstone	LEXICON
are	O
progressively	O
cut	O
out	O
at	O
an	O
unconformity	O
at	O
the	O
base	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

Evidence	O
of	O
the	O
regional	O
nature	O
of	O
this	O
unconformity	O
,	O
and	O
of	O
its	O
presence	O
within	O
the	O
concealed	O
SSG	O
in	O
the	O
Cheshire	O
Basin	O
,	O
has	O
been	O
compiled	O
from	O
geophysical	O
studies	O
.	O

Above	O
the	O
unconformity	O
,	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
reflects	O
the	O
re-establishment	O
,	O
in	O
the	O
early	O
Mid-Triassic	CHRONOSTRAT
,	O
of	O
a	O
continental	O
fluvial	O
system	O
which	O
drained	O
northwards	O
into	O
the	O
EISB	O
.	O

Continental	O
sedimentation	O
in	O
the	O
EISB	O
was	O
superseded	O
by	O
the	O
deposition	O
of	O
fine-grained	O
sediments	O
with	O
evaporites	O
,	O
which	O
form	O
the	O
lowest	O
part	O
of	O
the	O
MMG	O
and	O
were	O
deposited	O
partly	O
in	O
water	O
of	O
marine	O
origin	O
.	O

During	O
Mid-Triassic	CHRONOSTRAT
times	O
this	O
environment	O
,	O
and	O
the	O
area	O
of	O
MMG	O
deposition	O
,	O
expanded	O
southwards	O
to	O
occupy	O
the	O
Cheshire	O
Basin	O
and	O
other	O
areas	O
further	O
south	O
in	O
England	O
where	O
the	O
SSG	O
had	O
accumulated	O
previously	O
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
lacks	O
fossils	O
,	O
but	O
,	O
because	O
of	O
its	O
lateral	O
equivalence	O
to	O
the	O
aeolian	O
Collyhurst	LEXICON
Sandstone	LEXICON
and	O
the	O
partly	O
marine	O
Manchester	LEXICON
Marls	LEXICON
,	O
it	O
is	O
regarded	O
as	O
largely	O
Permian	CHRONOSTRAT
in	O
age	O
.	O

The	O
thickness	O
of	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
increases	O
southwards	O
from	O
73m	O
in	O
the	O
Knutsford	O
Borehole	O
to	O
110m	O
in	O
the	O
Prees	O
Borehole	O
;	O
this	O
trend	O
parallels	O
a	O
thinning	O
of	O
the	O
underlying	O
Manchester	LEXICON
Marls	LEXICON
and	O
may	O
reflect	O
the	O
southward	O
passage	O
of	O
the	O
upper	O
part	O
of	O
that	O
formation	O
into	O
more	O
arenaceous	O
beds	O
.	O

Palaeowind	O
vectors	O
indicate	O
that	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
,	O
like	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
,	O
was	O
deposited	O
under	O
the	O
influence	O
of	O
winds	O
from	O
an	O
easterly	O
direction	O
.	O

In	O
the	O
Chester	O
district	O
from	O
Permian	CHRONOSTRAT
aeolian	O
deposits	O
in	O
the	O
North	O
Sea	O
Basin	O
.	O

In	O
the	O
Chester	O
district	O
,	O
14m	O
of	O
very	O
micaceous	O
sandstones	O
,	O
described	O
by	O
Thompson	O
as	O
at	O
the	O
`	O
predicted	O
horizon	O
'	O
of	O
the	O
Manchester	LEXICON
Marls	LEXICON
,	O
forms	O
a	O
transition	O
upwards	O
into	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

These	O
sandstones	O
may	O
correlate	O
with	O
the	O
Bold	LEXICON
Formation	LEXICON
,	O
a	O
unit	O
recognised	O
by	O
geologists	O
of	O
the	O
North	O
West	O
Water	O
Authority	O
in	O
the	O
Runcorn	O
district	O
.	O

The	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
is	O
recognised	O
at	O
depth	O
in	O
the	O
Prees	O
and	O
Knutsford	O
boreholes	O
.	O

Elsewhere	O
,	O
it	O
locally	O
rests	O
unconformably	O
on	O
the	O
Bold	LEXICON
Formation	LEXICON
,	O
Manchester	LEXICON
Marls	LEXICON
,	O
Collyhurst	LEXICON
Sandstone	LEXICON
and	O
Carboniferous	CHRONOSTRAT
rocks	O
and	O
,	O
in	O
the	O
south-eastern	O
part	O
of	O
the	O
basin	O
,	O
is	O
overlain	O
unconformably	O
by	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

The	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
comprise	O
conglomerates	O
,	O
pebbly	O
sandstones	O
and	O
sandstones	O
and	O
are	O
of	O
continental	O
origin	O
.	O

North-westwards	O
,	O
into	O
the	O
EISB	O
,	O
the	O
formation	O
shows	O
a	O
decrease	O
in	O
pebble	O
content	O
and	O
becomes	O
indistinguishable	O
from	O
sandstones	O
of	O
the	O
overlying	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Beyond	O
the	O
limit	O
of	O
the	O
occurrence	O
of	O
pebbles	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
,	O
the	O
lateral	O
equivalents	O
of	O
that	O
formation	O
and	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
occur	O
in	O
the	O
St	LEXICON
Bees	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Thompson	O
are	O
equivalent	O
to	O
the	O
Bold	LEXICON
Formation	LEXICON
.	O

No	O
stratigraphically	O
useful	O
fossils	O
are	O
known	O
from	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
which	O
,	O
from	O
their	O
position	O
above	O
the	O
Late	CHRONOSTRAT
Permian	CHRONOSTRAT
Manchester	LEXICON
Marls	LEXICON
are	O
assessed	O
as	O
Early	CHRONOSTRAT
Triassic	CHRONOSTRAT
in	O
age	O
.	O

It	O
rests	O
on	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
;	O
at	O
outcrop	O
in	O
west	O
Cheshire	O
and	O
within	O
the	O
basin	O
it	O
is	O
succeeded	O
by	O
the	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Elsewhere	O
the	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
is	O
overlapped	O
by	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
which	O
comes	O
to	O
rest	O
unconformably	O
on	O
,	O
or	O
completely	O
cuts	O
out	O
,	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
comprises	O
predominantly	O
red	O
,	O
fine-grained	O
,	O
argillaceous	O
,	O
cross-bedded	O
sandstones	O
,	O
with	O
some	O
interbedded	O
siltstones	O
and	O
mudstones	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
lacks	O
stratigraphically	O
useful	O
fossils	O
.	O

From	O
its	O
position	O
beneath	O
an	O
inferred	O
representative	O
of	O
the	O
Hardegsen	O
disconformity	O
,	O
which	O
affects	O
beds	O
high	O
in	O
the	O
Middle	O
Bunter	O
of	O
Germany	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
is	O
assessed	O
,	O
with	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
,	O
as	O
Early	CHRONOSTRAT
Triassic	CHRONOSTRAT
in	O
age	O
.	O

It	O
succeeds	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
conformably	O
but	O
is	O
overlapped	O
by	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
above	O
an	O
unconformity	O
that	O
was	O
correlated	O
.	O

Evidence	O
of	O
the	O
presence	O
of	O
this	O
unconformity	O
within	O
the	O
concealed	O
SSG	O
in	O
the	O
Cheshire	O
Basin	O
,	O
and	O
of	O
the	O
concealed	O
extent	O
of	O
the	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
,	O
has	O
been	O
compiled	O
from	O
geophysical	O
studies	O
which	O
suggest	O
a	O
maximum	O
thickness	O
for	O
the	O
formation	O
of	O
about	O
220m	O
towards	O
the	O
basin	O
centre	O
.	O

It	O
lacks	O
fossils	O
,	O
but	O
its	O
stratigraphical	O
position	O
is	O
analogous	O
to	O
that	O
of	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
it	O
is	O
similarly	O
assessed	O
as	O
Early	CHRONOSTRAT
Triassic	CHRONOSTRAT
in	O
age	O
.	O

This	O
formation	O
has	O
an	O
almost	O
continuous	O
,	O
though	O
faulted	O
,	O
outcrop	O
which	O
fringes	O
that	O
of	O
the	O
MMG	O
in	O
the	O
northern	O
,	O
western	O
and	O
southern	O
parts	O
of	O
the	O
basin	O
.	O

The	O
Helsby	LEXICON
Sandstone	LEXICON
was	O
proved	O
at	O
depth	O
in	O
the	O
Prees	O
and	O
Knutsford	O
boreholes	O
.	O

It	O
succeeds	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
unconformably	O
and	O
is	O
overlain	O
,	O
conformably	O
,	O
by	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
,	O
the	O
lowest	O
formation	O
of	O
the	O
MMG	O
.	O

The	O
stratigraphy	O
and	O
sedimentology	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
in	O
the	O
Cheshire	O
Basin	O
have	O
been	O
studied	O
by	O
Thompson	O
.	O

The	O
Soft	O
Sandstones	O
,	O
of	O
fluvial	O
,	O
fluvio-lacustrine	O
and	O
aeolian	O
origin	O
,	O
occur	O
principally	O
in	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
but	O
are	O
also	O
present	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

The	O
Red	O
Pebbly	O
Sandstones	O
,	O
representing	O
fluvial	O
-	O
channel	O
and	O
associated	O
overbank	O
deposits	O
of	O
low	O
-	O
to	O
moderate-sinuosity	O
stream	O
systems	O
,	O
occur	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

Thompson	O
proposed	O
division	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
into	O
members	O
distinguished	O
by	O
the	O
predominance	O
of	O
fluvial	O
or	O
of	O
aeolian	O
sediments	O
.	O

The	O
principal	O
members	O
are	O
the	O
Thurstaston	LEXICON
Soft	LEXICON
Sandstone	LEXICON
Member	LEXICON
,	O
the	O
Delamere	LEXICON
Pebbly	LEXICON
Sandstone	LEXICON
Member	LEXICON
,	O
and	O
the	O
Frodsham	LEXICON
Soft	LEXICON
Sandstone	LEXICON
Member	LEXICON
which	O
occur	O
broadly	O
in	O
that	O
stratigraphical	O
order	O
.	O

The	O
Helsby	LEXICON
Sandstone	LEXICON
is	O
230m	O
thick	O
in	O
the	O
Prees	O
Borehole	O
and	O
205m	O
at	O
Knutsford	O
.	O

In	O
the	O
early	O
stage	O
of	O
Helsby	LEXICON
Sandstone	LEXICON
sedimentation	O
,	O
braided	O
river	O
channels	O
were	O
the	O
sites	O
of	O
deposition	O
of	O
pebbly	O
transverse	O
sand	O
bars	O
and	O
dunes	O
and	O
some	O
pebbly	O
channel	O
deposits	O
during	O
high-discharge	O
phases	O
.	O

Sediments	O
of	O
the	O
Thurstaston	LEXICON
Member	LEXICON
facies	O
accumulated	O
between	O
these	O
distributaries	O
and	O
are	O
more	O
widely	O
developed	O
across	O
the	O
basin	O
;	O
they	O
comprise	O
low-energy	O
fluvial	O
sands	O
and	O
some	O
possible	O
aeolian	O
dunes	O
that	O
formed	O
on	O
dry	O
interdistributary	O
tracts	O
.	O

The	O
succeeding	O
stage	O
of	O
Helsby	LEXICON
Sandstone	LEXICON
sedimentation	O
witnessed	O
the	O
more	O
widespread	O
deposition	O
of	O
pebbly	O
fluvial	O
sands	O
,	O
of	O
the	O
Delamere	LEXICON
Member	LEXICON
facies	O
,	O
in	O
distributaries	O
of	O
low	O
to	O
moderate	O
sinuosity	O
.	O

Subsequently	O
,	O
fluvial	O
deposition	O
waned	O
substantially	O
and	O
aeolian	O
deposits	O
of	O
the	O
Frodsham	LEXICON
Member	LEXICON
facies	O
dominated	O
the	O
basin	O
;	O
localised	O
fluvial	O
deposits	O
formed	O
in	O
discrete	O
distributary	O
channels	O
,	O
mainly	O
in	O
the	O
eastern	O
part	O
of	O
the	O
basin	O
.	O

In	O
the	O
EISB	O
the	O
equivalent	O
beds	O
are	O
termed	O
the	O
Ormskirk	LEXICON
Sandstone	LEXICON
Formation	LEXICON
recognised	O
five	O
major	O
facies	O
associations	O
.	O

Palaeogeographical	O
interpretations	O
for	O
similar	O
associations	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
in	O
the	O
Cheshire	O
Basin	O
.	O

The	O
age	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
is	O
,	O
on	O
biostratigraphic	O
evidence	O
,	O
early	O
Mid-Triassic	CHRONOSTRAT
.	O

In	O
the	O
absence	O
of	O
stratigraphically	O
significant	O
fossils	O
from	O
formations	O
lower	O
in	O
the	O
SSG	O
,	O
the	O
position	O
of	O
the	O
Permian	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
boundary	O
is	O
poorly	O
constrained	O
.	O

In	O
the	O
northern	O
part	O
of	O
the	O
basin	O
it	O
is	O
within	O
some	O
1200m	O
of	O
strata	O
between	O
the	O
highest	O
fossiliferous	O
beds	O
in	O
the	O
Manchester	LEXICON
Marls	LEXICON
and	O
the	O
base	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
;	O
it	O
may	O
,	O
therefore	O
,	O
occur	O
within	O
the	O
topmost	O
Manchester	LEXICON
Marls	LEXICON
or	O
the	O
lower	O
part	O
of	O
the	O
SSG	O
.	O

Further	O
south	O
in	O
the	O
basin	O
it	O
is	O
considered	O
to	O
occur	O
within	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
.	O

This	O
group	O
has	O
an	O
extensive	O
outcrop	O
,	O
enclosing	O
the	O
outliers	O
of	O
the	O
Penarth	LEXICON
and	O
Lias	LEXICON
groups	O
in	O
the	O
southern	O
part	O
of	O
the	O
basin	O
and	O
almost	O
surrounded	O
by	O
the	O
outcrop	O
of	O
the	O
SSG	O
.	O

The	O
MMG	O
comprises	O
six	O
predominantly	O
fine-grained	O
clastic	O
formations	O
,	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
,	O
Bollin	LEXICON
Mudstone	LEXICON
,	O
Byley	LEXICON
Mudstone	LEXICON
,	O
Wych	LEXICON
Mudstone	LEXICON
,	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
and	O
Blue	LEXICON
Anchor	LEXICON
formations	O
,	O
and	O
two	O
halite	O
-	O
bearing	O
units	O
.	O

The	O
lower	O
halite	O
-	O
bearing	O
unit	O
,	O
the	O
Northwich	LEXICON
Halite	LEXICON
Formation	LEXICON
occurs	O
between	O
the	O
Bollin	LEXICON
and	O
Byley	LEXICON
mudstones	O
,	O
and	O
the	O
upper	O
unit	O
,	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
Formation	LEXICON
,	O
between	O
the	O
Wych	LEXICON
and	O
Brooks	LEXICON
Mill	LEXICON
mudstones	O
.	O

The	O
MMG	O
succession	O
in	O
the	O
Cheshire	O
Basin	O
was	O
first	O
demonstrated	O
in	O
the	O
Geological	O
Survey	O
Wilkesley	O
Borehole	O
.	O

The	O
mudstone	O
formations	O
in	O
the	O
MMG	O
include	O
structureless	O
and	O
laminated	O
units	O
.	O

The	O
former	O
constitute	O
the	O
bulk	O
of	O
the	O
Wych	LEXICON
and	O
Brooks	LEXICON
Mill	LEXICON
mudstones	O
and	O
the	O
lower	O
part	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
,	O
and	O
also	O
occur	O
within	O
the	O
Byley	LEXICON
Mudstone	LEXICON
.	O

Laminated	O
beds	O
are	O
dominant	O
in	O
the	O
upper	O
part	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
and	O
also	O
occur	O
in	O
the	O
Byley	LEXICON
Mudstone	LEXICON
.	O

The	O
lowest	O
formation	O
in	O
the	O
MMG	O
,	O
it	O
is	O
at	O
least	O
280m	O
thick	O
in	O
the	O
Ashley	O
Borehole	O
-LSB-	O
7738	O
8355	O
-RSB-	O
,	O
south	O
of	O
Altrincham	O
and	O
between	O
200	O
and	O
230m	O
thick	O
in	O
several	O
boreholes	O
elsewhere	O
in	O
the	O
Cheshire	O
Basin	O
.	O

The	O
multiple	O
seismic	O
reflector	O
associated	O
with	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
-	O
Tarporley	LEXICON
Siltstone	LEXICON
succession	O
is	O
identifiable	O
widely	O
in	O
the	O
Cheshire	O
Basin	O
.	O

Towards	O
the	O
basin	O
edge	O
,	O
however	O
,	O
100m	O
is	O
a	O
more	O
common	O
thickness	O
for	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
,	O
with	O
a	O
likelihood	O
that	O
the	O
unit	O
thins	O
out	O
locally	O
on	O
the	O
eastern	O
fringe	O
near	O
Alsager	O
.	O

The	O
Tarporley	LEXICON
Siltstone	LEXICON
comprises	O
a	O
distinctive	O
facies	O
that	O
consists	O
of	O
alternating	O
siltstones	O
,	O
reddish	O
brown	O
and	O
greenish	O
grey	O
mudstones	O
and	O
thin	O
fine	O
-	O
to	O
medium-grained	O
sandstones	O
;	O
desiccation	O
surfaces	O
and	O
pseudomorphs	O
after	O
halite	O
point	O
to	O
arid	O
conditions	O
.	O

This	O
unit	O
,	O
the	O
Malpas	LEXICON
Sandstone	LEXICON
,	O
contains	O
abundant	O
wind-blown	O
grains	O
but	O
includes	O
water-laid	O
sandstone	O
,	O
with	O
current-ripple	O
lamination	O
and	O
clasts	O
of	O
mudstone	O
.	O

In	O
the	O
south-eastern	O
part	O
of	O
the	O
basin	O
,	O
near	O
Norton	O
in	O
Hales	O
-LSB-	O
720	O
380	O
-RSB-	O
,	O
beds	O
of	O
Tarporley	LEXICON
Siltstone	LEXICON
facies	O
alternate	O
with	O
up	O
to	O
six	O
sandstone	O
units	O
some	O
20	O
to	O
30m	O
thick	O
,	O
of	O
both	O
aeolian	O
and	O
subaqueous	O
origin	O
,	O
with	O
rip-up	O
clasts	O
and	O
cross-bedding	O
.	O

These	O
strata	O
have	O
been	O
assigned	O
to	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
in	O
recent	O
BGS	O
mapping	O
.	O

The	O
formation	O
is	O
defined	O
as	O
the	O
beds	O
between	O
the	O
highest	O
sandstone	O
interbed	O
at	O
the	O
top	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
and	O
the	O
base	O
of	O
the	O
first	O
bed	O
of	O
halite	O
over	O
2m	O
in	O
thickness	O
,	O
marking	O
the	O
base	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

The	O
type	O
section	O
is	O
in	O
the	O
banks	O
of	O
the	O
River	O
Bollin	O
-LSB-	O
7953	O
8453	O
to	O
8281	O
8350	O
-RSB-	O
,	O
close	O
to	O
Manchester	O
Airport	O
.	O

In	O
the	O
northern	O
half	O
of	O
the	O
basin	O
there	O
is	O
commonly	O
a	O
repetition	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
facies	O
in	O
the	O
overlying	O
Bollin	LEXICON
Mudstone	LEXICON
.	O

The	O
formation	O
probably	O
exceeds	O
500m	O
in	O
thickness	O
at	O
the	O
depocentre	O
,	O
which	O
extends	O
from	O
the	O
Northwich	O
area	O
,	O
south-westwards	O
to	O
Wych	O
Brook	O
.	O

The	O
upper	O
part	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
is	O
seen	O
in	O
a	O
number	O
of	O
scattered	O
sections	O
along	O
the	O
river	O
Bollin	O
and	O
in	O
Wych	O
Brook	O
,	O
near	O
Malpas	O
.	O

An	O
insect	O
wing	O
and	O
the	O
branchiopod	O
Euestheria	O
minuta	O
from	O
Giant	O
's	O
Castle	O
Rocks	O
,	O
the	O
best	O
exposure	O
on	O
the	O
Bollin	O
.	O

The	O
thickest	O
known	O
development	O
,	O
of	O
283.2m	O
,	O
is	O
in	O
Byley	O
Borehole	O
-LSB-	O
7207	O
6942	O
-RSB-	O
.	O

Similarly	O
,	O
to	O
the	O
south-west	O
,	O
in	O
Wych	O
Brook	O
,	O
the	O
narrow	O
width	O
of	O
the	O
collapsed	O
zone	O
overlying	O
the	O
halite	O
suggests	O
attenuation	O
of	O
the	O
formation	O
.	O

Earp	O
and	O
Taylor	O
estimated	O
that	O
some	O
25%	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
consists	O
of	O
mudstone	O
.	O

Further	O
evidence	O
that	O
deposition	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
was	O
in	O
shallow	O
water	O
comes	O
from	O
laboratory	O
experiments	O
and	O
studies	O
of	O
core	O
by	O
Arthurton	O
.	O

The	O
bromine	O
content	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
suggest	O
a	O
marine	O
origin	O
for	O
the	O
brines	O
.	O

The	O
Byley	LEXICON
Mudstone	LEXICON
,	O
the	O
lower	O
part	O
of	O
the	O
former	O
`	O
Middle	LEXICON
Keuper	LEXICON
Marl	LEXICON
'	O
and	O
the	O
`	O
middle	O
mudstone	O
division	O
of	O
the	O
MMG	O
'	O
in	O
the	O
Cheshire	O
Basin	O
comprises	O
a	O
distinctive	O
alternation	O
of	O
laminated	O
and	O
structureless	O
mudstones	O
and	O
varies	O
from	O
150	O
to	O
182m	O
in	O
thickness	O
.	O

The	O
contact	O
with	O
the	O
overlying	O
Wych	LEXICON
Mudstone	LEXICON
is	O
taken	O
at	O
the	O
top	O
of	O
the	O
highest	O
substantial	O
laminated	O
greenish	O
grey	O
unit	O
.	O

The	O
type	O
section	O
is	O
in	O
the	O
Byley	O
Borehole	O
-LSB-	O
7207	O
6942	O
-RSB-	O
,	O
which	O
also	O
shows	O
the	O
thickest	O
development	O
and	O
appears	O
to	O
lie	O
near	O
the	O
depocentre	O
for	O
a	O
combination	O
of	O
the	O
two	O
formations	O
.	O

The	O
strata	O
are	O
best	O
known	O
from	O
boreholes	O
,	O
but	O
the	O
lowermost	O
beds	O
are	O
seen	O
in	O
the	O
River	O
Dane	O
-LSB-	O
8808	O
6536	O
-RSB-	O
and	O
the	O
uppermost	O
in	O
Wych	O
Brook	O
.	O

At	O
surface	O
,	O
these	O
beds	O
weather	O
to	O
a	O
sticky	O
red	O
clay	O
and	O
are	O
seen	O
in	O
scattered	O
cliffs	O
in	O
the	O
valleys	O
of	O
Wych	O
Brook	O
-LSB-	O
4887	O
4469	O
to	O
4931	O
4530	O
-RSB-	O
and	O
on	O
the	O
River	O
Dane	O
west	O
of	O
Congleton	O
-LSB-	O
7870	O
6766	O
,	O
8469	O
6407	O
-RSB-	O
.	O

The	O
Wilkesley	LEXICON
Halite	LEXICON
is	O
the	O
thicker	O
of	O
the	O
two	O
saliferous	O
formations	O
in	O
the	O
Cheshire	O
Basin	O
.	O

The	O
only	O
complete	O
penetrations	O
of	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
are	O
in	O
the	O
Prees	O
Syncline	O
,	O
where	O
the	O
unit	O
was	O
404.50m	O
thick	O
in	O
the	O
Wilkesley	O
Borehole	O
and	O
about	O
350m	O
in	O
the	O
Prees	O
Borehole	O
.	O

The	O
upper	O
half	O
of	O
the	O
formation	O
is	O
somewhat	O
purer	O
than	O
the	O
average	O
analysis	O
for	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

The	O
Wilkesley	LEXICON
Halite	LEXICON
contains	O
four	O
significant	O
sandstone	O
beds	O
0.30	O
to	O
1.65m	O
in	O
thickness	O
,	O
as	O
well	O
as	O
a	O
few	O
thinner	O
sandstone	O
layers	O
,	O
all	O
within	O
the	O
mudstone	O
partings	O
.	O

In	O
contrast	O
,	O
there	O
are	O
no	O
sandstone	O
beds	O
in	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

Besides	O
the	O
main	O
outcrop	O
in	O
the	O
Prees	O
Syncline	O
,	O
further	O
occurrences	O
of	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
in	O
and	O
west	O
of	O
Nantwich	O
were	O
proved	O
in	O
the	O
Burland	O
Borehole	O
-LSB-	O
6018	O
5333	O
-RSB-	O
and	O
probably	O
in	O
the	O
area	O
5km	O
south	O
of	O
Crewe	O
,	O
on	O
the	O
evidence	O
of	O
subsidence	O
hollows	O
and	O
seismic	O
reflection	O
data	O
.	O

An	O
outlier	O
around	O
Sandbach	O
,	O
restricted	O
to	O
the	O
lower	O
beds	O
of	O
the	O
formation	O
,	O
marks	O
the	O
site	O
of	O
the	O
only	O
exploitation	O
of	O
brine	O
from	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
in	O
the	O
present	O
century	O
.	O

Since	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
is	O
not	O
seen	O
in	O
mines	O
and	O
there	O
are	O
no	O
specimens	O
of	O
any	O
of	O
the	O
clastic	O
interbeds	O
,	O
less	O
is	O
known	O
about	O
the	O
likely	O
origin	O
of	O
this	O
formation	O
than	O
that	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

Much	O
of	O
the	O
lower	O
part	O
of	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
does	O
,	O
however	O
,	O
consist	O
of	O
haselgebirge	O
,	O
a	O
lithology	O
known	O
to	O
have	O
been	O
deposited	O
in	O
shallow	O
water	O
during	O
the	O
deposition	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

This	O
formation	O
,	O
the	O
former	O
`	O
Upper	LEXICON
Keuper	LEXICON
Marl	LEXICON
'	O
,	O
is	O
generally	O
drift-mantled	O
and	O
is	O
named	O
from	O
small	O
exposures	O
-LSB-	O
6296	O
4370	O
,	O
6315	O
4384	O
-RSB-	O
near	O
Brooks	LEXICON
Mill	LEXICON
on	O
the	O
south	O
bank	O
of	O
the	O
River	O
Weaver	O
.	O

The	O
base	O
of	O
the	O
formation	O
is	O
at	O
the	O
top	O
of	O
the	O
highest	O
halite	O
bed	O
in	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
and	O
the	O
top	O
is	O
placed	O
at	O
the	O
incoming	O
of	O
the	O
greenish	O
grey	O
mudstones	O
of	O
the	O
Blue	LEXICON
Anchor	LEXICON
Formation	LEXICON
.	O

The	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
consists	O
dominantly	O
of	O
structureless	O
reddish	O
brown	O
mudstones	O
with	O
anhydrite	O
or	O
gypsum	O
nodules	O
.	O

The	O
structureless	O
mudstones	O
which	O
dominate	O
this	O
formation	O
are	O
,	O
like	O
those	O
in	O
the	O
Wych	LEXICON
Mudstone	LEXICON
,	O
probably	O
largely	O
of	O
aeolian	O
origin	O
.	O

The	O
Blue	LEXICON
Anchor	LEXICON
Formation	LEXICON
comprises	O
poorly	O
laminated	O
,	O
greenish	O
grey	O
mudstones	O
,	O
with	O
some	O
chocolate-coloured	O
mottling	O
and	O
a	O
transitional	O
colour	O
change	O
to	O
reddish	O
brown	O
at	O
the	O
base	O
.	O

The	O
MMG	O
successions	O
in	O
the	O
Cheshire	O
Basin	O
and	O
the	O
adjacent	O
EISB	O
show	O
an	O
increasing	O
degree	O
of	O
similarity	O
at	O
progressively	O
higher	O
levels	O
in	O
the	O
sequence	O
.	O

The	O
lowest	O
formation	O
,	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
of	O
Cheshire	O
and	O
its	O
approximate	O
equivalent	O
on	O
palynological	O
grounds	O
,	O
the	O
Hambleton	LEXICON
Mudstone	LEXICON
Formation	LEXICON
on	O
the	O
eastern	O
margin	O
of	O
the	O
EISB	O
,	O
show	O
little	O
similarity	O
of	O
facies	O
.	O

The	O
lower	O
half	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
of	O
Cheshire	O
,	O
like	O
the	O
Singleton	LEXICON
Mudstone	LEXICON
Formation	LEXICON
of	O
Blackpool	O
,	O
contains	O
much	O
structureless	O
reddish	O
brown	O
mudstone	O
,	O
but	O
there	O
may	O
be	O
rather	O
more	O
laminated	O
strata	O
in	O
Cheshire	O
.	O

The	O
upper	O
half	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
,	O
like	O
the	O
Thornton	LEXICON
Mudstone	LEXICON
Member	LEXICON
of	O
Blackpool	O
in	O
the	O
EISB	O
,	O
consists	O
very	O
largely	O
of	O
interlaminated	O
mudstones	O
and	O
dolomitic	O
siltstones	O
,	O
with	O
abundant	O
desiccation	O
cracks	O
and	O
pseudomorphs	O
after	O
halite	O
.	O

The	O
Northwich	LEXICON
and	O
Preesall	LEXICON
halites	O
were	O
,	O
on	O
palynological	O
evidence	O
,	O
laid	O
down	O
at	O
about	O
the	O
same	O
time	O
and	O
it	O
is	O
possible	O
that	O
the	O
two	O
basins	O
had	O
become	O
a	O
single	O
depositional	O
area	O
by	O
then	O
.	O

The	O
Northwich	LEXICON
Halite	LEXICON
does	O
not	O
persist	O
eastwards	O
into	O
the	O
Stafford	O
Basin	O
,	O
however	O
.	O

The	O
Byley	LEXICON
Mudstone	LEXICON
,	O
which	O
overlies	O
the	O
Northwich	LEXICON
Halite	LEXICON
,	O
is	O
closely	O
similar	O
to	O
the	O
Coat	LEXICON
Walls	LEXICON
Mudstone	LEXICON
Member	LEXICON
of	O
Blackpool	O
.	O

However	O
,	O
palynological	O
evidence	O
suggests	O
that	O
,	O
despite	O
the	O
close	O
lithological	O
similarities	O
,	O
the	O
Anisian	CHRONOSTRAT
-	O
Ladinian	CHRONOSTRAT
boundary	O
lies	O
closely	O
above	O
the	O
base	O
of	O
the	O
Coat	LEXICON
Walls	LEXICON
Mudstone	LEXICON
Member	LEXICON
in	O
the	O
Blackpool	O
area	O
.	O

The	O
Wych	LEXICON
Mudstone	LEXICON
of	O
Cheshire	O
closely	O
resembles	O
the	O
Breckells	LEXICON
Mudstone	LEXICON
Formation	LEXICON
of	O
the	O
EISB	O
in	O
the	O
abundance	O
of	O
gypsum	O
and	O
anhydrite	O
nodules	O
in	O
structureless	O
reddish	O
brown	O
mudstone	O
.	O

The	O
Wilkesley	LEXICON
Halite	LEXICON
of	O
Cheshire	O
is	O
the	O
thicker	O
of	O
the	O
two	O
great	O
salt	O
deposits	O
and	O
is	O
represented	O
to	O
the	O
south-east	O
,	O
in	O
the	O
Stafford	O
Basin	O
,	O
by	O
the	O
Stafford	LEXICON
Halite	LEXICON
.	O

The	O
equivalent	O
of	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
of	O
Cheshire	O
is	O
not	O
preserved	O
on	O
land	O
at	O
the	O
eastern	O
margin	O
of	O
the	O
EISB	O
,	O
but	O
is	O
almost	O
certainly	O
present	O
in	O
the	O
same	O
facies	O
offshore	O
.	O

There	O
is	O
similar	O
widespread	O
similarity	O
of	O
facies	O
at	O
the	O
level	O
of	O
the	O
Blue	LEXICON
Anchor	LEXICON
Formation	LEXICON
,	O
though	O
this	O
has	O
not	O
yet	O
been	O
verified	O
in	O
the	O
EISB	O
.	O

The	O
presence	O
of	O
the	O
Penarth	LEXICON
Group	LEXICON
,	O
formerly	O
the	O
`	O
Rhaetic	LEXICON
'	O
.	O

The	O
outliers	O
of	O
those	O
beds	O
and	O
the	O
succeeding	O
Lias	LEXICON
Group	LEXICON
in	O
the	O
Prees	O
and	O
Frith	O
Farm	O
areas	O
of	O
the	O
Nantwich	O
and	O
Wem	O
districts	O
.	O

The	O
Penarth	LEXICON
Group	LEXICON
comprises	O
the	O
Westbury	LEXICON
Formation	LEXICON
and	O
the	O
succeeding	O
Lilstock	LEXICON
Formation	LEXICON
.	O

The	O
Penarth	LEXICON
Group	LEXICON
rests	O
on	O
a	O
minor	O
unconformity	O
,	O
represented	O
by	O
an	O
erosion	O
surface	O
at	O
the	O
top	O
of	O
the	O
MMG	O
,	O
and	O
is	O
succeeded	O
conformably	O
by	O
the	O
Lias	LEXICON
.	O

The	O
age	O
of	O
the	O
group	O
is	O
,	O
on	O
biostratigraphical	O
evidence	O
,	O
late	O
Late	CHRONOSTRAT
Triassic	CHRONOSTRAT
.	O

Rocks	O
of	O
the	O
Lias	LEXICON
Group	LEXICON
were	O
first	O
noted	O
in	O
the	O
Cheshire	O
Basin	O
by	O
Murchison	O
.	O

The	O
Prees	O
Borehole	O
proved	O
597m	O
of	O
beds	O
here	O
assigned	O
to	O
the	O
Lower	O
Lias	LEXICON
.	O

The	O
Lias	LEXICON
comprises	O
dominantly	O
grey	O
fissile	O
mudstones	O
,	O
shales	O
and	O
thin	O
limestones	O
,	O
and	O
was	O
deposited	O
in	O
a	O
marine	O
environment	O
.	O

The	O
succession	O
in	O
the	O
Prees	O
outlier	O
is	O
,	O
on	O
biostratigraphic	O
evidence	O
,	O
latest	O
Triassic	CHRONOSTRAT
in	O
age	O
.	O

The	O
boundary	O
between	O
the	O
Triassic	CHRONOSTRAT
and	O
Jurassic	CHRONOSTRAT
systems	O
is	O
placed	O
at	O
the	O
level	O
of	O
the	O
appearance	O
of	O
ammonites	O
of	O
the	O
genus	O
Psiloceras	O
.	O

Biostratigraphical	O
information	O
is	O
available	O
for	O
the	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
,	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
the	O
MMG	O
,	O
and	O
the	O
Penarth	LEXICON
and	O
Lias	LEXICON
groups	O
.	O

The	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
has	O
yielded	O
plant	O
remains	O
.	O

The	O
fossil	O
associations	O
are	O
comparable	O
to	O
those	O
known	O
from	O
the	O
Zechstein	LEXICON
and	O
are	O
indicative	O
of	O
a	O
Late	CHRONOSTRAT
Permian	CHRONOSTRAT
age	O
.	O

The	O
occurrence	O
of	O
the	O
pollen	O
Lueckisporites	O
virkkiae	O
in	O
the	O
Manchester	LEXICON
Marls	LEXICON
at	O
Manchester	O
.	O

The	O
basal	O
member	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
at	O
Alderley	O
Edge	O
-LSB-	O
859	O
774	O
-RSB-	O
.	O

Fossils	O
are	O
commoner	O
in	O
parts	O
of	O
the	O
MMG	O
than	O
in	O
the	O
SSG	O
in	O
the	O
Cheshire	O
Basin	O
.	O

Records	O
of	O
spores	O
and	O
pollen	O
from	O
independently	O
dated	O
Triassic	CHRONOSTRAT
successions	O
elsewhere	O
in	O
Europe	O
provide	O
a	O
basis	O
for	O
the	O
dating	O
of	O
part	O
of	O
the	O
MMG	O
succession	O
in	O
the	O
Cheshire	O
Basin	O
.	O

The	O
base	O
of	O
the	O
Anisian	CHRONOSTRAT
Stage	O
is	O
marked	O
by	O
the	O
lowest	O
occurrences	O
of	O
Stellapollenites	O
thiergartii	O
and	O
Angustisulcites	O
spp	O
.	O

The	O
highest	O
occurrence	O
of	O
S.	O
thiergartii	O
and	O
the	O
lowest	O
occurrence	O
of	O
Ovalipollis	O
pseudoalatus	O
are	O
at	O
or	O
just	O
above	O
the	O
Anisian	CHRONOSTRAT
-	O
Ladinian	CHRONOSTRAT
boundary	O
.	O

Miospore	O
assemblages	O
from	O
the	O
MMG	O
in	O
the	O
Cheshire	O
Basin	O
indicate	O
,	O
by	O
reference	O
to	O
the	O
above	O
criteria	O
,	O
that	O
the	O
Anisian	CHRONOSTRAT
succession	O
extends	O
upwards	O
from	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
to	O
a	O
level	O
above	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

In	O
addition	O
to	O
occurring	O
in	O
the	O
basal	O
Helsby	LEXICON
Sandstone	LEXICON
at	O
Alderley	O
Edge	O
,	O
Angustisulcites	O
spp	O
.	O

are	O
recorded	O
,	O
together	O
with	O
Stellapollenites	O
thiergartii	O
and	O
other	O
taxa	O
,	O
such	O
as	O
Perotilites	O
minor	O
,	O
that	O
are	O
indicative	O
of	O
an	O
Anisian	CHRONOSTRAT
age	O
,	O
from	O
the	O
overlying	O
Tarporley	LEXICON
Siltstone	LEXICON
at	O
Liverpool	O
.	O

Palynological	O
evidence	O
of	O
an	O
Anisian	CHRONOSTRAT
age	O
has	O
also	O
been	O
obtained	O
from	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
in	O
the	O
Chester	O
district	O
.	O

Assemblages	O
containing	O
Angustisulcites	O
spp.	O
,	O
P.	O
minor	O
and	O
S.	O
thiergartii	O
have	O
also	O
been	O
recovered	O
from	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
,	O
and	O
Angustisulcites	O
spp	O
.	O

occurs	O
with	O
Tsugaepollenites	O
oriens	O
in	O
the	O
upper	O
part	O
of	O
the	O
Byley	LEXICON
Mudstone	LEXICON
,	O
which	O
is	O
now	O
assessed	O
as	O
late	O
Anisian	CHRONOSTRAT
in	O
age	O
.	O

The	O
palynological	O
evidence	O
suggests	O
that	O
the	O
Anisian	CHRONOSTRAT
-	O
Ladinian	CHRONOSTRAT
boundary	O
lies	O
at	O
the	O
top	O
of	O
the	O
Byley	LEXICON
Mudstone	LEXICON
.	O

Few	O
miospore	O
assemblages	O
have	O
been	O
recovered	O
from	O
higher	O
levels	O
in	O
the	O
MMG	O
.	O

The	O
Wilkesley	LEXICON
Halite	LEXICON
may	O
,	O
on	O
very	O
sparse	O
palynological	O
evidence	O
,	O
span	O
the	O
Mid	CHRONOSTRAT
to	O
Late	CHRONOSTRAT
Triassic	CHRONOSTRAT
in	O
age	O
.	O

There	O
is	O
no	O
satisfactory	O
biostratigraphical	O
evidence	O
for	O
the	O
age	O
of	O
the	O
succeeding	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
and	O
Blue	LEXICON
Anchor	LEXICON
formations	O
.	O

The	O
succession	O
between	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
and	O
the	O
Penarth	LEXICON
Group	LEXICON
is	O
therefore	O
considered	O
to	O
be	O
Late	CHRONOSTRAT
Triassic	CHRONOSTRAT
and	O
to	O
comprise	O
beds	O
of	O
Norian	CHRONOSTRAT
and	O
probably	O
early	O
Rhaetian	CHRONOSTRAT
age	O
.	O

Anderson	O
recorded	O
ostracods	O
from	O
the	O
Penarth	LEXICON
Group	LEXICON
of	O
the	O
Plattlane	O
Borehole	O
.	O

The	O
base	O
of	O
the	O
Jurassic	CHRONOSTRAT
is	O
placed	O
at	O
the	O
level	O
of	O
the	O
appearance	O
of	O
ammonites	O
of	O
the	O
genus	O
Psiloceras	O
this	O
occurs	O
9.37m	O
above	O
the	O
base	O
of	O
the	O
Lias	LEXICON
.	O

The	O
youngest	O
unit	O
in	O
the	O
Lias	LEXICON
succession	O
preserved	O
in	O
the	O
Prees	O
outlier	O
is	O
of	O
late	O
Pliensbachian	CHRONOSTRAT
.	O

The	O
preserved	O
fill	O
ranges	O
in	O
age	O
from	O
Early	CHRONOSTRAT
Permian	CHRONOSTRAT
.	O

The	O
poorly	O
constrained	O
lower	O
part	O
of	O
the	O
fill	O
,	O
comprising	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
,	O
Manchester	LEXICON
Marls	LEXICON
,	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
Wilmslow	LEXICON
Sandstone	LEXICON
formations	O
,	O
comprises	O
nearly	O
1900m	O
of	O
mostly	O
coarse	O
clastic	O
sediments	O
that	O
accumulated	O
during	O
a	O
maximum	O
time	O
of	O
58	O
+-	O
5Ma	O
.	O

The	O
part	O
of	O
this	O
sequence	O
comprising	O
the	O
Late	CHRONOSTRAT
Permian	CHRONOSTRAT
Manchester	LEXICON
Marls	LEXICON
and	O
the	O
succeeding	O
units	O
below	O
the	O
Mid-Triassic	CHRONOSTRAT
Helsby	LEXICON
Sandstone	LEXICON
accumulated	O
in	O
about	O
18	O
+-	O
5Ma	O
and	O
is	O
represented	O
by	O
some	O
1300m	O
of	O
sediments	O
.	O

The	O
succession	O
comprising	O
the	O
Manchester	LEXICON
Marls	LEXICON
and	O
beds	O
up	O
to	O
and	O
including	O
those	O
of	O
Anisian	CHRONOSTRAT
age	O
above	O
the	O
Northwich	LEXICON
Halite	LEXICON
spans	O
approximately	O
25	O
+-	O
5Ma	O
and	O
is	O
represented	O
by	O
more	O
than	O
2300m	O
of	O
sediments	O
.	O

The	O
Anisian	CHRONOSTRAT
succession	O
comprises	O
more	O
than	O
1000m	O
of	O
sandstones	O
,	O
mudstones	O
and	O
evaporites	O
that	O
accumulated	O
in	O
as	O
little	O
as	O
7Ma	O
.	O

The	O
remainder	O
of	O
the	O
MMG	O
,	O
together	O
with	O
the	O
Penarth	LEXICON
Group	LEXICON
and	O
basal	O
.	O

The	O
600m	O
of	O
Jurassic	CHRONOSTRAT
rocks	O
preserved	O
in	O
the	O
basin	O
accumulated	O
over	O
a	O
period	O
of	O
some	O
18Ma	O
.	O

During	O
this	O
phase	O
the	O
SSG	O
and	O
part	O
of	O
the	O
MMG	O
accumulated	O
under	O
conditions	O
of	O
fault-controlled	O
subsidence	O
.	O

The	O
boreholes	O
contained	O
strata	O
ranging	O
from	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
to	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
.	O

Detailed	O
logs	O
of	O
boreholes	O
through	O
the	O
MMG	O
are	O
summarised	O
by	O
Wilson	O
and	O
in	O
Figures	O
12	O
,	O
13	O
,	O
14	O
,	O
16	O
,	O
18	O
,	O
19	O
,	O
20	O
and	O
21	O
.	O

The	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
was	O
not	O
present	O
in	O
any	O
of	O
the	O
boreholes	O
studied	O
,	O
but	O
a	O
10m	O
sandstone	O
unit	O
underlying	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
in	O
the	O
Speke	O
Reservoir	O
Borehole	O
is	O
attributed	O
to	O
the	O
Bold	LEXICON
Formation	LEXICON
.	O

If	O
this	O
attribution	O
is	O
correct	O
,	O
the	O
overlying	O
Kinnerton	LEXICON
Sandstone	LEXICON
must	O
have	O
been	O
eroded	O
in	O
this	O
area	O
.	O

The	O
Thurstaston	LEXICON
Soft	LEXICON
Sandstone	LEXICON
Member	LEXICON
was	O
examined	O
in	O
the	O
Gallantry	O
Bank	O
boreholes	O
.	O

The	O
Delamere	LEXICON
Pebbly	LEXICON
Sandstone	LEXICON
Member	LEXICON
was	O
examined	O
in	O
the	O
Gallantry	O
Bank	O
and	O
Saughall	O
Massie	O
boreholes	O
,	O
where	O
it	O
consists	O
of	O
interbedded	O
fine	O
-	O
,	O
medium	O
-	O
and	O
medium	O
-	O
to	O
coarse-grained	O
sandstones	O
with	O
subordinate	O
claystones	O
and	O
siltstones	O
,	O
interpreted	O
as	O
deposits	O
of	O
low-sinuosity	O
fluvial	O
channels	O
.	O

The	O
Frodsham	LEXICON
Soft	LEXICON
Sandstone	LEXICON
Member	LEXICON
in	O
the	O
Saughall	O
Massie	O
Borehole	O
is	O
an	O
orange-brown	O
,	O
fine	O
-	O
to	O
medium-grained	O
,	O
poorly	O
cemented	O
sandstone	O
.	O

A	O
95m	O
sequence	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
was	O
examined	O
from	O
the	O
Saughall	O
Massie	O
Borehole	O
.	O

A	O
colour-shaded	O
gravity	O
image	O
of	O
the	O
basin	O
illustrates	O
its	O
gross	O
morphology	O
,	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basin	O
fill	O
corresponding	O
closely	O
to	O
a	O
large	O
negative	O
gravity	O
anomaly	O
.	O

During	O
early	O
Palaeozoic	CHRONOSTRAT
times	O
,	O
present-day	O
Precambrian	CHRONOSTRAT
inliers	O
such	O
as	O
those	O
of	O
the	O
Longmynd	O
probably	O
formed	O
elevated	O
areas	O
around	O
the	O
margin	O
of	O
the	O
Welsh	O
Basin	O
.	O

Thin	O
sequences	O
were	O
deposited	O
here	O
,	O
Tremadocian	CHRONOSTRAT
and	O
Caradocian	CHRONOSTRAT
strata	O
being	O
the	O
only	O
Ordovician	CHRONOSTRAT
rocks	O
preserved	O
.	O

A	O
thicker	O
,	O
more	O
complete	O
Cambrian	CHRONOSTRAT
Silurian	CHRONOSTRAT
sequence	O
was	O
deposited	O
west	O
of	O
the	O
Pontesford	O
Linley	O
Fault	O
,	O
which	O
is	O
interpreted	O
as	O
a	O
down-west	O
syn-sedimentary	O
fault	O
.	O

Ordovician	CHRONOSTRAT
rocks	O
in	O
the	O
Welsh	O
Basin	O
are	O
associated	O
with	O
arc	O
volcanics	O
,	O
whereas	O
Silurian	CHRONOSTRAT
rocks	O
are	O
turbidites	O
derived	O
from	O
the	O
rising	O
Caledonides	O
in	O
the	O
west	O
,	O
and	O
probably	O
shed	O
into	O
a	O
foreland	O
basin	O
.	O

The	O
Pontesford	O
Linley	O
Fault	O
probably	O
developed	O
in	O
Cambrian	CHRONOSTRAT
times	O
,	O
ceasing	O
normal	O
movement	O
in	O
the	O
late	O
Ordovician	CHRONOSTRAT
.	O

From	O
then	O
to	O
late	O
Llandovery	CHRONOSTRAT
times	O
,	O
basin	O
inversion	O
occurred	O
,	O
with	O
reversal	O
of	O
the	O
Pontesford	O
Linley	O
Fault	O
and	O
development	O
of	O
the	O
Shelve	O
Anticline	O
.	O

Preservation	O
of	O
Caradoc	CHRONOSTRAT
rocks	O
in	O
a	O
depression	O
east	O
of	O
the	O
Pontesford	O
Linley	O
Fault	O
,	O
unconformably	O
overlying	O
both	O
Uriconian	CHRONOSTRAT
and	O
Longmyndian	CHRONOSTRAT
rocks	O
,	O
suggests	O
that	O
basin	O
inversion	O
occurred	O
soon	O
after	O
Caradoc	CHRONOSTRAT
times	O
.	O

Cambrian	CHRONOSTRAT
and	O
Tremadoc	CHRONOSTRAT
rocks	O
probably	O
subcrop	O
beneath	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
west	O
of	O
the	O
Pontesford	O
and	O
Hodnet	O
faults	O
as	O
far	O
as	O
the	O
Prees	O
Borehole	O
,	O
consistent	O
with	O
late	O
Ordovician	CHRONOSTRAT
basin	O
inversion	O
beneath	O
the	O
southern	O
part	O
of	O
the	O
Cheshire	O
Basin	O
.	O

A	O
borehole	O
in	O
the	O
Hanwood	O
Coalfield	O
penetrated	O
Coal	LEXICON
Measures	LEXICON
,	O
which	O
rest	O
on	O
a	O
?	O

Cambrian	CHRONOSTRAT
sandstone	O
.	O

Upper	CHRONOSTRAT
Llandovery	CHRONOSTRAT
strata	O
are	O
unconformable	O
on	O
rocks	O
of	O
Longmyndian	LEXICON
to	O
Ordovician	CHRONOSTRAT
age	O
,	O
and	O
thicken	O
eastwards	O
towards	O
the	O
Pontesford	O
Linley	O
Fault	O
,	O
indicating	O
some	O
reactivated	O
downthrow	O
to	O
the	O
west	O
.	O

It	O
is	O
likely	O
that	O
a	O
Silurian	CHRONOSTRAT
basin	O
lay	O
to	O
the	O
north	O
of	O
the	O
Shelve	O
inlier	O
,	O
as	O
well	O
as	O
to	O
the	O
south	O
,	O
where	O
littoral	O
deposits	O
were	O
described	O
by	O
Whittard	O
.	O

Much	O
of	O
the	O
Welsh	O
Basin	O
and	O
the	O
subsurface	O
to	O
the	O
north-east	O
are	O
devoid	O
of	O
rocks	O
of	O
Devonian	CHRONOSTRAT
age	O
.	O

The	O
first	O
was	O
associated	O
with	O
the	O
late	O
Ordovician	CHRONOSTRAT
basin	O
inversion	O
.	O

The	O
second	O
,	O
Acadian	O
,	O
event	O
,	O
in	O
early	O
to	O
mid	O
-	O
Devonian	CHRONOSTRAT
times	O
,	O
uplifted	O
the	O
whole	O
Welsh	O
Basin	O
.	O

Reactivation	O
of	O
this	O
structure	O
appears	O
to	O
have	O
strongly	O
influenced	O
both	O
Carboniferous	CHRONOSTRAT
and	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
structural	O
development	O
of	O
the	O
Cheshire	O
Basin	O
.	O

The	O
plate-tectonic	O
process	O
which	O
most	O
strongly	O
influenced	O
Carboniferous	CHRONOSTRAT
structural	O
development	O
of	O
the	O
Cheshire	O
Basin	O
region	O
was	O
the	O
formation	O
,	O
several	O
hundred	O
km	O
to	O
the	O
south	O
,	O
of	O
a	O
collision-type	O
orogenic	O
belt	O
in	O
the	O
Iberian	O
Armorican	O
Massif	O
Central	O
region	O
of	O
the	O
Hercynides	O
.	O

Broadly	O
speaking	O
,	O
Carboniferous	CHRONOSTRAT
basin	O
development	O
in	O
the	O
Cheshire	O
Basin	O
region	O
can	O
be	O
split	O
into	O
two	O
main	O
phases	O
.	O

In	O
early	O
Carboniferous	CHRONOSTRAT
times	O
,	O
rapidly	O
subsiding	O
fault-controlled	O
extensional	O
basins	O
developed	O
between	O
structurally	O
elevated	O
,	O
largely	O
emergent	O
blocks	O
.	O

This	O
was	O
followed	O
,	O
in	O
late	O
Carboniferous	CHRONOSTRAT
times	O
,	O
by	O
more	O
regional	O
subsidence	O
,	O
which	O
was	O
characterised	O
by	O
a	O
lack	O
of	O
major	O
fault	O
control	O
and	O
led	O
to	O
submergence	O
and	O
depositional	O
onlap	O
of	O
the	O
earlier	O
structural	O
highs	O
.	O

Details	O
of	O
Carboniferous	CHRONOSTRAT
basin	O
development	O
are	O
sketchy	O
because	O
the	O
seismic	O
reflection	O
data	O
do	O
not	O
image	O
the	O
Carboniferous	CHRONOSTRAT
sequence	O
effectively	O
.	O

Comparison	O
with	O
the	O
better	O
described	O
early	O
Carboniferous	CHRONOSTRAT
extensional	O
basins	O
of	O
northern	O
England	O
suggests	O
that	O
an	O
extensional	O
Carboniferous	CHRONOSTRAT
basin	O
underlies	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
Cheshire	O
Basin	O
.	O

It	O
is	O
,	O
moreover	O
,	O
likely	O
to	O
have	O
a	O
geometry	O
markedly	O
different	O
to	O
the	O
overlying	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basin	O
,	O
given	O
the	O
roughly	O
orthogonal	O
extension	O
directions	O
.	O

Structural	O
trends	O
of	O
the	O
principal	O
early	O
Carboniferous	CHRONOSTRAT
faults	O
were	O
strongly	O
influenced	O
by	O
the	O
structural	O
grain	O
of	O
the	O
underlying	O
basement	O
.	O

In	O
latest	O
Carboniferous	CHRONOSTRAT
times	O
,	O
final	O
closure	O
of	O
the	O
Rheic	O
Ocean	O
culminated	O
in	O
the	O
Variscan	O
Orogeny	O
,	O
with	O
large-scale	O
thrust	O
and	O
nappe	O
emplacement	O
and	O
regional	O
crustal	O
shortening	O
in	O
northern	O
France	O
,	O
Belgium	O
,	O
southern	O
England	O
,	O
South	O
Wales	O
and	O
southern	O
Ireland	O
.	O

Variscan	O
deformation	O
was	O
much	O
less	O
pervasive	O
here	O
,	O
being	O
largely	O
restricted	O
to	O
the	O
reversal	O
of	O
pre-existing	O
Dinantian	CHRONOSTRAT
normal	O
faults	O
and	O
associated	O
basin	O
inversion	O
.	O

The	O
main	O
Variscan	O
movements	O
in	O
the	O
Cheshire	O
Basin	O
region	O
probably	O
postdated	O
the	O
preserved	O
Westphalian	CHRONOSTRAT
rocks	O
and	O
predate	O
deposition	O
of	O
the	O
Permian	CHRONOSTRAT
strata	O
which	O
rest	O
unconformably	O
on	O
the	O
Carboniferous	CHRONOSTRAT
beds	O
.	O

Dating	O
the	O
precise	O
onset	O
of	O
the	O
main	O
Variscan	O
movements	O
is	O
difficult	O
,	O
but	O
evidence	O
from	O
central	O
England	O
suggests	O
that	O
inversion	O
may	O
have	O
commenced	O
as	O
early	O
as	O
Westphalian	CHRONOSTRAT
C	CHRONOSTRAT
times	O
.	O

The	O
main	O
effect	O
of	O
Variscan	CHRONOSTRAT
compression	O
in	O
the	O
region	O
appears	O
to	O
have	O
been	O
reversal	O
of	O
important	O
Caledonian	O
lines	O
of	O
weakness	O
and	O
associated	O
early	O
Carboniferous	CHRONOSTRAT
faults	O
,	O
which	O
led	O
to	O
structural	O
inversion	O
of	O
the	O
Carboniferous	CHRONOSTRAT
basins	O
.	O

Evidence	O
of	O
this	O
comes	O
from	O
the	O
south-east	O
margin	O
of	O
the	O
Cheshire	O
Basin	O
,	O
where	O
seismic	O
reflection	O
data	O
show	O
west-dipping	O
reflections	O
between	O
0.1	O
and	O
0.65s	O
two-way	O
travel	O
time	O
,	O
beneath	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
cover	O
.	O

Seismic	O
character	O
and	O
regional	O
correlation	O
suggest	O
that	O
these	O
reflections	O
correspond	O
to	O
concealed	O
Westphalian	CHRONOSTRAT
Coal	LEXICON
Measures	LEXICON
.	O

Their	O
relationship	O
to	O
the	O
Carboniferous	CHRONOSTRAT
succession	O
imaged	O
at	O
the	O
extreme	O
eastern	O
end	O
of	O
the	O
line	O
,	O
where	O
the	O
Keele	LEXICON
Formation	LEXICON
outcrops	O
,	O
suggests	O
that	O
the	O
formations	O
are	O
separated	O
by	O
a	O
down-east	O
reverse	O
fault	O
.	O

Precise	O
displacement	O
of	O
the	O
Westphalian	CHRONOSTRAT
strata	O
is	O
difficult	O
to	O
assess	O
,	O
because	O
of	O
their	O
complex	O
structure	O
and	O
uncertain	O
seismic	O
character	O
matches	O
.	O

In	O
the	O
footwall	O
of	O
this	O
fault	O
,	O
other	O
,	O
smaller	O
,	O
down-east	O
reverse	O
faults	O
displace	O
the	O
Coal	LEXICON
Measures	LEXICON
and	O
Barren	LEXICON
Measures	LEXICON
.	O

A	O
few	O
km	O
to	O
the	O
south	O
,	O
seismic	O
reflection	O
and	O
gravity	O
data	O
show	O
the	O
sub	O
-	O
Permian	CHRONOSTRAT
basement	O
structure	O
along	O
Section	O
4	O
of	O
Figure	O
38	O
.	O

Carboniferous	CHRONOSTRAT
strata	O
pinch	O
out	O
eastwards	O
beneath	O
the	O
Wem	O
Audlem	O
Sub-basin	O
,	O
with	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
rocks	O
forming	O
the	O
pre	O
-	O
Permian	CHRONOSTRAT
subcrop	O
on	O
the	O
hangingwall	O
block	O
of	O
the	O
Wem	O
Fault	O
.	O

In	O
contrast	O
,	O
east	O
of	O
the	O
Wem	O
Fault	O
,	O
on	O
its	O
footwall	O
block	O
,	O
the	O
gravity	O
interpretation	O
,	O
indicate	O
that	O
thick	O
Carboniferous	CHRONOSTRAT
strata	O
occur	O
beneath	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
cover	O
.	O

Variscan	CHRONOSTRAT
reversal	O
of	O
the	O
Wem	O
Fault	O
led	O
to	O
uplift	O
of	O
its	O
hangingwall	O
block	O
and	O
inversion	O
of	O
the	O
Carboniferous	CHRONOSTRAT
basin	O
.	O

The	O
Edgerley	O
Fault	O
,	O
in	O
the	O
western	O
part	O
of	O
the	O
basin	O
may	O
also	O
be	O
associated	O
with	O
reactivation	O
of	O
the	O
Bala	O
Fault	O
,	O
another	O
important	O
Caledonian	CHRONOSTRAT
,	O
Carboniferous	CHRONOSTRAT
and	O
Variscan	CHRONOSTRAT
basement	O
structure	O
.	O

By	O
earliest	O
Permian	CHRONOSTRAT
times	O
,	O
Variscan	CHRONOSTRAT
continental	O
collision	O
had	O
led	O
to	O
final	O
suturing	O
and	O
consolidation	O
of	O
the	O
Pangaean	O
supercontinent	O
.	O

Variscan	CHRONOSTRAT
basin	O
inversion	O
and	O
regional	O
uplift	O
had	O
resulted	O
in	O
considerable	O
elevation	O
of	O
the	O
land	O
surface	O
,	O
which	O
,	O
during	O
Permian	CHRONOSTRAT
times	O
,	O
underwent	O
progressive	O
peneplanation	O
.	O

By	O
late	O
Permian	CHRONOSTRAT
,	O
and	O
,	O
particularly	O
,	O
early	O
Triassic	CHRONOSTRAT
times	O
,	O
the	O
north-west	O
European	O
region	O
formed	O
an	O
isthmus	O
between	O
the	O
rapidly	O
developing	O
Arctic	O
North	O
Atlantic	O
rift	O
system	O
to	O
the	O
north	O
and	O
the	O
Tethys	O
Central	O
Atlantic	O
Gulf	O
of	O
Mexico	O
rift-wrench	O
system	O
to	O
the	O
south	O
.	O

The	O
Cheshire	O
Basin	O
formed	O
part	O
of	O
a	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rift	O
system	O
which	O
extended	O
from	O
the	O
English	O
Channel	O
Basin	O
in	O
the	O
south	O
to	O
the	O
East	O
Irish	O
Sea	O
Basin	O
in	O
the	O
north	O
.	O

The	O
post	O
-	O
Triassic	CHRONOSTRAT
evolution	O
of	O
the	O
Cheshire	O
Basin	O
is	O
poorly	O
understood	O
because	O
of	O
the	O
paucity	O
of	O
preserved	O
strata	O
.	O

It	O
is	O
likely	O
,	O
however	O
,	O
that	O
regional	O
crustal	O
extension	O
continued	O
episodically	O
,	O
prior	O
to	O
the	O
onset	O
of	O
North	O
Atlantic	O
sea-floor	O
spreading	O
in	O
mid	O
-	O
Cretaceous	CHRONOSTRAT
times	O
.	O

Regional	O
considerations	O
,	O
and	O
,	O
particularly	O
,	O
evidence	O
from	O
more	O
fully	O
preserved	O
sedimentary	O
sequences	O
to	O
the	O
south	O
,	O
indicate	O
that	O
extensional	O
basin	O
subsidence	O
continued	O
into	O
early	O
Jurassic	CHRONOSTRAT
times	O
.	O

Renewed	O
extension	O
in	O
the	O
late	O
Jurassic	CHRONOSTRAT
and	O
early	O
Cretaceous	CHRONOSTRAT
was	O
associated	O
with	O
sea-floor	O
spreading	O
in	O
the	O
southern	O
part	O
of	O
the	O
North	O
Atlantic	O
region	O
as	O
Iberia	O
and	O
America	O
separated	O
.	O

Erosion	O
associated	O
with	O
development	O
of	O
the	O
widespread	O
late	O
Cimmerian	CHRONOSTRAT
unconformity	O
is	O
likely	O
to	O
have	O
affected	O
much	O
of	O
the	O
Cheshire	O
Basin	O
region	O
in	O
the	O
early	O
Cretaceous	CHRONOSTRAT
.	O

Most	O
of	O
any	O
lower	O
Cretaceous	CHRONOSTRAT
deposits	O
,	O
together	O
with	O
a	O
substantial	O
thickness	O
of	O
Jurassic	CHRONOSTRAT
and	O
possibly	O
Triassic	CHRONOSTRAT
strata	O
,	O
are	O
likely	O
to	O
have	O
been	O
removed	O
at	O
this	O
time	O
,	O
particularly	O
from	O
the	O
basin	O
edges	O
.	O

Deposition	O
recommenced	O
in	O
the	O
late	O
Cretaceous	CHRONOSTRAT
,	O
as	O
regional	O
,	O
post-extensional	O
shelf	O
subsidence	O
became	O
established	O
,	O
with	O
deposition	O
of	O
the	O
laterally	O
uniform	O
Chalk	O
.	O

Basin	O
inversion	O
,	O
not	O
necessarily	O
contemporaneous	O
with	O
the	O
regional	O
uplift	O
,	O
corresponded	O
to	O
one	O
or	O
more	O
of	O
three	O
inversion	O
episodes	O
in	O
southern	O
Britain	O
:	O
the	O
late	O
Cretaceous	CHRONOSTRAT
inversion	O
in	O
the	O
southern	O
North	O
Sea	O
.	O

Well-documented	O
cases	O
of	O
basin	O
inversion	O
reasonably	O
close	O
to	O
the	O
region	O
include	O
the	O
Sole	O
Pit	O
Trough	O
,	O
where	O
the	O
main	O
phase	O
of	O
inversion	O
occurred	O
in	O
Oligo	CHRONOSTRAT
-	O
Miocene	CHRONOSTRAT
times	O
,	O
corresponding	O
to	O
major	O
Alpine	O
nappe	O
development	O
.	O

The	O
detailed	O
structure	O
of	O
the	O
Cheshire	O
Basin	O
and	O
aspects	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
subsequent	O
phases	O
of	O
basin	O
evolution	O
,	O
are	O
examined	O
in	O
more	O
detail	O
below	O
.	O

The	O
MMG	O
is	O
imaged	O
as	O
a	O
seismically	O
banded	O
sequence	O
.	O

The	O
Bollin	LEXICON
Mudstone	LEXICON
and	O
Tarporley	LEXICON
Siltstone	LEXICON
formations	O
and	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
of	O
the	O
underlying	O
SSG	O
can	O
usually	O
be	O
identified	O
as	O
groups	O
of	O
moderate	O
-	O
to	O
high-amplitude	O
continuous	O
reflections	O
.	O

The	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
beneath	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
gives	O
rise	O
to	O
a	O
seismically	O
layered	O
interval	O
,	O
within	O
which	O
three	O
poorly	O
reflective	O
zones	O
are	O
developed	O
,	O
corresponding	O
to	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
,	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
Collyhurst	LEXICON
Sandstone	LEXICON
formations	O
.	O

These	O
three	O
transparent	O
zones	O
are	O
separated	O
by	O
two	O
layers	O
of	O
high-amplitude	O
,	O
coherent	O
reflections	O
,	O
corresponding	O
to	O
the	O
top	O
of	O
the	O
Silicified	O
Zone	O
within	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
Kinnerton	LEXICON
Sandstone	LEXICON
formations	O
.	O

The	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
is	O
in	O
places	O
marked	O
by	O
a	O
high-amplitude	O
,	O
continuous	O
event	O
,	O
commonly	O
associated	O
with	O
truncation	O
of	O
underlying	O
reflections	O
from	O
Westphalian	CHRONOSTRAT
strata	O
.	O

This	O
characteristic	O
seismic	O
stratigraphy	O
,	O
together	O
with	O
data	O
from	O
many	O
shallow	O
boreholes	O
and	O
the	O
surface	O
geology	O
,	O
enables	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
reflectors	O
to	O
be	O
identified	O
across	O
much	O
of	O
the	O
basin	O
with	O
a	O
fair	O
degree	O
of	O
precision	O
.	O

In	O
the	O
north-west	O
of	O
the	O
basin	O
however	O
,	O
seismic	O
data	O
are	O
of	O
generally	O
poorer	O
quality	O
,	O
with	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
and	O
,	O
in	O
particular	O
,	O
the	O
base	O
of	O
the	O
SSG	O
being	O
somewhat	O
uncertain	O
.	O

Most	O
of	O
these	O
smaller	O
faults	O
penetrate	O
to	O
the	O
surface	O
;	O
throws	O
are	O
typically	O
in	O
the	O
range	O
100	O
500m	O
and	O
tend	O
to	O
decrease	O
upwards	O
,	O
indicating	O
both	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
probable	O
post	O
-	O
Triassic	CHRONOSTRAT
syndepositional	O
movement	O
.	O

Curved	O
listric	O
fault	O
geometry	O
is	O
developed	O
only	O
locally	O
,	O
and	O
evidence	O
of	O
faults	O
detaching	O
onto	O
the	O
salt	O
units	O
of	O
the	O
MMG	O
is	O
sparse	O
.	O

The	O
deepest	O
parts	O
of	O
the	O
Cheshire	O
Basin	O
are	O
presently	O
within	O
the	O
Wem	O
Audlem	O
and	O
Sandbach	O
Knutsford	O
sub-basins	O
,	O
where	O
the	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
lies	O
at	O
depths	O
greater	O
than	O
4000m	O
.	O

Pre	O
-	O
Permian	CHRONOSTRAT
basement	O
lies	O
at	O
depths	O
greater	O
than	O
4500m	O
in	O
the	O
hangingwall	O
block	O
of	O
the	O
Wem	O
Fault	O
,	O
west	O
of	O
the	O
Prees	O
Borehole	O
,	O
and	O
greater	O
than	O
4250m	O
in	O
the	O
hangingwall	O
block	O
of	O
the	O
Bridgemere	O
Fault	O
,	O
south-east	O
of	O
the	O
Burford	O
Borehole	O
.	O

The	O
Permian	CHRONOSTRAT
,	O
SSG	O
and	O
MMG	O
all	O
thicken	O
south-east	O
into	O
the	O
sub-basin	O
,	O
indicating	O
that	O
it	O
developed	O
as	O
a	O
structural	O
feature	O
throughout	O
the	O
extensional	O
phase	O
of	O
basin	O
evolution	O
,	O
by	O
contemporaneous	O
normal	O
displacements	O
on	O
the	O
Wem	O
and	O
Bridgemere	O
faults	O
.	O

The	O
two	O
areas	O
in	O
the	O
Wem	O
Audlem	O
Sub-basin	O
where	O
the	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
is	O
at	O
the	O
greatest	O
depth	O
appear	O
to	O
have	O
had	O
significantly	O
different	O
structural	O
histories	O
.	O

Whereas	O
the	O
base	O
of	O
the	O
SSG	O
and	O
MMG	O
and	O
the	O
base	O
of	O
the	O
Jurassic	CHRONOSTRAT
succession	O
also	O
reach	O
their	O
greatest	O
depth	O
in	O
the	O
area	O
west	O
of	O
Prees	O
,	O
the	O
more	O
northerly	O
area	O
of	O
deep	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
,	O
south-east	O
of	O
Burford	O
,	O
is	O
not	O
well	O
defined	O
at	O
higher	O
stratigraphical	O
levels	O
.	O

Indeed	O
,	O
at	O
the	O
base	O
of	O
the	O
MMG	O
it	O
marks	O
a	O
local	O
structural	O
high	O
.	O

Depth-of-burial	O
and	O
backstripping	O
studies	O
indicate	O
that	O
the	O
latter	O
area	O
marked	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
depocentre	O
of	O
the	O
Cheshire	O
Basin	O
,	O
but	O
suffered	O
significantly	O
more	O
uplift	O
than	O
surrounding	O
areas	O
during	O
Cenozoic	CHRONOSTRAT
basin	O
inversion	O
.	O

Pre	O
-	O
Permian	CHRONOSTRAT
basement	O
lies	O
at	O
depths	O
in	O
excess	O
of	O
4000m	O
in	O
the	O
hangingwall	O
block	O
of	O
the	O
King	O
Street	O
Fault	O
.	O

Permian	CHRONOSTRAT
strata	O
,	O
the	O
SSG	O
and	O
the	O
MMG	O
all	O
thicken	O
across	O
the	O
bounding	O
faults	O
of	O
the	O
sub-basin	O
,	O
indicating	O
that	O
it	O
developed	O
as	O
a	O
structural	O
feature	O
throughout	O
the	O
extensional	O
phase	O
of	O
basin	O
evolution	O
by	O
contemporaneous	O
normal	O
displacement	O
of	O
these	O
faults	O
.	O

West	O
of	O
these	O
two	O
important	O
sub-basins	O
,	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basin	O
fill	O
is	O
much	O
thinner	O
.	O

The	O
western	O
updip	O
flank	O
of	O
the	O
Wem	O
Audlem	O
Sub-basin	O
''	O
the	O
Western	O
Slope	O
''	O
is	O
characterised	O
by	O
a	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sequence	O
which	O
has	O
a	O
regional	O
east-south-east	O
dip	O
and	O
which	O
thins	O
gradually	O
towards	O
the	O
more	O
or	O
less	O
unfaulted	O
western	O
basin	O
margin	O
.	O

The	O
westerly	O
edge	O
of	O
this	O
east-dipping	O
tilt-block	O
suffered	O
sufficient	O
relative	O
uplift	O
during	O
the	O
extensional	O
phase	O
of	O
basin	O
development	O
for	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
rocks	O
to	O
be	O
exposed	O
at	O
surface	O
at	O
the	O
present	O
day	O
.	O

North	O
of	O
the	O
Western	O
Slope	O
,	O
an	O
area	O
of	O
shallow	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
,	O
generally	O
less	O
than	O
1000m	O
deep	O
,	O
has	O
many	O
small	O
normal	O
faults	O
,	O
throwing	O
both	O
down-east	O
and	O
down-west	O
to	O
create	O
a	O
complex	O
system	O
of	O
tilt-blocks	O
.	O

In	O
the	O
north-west	O
corner	O
of	O
the	O
basin	O
the	O
Ellesmere	O
Saddle	O
has	O
outcropping	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
to	O
the	O
north-east	O
and	O
south-west	O
,	O
and	O
connects	O
the	O
Cheshire	O
Basin	O
to	O
the	O
West	O
Lancashire	O
East	O
Irish	O
Sea	O
Basin	O
.	O

East	O
of	O
the	O
Ellesmere	O
Saddle	O
,	O
the	O
northern	O
part	O
of	O
the	O
Cheshire	O
Basin	O
is	O
characterised	O
by	O
regional	O
southerly	O
dips	O
,	O
with	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
strata	O
dipping	O
and	O
thickening	O
southwards	O
into	O
the	O
Wem	O
Audlem	O
and	O
Sandbach	O
Knutsford	O
sub-basins	O
.	O

Stratigraphical	O
thickening	O
is	O
particularly	O
pronounced	O
in	O
the	O
Permian	CHRONOSTRAT
succession	O
,	O
which	O
is	O
extremely	O
condensed	O
close	O
to	O
the	O
northern	O
edge	O
of	O
the	O
basin	O
.	O

The	O
Permian	CHRONOSTRAT
succession	O
is	O
particularly	O
condensed	O
on	O
the	O
footwall	O
block	O
of	O
the	O
Brook	O
House	O
Fault	O
the	O
extensional	O
phase	O
of	O
basin	O
development	O
.	O

The	O
Alderley	O
High	O
is	O
characterised	O
by	O
relatively	O
thin	O
Permian	CHRONOSTRAT
and	O
SSG	O
sequences	O
,	O
the	O
former	O
thinning	O
eastwards	O
towards	O
the	O
basin	O
margin	O
.	O

The	O
MMG	O
is	O
absent	O
or	O
partially	O
preserved	O
,	O
having	O
been	O
removed	O
by	O
later	O
erosion	O
.	O

The	O
Permian	CHRONOSTRAT
sequence	O
is	O
very	O
thin	O
or	O
absent	O
,	O
suggesting	O
that	O
displacement	O
on	O
the	O
WBRRFS	O
was	O
largely	O
restricted	O
to	O
the	O
Bridgemere	O
Fault	O
in	O
Permian	CHRONOSTRAT
times	O
,	O
initiating	O
the	O
Wem	O
Audlem	O
Sub-basin	O
in	O
its	O
hangingwall	O
block	O
,	O
but	O
leaving	O
its	O
footwall	O
block	O
largely	O
subaerially	O
exposed	O
.	O

By	O
early	O
Triassic	CHRONOSTRAT
times	O
,	O
displacement	O
along	O
the	O
Wem	O
Fault	O
led	O
to	O
deposition	O
of	O
SSG	O
on	O
the	O
Terrace	O
,	O
which	O
nonetheless	O
continued	O
as	O
a	O
structural	O
feature	O
during	O
subsequent	O
extensional	O
development	O
,	O
with	O
SSG	O
and	O
MMG	O
sequences	O
markedly	O
thinner	O
than	O
in	O
the	O
Wem	O
Audlem	O
Sub-basin	O
to	O
the	O
west	O
.	O

It	O
is	O
similar	O
to	O
the	O
Blakenhall	O
Terrace	O
,	O
though	O
somewhat	O
larger	O
,	O
and	O
is	O
also	O
characterised	O
by	O
a	O
thin	O
,	O
locally	O
absent	O
,	O
Permian	CHRONOSTRAT
sequence	O
.	O

It	O
probably	O
existed	O
as	O
an	O
active	O
structural	O
feature	O
throughout	O
the	O
extensional	O
phase	O
of	O
basin	O
development	O
,	O
with	O
SSG	O
and	O
MMG	O
sequences	O
markedly	O
thinner	O
than	O
in	O
the	O
Wem	O
Audlem	O
Sub-basin	O
to	O
the	O
west	O
.	O

The	O
cumulative	O
throw	O
on	O
the	O
WBRRFS	O
is	O
greatest	O
in	O
its	O
southern-central	O
section	O
where	O
it	O
locally	O
exceeds	O
4000m	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
.	O

However	O
,	O
because	O
Carboniferous	CHRONOSTRAT
rocks	O
outcrop	O
on	O
the	O
footwall	O
block	O
of	O
the	O
Red	O
Rock	O
Fault	O
,	O
along	O
much	O
of	O
its	O
length	O
,	O
only	O
minimum	O
estimates	O
of	O
its	O
true	O
throw	O
can	O
be	O
made	O
;	O
the	O
real	O
throw	O
may	O
be	O
much	O
greater	O
.	O

Its	O
throw	O
,	O
at	O
the	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
,	O
is	O
believed	O
to	O
be	O
of	O
the	O
order	O
of	O
several	O
hundred	O
metres	O
,	O
decreasing	O
markedly	O
upwards	O
.	O

Thickening	O
of	O
the	O
Permian	CHRONOSTRAT
sequence	O
is	O
particularly	O
marked	O
,	O
indicating	O
that	O
the	O
fault	O
was	O
an	O
important	O
structure	O
early	O
in	O
basin	O
evolution	O
.	O

Throws	O
on	O
the	O
King	O
Street	O
Fault	O
approach	O
1000m	O
at	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
level	O
,	O
but	O
diminish	O
north	O
and	O
south	O
.	O

Eastwards	O
stratigraphical	O
thickening	O
occurs	O
across	O
the	O
fault	O
,	O
particularly	O
in	O
the	O
SSG	O
,	O
but	O
in	O
contrast	O
to	O
the	O
Brook	O
House	O
Fault	O
,	O
thickening	O
of	O
the	O
Permian	CHRONOSTRAT
sequence	O
is	O
minor	O
.	O

Easterly	O
downthrows	O
locally	O
exceed	O
1000m	O
,	O
at	O
the	O
top	O
of	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
.	O

There	O
is	O
only	O
minor	O
eastward	O
thickening	O
of	O
preserved	O
strata	O
across	O
the	O
faults	O
,	O
suggesting	O
that	O
most	O
of	O
the	O
displacement	O
took	O
place	O
after	O
deposition	O
of	O
the	O
SSG	O
.	O

The	O
fault	O
downthrows	O
to	O
the	O
west	O
,	O
locally	O
almost	O
1000m	O
where	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
outcrops	O
in	O
the	O
footwall	O
block	O
at	O
the	O
western	O
edge	O
of	O
the	O
Milton	O
Green	O
inlier	O
.	O

Seismic	O
data	O
suggest	O
that	O
the	O
sub-cropping	O
Carboniferous	CHRONOSTRAT
sequence	O
is	O
different	O
on	O
either	O
side	O
of	O
the	O
fault	O
,	O
and	O
thus	O
displacements	O
pre-dated	O
deposition	O
of	O
the	O
Permian	CHRONOSTRAT
.	O

Carboniferous	CHRONOSTRAT
rocks	O
,	O
comprising	O
a	O
Dinantian	CHRONOSTRAT
sequence	O
overlain	O
by	O
Silesian	CHRONOSTRAT
.	O

The	O
Carboniferous	CHRONOSTRAT
succession	O
is	O
clearly	O
imaged	O
on	O
seismic	O
profiles	O
beneath	O
the	O
northern	O
and	O
western	O
parts	O
of	O
the	O
basin	O
,	O
where	O
it	O
is	O
locally	O
more	O
than	O
4000m	O
thick	O
.	O

Elsewhere	O
,	O
the	O
thickness	O
of	O
Carboniferous	CHRONOSTRAT
strata	O
is	O
constrained	O
by	O
the	O
gravity	O
interpretation	O
.	O

Gravity	O
stripping	O
can	O
not	O
be	O
wholly	O
explained	O
by	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basin	O
fill	O
:	O
considerable	O
thicknesses	O
of	O
upper	O
Carboniferous	CHRONOSTRAT
strata	O
are	O
also	O
required	O
.	O

2-D	O
gravity	O
modelling	O
along	O
basinwide	O
traverses	O
indicates	O
upper	O
Carboniferous	CHRONOSTRAT
.	O

Much	O
of	O
the	O
lithostratigraphical	O
information	O
relating	O
to	O
the	O
concealed	O
Carboniferous	CHRONOSTRAT
sequence	O
beneath	O
the	O
Cheshire	O
Basin	O
comes	O
from	O
boreholes	O
and	O
outcrops	O
outside	O
the	O
basin	O
.	O

Dinantian	CHRONOSTRAT
rocks	O
in	O
the	O
Cheshire	O
Basin	O
are	O
proved	O
only	O
in	O
the	O
Milton	O
Green	O
,	O
Blacon	O
East	O
,	O
Ternhill	O
,	O
Stoke-on-Tern	O
and	O
Bowsey	O
Wood	O
boreholes	O
,	O
and	O
the	O
top	O
Carboniferous	CHRONOSTRAT
Limestone	O
reflector	O
can	O
not	O
be	O
traced	O
very	O
widely	O
from	O
Milton	O
Green	O
,	O
so	O
deductions	O
about	O
Dinantian	CHRONOSTRAT
rocks	O
and	O
structures	O
are	O
based	O
largely	O
on	O
the	O
surrounding	O
outcrops	O
.	O

In	O
north-east	O
Wales	O
a	O
north-north-west-striking	O
outcrop	O
of	O
Dinantian	CHRONOSTRAT
rocks	O
.	O

Both	O
faults	O
have	O
thicker	O
Dinantian	CHRONOSTRAT
successions	O
on	O
their	O
northern	O
blocks	O
.	O

Subsequent	O
dating	O
of	O
the	O
sequence	O
indicates	O
that	O
although	O
late	O
Asbian	CHRONOSTRAT
and	O
Brigantian	CHRONOSTRAT
rocks	O
thicken	O
on	O
the	O
downthrown	O
sides	O
of	O
the	O
faults	O
most	O
of	O
the	O
displacement	O
occurred	O
early	O
in	O
the	O
Dinantian	CHRONOSTRAT
.	O

Information	O
from	O
deep	O
boreholes	O
to	O
the	O
east	O
indicates	O
that	O
the	O
Milton	O
Green	O
Carboniferous	CHRONOSTRAT
inlier	O
corresponds	O
to	O
a	O
Dinantian	CHRONOSTRAT
structural	O
high	O
.	O

On	O
the	O
outcrop	O
to	O
the	O
west	O
at	O
Minera	O
,	O
Dinantian	CHRONOSTRAT
rocks	O
are	O
260m	O
thick	O
.	O

The	O
borehole	O
proved	O
thick	O
Pendleian	CHRONOSTRAT
to	O
Brigantian	CHRONOSTRAT
rocks	O
,	O
with	O
a	O
thick	O
Lower	LEXICON
Bowland	LEXICON
Shale	LEXICON
equivalent	O
.	O

A	O
seismic	O
reflector	O
,	O
deeper	O
than	O
the	O
borehole	O
,	O
dips	O
towards	O
the	O
subsurface	O
continuation	O
of	O
the	O
Llanelidan	O
Fault	O
,	O
suggesting	O
thickening	O
of	O
the	O
early	O
Dinantian	CHRONOSTRAT
rocks	O
in	O
this	O
sub-basin	O
.	O

Dinantian	CHRONOSTRAT
rocks	O
in	O
the	O
Blacon	O
East	O
borehole	O
total	O
more	O
than	O
400m	O
,	O
with	O
the	O
possibility	O
of	O
a	O
further	O
600m	O
beneath	O
terminal	O
depth	O
.	O

In	O
the	O
south	O
of	O
the	O
basin	O
the	O
WBRRFS	O
throws	O
Triassic	CHRONOSTRAT
strata	O
against	O
Westphalian	CHRONOSTRAT
rocks	O
.	O

Further	O
north	O
,	O
near	O
Astbury	O
,	O
Namurian	CHRONOSTRAT
and	O
Dinantian	CHRONOSTRAT
rocks	O
outcrop	O
on	O
the	O
footwall	O
block	O
.	O

A	O
syn-sedimentary	O
fault	O
may	O
form	O
the	O
eastern	O
margin	O
of	O
the	O
North	O
Staffordshire	O
Coalfield	O
,	O
between	O
Astbury	O
and	O
Gun	O
Hill	O
,	O
as	O
envisaged	O
for	O
Namurian	CHRONOSTRAT
times	O
.	O

If	O
,	O
as	O
seems	O
likely	O
,	O
the	O
Red	O
Rock	O
Fault	O
acted	O
as	O
a	O
Dinantian	CHRONOSTRAT
syn-sedimentary	O
fault	O
then	O
Astbury	O
stood	O
on	O
a	O
structural	O
high	O
which	O
was	O
bounded	O
by	O
two	O
differently	O
trending	O
Dinantian	CHRONOSTRAT
syn-sedimentary	O
faults	O
.	O

Beneath	O
the	O
southern	O
part	O
of	O
the	O
Cheshire	O
Basin	O
,	O
where	O
Carboniferous	CHRONOSTRAT
reflectors	O
are	O
few	O
,	O
the	O
Carboniferous	CHRONOSTRAT
structure	O
can	O
not	O
be	O
resolved	O
directly	O
.	O

Along	O
the	O
south-eastern	O
margin	O
of	O
the	O
basin	O
large	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
faults	O
connect	O
south-westwards	O
to	O
major	O
Caledonian	O
structures	O
such	O
as	O
the	O
Pontesford	O
Linley	O
structure	O
.	O

No	O
Dinantian	CHRONOSTRAT
rocks	O
were	O
encountered	O
in	O
the	O
Edgmond	O
Borehole	O
,	O
whereas	O
more	O
than	O
200m	O
are	O
present	O
at	O
Stoke-on-Tern	O
.	O

Over	O
100m	O
of	O
Dinantian	CHRONOSTRAT
was	O
proved	O
in	O
the	O
Ternhill	O
Borehole	O
,	O
close	O
to	O
the	O
Hodnet	O
Fault	O
.	O

The	O
cross-section	O
shows	O
the	O
Dinantian	CHRONOSTRAT
sequence	O
thickening	O
southwards	O
to	O
the	O
limit	O
of	O
outcrop	O
at	O
Llanymynech	O
,	O
which	O
may	O
be	O
related	O
to	O
syn-depositional	O
movement	O
on	O
the	O
Wem	O
Fault	O
.	O

In	O
the	O
subsurface	O
,	O
seismic	O
profiles	O
show	O
thickening	O
of	O
the	O
Dinantian	CHRONOSTRAT
sequence	O
southwards	O
from	O
Milton	O
Green	O
.	O

Dinantian	CHRONOSTRAT
rocks	O
are	O
overlapped	O
by	O
unconformable	O
Westphalian	CHRONOSTRAT
D	CHRONOSTRAT
rocks	O
beneath	O
the	O
south-western	O
part	O
of	O
the	O
basin	O
.	O

Deep	O
seismic	O
reflectors	O
in	O
this	O
area	O
,	O
not	O
proved	O
by	O
drilling	O
,	O
probably	O
correspond	O
to	O
rocks	O
in	O
Dinantian	CHRONOSTRAT
basins	O
,	O
controlled	O
by	O
north-north-west-trending	O
faults	O
.	O

The	O
basin	O
may	O
link	O
northwards	O
to	O
the	O
Rainford	O
Sub-Basin	O
,	O
where	O
eastwards-thinning	O
Dinantian	CHRONOSTRAT
may	O
reach	O
the	O
Brook	O
House	O
Fault	O
.	O

Approximately	O
170m	O
of	O
Namurian	CHRONOSTRAT
rocks	O
were	O
intersected	O
in	O
the	O
Milton	O
Green	O
Borehole	O
on	O
the	O
Cyrn-y-Brain	O
High	O
,	O
and	O
more	O
than	O
800m	O
in	O
the	O
Blacon	O
East	O
Borehole	O
in	O
the	O
Blacon	O
Sub-basin	O
;	O
Namurian	CHRONOSTRAT
strata	O
were	O
also	O
intersected	O
in	O
a	O
few	O
other	O
boreholes	O
.	O

The	O
Aqueduct	LEXICON
Grit	LEXICON
is	O
a	O
distinctive	O
low-gamma	O
unit	O
within	O
the	O
Namurian	CHRONOSTRAT
Series	O
in	O
the	O
Milton	O
Green	O
Borehole	O
.	O

In	O
the	O
Talwrn	O
Borehole	O
,	O
Namurian	CHRONOSTRAT
rocks	O
may	O
reach	O
230m	O
in	O
thickness	O
;	O
they	O
probably	O
thin	O
northwards	O
,	O
in	O
the	O
Wrexham	O
district	O
,	O
on	O
to	O
the	O
Cyrn-y-Brain	O
High	O
.	O

Namurian	CHRONOSTRAT
rocks	O
have	O
a	O
narrower	O
outcrop	O
width	O
south	O
of	O
the	O
Aqueduct	O
Fault	O
,	O
compared	O
to	O
its	O
northern	O
hangingwall	O
block	O
.	O

In	O
the	O
Oswestry	O
district	O
,	O
the	O
outcrop	O
width	O
suggests	O
that	O
the	O
Namurian	CHRONOSTRAT
rocks	O
thin	O
to	O
the	O
south	O
.	O

Towards	O
the	O
top	O
of	O
the	O
Namurian	CHRONOSTRAT
succession	O
the	O
Aqueduct	LEXICON
Grit	LEXICON
has	O
a	O
feldspathic	O
composition	O
,	O
consistent	O
with	O
the	O
incursion	O
of	O
southward	O
spreading	O
Pennine	O
deltas	O
.	O

In	O
the	O
extreme	O
south-west	O
of	O
the	O
basin	O
,	O
Namurian	CHRONOSTRAT
rocks	O
are	O
overlapped	O
by	O
unconformable	O
Westphalian	CHRONOSTRAT
D	CHRONOSTRAT
strata	O
,	O
beneath	O
Permian	CHRONOSTRAT
rocks	O
.	O

East	O
of	O
the	O
Red	O
Rock	O
Fault	O
a	O
basinal	O
Namurian	CHRONOSTRAT
succession	O
shows	O
the	O
relationship	O
between	O
the	O
southern	O
and	O
northern	O
clastic	O
sources	O
more	O
clearly	O
.	O

Northward	O
thinning	O
of	O
the	O
southerly	O
derived	O
turbidites	O
in	O
the	O
Macclesfield	O
district	O
may	O
have	O
caused	O
starved	O
sedimentation	O
of	O
Edale	LEXICON
Shale	LEXICON
type	O
beneath	O
this	O
part	O
of	O
the	O
Cheshire	O
Basin	O
,	O
resulting	O
in	O
the	O
deposition	O
of	O
potential	O
hydrocarbon	O
source	O
rocks	O
.	O

They	O
are	O
unconformable	O
on	O
Dinantian	CHRONOSTRAT
rocks	O
across	O
the	O
feather	O
edge	O
of	O
Namurian	CHRONOSTRAT
strata	O
.	O

Namurian	CHRONOSTRAT
rocks	O
are	O
also	O
absent	O
from	O
the	O
Market	O
Drayton	O
High	O
.	O

Westphalian	CHRONOSTRAT
strata	O
are	O
present	O
beneath	O
much	O
of	O
the	O
Cheshire	O
Basin	O
.	O

Within	O
the	O
Westphalian	CHRONOSTRAT
succession	O
the	O
Symon	O
Unconformity	O
separates	O
sequences	O
thickening	O
in	O
opposite	O
directions	O
.	O

Thus	O
,	O
beneath	O
the	O
unconformity	O
,	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
,	O
encompassing	O
rocks	O
of	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
,	O
B	CHRONOSTRAT
and	O
part	O
of	O
C	CHRONOSTRAT
,	O
thicken	O
northwards	O
to	O
a	O
depocentre	O
near	O
Manchester	O
,	O
with	O
splitting	O
of	O
seams	O
in	O
a	O
northerly	O
direction	O
.	O

In	O
contrast	O
,	O
red	O
beds	O
above	O
the	O
unconformity	O
appear	O
to	O
thicken	O
southwards	O
,	O
successively	O
down-cutting	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
,	O
Namurian	CHRONOSTRAT
and	O
Dinantian	CHRONOSTRAT
strata	O
to	O
rest	O
unconformably	O
on	O
Silurian	CHRONOSTRAT
and	O
older	O
rocks	O
.	O

The	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
about	O
450m	O
thick	O
in	O
the	O
boreholes	O
and	O
about	O
500m	O
thick	O
in	O
the	O
Denbighshire	O
Coalfield	O
.	O

The	O
Carboniferous	CHRONOSTRAT
outcrop	O
terminates	O
in	O
the	O
Oswestry	O
district	O
,	O
west	O
of	O
Eardiston	O
copper	O
mine	O
.	O

The	O
Symon	O
Unconformity	O
is	O
represented	O
here	O
by	O
overlap	O
of	O
the	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
,	O
Namurian	CHRONOSTRAT
and	O
Dinantian	CHRONOSTRAT
rocks	O
by	O
the	O
Ruabon	LEXICON
Marl	LEXICON
and	O
Coed-yr-Allt	LEXICON
Formation	LEXICON
.	O

No	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
known	O
from	O
the	O
Shrewsbury	O
Coalfield	O
,	O
where	O
the	O
red	O
beds	O
rest	O
on	O
Cambrian	CHRONOSTRAT
rocks	O
.	O

The	O
Leebotwood	O
Coalfield	O
also	O
features	O
red	O
beds	O
unconformable	O
on	O
late	O
Precambrian	CHRONOSTRAT
Longmyndian	LEXICON
rocks	O
.	O

In	O
the	O
Coalbrookdale	O
Coalfield	O
,	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
rest	O
unconformably	O
on	O
Silurian	CHRONOSTRAT
rocks	O
;	O
the	O
Dinantian	CHRONOSTRAT
rocks	O
of	O
the	O
Little	O
Wenlock	O
area	O
have	O
been	O
overlapped	O
here	O
.	O

In	O
the	O
Madeley	O
Coalfield	O
,	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
known	O
in	O
the	O
north	O
,	O
but	O
have	O
been	O
removed	O
in	O
the	O
south	O
by	O
the	O
Symon	O
Unconformity	O
.	O

The	O
North	O
Staffordshire	O
Coalfield	O
has	O
thick	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

The	O
northward	O
thickening	O
of	O
the	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
reflects	O
the	O
Pennine	O
depocentre	O
near	O
Manchester	O
.	O

The	O
more	O
complete	O
sequence	O
of	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
,	O
compared	O
with	O
that	O
of	O
Madeley	O
,	O
suggests	O
that	O
the	O
Symon	O
Unconformity	O
was	O
formerly	O
a	O
south-dipping	O
palaeoslope	O
.	O

The	O
Knutsford	O
Borehole	O
reached	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sequence	O
at	O
2821m	O
,	O
and	O
penetrated	O
a	O
further	O
224m	O
of	O
coals	O
and	O
limestones	O
of	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
which	O
are	O
probably	O
part	O
of	O
the	O
Newcastle	LEXICON
Formation	LEXICON
,	O
equivalent	O
to	O
the	O
Coed-yr-Allt	LEXICON
Formation	LEXICON
to	O
the	O
west	O
of	O
the	O
basin	O
.	O

If	O
this	O
correlation	O
is	O
correct	O
,	O
the	O
Keele	LEXICON
Formation	LEXICON
,	O
equivalent	O
to	O
the	O
Erbistock	LEXICON
Beds	LEXICON
,	O
must	O
have	O
been	O
eroded	O
prior	O
to	O
Permian	CHRONOSTRAT
deposition	O
.	O

Rocks	O
of	O
the	O
Etruria	LEXICON
Formation	LEXICON
,	O
equivalent	O
to	O
the	O
Ruabon	LEXICON
Marl	LEXICON
,	O
would	O
be	O
expected	O
below	O
terminal	O
depth	O
in	O
the	O
borehole	O
,	O
with	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
at	O
greater	O
depth	O
.	O

In	O
the	O
Lancashire	O
Coalfield	O
to	O
the	O
north	O
and	O
north-east	O
of	O
the	O
Cheshire	O
Basin	O
,	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
are	O
1600m	O
thick	O
,	O
thinning	O
westwards	O
.	O

The	O
basement	O
rocks	O
which	O
underlie	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
strata	O
of	O
the	O
Cheshire	O
Basin	O
are	O
thought	O
to	O
be	O
principally	O
of	O
early	O
Palaeozoic	CHRONOSTRAT
age	O
;	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
strata	O
were	O
intersected	O
in	O
the	O
Milton	O
Green	O
Borehole	O
and	O
in	O
the	O
Prees	O
Borehole	O
,	O
as	O
well	O
as	O
beneath	O
the	O
Dinantian	CHRONOSTRAT
outcrop	O
to	O
the	O
west	O
in	O
several	O
shallow	O
provings	O
in	O
the	O
Halkyn	O
Minera	O
mining	O
district	O
of	O
north-east	O
Wales	O
.	O

No	O
Devonian	CHRONOSTRAT
rocks	O
are	O
known	O
,	O
but	O
a	O
borehole	O
at	O
Edgmond	O
discovered	O
Precambrian	CHRONOSTRAT
volcanic	O
rocks	O
beneath	O
Coal	LEXICON
Measures	LEXICON
.	O

These	O
rocks	O
,	O
probably	O
of	O
Uriconian	CHRONOSTRAT
affinity	O
,	O
continue	O
in	O
the	O
subsurface	O
to	O
Lilleshall	O
,	O
the	O
Wrekin	O
and	O
south-east	O
to	O
Caer	O
Caradoc	CHRONOSTRAT
.	O

In	O
the	O
Wych	LEXICON
and	O
Byley	LEXICON
mudstone	O
formations	O
and	O
the	O
upper	O
part	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
,	O
evaporite	O
beds	O
can	O
be	O
identified	O
on	O
density	O
logs	O
and	O
can	O
thus	O
be	O
eliminated	O
.	O

Elsewhere	O
in	O
the	O
MMG	O
however	O
,	O
evaporites	O
are	O
mixed	O
with	O
mudstones	O
as	O
lamellae	O
and	O
nodules	O
,	O
and	O
histograms	O
of	O
density	O
values	O
show	O
bimodal	O
distributions	O
.	O

At	O
the	O
Burford	O
Borehole	O
,	O
where	O
a	O
porosity	O
log	O
is	O
available	O
for	O
the	O
SSG	O
,	O
the	O
sandstones	O
have	O
porosities	O
between	O
6	O
and	O
24%	O
,	O
which	O
may	O
produce	O
an	O
underestimate	O
of	O
the	O
depth	O
of	O
burial	O
.	O

The	O
cross-plots	O
for	O
the	O
Lower	LEXICON
Lias	LEXICON
,	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
,	O
Bollin	LEXICON
Mudstone	LEXICON
,	O
Malpas	LEXICON
Sandstone	LEXICON
,	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
Kinnerton	LEXICON
Sandstone	LEXICON
formations	O
at	O
Prees	O
and	O
Burford	O
showed	O
clear	O
linear	O
trends	O
,	O
and	O
best-fit	O
lines	O
were	O
constructed	O
to	O
convert	O
sonic-log	O
values	O
from	O
other	O
boreholes	O
to	O
density	O
values	O
,	O
enabling	O
the	O
depth	O
of	O
burial	O
to	O
be	O
estimated	O
.	O

The	O
cross-plot	O
for	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
at	O
Crewe	O
did	O
not	O
show	O
a	O
linear	O
trend	O
,	O
and	O
density	O
values	O
estimated	O
from	O
it	O
were	O
much	O
higher	O
than	O
those	O
obtained	O
from	O
the	O
Prees	O
and	O
Burford	O
cross-plots	O
.	O

Cross-plots	O
for	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
,	O
Northwich	LEXICON
Halite	LEXICON
,	O
Wych	LEXICON
and	O
Byley	LEXICON
Mudstone	LEXICON
,	O
Tarporley	LEXICON
Siltstone	LEXICON
and	O
Collyhurst	LEXICON
Sandstone	LEXICON
formations	O
showed	O
too	O
much	O
scatter	O
to	O
enable	O
reliable	O
trend	O
lines	O
to	O
be	O
plotted	O
.	O

The	O
reliability	O
of	O
the	O
estimated	O
values	O
for	O
overburden	O
thickness	O
was	O
tested	O
by	O
adding	O
them	O
to	O
the	O
observed	O
depth	O
to	O
the	O
base	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
in	O
each	O
borehole	O
and	O
contouring	O
the	O
resulting	O
data	O
.	O

The	O
base	O
of	O
the	O
SSG	O
lay	O
at	O
depths	O
locally	O
greater	O
than	O
5000m	O
,	O
the	O
base	O
of	O
the	O
MMG	O
at	O
depths	O
locally	O
greater	O
than	O
3000m	O
and	O
the	O
base	O
of	O
Jurassic	CHRONOSTRAT
strata	O
at	O
depths	O
locally	O
greater	O
than	O
2000m	O
.	O

Regional	O
tectonic	O
considerations	O
and	O
apatite	O
fission-track	O
data	O
suggest	O
that	O
the	O
maximum	O
depth	O
of	O
burial	O
probably	O
occurred	O
about	O
60Ma	O
ago	O
in	O
Palaeocene	CHRONOSTRAT
times	O
,	O
immediately	O
prior	O
to	O
Cenozoic	CHRONOSTRAT
uplift	O
,	O
inversion	O
and	O
erosion	O
.	O

The	O
ISM	O
structure-contour	O
grids	O
for	O
Base	O
Jurassic	CHRONOSTRAT
,	O
Base	O
MMG	O
,	O
Base	O
SSG	O
and	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
were	O
thinned	O
to	O
a	O
grid-node	O
spacing	O
of	O
1km	O
to	O
reduce	O
the	O
data	O
volume	O
to	O
the	O
limits	O
required	O
by	O
the	O
HotPot	O
program	O
.	O

The	O
total	O
thickness	O
of	O
eroded	O
overburden	O
strata	O
,	O
and	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

The	O
Upper	CHRONOSTRAT
Cretaceous	CHRONOSTRAT
and	O
Palaeocene	CHRONOSTRAT
component	O
was	O
assumed	O
to	O
have	O
formed	O
a	O
uniform	O
blanket	O
400m	O
thick	O
over	O
the	O
whole	O
area	O
.	O

The	O
combined	O
thickness	O
of	O
the	O
Triassic	CHRONOSTRAT
and	O
Jurassic	CHRONOSTRAT
components	O
was	O
thus	O
calculated	O
by	O
subtracting	O
400m	O
from	O
the	O
total-overburden	O
grid	O
.	O

The	O
fact	O
that	O
no	O
Triassic	CHRONOSTRAT
strata	O
were	O
eroded	O
where	O
Jurassic	CHRONOSTRAT
rocks	O
are	O
still	O
preserved	O
and	O
the	O
assumption	O
that	O
preserved	O
Jurassic	CHRONOSTRAT
strata	O
would	O
have	O
been	O
of	O
negligible	O
thickness	O
towards	O
the	O
northern	O
and	O
western	O
limits	O
of	O
the	O
basin	O
,	O
were	O
used	O
to	O
constrain	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
Jurassic	CHRONOSTRAT
components	O
of	O
the	O
eroded	O
succession	O
.	O

Preserved	O
thicknesses	O
of	O
Permian	CHRONOSTRAT
strata	O
are	O
locally	O
in	O
excess	O
of	O
1300m	O
.	O

Thicknesses	O
decrease	O
gradually	O
north-west	O
from	O
this	O
depocentre	O
,	O
so	O
,	O
at	O
the	O
end	O
of	O
Permian	CHRONOSTRAT
times	O
,	O
the	O
Cheshire	O
Basin	O
had	O
the	O
overall	O
form	O
of	O
a	O
half	O
graben	O
.	O

Preserved	O
thicknesses	O
of	O
the	O
SSG	O
appear	O
to	O
define	O
two	O
depocentres	O
in	O
the	O
southern	O
and	O
northern	O
parts	O
of	O
the	O
Wem	O
Audlem	O
Sub-basin	O
,	O
which	O
locally	O
have	O
more	O
than	O
2200m	O
of	O
strata	O
.	O

At	O
the	O
end	O
of	O
SSG	O
deposition	O
the	O
basin	O
had	O
a	O
maximum	O
depth	O
in	O
excess	O
of	O
3500m	O
.	O

The	O
MMG	O
is	O
presently	O
thickest	O
in	O
the	O
Wem	O
Audlem	O
and	O
Sandbach	O
Knutsford	O
Sub-basins	O
.	O

In	O
the	O
latter	O
,	O
although	O
the	O
sequence	O
is	O
less	O
complete	O
,	O
it	O
is	O
locally	O
more	O
than	O
1700m	O
thick	O
,	O
suggesting	O
that	O
the	O
area	O
marked	O
the	O
original	O
MMG	O
depocentre	O
.	O

Separate	O
depocentres	O
,	O
characteristic	O
of	O
the	O
earlier	O
basin	O
evolution	O
,	O
were	O
no	O
longer	O
so	O
clearly	O
defined	O
,	O
and	O
it	O
seems	O
likely	O
that	O
there	O
was	O
a	O
single	O
depocentre	O
for	O
the	O
MMG	O
.	O

End	O
-	O
Triassic	CHRONOSTRAT
depths	O
can	O
not	O
be	O
tightly	O
constrained	O
,	O
because	O
they	O
incorporate	O
a	O
putative	O
amount	O
of	O
eroded	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
strata	O
.	O

Nevertheless	O
,	O
it	O
is	O
estimated	O
that	O
at	O
the	O
end	O
of	O
Triassic	CHRONOSTRAT
times	O
the	O
basin	O
contained	O
more	O
than	O
5000m	O
of	O
strata	O
.	O

It	O
is	O
likely	O
that	O
Triassic	CHRONOSTRAT
strata	O
spread	O
considerably	O
beyond	O
the	O
present-day	O
boundaries	O
of	O
the	O
basin	O
,	O
onto	O
adjacent	O
block	O
areas	O
.	O

Only	O
small	O
outliers	O
of	O
Jurassic	CHRONOSTRAT
strata	O
are	O
preserved	O
.	O

They	O
lie	O
in	O
the	O
central	O
part	O
of	O
the	O
Wem	O
Audlem	O
Sub-basin	O
,	O
to	O
the	O
south	O
of	O
the	O
MMG	O
depocentre	O
,	O
and	O
it	O
is	O
thought	O
unlikely	O
that	O
they	O
correspond	O
precisely	O
to	O
the	O
Jurassic	CHRONOSTRAT
depocentre	O
.	O

Sedimentary	O
thicknesses	O
,	O
but	O
estimates	O
are	O
poorly	O
constrained	O
,	O
incorporating	O
a	O
putative	O
amount	O
of	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
,	O
Jurassic	CHRONOSTRAT
and	O
lower	O
Cretaceous	CHRONOSTRAT
overburden	O
.	O

The	O
tendency	O
towards	O
a	O
single	O
basin	O
depocentre	O
clearly	O
continued	O
in	O
Jurassic	CHRONOSTRAT
times	O
,	O
as	O
fault-controlled	O
subsidence	O
gradually	O
diminished	O
and	O
post-extensional	O
regional	O
subsidence	O
prevailed	O
.	O

Sedimentary	O
thicknesses	O
in	O
early	O
Palaeocene	CHRONOSTRAT
times	O
,	O
incorporating	O
the	O
total	O
estimated	O
thickness	O
of	O
eroded	O
strata	O
,	O
locally	O
approached	O
6500m	O
,	O
and	O
marked	O
the	O
maximum	O
development	O
of	O
the	O
basin	O
,	O
immediately	O
prior	O
to	O
uplift	O
and	O
erosion	O
.	O

Very	O
rapid	O
early	O
Triassic	CHRONOSTRAT
subsidence	O
marked	O
the	O
main	O
phase	O
of	O
basin	O
development	O
.	O

This	O
was	O
followed	O
by	O
more	O
gradual	O
subsidence	O
in	O
Jurassic	CHRONOSTRAT
and	O
Cretaceous	CHRONOSTRAT
times	O
,	O
followed	O
in	O
turn	O
by	O
Cenozoic	CHRONOSTRAT
uplift	O
.	O

The	O
large	O
down-west	O
normal	O
faults	O
of	O
the	O
WBRRFS	O
lie	O
in	O
the	O
hangingwall	O
blocks	O
of	O
Variscan	O
reverse	O
faults	O
,	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
being	O
progressively	O
faulted	O
down	O
to	O
the	O
west	O
.	O

This	O
was	O
a	O
consequence	O
of	O
extensional	O
reactivation	O
of	O
the	O
basement	O
reverse	O
faults	O
in	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
times	O
which	O
led	O
to	O
collapse	O
of	O
their	O
hangingwall	O
blocks	O
by	O
upward	O
propagation	O
of	O
steeper	O
normal	O
faults	O
,	O
to	O
form	O
the	O
basin	O
margin	O
.	O

On	O
a	O
more	O
regional	O
scale	O
,	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rift	O
system	O
of	O
southern	O
Britain	O
can	O
be	O
divided	O
structurally	O
into	O
three	O
segments	O
which	O
reflect	O
the	O
structural	O
grain	O
of	O
the	O
underlying	O
basement	O
.	O

This	O
is	O
interpreted	O
as	O
indicative	O
of	O
a	O
cumulative	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
extension	O
vector	O
oriented	O
roughly	O
west-south-west	O
.	O

The	O
dominant	O
fault	O
strike	O
is	O
not	O
parallel	O
to	O
the	O
main	O
Caledonoid	O
trend	O
,	O
and	O
may	O
reflect	O
a	O
reactivated	O
Carboniferous	CHRONOSTRAT
structural	O
trend	O
:	O
a	O
strong	O
north-north-westerly	O
trend	O
is	O
evident	O
in	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
of	O
the	O
Rossendale	O
area	O
to	O
the	O
north	O
,	O
visible	O
on	O
the	O
aeromagnetic	O
data	O
.	O

Results	O
are	O
generally	O
in	O
good	O
agreement	O
with	O
the	O
regional	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
extension	O
direction	O
in	O
southern	O
Britain	O
,	O
estimated	O
by	O
Chadwick	O
and	O
Evans	O
using	O
different	O
structural	O
criteria	O
at	O
075	O
255	O
degrees	O
.	O

Regional	O
tectonic	O
considerations	O
indicate	O
that	O
roughly	O
east	O
west	O
extension	O
was	O
probably	O
dominant	O
throughout	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
early	O
Jurassic	CHRONOSTRAT
,	O
the	O
period	O
which	O
encompassed	O
most	O
of	O
the	O
extensional	O
faulting	O
.	O

The	O
cumulative	O
heaves	O
on	O
transects	O
AA	O
to	O
JJ	O
are	O
marked	O
with	O
an	O
asterisk	O
signifying	O
that	O
they	O
are	O
minimum	O
values	O
,	O
because	O
on	O
these	O
transects	O
the	O
eastern	O
basin	O
margin	O
includes	O
faults	O
with	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
rocks	O
at	O
outcrop	O
in	O
the	O
footwall	O
blocks	O
.	O

The	O
true	O
heaves	O
of	O
these	O
faults	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
can	O
not	O
be	O
seen	O
;	O
observed	O
heaves	O
are	O
therefore	O
minimum	O
estimates	O
.	O

Because	O
of	O
the	O
progressively	O
smaller	O
outcrop	O
areas	O
of	O
horizons	O
above	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
it	O
is	O
not	O
possible	O
to	O
use	O
all	O
of	O
the	O
15	O
extension-parallel	O
transects	O
.	O

Heaves	O
were	O
measured	O
for	O
all	O
the	O
faults	O
on	O
DD	O
*	O
LL	O
*	O
at	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
,	O
Base	O
SSG	O
and	O
Base	O
MMG	O
.	O

On	O
each	O
transect	O
,	O
observed	O
heaves	O
for	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
are	O
greater	O
than	O
those	O
for	O
Base	O
SSG	O
,	O
which	O
in	O
turn	O
are	O
greater	O
than	O
those	O
for	O
Base	O
MMG	O
.	O

The	O
cumulative	O
profile	O
indicates	O
that	O
measured	O
heaves	O
at	O
Base	O
MMG	O
and	O
Base	O
SSG	O
are	O
typically	O
56%	O
and	O
80%	O
of	O
the	O
total	O
observed	O
heaves	O
.	O

The	O
large	O
down-west	O
normal	O
faults	O
of	O
the	O
WBRRFS	O
lie	O
in	O
the	O
hangingwall	O
blocks	O
of	O
Variscan	CHRONOSTRAT
reverse	O
faults	O
,	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
being	O
progressively	O
faulted	O
down	O
to	O
the	O
west	O
.	O

This	O
was	O
a	O
consequence	O
of	O
extensional	O
reactivation	O
of	O
the	O
basement	O
reverse	O
faults	O
in	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
times	O
which	O
led	O
to	O
collapse	O
of	O
their	O
hangingwall	O
blocks	O
by	O
upward	O
propagation	O
of	O
steeper	O
normal	O
faults	O
,	O
to	O
form	O
the	O
basin	O
margin	O
.	O

On	O
a	O
more	O
regional	O
scale	O
,	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rift	O
system	O
of	O
southern	O
Britain	O
can	O
be	O
divided	O
structurally	O
into	O
three	O
segments	O
which	O
reflect	O
the	O
structural	O
grain	O
of	O
the	O
underlying	O
basement	O
.	O

This	O
is	O
interpreted	O
as	O
indicative	O
of	O
a	O
cumulative	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
extension	O
vector	O
oriented	O
roughly	O
west-south-west	O
.	O

The	O
dominant	O
fault	O
strike	O
is	O
not	O
parallel	O
to	O
the	O
main	O
Caledonoid	O
trend	O
,	O
and	O
may	O
reflect	O
a	O
reactivated	O
Carboniferous	CHRONOSTRAT
structural	O
trend	O
:	O
a	O
strong	O
north-north-westerly	O
trend	O
is	O
evident	O
in	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
of	O
the	O
Rossendale	O
area	O
to	O
the	O
north	O
,	O
visible	O
on	O
the	O
aeromagnetic	O
data	O
.	O

Results	O
are	O
generally	O
in	O
good	O
agreement	O
with	O
the	O
regional	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
extension	O
direction	O
in	O
southern	O
Britain	O
,	O
estimated	O
by	O
Chadwick	O
and	O
Evans	O
using	O
different	O
structural	O
criteria	O
at	O
075	O
255	O
degrees	O
.	O

Regional	O
tectonic	O
considerations	O
indicate	O
that	O
roughly	O
east	O
west	O
extension	O
was	O
probably	O
dominant	O
throughout	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
early	O
Jurassic	CHRONOSTRAT
,	O
the	O
period	O
which	O
encompassed	O
most	O
of	O
the	O
extensional	O
faulting	O
.	O

The	O
cumulative	O
heaves	O
on	O
transects	O
AA	O
to	O
JJ	O
are	O
marked	O
with	O
an	O
asterisk	O
signifying	O
that	O
they	O
are	O
minimum	O
values	O
,	O
because	O
on	O
these	O
transects	O
the	O
eastern	O
basin	O
margin	O
includes	O
faults	O
with	O
pre	O
-	O
Permian	CHRONOSTRAT
basement	O
rocks	O
at	O
outcrop	O
in	O
the	O
footwall	O
blocks	O
.	O

The	O
true	O
heaves	O
of	O
these	O
faults	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
can	O
not	O
be	O
seen	O
;	O
observed	O
heaves	O
are	O
therefore	O
minimum	O
estimates	O
.	O

Because	O
of	O
the	O
progressively	O
smaller	O
outcrop	O
areas	O
of	O
horizons	O
above	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
it	O
is	O
not	O
possible	O
to	O
use	O
all	O
of	O
the	O
15	O
extension-parallel	O
transects	O
.	O

Heaves	O
were	O
measured	O
for	O
all	O
the	O
faults	O
on	O
DD	O
*	O
LL	O
*	O
at	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
,	O
Base	O
SSG	O
and	O
Base	O
MMG	O
.	O

On	O
each	O
transect	O
,	O
observed	O
heaves	O
for	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
are	O
greater	O
than	O
those	O
for	O
Base	O
SSG	O
,	O
which	O
in	O
turn	O
are	O
greater	O
than	O
those	O
for	O
Base	O
MMG	O
.	O

The	O
cumulative	O
profile	O
indicates	O
that	O
measured	O
heaves	O
at	O
Base	O
MMG	O
and	O
Base	O
SSG	O
are	O
typically	O
56%	O
and	O
80%	O
of	O
the	O
total	O
observed	O
heaves	O
.	O

Because	O
of	O
the	O
progressively	O
smaller	O
outcrop	O
areas	O
of	O
horizons	O
above	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
it	O
is	O
not	O
possible	O
to	O
use	O
all	O
of	O
the	O
15	O
extension-parallel	O
transects	O
.	O

Heaves	O
were	O
measured	O
for	O
all	O
the	O
faults	O
on	O
DD	O
*	O
LL	O
*	O
at	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
,	O
Base	O
SSG	O
and	O
Base	O
MMG	O
.	O

On	O
each	O
transect	O
,	O
observed	O
heaves	O
for	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
are	O
greater	O
than	O
those	O
for	O
Base	O
SSG	O
,	O
which	O
in	O
turn	O
are	O
greater	O
than	O
those	O
for	O
Base	O
MMG	O
.	O

The	O
cumulative	O
profile	O
indicates	O
that	O
measured	O
heaves	O
at	O
Base	O
MMG	O
and	O
Base	O
SSG	O
are	O
typically	O
56%	O
and	O
80%	O
of	O
the	O
total	O
observed	O
heaves	O
.	O

Present-day	O
temperature	O
maps	O
for	O
the	O
bases	O
of	O
the	O
Jurassic	CHRONOSTRAT
,	O
MMG	O
,	O
SSG	O
and	O
Permian	CHRONOSTRAT
,	O
computed	O
using	O
the	O
mean	O
present-day	O
heat	O
flow	O
of	O
52mWm	O
2	O
,	O
indicate	O
that	O
the	O
basin	O
is	O
quite	O
cool	O
,	O
with	O
mean	O
temperatures	O
ranging	O
from	O
20	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
to	O
37	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

The	O
highest	O
temperatures	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
in	O
the	O
deeper	O
parts	O
of	O
the	O
basin	O
locally	O
exceed	O
70	O
degrees	O
C	O
in	O
parts	O
of	O
the	O
Wem	O
Audlem	O
Sub-basin	O
and	O
65	O
degrees	O
C	O
in	O
the	O
Sandbach	O
Knutsford	O
Sub-basin	O
.	O

Calculated	O
temperatures	O
near	O
the	O
Alderley	O
Edge	O
mineralisation	O
range	O
from	O
25	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
SSG	O
to	O
33	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

Decreasing	O
the	O
heat	O
flow	O
to	O
40mWm	O
2	O
depressed	O
mean	O
basin	O
subsurface	O
temperatures	O
by	O
about	O
3	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
,	O
and	O
6	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

Increasing	O
the	O
heat	O
flow	O
to	O
64mWm	O
2	O
raised	O
the	O
mean	O
temperatures	O
by	O
about	O
2	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
and	O
7	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

The	O
extension	O
that	O
led	O
to	O
this	O
cumulative	O
extension	O
factor	O
was	O
distributed	O
over	O
a	O
long	O
period	O
of	O
time	O
,	O
from	O
latest	O
Permian	CHRONOSTRAT
times	O
to	O
the	O
early	O
Cretaceous	CHRONOSTRAT
.	O

For	O
the	O
purposes	O
of	O
this	O
study	O
a	O
single	O
,	O
instantaneous	O
pulse	O
of	O
extension	O
occurring	O
at	O
the	O
beginning	O
of	O
the	O
Triassic	CHRONOSTRAT
is	O
assumed	O
.	O

Curry	O
gives	O
a	O
value	O
of	O
20	O
degrees	O
C	O
for	O
the	O
early	O
Palaeocene	CHRONOSTRAT
,	O
corresponding	O
to	O
the	O
maximum	O
depth	O
of	O
burial	O
in	O
the	O
region	O
.	O

In	O
the	O
Wem	O
Audlem	O
Sub-basin	O
,	O
peak	O
temperatures	O
reached	O
c.	O
90	O
degrees	O
C	O
locally	O
at	O
the	O
base	O
of	O
the	O
Jurassic	LEXICON
sequence	O
,	O
c.	O
105	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
,	O
c.	O
130	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
SSG	O
and	O
c.	O
140	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

Corresponding	O
values	O
in	O
the	O
Sandbach	O
Knutsford	O
Sub-basin	O
were	O
Base	O
MMG	O
c.	O
95	O
degrees	O
C	O
,	O
Base	O
SSG	O
c.	O
120	O
degrees	O
C	O
and	O
Base	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
c.	O
135	O
degrees	O
C.	O

The	O
Alderley	O
Edge	O
area	O
was	O
,	O
at	O
this	O
time	O
,	O
assumed	O
to	O
be	O
buried	O
under	O
nearly	O
1500m	O
of	O
Chalk	O
,	O
Jurassic	CHRONOSTRAT
and	O
upper	O
Triassic	CHRONOSTRAT
strata	O
.	O

The	O
computed	O
temperatures	O
at	O
the	O
base	O
of	O
this	O
overburden	O
were	O
c.	O
65	O
degrees	O
C	O
,	O
at	O
the	O
base	O
of	O
the	O
SSG	O
c.	O
80	O
degrees	O
C	O
,	O
and	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
90	O
degrees	O
C.	O
Mapped	O
subsurface	O
temperatures	O
97Ma	O
ago	O
,	O
corresponding	O
to	O
the	O
end	O
of	O
late	O
Cimmerian	O
erosion	O
,	O
immediately	O
prior	O
to	O
the	O
onset	O
of	O
post-extension	O
subsidence	O
in	O
the	O
late	O
Cretaceous	CHRONOSTRAT
,	O
are	O
given	O
in	O
Chadwick	O
et	O
al.	O
.	O

Mean	O
temperatures	O
ranged	O
from	O
c.	O
75	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
to	O
c.	O
90	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

By	O
this	O
time	O
the	O
basin	O
had	O
a	O
single	O
depocentre	O
,	O
to	O
the	O
north-east	O
of	O
the	O
present	O
deepest	O
part	O
of	O
the	O
Wem	O
Audlem	O
Sub-basin	O
,	O
in	O
which	O
temperatures	O
attained	O
almost	O
c.	O
100	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
,	O
c.	O
125	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
SSG	O
and	O
c.	O
140	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

The	O
Alderley	O
Edge	O
area	O
was	O
at	O
this	O
time	O
buried	O
beneath	O
about	O
1100m	O
of	O
upper	O
Triassic	CHRONOSTRAT
and	O
Jurassic	CHRONOSTRAT
strata	O
.	O

Temperatures	O
at	O
the	O
top	O
and	O
base	O
of	O
the	O
preserved	O
SSG	O
at	O
were	O
c.	O
55	O
degrees	O
C	O
and	O
c.	O
75	O
degrees	O
C	O
,	O
and	O
85	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

Mapped	O
subsurface	O
temperatures	O
205Ma	O
ago	O
,	O
at	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
,	O
are	O
given	O
in	O
Chadwick	O
et	O
al.	O
.	O

The	O
mean	O
temperatures	O
in	O
the	O
basin	O
were	O
c.	O
40	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
,	O
c.	O
60	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
SSG	O
and	O
c.	O
70	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

Peak	O
temperatures	O
of	O
c.	O
60	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
;	O
c.	O
90	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
SSG	O
and	O
>	O
100	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
were	O
reached	O
locally	O
in	O
the	O
Sandbach	O
Knutsford	O
Sub-basin	O
.	O

In	O
the	O
Alderley	O
Edge	O
area	O
,	O
temperatures	O
were	O
c.	O
60	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
SSG	O
and	O
c.	O
70	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

Computed	O
pseudo-maturity	O
maps	O
of	O
the	O
bases	O
of	O
selected	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
layers	O
from	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
to	O
the	O
early	O
Palaeogene	CHRONOSTRAT
are	O
given	O
in	O
Chadwick	O
et	O
al.	O
.	O

In	O
summary	O
,	O
the	O
deepest	O
parts	O
of	O
the	O
Permian	CHRONOSTRAT
sequence	O
entered	O
the	O
oil	O
window	O
towards	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
and	O
left	O
it	O
during	O
Cenozoic	CHRONOSTRAT
uplift	O
.	O

A	O
large	O
proportion	O
of	O
the	O
Permian	CHRONOSTRAT
deposits	O
were	O
in	O
the	O
oil	O
window	O
at	O
the	O
time	O
of	O
maximum	O
burial	O
and	O
some	O
parts	O
were	O
at	O
temperatures	O
almost	O
high	O
enough	O
for	O
gas	O
generation	O
.	O

The	O
deepest	O
parts	O
of	O
the	O
SSG	O
were	O
in	O
the	O
oil	O
window	O
from	O
early	O
Jurassic	CHRONOSTRAT
to	O
mid	O
or	O
late	O
Palaeogene	CHRONOSTRAT
times	O
.	O

The	O
deepest	O
parts	O
of	O
the	O
MMG	O
were	O
perhaps	O
only	O
briefly	O
in	O
the	O
oil	O
window	O
from	O
late	O
Cretaceous	CHRONOSTRAT
to	O
early	O
Palaeogene	CHRONOSTRAT
times	O
.	O

Upper	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
strata	O
underlying	O
the	O
basin	O
would	O
have	O
entered	O
the	O
oil	O
window	O
earlier	O
than	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
strata	O
,	O
probably	O
in	O
mid	O
to	O
late	O
Triassic	CHRONOSTRAT
times	O
,	O
and	O
remained	O
in	O
the	O
oil	O
generation	O
zone	O
for	O
longer	O
,	O
probably	O
until	O
the	O
early	O
Neogene	CHRONOSTRAT
.	O

They	O
would	O
also	O
have	O
attained	O
higher	O
levels	O
of	O
maturity	O
,	O
well	O
into	O
the	O
gas-generation	O
zone	O
at	O
the	O
time	O
of	O
maximum	O
burial	O
in	O
the	O
early	O
Palaeocene	CHRONOSTRAT
.	O

The	O
last	O
major	O
deformation	O
episode	O
,	O
in	O
early	O
Devonian	CHRONOSTRAT
times	O
,	O
corresponded	O
to	O
the	O
late	O
Caledonian	O
orogeny	O
and	O
resulted	O
in	O
major	O
transpressive	O
faulting	O
,	O
uplift	O
and	O
regional	O
erosion	O
.	O

Carboniferous	CHRONOSTRAT
strata	O
were	O
deposited	O
unconformably	O
on	O
the	O
Caledonian	O
erosion	O
surface	O
.	O

Initially	O
,	O
Dinantian	CHRONOSTRAT
rocks	O
were	O
deposited	O
in	O
fault-bounded	O
extensional	O
basins	O
which	O
,	O
at	O
least	O
in	O
part	O
,	O
were	O
controlled	O
by	O
the	O
reactivation	O
of	O
older	O
,	O
basement	O
,	O
structures	O
.	O

Later	O
Carboniferous	CHRONOSTRAT
deposition	O
appears	O
to	O
have	O
been	O
of	O
a	O
more	O
regional	O
nature	O
.	O

Carboniferous	CHRONOSTRAT
rocks	O
underlie	O
most	O
of	O
the	O
Cheshire	O
Basin	O
,	O
being	O
thickest	O
in	O
the	O
north	O
where	O
more	O
than	O
4000m	O
of	O
strata	O
are	O
preserved	O
,	O
with	O
about	O
2000m	O
of	O
Upper	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
beds	O
.	O

At	O
the	O
end	O
of	O
Carboniferous	CHRONOSTRAT
times	O
Variscan	O
compressive	O
stresses	O
led	O
to	O
major	O
transpressional	O
fault	O
reactivation	O
,	O
basin	O
inversion	O
,	O
and	O
regional	O
erosion	O
.	O

The	O
Cheshire	O
Basin	O
is	O
filled	O
largely	O
with	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
strata	O
,	O
which	O
rest	O
unconformably	O
on	O
Carboniferous	CHRONOSTRAT
rocks	O
and	O
,	O
locally	O
,	O
in	O
the	O
south	O
,	O
on	O
Caledonian	CHRONOSTRAT
basement	O
.	O

It	O
is	O
markedly	O
asymmetrical	O
in	O
cross-section	O
,	O
having	O
,	O
in	O
general	O
terms	O
,	O
the	O
form	O
of	O
a	O
faulted	O
half	O
graben	O
,	O
deepest	O
in	O
the	O
south-east	O
,	O
where	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
lies	O
at	O
depths	O
locally	O
in	O
excess	O
of	O
4500m	O
.	O

The	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
subsequent	O
evolution	O
of	O
the	O
Cheshire	O
Basin	O
can	O
be	O
summarised	O
as	O
follows	O
:	O
The	O
initial	O
measurable	O
phase	O
of	O
basin	O
subsidence	O
corresponded	O
to	O
deposition	O
of	O
the	O
Permian	CHRONOSTRAT
sequence	O
.	O

Early	CHRONOSTRAT
Triassic	CHRONOSTRAT
subsidence	O
was	O
associated	O
with	O
the	O
deposition	O
of	O
much	O
of	O
the	O
SSG	O
.	O

The	O
upper	O
SSG	O
,	O
the	O
MMG	O
and	O
the	O
Penarth	LEXICON
Group	LEXICON
were	O
deposited	O
during	O
Middle	CHRONOSTRAT
and	O
Upper	CHRONOSTRAT
Triassic	CHRONOSTRAT
subsidence	O
.	O

Rates	O
of	O
subsidence	O
decreased	O
gradually	O
with	O
time	O
,	O
and	O
a	O
single	O
depocentre	O
developed	O
,	O
where	O
,	O
by	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
,	O
sedimentary	O
thicknesses	O
probably	O
exceeded	O
5000	O
m.	O
Preserved	O
Jurassic	CHRONOSTRAT
strata	O
are	O
restricted	O
to	O
outliers	O
of	O
limited	O
extent	O
,	O
so	O
the	O
Jurassic	CHRONOSTRAT
phase	O
of	O
basin	O
evolution	O
is	O
poorly	O
constrained	O
.	O

Regional	O
considerations	O
suggest	O
that	O
east	O
west	O
extension	O
probably	O
continued	O
into	O
early	O
Jurassic	CHRONOSTRAT
times	O
,	O
with	O
continued	O
fault-controlled	O
basin	O
subsidence	O
.	O

It	O
is	O
likely	O
that	O
the	O
preserved	O
Jurassic	CHRONOSTRAT
strata	O
lie	O
somewhat	O
to	O
the	O
south	O
of	O
the	O
Jurassic	CHRONOSTRAT
depocentre	O
,	O
which	O
probably	O
overlay	O
the	O
late	O
Triassic	CHRONOSTRAT
depocentre	O
.	O

Extension	O
probably	O
recommenced	O
in	O
late	O
Jurassic	CHRONOSTRAT
times	O
,	O
possibly	O
with	O
a	O
markedly	O
different	O
extension	O
direction	O

Total	O
sedimentary	O
thicknesses	O
at	O
the	O
end	O
of	O
this	O
period	O
may	O
have	O
exceeded	O
6000m	O
locally	O
,	O
with	O
the	O
deepest	O
parts	O
of	O
the	O
Permian	CHRONOSTRAT
succession	O
probably	O
entering	O
the	O
oil	O
window	O
.	O

Regional	O
considerations	O
suggest	O
that	O
crustal	O
extension	O
continued	O
into	O
early	O
Cretaceous	CHRONOSTRAT
times	O
,	O
but	O
contemporaneous	O
regional	O
uplift	O
caused	O
severe	O
erosion	O
of	O
the	O
basin	O
margins	O
,	O
with	O
lesser	O
erosion	O
of	O
the	O
basin	O
depocentre	O
.	O

It	O
is	O
likely	O
that	O
crustal	O
extension	O
ceased	O
in	O
early	O
Cretaceous	CHRONOSTRAT
times	O
,	O
extension	O
in	O
the	O
period	O
from	O
242Ma	O
to	O
97Ma	O
constituting	O
perhaps	O
48%	O
of	O
the	O
total	O
post-Variscan	O
extension	O
.	O

The	O
deepest	O
parts	O
of	O
the	O
SSG	O
and	O
the	O
Permian	CHRONOSTRAT
succession	O
probably	O
entered	O
the	O
oil	O
window	O
during	O
this	O
period	O
.	O

Maximum	O
basin	O
development	O
was	O
probably	O
attained	O
in	O
early	O
Palaeocene	CHRONOSTRAT
times	O
,	O
with	O
the	O
accumulation	O
of	O
nearly	O
6500m	O
of	O
strata	O
in	O
the	O
basin	O
depocentre	O
.	O

Peak	O
subsurface	O
temperatures	O
were	O
attained	O
at	O
this	O
time	O
,	O
with	O
the	O
deepest	O
parts	O
of	O
the	O
MMG	O
and	O
all	O
underlying	O
strata	O
within	O
the	O
oil	O
window	O
.	O

Regional	O
uplift	O
commenced	O
in	O
Palaeocene	CHRONOSTRAT
times	O
,	O
perhaps	O
associated	O
with	O
development	O
of	O
the	O
Iceland	O
Plume	O
.	O

Inversion	O
probably	O
culminated	O
in	O
the	O
Oligo	CHRONOSTRAT
-	O
Miocene	CHRONOSTRAT
,	O
associated	O
with	O
Alpine	O
compressional	O
events	O
to	O
the	O
south	O
.	O

Several	O
approaches	O
have	O
been	O
used	O
here	O
to	O
shed	O
light	O
on	O
the	O
provenance	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
fill	O
of	O
the	O
Cheshire	O
Basin	O
,	O
including	O
studies	O
of	O
heavy-mineral	O
assemblages	O
,	O
heavy-mineral	O
chemistry	O
,	O
clay	O
mineralogy	O
,	O
whole-rock	O
petrography	O
,	O
whole-rock	O
geochemistry	O
and	O
radiogenic	O
isotopes	O
.	O

However	O
,	O
most	O
of	O
the	O
boreholes	O
sampled	O
were	O
relatively	O
shallow	O
and	O
may	O
,	O
therefore	O
,	O
have	O
been	O
affected	O
by	O
Tertiary	CHRONOSTRAT
and	O
modern	O
weathering	O
and	O
shallow	O
groundwater	O
flow	O
.	O

In	O
all	O
,	O
92	O
samples	O
were	O
analysed	O
by	O
X-ray	O
diffraction	O
analysis	O
to	O
determine	O
their	O
clay	O
mineralogy	O
:	O
54	O
from	O
the	O
MMG	O
,	O
35	O
from	O
the	O
SSG	O
and	O
3	O
from	O
the	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
was	O
examined	O
in	O
boreholes	O
from	O
both	O
the	O
northern	O
and	O
southern	O
parts	O
of	O
the	O
Cheshire	O
Basin	O
.	O

The	O
SSG	O
examined	O
in	O
the	O
Perry	O
Farm	O
and	O
Little	O
Ness	O
boreholes	O
may	O
include	O
this	O
formation	O
,	O
but	O
the	O
stratigraphy	O
of	O
these	O
boreholes	O
is	O
very	O
poorly	O
constrained	O
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
composed	O
of	O
pebble-free	O
sandstones	O
.	O

Sandstone	O
rock	O
fragments	O
were	O
found	O
in	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
from	O
the	O
Rainhill	O
Borehole	O
.	O

This	O
type	O
of	O
monazite	O
has	O
been	O
found	O
in	O
Palaeozoic	CHRONOSTRAT
rocks	O
from	O
the	O
Welsh	O
Massif	O
,	O
south-west	O
England	O
,	O
Belgium	O
and	O
Brittany	O
,	O
as	O
well	O
as	O
in	O
rocks	O
ranging	O
from	O
Precambrian	CHRONOSTRAT
to	O
Permian	CHRONOSTRAT
in	O
age	O
further	O
afield	O
in	O
Europe	O
and	O
other	O
parts	O
of	O
the	O
world	O
.	O

Observations	O
on	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
are	O
biased	O
towards	O
the	O
north-west	O
and	O
south-east	O
of	O
the	O
basin	O
,	O
and	O
there	O
is	O
little	O
apparent	O
difference	O
between	O
these	O
areas	O
.	O

The	O
mineralogy	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
is	O
very	O
similar	O
to	O
that	O
of	O
the	O
the	O
underlying	O
Kinnerton	LEXICON
Sandstone	LEXICON
,	O
although	O
the	O
sandstones	O
generally	O
contain	O
a	O
greater	O
proportion	O
of	O
lithic	O
clasts	O
,	O
chert	O
and	O
K-feldspar	O
.	O

Lithic	O
fragments	O
are	O
dominated	O
by	O
chert	O
and	O
quartzite	O
,	O
with	O
subordinate	O
silicified	O
volcanic	O
clasts	O
and	O
silicified	O
bioclastic	O
rock	O
fragments	O
,	O
the	O
latter	O
probably	O
derived	O
from	O
the	O
Carboniferous	CHRONOSTRAT
.	O

Samples	O
from	O
the	O
north	O
of	O
the	O
basin	O
were	O
found	O
to	O
contain	O
an	O
assemblage	O
of	O
illite	O
,	O
smectite	O
and	O
chlorite	O
,	O
similar	O
to	O
the	O
underlying	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
although	O
locally	O
it	O
appears	O
that	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
are	O
more	O
chloritic	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
was	O
examined	O
in	O
a	O
wide	O
coverage	O
of	O
boreholes	O
from	O
the	O
north	O
and	O
south	O
of	O
the	O
basin	O
,	O
and	O
also	O
at	O
outcrop	O
at	O
Grinshill	O
.	O

Albite	O
appears	O
,	O
qualitatively	O
,	O
to	O
be	O
more	O
abundant	O
in	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
than	O
in	O
the	O
other	O
SSG	O
formations	O
.	O

Fragments	O
of	O
volcanic	O
rock	O
,	O
including	O
silicified	O
rhyolitic	O
and	O
highly	O
altered	O
ferruginous	O
varieties	O
,	O
are	O
probably	O
less	O
significant	O
than	O
in	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
and	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

The	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
was	O
studied	O
largely	O
in	O
the	O
north	O
and	O
north-west	O
of	O
the	O
basin	O
.	O

The	O
Bulkeley	LEXICON
Hill	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
which	O
lies	O
between	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
was	O
not	O
examined	O
in	O
this	O
study	O
.	O

This	O
sandstone	O
was	O
not	O
,	O
however	O
,	O
fully	O
penetrated	O
in	O
the	O
Wilkesley	O
Borehole	O
and	O
may	O
here	O
represent	O
the	O
top	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
petrological	O
and	O
sedimentological	O
characteristics	O
of	O
the	O
Malpas	LEXICON
Sandstone	LEXICON
are	O
so	O
similar	O
to	O
those	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
that	O
they	O
are	O
considered	O
together	O
in	O
this	O
section	O
.	O

The	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
dominated	O
by	O
quartz	O
arenites	O
interbedded	O
with	O
subordinate	O
quartz	O
and	O
cherty	O
sublitharenites	O
and	O
subarkosic	O
sandstones	O
,	O
and	O
occasional	O
quartz	O
wackes	O
,	O
quartz-rich	O
ferruginous	O
siltstones	O
and	O
silty	O
mudstones	O
.	O

Interlaminated	O
siltstones	O
and	O
mudflake	O
breccias	O
are	O
common	O
in	O
the	O
upper	O
parts	O
of	O
the	O
sequence	O
,	O
for	O
example	O
in	O
the	O
Saughall	O
Massie	O
Borehole	O
,	O
as	O
it	O
passes	O
into	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
.	O

In	O
general	O
,	O
however	O
,	O
quartz	O
arenites	O
dominate	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
the	O
sandstones	O
are	O
more	O
feldspathic	O
.	O

However	O
,	O
in	O
the	O
Malpas	LEXICON
Sandstone	LEXICON
of	O
the	O
Wilkesley	O
Borehole	O
,	O
well-rounded	O
,	O
low-grade	O
.	O

In	O
the	O
west	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
lacks	O
chlorite	O
.	O

The	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
has	O
a	O
distinctive	O
facies	O
of	O
alternating	O
siltstone	O
,	O
reddish	O
brown	O
and	O
greenish	O
grey	O
mudstone	O
and	O
thin	O
,	O
fine	O
-	O
to	O
medium-grained	O
sandstones	O
.	O

The	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
in	O
the	O
Marston	O
Salt	O
Union	O
Borehole	O
locally	O
contains	O
occasional	O
thin	O
laminae	O
of	O
aphanitic	O
lath-like	O
synsedimentary	O
anhydrite	O
.	O

Coarser	O
sandstones	O
and	O
siltstones	O
in	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
are	O
similar	O
to	O
those	O
of	O
the	O
underlying	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

XRD	O
studies	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
from	O
the	O
Wood	O
Lane	O
Borehole	O
indicate	O
that	O
the	O
<	O
2micrometre	O
fraction	O
clay	O
minerals	O
are	O
dominated	O
by	O
illite	O
with	O
a	O
variable	O
proportion	O
of	O
smectite	O
and	O
chlorite	O
.	O

It	O
is	O
commonly	O
found	O
in	O
many	O
modern-day	O
hypersaline	O
evaporitic	O
lacustrine	O
and	O
associated	O
syndepositional	O
diagenetic	O
environments	O
,	O
and	O
its	O
occurrence	O
is	O
consistent	O
with	O
the	O
inferred	O
depositional	O
environment	O
of	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
.	O

The	O
whole-rock	O
petrography	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
Formation	LEXICON
was	O
examined	O
only	O
in	O
samples	O
from	O
the	O
Meadowbank	O
Salt	O
Mine	O
.	O

Interbedded	O
mudstones	O
and	O
siltstones	O
are	O
very	O
similar	O
to	O
the	O
laminated	O
anhydritic	O
-	O
dolomicritic	O
siltstones	O
found	O
in	O
the	O
underlying	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
and	O
the	O
overlying	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
.	O

The	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
comprises	O
red	O
and	O
green	O
interlaminated	O
siltstones	O
and	O
mudstones	O
,	O
which	O
are	O
often	O
very	O
dolomitic	O
and	O
anhydritic	O
,	O
together	O
with	O
a	O
structureless	O
mudrock	O
facies	O
.	O

As	O
in	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
,	O
the	O
BSEM	O
reveals	O
very	O
fine-scale	O
cross-lamination	O
in	O
these	O
anhydritic	O
-	O
dolomitic	O
sediments	O
,	O
indicating	O
deposition	O
under	O
a	O
gentle	O
current	O
regime	O
.	O

In	O
general	O
,	O
the	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
is	O
similar	O
to	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
and	O
also	O
represents	O
deposition	O
in	O
a	O
shallow	O
hypersaline	O
environment	O
,	O
periodically	O
drying	O
out	O
with	O
localised	O
marginal	O
sabkha	O
development	O
.	O

The	O
Wych	LEXICON
Mudstone	LEXICON
Formation	LEXICON
,	O
as	O
typified	O
by	O
the	O
sequence	O
in	O
the	O
Crewe	O
Heat	O
Flow	O
Borehole	O
,	O
is	O
represented	O
by	O
dominantly	O
structureless	O
reddish	O
brown	O
siltstones	O
,	O
silty	O
mudstones	O
and	O
mudstones	O
,	O
with	O
occasional	O
thin	O
very	O
fine	O
quartz	O
arenites	O
.	O

As	O
in	O
the	O
underlying	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
,	O
the	O
clay	O
mineralogy	O
of	O
the	O
Wych	LEXICON
Mudstone	LEXICON
Formation	LEXICON
consists	O
of	O
a	O
uniform	O
assemblage	O
of	O
illite	O
,	O
corrensite	O
and	O
minor	O
chlorite	O
.	O

No	O
petrographic	O
analysis	O
was	O
undertaken	O
for	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
Formation	LEXICON
.	O

XRD	O
analysis	O
of	O
two	O
samples	O
from	O
the	O
Arclid	O
Bridge	O
2	O
Borehole	O
identify	O
a	O
clay-mineral	O
assemblage	O
of	O
illite	O
,	O
corrensite	O
and	O
minor	O
chlorite	O
similar	O
to	O
that	O
in	O
the	O
underlying	O
MMG	O
formations	O
.	O

Petrographic	O
analysis	O
of	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
is	O
limited	O
to	O
the	O
British	O
Gypsum	O
Audlem	O
AU17	O
Borehole	O
.	O

XRD	O
analysis	O
of	O
13	O
samples	O
of	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
Formation	O
from	O
the	O
Audlem	O
AU17	O
and	O
Lotus	O
Ltd	O
,	O
Stafford	O
boreholes	O
show	O
either	O
an	O
assemblage	O
of	O
illite	O
and	O
chlorite	O
,	O
or	O
illite	O
,	O
corrensite	O
and	O
chlorite	O
.	O

However	O
,	O
maximum	O
temperatures	O
and	O
burial	O
depths	O
for	O
the	O
SSG	O
can	O
not	O
be	O
inferred	O
directly	O
from	O
the	O
experimental	O
work	O
of	O
Hansley	O
or	O
the	O
North	O
Sea	O
analogy	O
,	O
because	O
dissolution	O
rates	O
also	O
depend	O
on	O
pore-water	O
chemistry	O
,	O
fluid	O
flux	O
and	O
heat	O
flow	O
.	O

The	O
relatively	O
advanced	O
garnet	O
dissolution	O
observed	O
in	O
the	O
SSG	O
of	O
the	O
Cheshire	O
Basin	O
therefore	O
implies	O
either	O
a	O
combination	O
of	O
the	O
above	O
.	O

Thirty	O
sandstone	O
samples	O
from	O
formations	O
underlying	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
were	O
included	O
in	O
the	O
study	O
.	O

Most	O
are	O
from	O
sandstones	O
assigned	O
to	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

One	O
sample	O
of	O
Bold	LEXICON
Formation	LEXICON
,	O
two	O
of	O
Collyhurst	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
two	O
of	O
arenaceous	O
units	O
near	O
the	O
top	O
of	O
the	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
were	O
also	O
included	O
.	O

As	O
data	O
from	O
the	O
Bold	LEXICON
,	O
Collyhurst	LEXICON
Sandstone	LEXICON
and	O
Manchester	LEXICON
Marls	LEXICON
formations	O
fall	O
within	O
the	O
ranges	O
shown	O
by	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
in	O
the	O
Stanlow	O
Borehole	O
shows	O
stratigraphical	O
variations	O
that	O
may	O
provide	O
a	O
basis	O
for	O
correlation	O
,	O
at	O
least	O
on	O
a	O
local	O
level	O
.	O

Tourmaline	O
compositions	O
were	O
determined	O
for	O
eight	O
samples	O
from	O
below	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

Type	O
2	O
occurs	O
in	O
Kinnerton	LEXICON
sandstones	O
of	O
the	O
Newport	O
UDC	O
and	O
Childs	O
Ercall	O
boreholes	O
,	O
whereas	O
Type	O
1	O
occurs	O
in	O
Collyhurst	LEXICON
,	O
Bold	LEXICON
and	O
Kinnerton	LEXICON
sandstones	O
of	O
the	O
Stanlow	O
,	O
Speke	O
Reservoir	O
and	O
Childs	O
Ercall	O
boreholes	O
.	O

Thirty-two	O
sandstone	O
samples	O
from	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
were	O
analysed	O
from	O
eight	O
boreholes	O
in	O
the	O
Cheshire	O
Basin	O
and	O
from	O
the	O
equivalent	O
Cannock	LEXICON
Chase	LEXICON
Formation	LEXICON
.	O

There	O
is	O
some	O
doubt	O
as	O
to	O
whether	O
the	O
succession	O
in	O
the	O
Perry	O
Farm	O
Borehole	O
is	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
or	O
Kinnerton	LEXICON
Sandstone	LEXICON
;	O
the	O
heavy-mineral	O
ratios	O
are	O
more	O
characteristic	O
of	O
the	O
former	O
.	O

Excluding	O
two	O
samples	O
from	O
the	O
base	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
in	O
the	O
Speke	O
Reservoir	O
Borehole	O
,	O
ATi	O
values	O
are	O
high	O
with	O
relatively	O
little	O
scatter	O
.	O

Tourmalines	O
were	O
analysed	O
from	O
six	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
sandstones	O
.	O

The	O
anomalous	O
sample	O
has	O
lower	O
FeO	O
and	O
higher	O
MgO	O
,	O
and	O
is	O
more	O
comparable	O
to	O
samples	O
from	O
the	O
overlying	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
boundary	O
between	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
has	O
been	O
placed	O
at	O
135m	O
in	O
the	O
borehole	O
,	O
some	O
8m	O
above	O
the	O
anomalous	O
sample	O
.	O

This	O
indicates	O
either	O
that	O
the	O
position	O
of	O
the	O
boundary	O
requires	O
revision	O
or	O
that	O
Wilmslow	O
-	O
type	O
sources	O
had	O
become	O
of	O
major	O
importance	O
during	O
late	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
times	O
.	O

Twenty-nine	O
samples	O
from	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
were	O
studied	O
from	O
five	O
boreholes	O
.	O

The	O
geological	O
map	O
suggests	O
that	O
the	O
borehole	O
should	O
start	O
in	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
but	O
the	O
geochemistry	O
and	O
the	O
borehole	O
log	O
suggest	O
that	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
is	O
represented	O
,	O
at	O
least	O
in	O
the	O
deeper	O
parts	O
of	O
the	O
hole	O
.	O

The	O
heavy-mineral	O
characteristics	O
are	O
very	O
clearly	O
of	O
Wilmslow	LEXICON
Sandstone	LEXICON
affinity	O
.	O

The	O
tourmaline	O
compositions	O
of	O
apatite-poor	O
and	O
apatite-rich	O
sandstones	O
from	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
are	O
very	O
similar	O
.	O

The	O
tourmaline	O
data	O
show	O
a	O
close	O
affinity	O
with	O
the	O
overlying	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

It	O
is	O
more	O
likely	O
that	O
the	O
apatite-poor	O
assemblage	O
was	O
formed	O
from	O
the	O
apatite-rich	O
assemblage	O
through	O
apatite	O
dissolution	O
,	O
as	O
a	O
result	O
of	O
an	O
intra	O
-	O
Triassic	CHRONOSTRAT
,	O
or	O
a	O
much	O
more	O
recent	O
,	O
event	O
.	O

On	O
the	O
other	O
hand	O
,	O
the	O
stratigraphical	O
position	O
of	O
the	O
apatite-poor	O
assemblage	O
,	O
which	O
appears	O
to	O
be	O
in	O
the	O
upper	O
part	O
of	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
beneath	O
the	O
Hardegsen	O
disconformity	O
,	O
suggests	O
that	O
the	O
action	O
of	O
acidic	O
groundwater	O
during	O
an	O
intra	O
-	O
Triassic	CHRONOSTRAT
event	O
is	O
the	O
most	O
likely	O
cause	O
.	O

The	O
provenance	O
of	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
differs	O
significantly	O
from	O
that	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

Monazite	O
is	O
less	O
abundant	O
,	O
with	O
a	O
mean	O
MZi	O
close	O
to	O
1.0	O
compared	O
with	O
4.0	O
for	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
,	O
and	O
there	O
are	O
fewer	O
FeO-rich	O
and	O
more	O
MgO-rich	O
tourmaline	O
grains	O
.	O

Therefore	O
,	O
although	O
the	O
source	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
is	O
likely	O
to	O
have	O
continued	O
to	O
contribute	O
to	O
the	O
basin	O
fill	O
,	O
generating	O
the	O
relatively	O
high	O
MZi	O
values	O
seen	O
in	O
some	O
Wilmslow	LEXICON
Sandstone	LEXICON
samples	O
,	O
the	O
source	O
of	O
much	O
of	O
the	O
material	O
appears	O
to	O
have	O
greater	O
affinities	O
with	O
that	O
supplying	O
the	O
Kinnerton	LEXICON
,	O
Collyhurst	LEXICON
and	O
Bold	LEXICON
sandstones	O
.	O

Eleven	O
samples	O
from	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
were	O
examined	O
.	O

As	O
noted	O
in	O
the	O
previous	O
section	O
,	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
may	O
also	O
be	O
represented	O
at	O
the	O
top	O
of	O
the	O
Bootle	O
Borehole	O
.	O

Apart	O
from	O
the	O
greater	O
abundance	O
of	O
garnet	O
in	O
Coton	O
Fields	O
,	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
has	O
generally	O
uniform	O
characteristics	O
.	O

Overall	O
,	O
these	O
parameters	O
are	O
very	O
similar	O
to	O
those	O
associated	O
with	O
the	O
apatite-rich	O
Wilmslow	LEXICON
Sandstone	LEXICON
.	O

This	O
suggests	O
that	O
the	O
provenance	O
of	O
the	O
fluvial	O
sandstones	O
has	O
some	O
affinity	O
with	O
that	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
,	O
and	O
that	O
this	O
influence	O
is	O
absent	O
in	O
the	O
aeolian	O
facies	O
.	O

Three	O
tourmaline	O
populations	O
were	O
studied	O
from	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
two	O
from	O
the	O
Thornton	O
Borehole	O
and	O
one	O
from	O
the	O
Wood	O
Lane	O
Borehole	O
.	O

Their	O
characteristics	O
are	O
similar	O
to	O
those	O
from	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
although	O
they	O
tend	O
towards	O
higher	O
FeO	O
and	O
MgO	O
values	O
.	O

This	O
supports	O
the	O
evidence	O
from	O
the	O
conventional	O
heavy-mineral	O
data	O
,	O
that	O
the	O
provenance	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
similar	O
to	O
that	O
of	O
the	O
Wilmslow	LEXICON
,	O
but	O
with	O
some	O
influence	O
from	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
sources	O
.	O

The	O
samples	O
from	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
are	O
characterised	O
by	O
a	O
greater	O
abundance	O
of	O
secondary	O
minerals	O
,	O
notable	O
carbonate	O
and	O
pyrite	O
,	O
than	O
in	O
the	O
underlying	O
sandstones	O
.	O

This	O
may	O
be	O
because	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
underlies	O
the	O
impermeable	O
MMG	O
,	O
which	O
probably	O
acted	O
as	O
a	O
source	O
and	O
caprock	O
to	O
mineralising	O
fluids	O
.	O

The	O
Nd-isotope	O
signatures	O
of	O
whole	O
rocks	O
and	O
pebbles	O
from	O
the	O
basin	O
fill	O
were	O
examined	O
in	O
order	O
to	O
obtain	O
information	O
about	O
the	O
rocks	O
which	O
were	O
weathered	O
and	O
eroded	O
to	O
produce	O
the	O
detritus	O
deposited	O
in	O
the	O
Cheshire	O
Basin	O
during	O
Permian	CHRONOSTRAT
and	O
Triassic	CHRONOSTRAT
times	O
.	O

In	O
contrast	O
,	O
the	O
isotope	O
signature	O
of	O
an	O
individual	O
clast	O
from	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
will	O
reflect	O
that	O
of	O
a	O
specific	O
source	O
.	O

Samples	O
from	O
the	O
SSG	O
were	O
selected	O
on	O
the	O
basis	O
of	O
the	O
results	O
of	O
the	O
first	O
stage	O
of	O
heavy-mineral	O
investigations	O
.	O

A	O
typical	O
sample	O
was	O
selected	O
from	O
each	O
of	O
the	O
four	O
sandstone	O
formations	O
and	O
,	O
in	O
addition	O
,	O
samples	O
with	O
unusual	O
heavy-mineral	O
contents	O
from	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
,	O
Wilmslow	LEXICON
Sandstone	LEXICON
,	O
and	O
Helsby	LEXICON
Sandstone	LEXICON
formations	O
were	O
analysed	O
,	O
as	O
these	O
were	O
considered	O
more	O
likely	O
to	O
have	O
a	O
secondary	O
source	O
component	O
.	O

Five	O
samples	O
were	O
collected	O
from	O
the	O
MMG	O
,	O
covering	O
the	O
range	O
of	O
colour	O
and	O
grain	O
size	O
;	O
they	O
included	O
examples	O
of	O
both	O
structureless	O
and	O
laminated	O
facies	O
,	O
ranging	O
from	O
red-brown	O
to	O
grey-green	O
to	O
light	O
grey	O
in	O
colour	O
.	O

One	O
sample	O
of	O
fine	O
sandstone	O
and	O
siltstone	O
was	O
taken	O
from	O
the	O
basal	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
and	O
four	O
comprising	O
siltstones	O
and	O
mudstones	O
from	O
lithologies	O
higher	O
in	O
the	O
sequence	O
.	O

In	O
addition	O
,	O
one	O
sample	O
of	O
dark	O
grey	O
mudstone	O
was	O
collected	O
from	O
the	O
Carboniferous	CHRONOSTRAT
basement	O
beneath	O
the	O
basin	O
to	O
provide	O
a	O
comparison	O
with	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basin	O
fill	O
.	O

Clasts	O
from	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
in	O
the	O
Cheshire	O
Basin	O
were	O
analysed	O
,	O
and	O
comparative	O
data	O
were	O
obtained	O
for	O
similar	O
conglomeratic	O
units	O
deposited	O
in	O
the	O
more	O
southerly	O
.	O

Pebbles	O
were	O
selected	O
from	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
at	O
two	O
outcrop	O
localities	O
in	O
the	O
north-west	O
of	O
the	O
basin	O
,	O
within	O
the	O
same	O
area	O
as	O
the	O
whole-rock	O
samples	O
.	O

The	O
age	O
chosen	O
lies	O
approximately	O
at	O
the	O
SSG	O
MMG	O
boundary	O
.	O

There	O
are	O
many	O
bordering	O
and	O
distal	O
massifs	O
which	O
were	O
available	O
to	O
contribute	O
detritus	O
into	O
the	O
basin	O
during	O
the	O
Triassic	CHRONOSTRAT
,	O
including	O
:	O
the	O
Welsh	O
Massif	O
;	O
the	O
Lake	O
District	O
,	O
the	O
Southern	O
Uplands	O
and	O
Highlands	O
Massifs	O
;	O
the	O
Anglo-Brabant	O
Massif	O
;	O
the	O
Cornubian	O
Massif	O
;	O
and	O
more	O
distal	O
sources	O
under	O
or	O
beyond	O
the	O
English	O
Channel	O
,	O
such	O
as	O
the	O
Armorican	O
Massif	O
.	O

The	O
Cornubian	O
Massif	O
,	O
another	O
potential	O
source	O
,	O
would	O
have	O
been	O
shedding	O
Permian	CHRONOSTRAT
mudstone	O
as	O
well	O
as	O
material	O
from	O
the	O
Hercynian	CHRONOSTRAT
granites	O
.	O

Armorican	O
faunas	O
have	O
been	O
reported	O
from	O
the	O
Budleigh	LEXICON
Salterton	LEXICON
Pebble	LEXICON
Bed	LEXICON
exposed	O
on	O
the	O
south	O
coast	O
of	O
England	O
,	O
which	O
may	O
occur	O
at	O
a	O
similar	O
stratigraphical	O
level	O
to	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

More	O
than	O
580	O
samples	O
were	O
collected	O
for	O
chemical	O
analysis	O
,	O
including	O
more	O
than	O
300	O
from	O
the	O
SSG	O
and	O
over	O
200	O
from	O
the	O
MMG	O
.	O

Helsby	LEXICON
,	O
etc.	O
.	O

A	O
few	O
of	O
the	O
samples	O
from	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
,	O
which	O
consisted	O
largely	O
of	O
halite	O
with	O
minor	O
mudstone	O
,	O
were	O
placed	O
in	O
water	O
to	O
remove	O
the	O
salt	O
,	O
and	O
the	O
residue	O
was	O
processed	O
in	O
the	O
same	O
way	O
as	O
the	O
whole-rock	O
samples	O
.	O

Approximately	O
50	O
samples	O
from	O
the	O
SSG	O
and	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
were	O
analysed	O
for	O
REE	O
by	O
ICP-MS	O
.	O

The	O
analysis	O
was	O
undertaken	O
on	O
the	O
SSG	O
and	O
MMG	O
as	O
a	O
whole	O
,	O
and	O
on	O
the	O
individual	O
component	O
formations	O
.	O

The	O
Helsby	LEXICON
Sandstone	LEXICON
data	O
were	O
run	O
once	O
with	O
all	O
samples	O
included	O
and	O
again	O
with	O
mineralised	O
samples	O
from	O
West	O
Mine	O
and	O
Clive	O
Mine	O
omitted	O
.	O

Factor	O
analysis	O
of	O
the	O
SSG	O
as	O
a	O
whole	O
reveals	O
aluminosilicate	O
,	O
mineralisation	O
and	O
carbonate	O
factors	O
.	O

This	O
factor	O
could	O
also	O
include	O
secondary	O
iron	O
oxides	O
,	O
which	O
are	O
more	O
abundant	O
in	O
the	O
clay-rich	O
rocks	O
of	O
the	O
SSG	O
.	O

In	O
addition	O
,	O
Ni	O
and	O
Cr	O
correlate	O
with	O
Al2O3	O
in	O
all	O
formations	O
except	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

Ba	O
,	O
Sr	O
,	O
Th	O
,	O
V	O
and	O
Zn	O
also	O
correlate	O
with	O
Al2O3	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
Sr	O
,	O
Th	O
,	O
V	O
and	O
Zn	O
in	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
.	O

MgO	O
is	O
present	O
in	O
this	O
factor	O
for	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
suggesting	O
that	O
in	O
this	O
formation	O
dolomite	O
is	O
the	O
most	O
important	O
MgO	O
mineral	O
.	O

This	O
is	O
supported	O
by	O
petrographical	O
observations	O
,	O
particularly	O
of	O
eodiagenetic	O
nodular	O
dolomite	O
,	O
in	O
the	O
Helsby	LEXICON
sandstone	O
.	O

The	O
second	O
factor	O
for	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
includes	O
Fe2O3	O
,	O
Co	O
,	O
Ni	O
and	O
V	O
,	O
suggesting	O
an	O
iron-oxide	O
or	O
sulphide	O
association	O
.	O

The	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
Wilmslow	LEXICON
Sandstone	LEXICON
have	O
a	O
probable	O
heavy-mineral	O
factor	O
,	O
dominated	O
by	O
Zr	O
,	O
with	O
a	O
less	O
significant	O
score	O
for	O
Th	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
P2O5	O
in	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
.	O

Baryte	O
emerges	O
as	O
a	O
probable	O
minor	O
factor	O
in	O
all	O
but	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
.	O

Taken	O
as	O
a	O
whole	O
,	O
the	O
MMG	O
does	O
not	O
show	O
a	O
very	O
coherent	O
result	O
from	O
factor	O
analysis	O
,	O
probably	O
because	O
many	O
elements	O
are	O
present	O
in	O
more	O
than	O
one	O
mineral	O
.	O

When	O
individual	O
formations	O
of	O
the	O
MMG	O
are	O
considered	O
the	O
dominant	O
factor	O
is	O
,	O
as	O
in	O
the	O
SSG	O
,	O
an	O
aluminosilicate	O
one	O
which	O
includes	O
Al2O3	O
,	O
TiO2	O
,	O
K2O	O
,	O
Ce	O
,	O
Cr	O
,	O
La	O
,	O
Nb	O
and	O
Rb	O
in	O
all	O
formations	O
.	O

However	O
,	O
unlike	O
the	O
SSG	O
,	O
Fe2O3	O
,	O
P2O5	O
and	O
Ni	O
are	O
always	O
present	O
,	O
but	O
Th	O
and	O
Y	O
do	O
not	O
always	O
appear	O
.	O

Minor	O
factors	O
include	O
:	O
Tarporley	LEXICON
Siltstones	LEXICON
:	O
As	O
,	O
Co	O
,	O
Pb	O
Bollin	LEXICON
Mudstones	LEXICON
:	O
As	O
,	O
Co	O
,	O
Ni	O
-LRB-	O
?	O

sulphides	O
-RRB-	O
Northwich	LEXICON
Halite	LEXICON
:	O
Zr	O
Byley	LEXICON
Mudstones	LEXICON
:	O
Ti	O
,	O
P	O
,	O
Ba	O
,	O
Ce	O
,	O
La	O
,	O
Nb	O
,	O
Y	O
,	O
Zr	O
Wych	LEXICON
Mudstones	LEXICON
:	O
La	O
,	O
Y	O
,	O
Zr	O
.	O

The	O
Kinnerton	LEXICON
and	O
Wilmslow	LEXICON
sandstones	O
display	O
less	O
variability	O
than	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
and	O
the	O
interquartile	O
range	O
for	O
most	O
elements	O
is	O
usually	O
narrower	O
.	O

Samples	O
taken	O
from	O
the	O
Kinnerton	LEXICON
and	O
Wilmslow	LEXICON
sandstones	O
are	O
dominantly	O
of	O
aeolian	O
facies	O
,	O
whereas	O
the	O
Pebble	LEXICON
Beds	LEXICON
are	O
mainly	O
fluvial	O
and	O
the	O
Helsby	LEXICON
samples	O
include	O
a	O
significant	O
number	O
from	O
fluvial	O
facies	O
.	O

The	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
have	O
higher	O
Fe2O3/Al2O3	O
but	O
lower	O
Zr/Al2O3	O
than	O
the	O
other	O
formations	O
.	O

The	O
Helsby	LEXICON
and	O
Kinnerton	LEXICON
sandstones	O
have	O
lower	O
K2O	O
levels	O
than	O
the	O
other	O
SSG	O
formations	O
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
differs	O
in	O
many	O
respects	O
from	O
most	O
or	O
all	O
of	O
the	O
other	O
units	O
.	O

Helsby	LEXICON
and	O
Grinshill	LEXICON
sandstones	O
,	O
higher	O
Fe2O3	O
than	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
later	O
units	O
and	O
low	O
Al2O3	O
,	O
TiO2	O
,	O
P2O5	O
,	O
Th	O
,	O
Y	O
except	O
compared	O
to	O
Helsby	LEXICON
,	O
?	O

Helsby	LEXICON
and	O
Grinshill	LEXICON
sandstones	O
.	O

Concentrations	O
of	O
Na2O	O
,	O
Ba	O
,	O
Sr	O
,	O
Rb	O
,	O
As	O
,	O
Pb	O
are	O
low	O
except	O
compared	O
to	O
the	O
Grinshill	LEXICON
Sandstone	LEXICON
,	O
K2O	O
levels	O
low	O
except	O
compared	O
to	O
the	O
Helsby	LEXICON
and	O
Grinshill	LEXICON
sandstones	O
and	O
Zr	O
low	O
except	O
compared	O
to	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

The	O
Fe2O3/Al2O3	O
ratio	O
is	O
higher	O
than	O
in	O
all	O
the	O
other	O
units	O
,	O
Ce/Al2O3	O
is	O
higher	O
than	O
in	O
all	O
formations	O
except	O
the	O
Grinshill	LEXICON
Sandstone	LEXICON
,	O
and	O
Ni/Al2O3	O
is	O
high	O
except	O
compared	O
to	O
the	O
Helsby	LEXICON
and	O
Grinshill	LEXICON
sandstones	O
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
has	O
low	O
Rb/Al2O3	O
except	O
in	O
comparison	O
to	O
the	O
Grinshill	LEXICON
Sandstone	LEXICON
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
is	O
predominantly	O
an	O
aeolian	O
unit	O
,	O
deposited	O
early	O
in	O
the	O
basins	O
history	O
,	O
prior	O
to	O
the	O
first	O
major	O
influx	O
of	O
fluvial	O
sediments	O
represented	O
by	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

All	O
units	O
deposited	O
subsequent	O
to	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
,	O
as	O
well	O
as	O
that	O
unit	O
itself	O
,	O
have	O
some	O
geochemical	O
signature	O
related	O
to	O
the	O
fluvial	O
material	O
from	O
the	O
south	O
.	O

It	O
is	O
interesting	O
to	O
compare	O
the	O
Kinnerton	LEXICON
and	O
Wilmslow	LEXICON
sandstones	O
,	O
as	O
both	O
are	O
predominantly	O
aeolian	O
,	O
particularly	O
in	O
the	O
boreholes	O
sampled	O
.	O

Both	O
sandstones	O
generally	O
have	O
higher	O
SiO2	O
than	O
other	O
units	O
,	O
but	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
has	O
higher	O
values	O
than	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
has	O
higher	O
Al2O3	O
,	O
Na2O	O
,	O
TiO2	O
,	O
K2O	O
,	O
MgO	O
,	O
P2O5	O
,	O
Sr	O
,	O
Ba	O
,	O
Rb	O
,	O
Th	O
,	O
Zr	O
,	O
Y	O
,	O
Ce	O
,	O
La	O
,	O
Cu	O
,	O
As	O
,	O
and	O
Pb	O
.	O

As	O
was	O
noted	O
on	O
p.	O
90	O
,	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
is	O
dominated	O
by	O
cherty	O
sublitharenites	O
,	O
thus	O
explaining	O
the	O
high	O
SiO2	O
content	O
,	O
whilst	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
is	O
more	O
argillaceous	O
and	O
,	O
therefore	O
,	O
richer	O
in	O
Al2O3	O
and	O
related	O
elements	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
has	O
higher	O
Na2O/Al2O3	O
,	O
K2O/Al2O3	O
,	O
Rb/Al2O3	O
,	O
Ba/Al2O3	O
,	O
Sr/Al2O3	O
,	O
Zr/Al2O3	O
,	O
and	O
Th/Al2O3	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
includes	O
arkosic	O
and	O
subarkosic	O
rocks	O
,	O
which	O
were	O
not	O
seen	O
in	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
.	O

However	O
,	O
as	O
was	O
noted	O
earlier	O
,	O
there	O
are	O
diagenetic	O
monazites	O
present	O
in	O
the	O
SSG	O
,	O
as	O
well	O
as	O
those	O
from	O
igneous	O
sources	O
;	O
Cornubia	O
or	O
Armorica	O
could	O
be	O
the	O
source	O
of	O
these	O
,	O
but	O
they	O
could	O
equally	O
be	O
supplied	O
from	O
other	O
areas	O
of	O
Palaeozoic	CHRONOSTRAT
rocks	O
in	O
Wales	O
or	O
the	O
Midlands	O
.	O

In	O
contrast	O
,	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
has	O
higher	O
Fe2O3	O
,	O
CaO	O
,	O
LOI	O
,	O
Zn	O
,	O
Fe2O3/Al2O3	O
,	O
Ce/Al2O3	O
,	O
Ni/Al2O3	O
and	O
V/Al2O3	O
.	O

The	O
higher	O
Ni/Al2O3	O
could	O
indicate	O
a	O
more	O
basic	O
igneous	O
input	O
,	O
possibly	O
from	O
Carboniferous	CHRONOSTRAT
volcanics	O
,	O
although	O
volcanic	O
clasts	O
observed	O
in	O
the	O
formation	O
appear	O
to	O
be	O
of	O
acid	O
or	O
felsic	O
composition	O
.	O

There	O
is	O
no	O
significant	O
difference	O
in	O
MnO	O
content	O
between	O
the	O
two	O
sandstones	O
,	O
but	O
the	O
levels	O
are	O
low	O
in	O
both	O
compared	O
with	O
those	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

It	O
is	O
difficult	O
to	O
test	O
geographical	O
variations	O
within	O
formations	O
rigorously	O
because	O
of	O
the	O
uneven	O
distribution	O
of	O
samples	O
,	O
but	O
some	O
differences	O
can	O
be	O
seen	O
for	O
the	O
Kinnerton	LEXICON
and	O
Wilmslow	LEXICON
sandstones	O
.	O

For	O
example	O
,	O
K2O/Al2O3	O
values	O
for	O
the	O
Kinnerton	LEXICON
and	O
Wilmslow	LEXICON
sandstone	O
are	O
higher	O
in	O
the	O
south	O
of	O
the	O
basin	O
than	O
in	O
the	O
northern	O
half	O
.	O

In	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
this	O
ratio	O
is	O
significantly	O
higher	O
in	O
the	O
south	O
than	O
the	O
north	O
,	O
which	O
may	O
be	O
related	O
to	O
the	O
greater	O
variety	O
of	O
lithic	O
clasts	O
seen	O
in	O
the	O
south	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
,	O
in	O
contrast	O
,	O
has	O
lower	O
Ni/Al2O3	O
in	O
the	O
south	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
data	O
may	O
thus	O
be	O
interpreted	O
in	O
terms	O
of	O
a	O
decline	O
in	O
coarser-grained	O
fluvial	O
detritus	O
northward	O
,	O
as	O
evidenced	O
by	O
the	O
decrease	O
in	O
pebble	O
content	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
in	O
this	O
direction	O
,	O
with	O
an	O
associated	O
decrease	O
in	O
feldspar	O
and	O
increase	O
in	O
clay-mineral	O
contents	O
.	O

The	O
differences	O
in	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
suggest	O
variations	O
in	O
source	O
area	O
.	O

REE	O
analysis	O
was	O
carried	O
out	O
on	O
selected	O
samples	O
from	O
the	O
SSG	O
and	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
to	O
assess	O
whether	O
the	O
patterns	O
would	O
provide	O
any	O
useful	O
information	O
on	O
provenance	O
.	O

In	O
conclusion	O
,	O
there	O
appears	O
to	O
be	O
a	O
mineralogical	O
control	O
on	O
the	O
REE	O
in	O
the	O
SSG	O
and	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
.	O

These	O
show	O
a	O
marked	O
difference	O
between	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
and	O
other	O
units	O
,	O
consistent	O
with	O
its	O
rather	O
different	O
general	O
geochemistry	O
.	O

This	O
may	O
be	O
related	O
to	O
the	O
fact	O
that	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
is	O
mainly	O
of	O
aeolian	O
facies	O
,	O
deposited	O
before	O
the	O
first	O
major	O
fluvial	O
influx	O
of	O
sediment	O
into	O
the	O
basin	O
represented	O
by	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

Later	O
aeolian	O
facies	O
were	O
probably	O
,	O
at	O
least	O
in	O
part	O
,	O
reworking	O
exotic	O
material	O
introduced	O
from	O
the	O
south	O
by	O
rivers	O
,	O
while	O
fluvial	O
facies	O
of	O
the	O
Wilmslow	LEXICON
and	O
Helsby	LEXICON
sandstones	O
are	O
known	O
to	O
have	O
this	O
southerly	O
derivation	O
.	O

Bollin	LEXICON
Mudstones	LEXICON
-RRB-	O
,	O
LOI	O
,	O
CaO	O
,	O
MgO	O
and	O
Sr.	O
.	O

This	O
is	O
borne	O
out	O
by	O
petrographic	O
study	O
which	O
shows	O
a	O
high	O
siliciclastic	O
component	O
,	O
very	O
similar	O
to	O
that	O
of	O
the	O
underlying	O
SSG	O
.	O

The	O
Byley	LEXICON
Mudstones	LEXICON
are	O
generally	O
distinct	O
from	O
the	O
other	O
units	O
,	O
but	O
most	O
similar	O
to	O
the	O
Wych	LEXICON
Mudstones	LEXICON
and	O
?	O

Bollin	LEXICON
Mudstones	LEXICON
.	O

Bollin	LEXICON
Mudstones	LEXICON
-RRB-	O
,	O
TiO2	O
-LRB-	O
except	O
for	O
the	O
?	O

Bollin	LEXICON
Mudstones	O
and	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
-RRB-	O
and	O
Zr	O
.	O

Anhydritic	O
and	O
dolomitic	O
rocks	O
are	O
well	O
developed	O
in	O
the	O
Byley	LEXICON
Mudstones	LEXICON
and	O
,	O
to	O
a	O
lesser	O
extent	O
,	O
in	O
the	O
upper	O
Bollin	LEXICON
and	O
Wych	LEXICON
mudstones	O
.	O

Bollin	LEXICON
Mudstones	LEXICON
,	O
seem	O
to	O
be	O
geochemically	O
most	O
similar	O
to	O
the	O
Byley	LEXICON
Mudstones	LEXICON
of	O
the	O
Cheshire	O
Basin	O
.	O

For	O
some	O
elements	O
the	O
lower	O
part	O
of	O
the	O
MMG	O
.	O

The	O
common	O
pattern	O
of	O
these	O
elements	O
is	O
for	O
similar	O
,	O
and	O
relatively	O
high	O
levels	O
in	O
the	O
Tarporley	LEXICON
Siltstones	LEXICON
,	O
Bollin	LEXICON
Mudstones	LEXICON
and	O
Northwich	LEXICON
Halite	LEXICON
,	O
a	O
marked	O
fall	O
in	O
the	O
Byley	LEXICON
Mudstones	LEXICON
,	O
and	O
then	O
a	O
consistent	O
rise	O
in	O
median	O
concentrations	O
up	O
to	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstones	LEXICON
.	O

The	O
petrography	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
and	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
is	O
similar	O
,	O
with	O
both	O
formations	O
containing	O
a	O
significant	O
arenaceous	O
siliciclastic	O
component	O
.	O

Bollin	LEXICON
Mudstones	LEXICON
.	O

Values	O
are	O
also	O
generally	O
high	O
in	O
the	O
Bollin	LEXICON
and	O
Brooks	LEXICON
Mill	LEXICON
Mudstones	LEXICON
,	O
and	O
in	O
the	O
Stafford	LEXICON
Halite	LEXICON
.	O

The	O
Bollin	LEXICON
Mudstones	LEXICON
,	O
?	O

Bollin	LEXICON
Mudstones	LEXICON
and	O
Northwich	LEXICON
Halite	LEXICON
have	O
higher	O
TiO2/Al2O3	O
.	O

The	O
Tarporley	LEXICON
Siltstones	LEXICON
and	O
Bollin	LEXICON
Mudstones	LEXICON
have	O
lower	O
Sr/Al2O3	O
.	O

Bollin	LEXICON
Mudstones	LEXICON
and	O
the	O
Stafford	LEXICON
Halite	LEXICON
have	O
low	O
Fe2O3/Al2O3	O
compared	O
with	O
all	O
except	O
the	O
Tarporley	LEXICON
Siltstones	LEXICON
.	O

The	O
Wych	LEXICON
and	O
Byley	LEXICON
mudstones	O
have	O
low	O
Y/Al2O3	O
,	O
Ce/Al2O3	O
,	O
Zr/Al2O3	O
,	O
La/Al2O3	O
and	O
Rb/Al2O3	O
and	O
high	O
Cr/Al2O3	O
,	O
Ni/Al2O3	O
compared	O
with	O
most	O
other	O
units	O
.	O

The	O
gross	O
differences	O
between	O
formations	O
were	O
also	O
examined	O
by	O
comparing	O
geochemical	O
profiles	O
in	O
the	O
Wilkesley	O
Borehole	O
:	O
samples	O
show	O
higher	O
Cr/Al2O3	O
and	O
Ni/Al2O3	O
and	O
lower	O
Zr/Al2O3	O
in	O
the	O
Wych	LEXICON
and	O
Byley	LEXICON
mudstones	O
than	O
in	O
any	O
of	O
the	O
other	O
formations	O
.	O

Geographical	O
variation	O
is	O
also	O
apparent	O
within	O
the	O
Byley	LEXICON
and	O
Wych	LEXICON
mudstones	O
,	O
as	O
the	O
Cr/Al2O3	O
and	O
Ni/Al2O3	O
ratios	O
are	O
higher	O
and	O
the	O
Zr/Al2O3	O
ratio	O
lower	O
,	O
in	O
the	O
Crewe	O
,	O
Wilkesley	O
and	O
Lower	O
Wych	O
boreholes	O
than	O
in	O
other	O
boreholes	O
.	O

As	O
a	O
contrast	O
to	O
the	O
above	O
relationships	O
,	O
there	O
is	O
a	O
positive	O
correlation	O
between	O
Zr/Al2O3	O
and	O
Cr/Al2O3	O
in	O
the	O
lower	O
part	O
of	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
of	O
Wilkesley	O
Borehole	O
.	O

Two	O
broad	O
facies	O
types	O
can	O
be	O
recognised	O
in	O
the	O
MMG	O
:	O
.	O

Both	O
facies	O
are	O
present	O
in	O
the	O
Byley	LEXICON
Mudstones	LEXICON
of	O
the	O
Crewe	O
Borehole	O
.	O

The	O
Saughall	O
Massie	O
Borehole	O
shows	O
a	O
contrast	O
between	O
the	O
Tarporley	LEXICON
Siltstones	LEXICON
and	O
the	O
underlying	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

In	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
and	O
basal	O
Tarporley	LEXICON
Siltstone	LEXICON
,	O
in	O
contrast	O
,	O
the	O
Ni/Al2O3	O
and	O
Zr/Al2O3	O
profiles	O
run	O
almost	O
parallel	O
,	O
with	O
Cr/Al2O3	O
showing	O
a	O
similar	O
trend	O
in	O
the	O
Delamere	LEXICON
Member	LEXICON
,	O
suggesting	O
that	O
sedimentological	O
factors	O
were	O
the	O
dominant	O
influence	O
.	O

There	O
are	O
strong	O
differences	O
between	O
the	O
Manchester	LEXICON
Marls	LEXICON
and	O
the	O
MMG	O
.	O

Although	O
SiO2	O
,	O
CaO	O
and	O
LOI	O
in	O
the	O
former	O
lie	O
between	O
the	O
levels	O
of	O
the	O
Tarporley	LEXICON
Siltstones	LEXICON
and	O
other	O
MMG	O
units	O
,	O
Al2O3	O
,	O
TiO2	O
,	O
Fe2O3	O
,	O
K2O	O
,	O
Cr	O
,	O
Ce	O
,	O
Co	O
,	O
Pb	O
,	O
La	O
,	O
Rb	O
,	O
Nb	O
,	O
V	O
and	O
Y	O
are	O
higher	O
than	O
in	O
the	O
MMG	O
and	O
Na2O	O
and	O
MgO	O
lower	O
.	O

This	O
suggests	O
generally	O
that	O
the	O
Manchester	LEXICON
Marls	LEXICON
have	O
higher	O
quartz	O
and	O
aluminosilicate	O
contents	O
than	O
the	O
MMG	O
and	O
lower	O
levels	O
of	O
carbonates	O
,	O
sulphates	O
and	O
,	O
perhaps	O
,	O
Mg-rich	O
clays	O
.	O

Many	O
elements	O
are	O
similar	O
to	O
certain	O
groups	O
of	O
the	O
MMG	O
but	O
differ	O
from	O
others	O
.	O

The	O
Bollin	LEXICON
Mudstones	LEXICON
are	O
most	O
similar	O
overall	O
but	O
differ	O
for	O
Nb	O
and	O
Th	O
,	O
as	O
well	O
as	O
the	O
major	O
elements	O
referred	O
to	O
above	O
.	O

The	O
SSG	O
was	O
laid	O
down	O
within	O
a	O
long	O
northward-draining	O
fluvial	O
basin	O
system	O
,	O
originating	O
in	O
the	O
Armorican	O
Highlands	O
to	O
the	O
south	O
of	O
Britain	O
and	O
developed	O
along	O
a	O
series	O
of	O
linked	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
extensional	O
basins	O
along	O
the	O
west	O
side	O
of	O
the	O
country	O
.	O

The	O
lithic	O
clasts	O
and	O
heavy	O
minerals	O
seen	O
in	O
whole-rock	O
petrographic	O
studies	O
of	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
indicate	O
derivation	O
from	O
a	O
complex	O
source	O
terrain	O
,	O
which	O
included	O
high-grade	O
metamorphic	O
rocks	O
,	O
syenite	O
,	O
acid	O
volcanics	O
,	O
quartzite	O
,	O
sandstones	O
and	O
siltstones	O
.	O

The	O
whole-rock	O
petrography	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
suggests	O
a	O
similarly	O
mixed	O
source	O
terrain	O
.	O

The	O
greater	O
importance	O
of	O
albite	O
and	O
reduction	O
of	O
volcanic	O
fragments	O
in	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
suggests	O
a	O
continued	O
evolution	O
of	O
the	O
source	O
terrain	O
.	O

This	O
trend	O
continued	O
into	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
which	O
also	O
,	O
locally	O
,	O
shows	O
clear	O
evidence	O
for	O
inputs	O
from	O
the	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
of	O
the	O
Midlands	O
or	O
Wales	O
.	O

The	O
feldspar	O
may	O
reflect	O
the	O
increased	O
importance	O
of	O
granitic	O
inputs	O
from	O
Armorica	O
or	O
Cornubia	O
,	O
whilst	O
the	O
sedimentary	O
clasts	O
suggest	O
more	O
local	O
sources	O
in	O
the	O
Carboniferous	CHRONOSTRAT
of	O
the	O
Anglo-Brabant	O
Massif	O
,	O
Pennines	O
or	O
Wales	O
and	O
perhaps	O
the	O
Devonian	CHRONOSTRAT
.	O

Clasts	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
in	O
the	O
Cheshire	O
Basin	O
,	O
as	O
in	O
other	O
basins	O
,	O
are	O
dominated	O
by	O
quartzite	O
and	O
vein	O
quartz	O
.	O

The	O
quartzites	O
rarely	O
contain	O
derived	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
fossils	O
,	O
and	O
chert	O
and	O
limestone	O
pebbles	O
rarely	O
include	O
Carboniferous	CHRONOSTRAT
fossils	O
.	O

Previous	O
studies	O
of	O
the	O
Kidderminster	LEXICON
Formation	LEXICON
of	O
the	O
West	O
Midlands	O
and	O
Budleigh	O
Salterton	O
Pebble	O
Beds	O
of	O
south-west	O
England	O
''	O
equivalent	O
formations	O
to	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
''	O
have	O
identified	O
components	O
of	O
Cornubian	O
and	O
Armorican	O
affinity	O
.	O

With	O
the	O
exception	O
of	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
which	O
displays	O
an	O
apparent	O
decrease	O
in	O
the	O
proportion	O
of	O
polycrystalline	O
quartz	O
to	O
single-crystal	O
quartz	O
and	O
a	O
decline	O
in	O
the	O
content	O
and	O
change	O
in	O
the	O
composition	O
of	O
lithic	O
fragments	O
from	O
south	O
to	O
north	O
,	O
the	O
SSG	O
shows	O
no	O
gross	O
variations	O
in	O
detrital	O
mineralogy	O
across	O
the	O
Cheshire	O
Basin	O
.	O

However	O
,	O
there	O
are	O
significant	O
differences	O
between	O
the	O
SSG	O
of	O
the	O
Cheshire	O
Basin	O
and	O
other	O
UK	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
.	O

In	O
the	O
Cheshire	O
Basin	O
,	O
sandstones	O
are	O
characterised	O
by	O
moderately	O
low	O
feldspar	O
contents	O
,	O
and	O
are	O
represented	O
by	O
cherty	O
litharenites	O
and	O
sublitharenites	O
,	O
with	O
quartz	O
arenites	O
becoming	O
more	O
significant	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
SSG	O
of	O
the	O
Wessex	O
Basin	O
is	O
significantly	O
different	O
in	O
character	O
and	O
is	O
represented	O
by	O
very	O
feldspathic	O
sandstones	O
:	O
lithic	O
arkoses	O
,	O
arkoses	O
and	O
subarkoses	O
with	O
up	O
to	O
55%	O
K-feldspar	O
.	O

The	O
SSG	O
of	O
the	O
Lincolnshire	O
East	O
Yorkshire	O
Basin	O
is	O
similarly	O
feldspathic	O
,	O
although	O
the	O
proportion	O
of	O
K-feldspar	O
.	O

Furthermore	O
,	O
the	O
SSG	O
of	O
the	O
Wessex	O
Basin	O
includes	O
a	O
high	O
proportion	O
of	O
detrital	O
Ba-rich	O
K-feldspar	O
.	O

This	O
is	O
not	O
a	O
characteristic	O
of	O
the	O
SSG	O
of	O
the	O
Cheshire	O
Basin	O
.	O

However	O
,	O
whereas	O
detrital	O
chert	O
is	O
prominent	O
in	O
the	O
SSG	O
of	O
the	O
Cheshire	O
Basin	O
it	O
appears	O
to	O
be	O
less	O
significant	O
in	O
adjacent	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
.	O

Since	O
chert	O
is	O
not	O
as	O
important	O
in	O
other	O
basins	O
,	O
the	O
most	O
likely	O
source	O
is	O
from	O
the	O
common	O
cherty	O
horizons	O
in	O
Dinantian	CHRONOSTRAT
limestones	O
of	O
North	O
Wales	O
,	O
the	O
Welsh	O
Borders	O
,	O
the	O
south	O
Pennines	O
and	O
the	O
Midlands	O
.	O

This	O
suggests	O
that	O
Namurian	CHRONOSTRAT
and	O
Westphalian	CHRONOSTRAT
strata	O
had	O
already	O
been	O
at	O
least	O
partly	O
eroded	O
from	O
these	O
areas	O
.	O

There	O
is	O
evidence	O
for	O
this	O
in	O
the	O
South	O
Pennines	O
,	O
where	O
neptunian	O
dykes	O
in	O
Dinantian	CHRONOSTRAT
limestones	O
in	O
the	O
Ashbourne	O
area	O
are	O
filled	O
with	O
probable	O
Triassic	CHRONOSTRAT
sediment	O
,	O
and	O
some	O
pocket	O
deposits	O
in	O
the	O
limestones	O
may	O
be	O
of	O
Triassic	CHRONOSTRAT
age	O
.	O

Areas	O
where	O
Dinantian	CHRONOSTRAT
strata	O
are	O
known	O
or	O
inferred	O
to	O
subcrop	O
beneath	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
are	O
outlined	O
south	O
of	O
the	O
Pennines	O
,	O
in	O
the	O
Welsh	O
Borders	O
and	O
in	O
the	O
area	O
of	O
the	O
London	O
Brabant	O
Massif	O
.	O

Variations	O
in	O
heavy-mineral	O
assemblages	O
and	O
the	O
chemistry	O
of	O
detrital	O
tourmaline	O
indicate	O
that	O
a	O
number	O
of	O
distinct	O
sources	O
supplied	O
sediment	O
to	O
the	O
Cheshire	O
Basin	O
during	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
,	O
and	O
that	O
these	O
varied	O
in	O
relative	O
importance	O
with	O
time	O
.	O

The	O
former	O
characterises	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
,	O
whereas	O
the	O
latter	O
is	O
typical	O
of	O
both	O
the	O
earlier	O
.	O

The	O
maximum	O
influence	O
of	O
the	O
southerly	O
source	O
took	O
place	O
during	O
deposition	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
,	O
coinciding	O
with	O
the	O
time	O
of	O
greatest	O
runoff	O
from	O
this	O
source	O
and	O
ensuing	O
higher-energy	O
depositional	O
conditions	O
.	O

The	O
available	O
regional	O
information	O
on	O
Triassic	CHRONOSTRAT
sandstones	O
of	O
the	O
UK	O
shows	O
an	O
overall	O
decrease	O
in	O
the	O
abundance	O
of	O
detrital	O
monazite	O
from	O
south	O
to	O
north	O
,	O
indicating	O
that	O
the	O
southerly	O
source	O
area	O
was	O
characterised	O
by	O
high	O
amounts	O
of	O
detrital	O
monazite	O
:	O
the	O
progressive	O
northward	O
decrease	O
in	O
MZi	O
values	O
is	O
interpreted	O
as	O
the	O
result	O
of	O
dilution	O
by	O
more	O
local	O
material	O
low	O
in	O
detrital	O
monazite	O
.	O

More	O
local	O
sources	O
were	O
of	O
greater	O
importance	O
in	O
the	O
preceding	O
Collyhurst	LEXICON
,	O
Kinnerton	LEXICON
and	O
associated	O
sandstones	O
and	O
the	O
overlying	O
Wilmslow	LEXICON
and	O
Helsby	LEXICON
sandstones	O
,	O
in	O
which	O
detrital	O
monazite	O
is	O
markedly	O
less	O
abundant	O
and	O
tourmaline	O
suites	O
are	O
generally	O
more	O
Mg-rich	O
.	O

Aeolian	O
sandstones	O
in	O
formations	O
below	O
and	O
above	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
were	O
dominantly	O
transported	O
from	O
the	O
east	O
.	O

During	O
the	O
Triassic	CHRONOSTRAT
,	O
the	O
Pennine	O
area	O
was	O
probably	O
mostly	O
blanketed	O
by	O
Late	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
clastics	O
,	O
but	O
the	O
scarcity	O
of	O
modern	O
heavy-mineral	O
data	O
on	O
Late	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
sandstones	O
from	O
the	O
region	O
prevents	O
a	O
more	O
detailed	O
assessment	O
of	O
their	O
suitability	O
as	O
source	O
material	O
.	O

The	O
only	O
comparable	O
data	O
presently	O
available	O
are	O
from	O
Namurian	CHRONOSTRAT
sandstones	O
of	O
the	O
Lancaster	O
area	O
.	O

It	O
is	O
possible	O
that	O
younger	O
Carboniferous	CHRONOSTRAT
sandstones	O
lacked	O
this	O
component	O
,	O
and	O
it	O
is	O
equally	O
possible	O
that	O
there	O
are	O
regional	O
variations	O
in	O
detrital	O
monazite	O
distribution	O
.	O

The	O
presence	O
of	O
appreciable	O
amounts	O
of	O
detrital	O
monazite	O
in	O
some	O
samples	O
from	O
the	O
Wilmslow	LEXICON
and	O
Helsby	LEXICON
sandstones	O
indicates	O
that	O
sediment	O
supply	O
from	O
the	O
south	O
continued	O
throughout	O
the	O
deposition	O
of	O
the	O
later	O
formations	O
of	O
the	O
SSG	O
but	O
that	O
its	O
importance	O
in	O
the	O
Cheshire	O
Basin	O
was	O
markedly	O
reduced	O
.	O

The	O
evidence	O
from	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
of	O
the	O
Thornton	O
Borehole	O
,	O
in	O
which	O
aeolian	O
sandstones	O
have	O
very	O
low	O
MZi	O
values	O
and	O
fluvial	O
sandstones	O
have	O
significantly	O
higher	O
detrital	O
monazite	O
abundances	O
,	O
provides	O
good	O
evidence	O
that	O
the	O
northward-flowing	O
fluvial	O
system	O
was	O
still	O
supplying	O
monazite-rich	O
detritus	O
.	O

Thus	O
the	O
fluvial	O
input	O
continued	O
to	O
have	O
a	O
similar	O
character	O
to	O
that	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
,	O
whereas	O
the	O
aeolian	O
sediments	O
appear	O
to	O
have	O
a	O
strong	O
affinity	O
with	O
those	O
of	O
the	O
earlier	O
Collyhurst	LEXICON
and	O
Kinnerton	LEXICON
sandstones	O
.	O

There	O
are	O
stratigraphical	O
and	O
regional	O
variations	O
in	O
the	O
nature	O
of	O
the	O
low-monazite	O
assemblages	O
:	O
for	O
example	O
,	O
the	O
Wilmslow	LEXICON
and	O
Helsby	LEXICON
sandstones	O
have	O
higher	O
ATi	O
and	O
RZi	O
values	O
and	O
lower	O
rutile/anatase	O
ratios	O
than	O
the	O
Kinnerton	LEXICON
and	O
associated	O
sandstones	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
characterised	O
by	O
two	O
distinct	O
heavy-mineral	O
assemblages	O
,	O
one	O
being	O
apatite-rich	O
and	O
the	O
other	O
apatite-poor	O
.	O

There	O
is	O
little	O
evidence	O
that	O
this	O
difference	O
resulted	O
from	O
changes	O
in	O
sediment	O
provenance	O
,	O
and	O
the	O
most	O
reasonable	O
explanation	O
for	O
the	O
variation	O
is	O
that	O
it	O
resulted	O
from	O
apatite	O
dissolution	O
during	O
the	O
interval	O
represented	O
by	O
the	O
Hardegsen	O
disconformity	O
,	O
at	O
the	O
boundary	O
between	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
formations	O
.	O

Ideally	O
,	O
the	O
variation	O
in	O
apatite	O
abundance	O
should	O
be	O
examined	O
by	O
reference	O
to	O
a	O
cored	O
sequence	O
unequivocally	O
passing	O
through	O
the	O
boundary	O
between	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
but	O
no	O
such	O
material	O
was	O
available	O
for	O
study	O
.	O

The	O
whole-rock	O
geochemistry	O
of	O
the	O
SSG	O
indicates	O
that	O
the	O
predominantly	O
aeolian	O
sediments	O
differed	O
in	O
composition	O
from	O
later	O
sediments	O
.	O

The	O
whole-rock	O
geochemistry	O
suggests	O
that	O
the	O
formations	O
above	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
contained	O
a	O
certain	O
amount	O
of	O
fluvially	O
transported	O
sediment	O
derived	O
from	O
the	O
south	O
,	O
and	O
elements	O
of	O
this	O
effect	O
were	O
observed	O
in	O
the	O
heavy-mineral	O
investigations	O
.	O

Comparison	O
of	O
mainly	O
aeolian	O
facies	O
above	O
and	O
below	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
is	O
consistent	O
with	O
the	O
addition	O
of	O
granitic	O
material	O
,	O
presumably	O
from	O
a	O
Cornubian	O
or	O
Amorican	O
source	O
,	O
in	O
the	O
later	O
formation	O
.	O

The	O
middle	O
part	O
of	O
the	O
MMG	O
is	O
geochemically	O
distinctive	O
,	O
with	O
a	O
composition	O
suggesting	O
a	O
greater	O
input	O
from	O
a	O
basic	O
igneous	O
source	O
relative	O
to	O
acid	O
igneous	O
or	O
sedimentary	O
components	O
.	O

The	O
nearest	O
source	O
of	O
basic	O
material	O
was	O
probably	O
the	O
Carboniferous	CHRONOSTRAT
volcanics	O
and	O
intrusives	O
of	O
the	O
South	O
Pennines	O
.	O

As	O
part	O
of	O
the	O
present	O
investigation	O
,	O
petrological	O
studies	O
were	O
carried	O
out	O
to	O
address	O
the	O
diagenesis	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
of	O
the	O
basin	O
and	O
its	O
genetic	O
relationship	O
to	O
the	O
sandstone-hosted	O
red-bed	O
Cu-Pb-Ba	O
mineralisation	O
and	O
hydrocarbons	O
.	O

The	O
main	O
objectives	O
were	O
:	O
to	O
identify	O
the	O
principal	O
effects	O
of	O
diagenesis	O
on	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
;	O
to	O
establish	O
the	O
relative	O
chronology	O
of	O
diagenetic	O
mineralisation	O
of	O
the	O
fluids	O
responsible	O
for	O
diagenesis	O
and	O
mineralisation	O
.	O

Due	O
to	O
the	O
lack	O
of	O
available	O
material	O
,	O
only	O
a	O
very	O
limited	O
study	O
was	O
made	O
of	O
pre	O
-	O
SSG	O
strata	O
.	O

A	O
total	O
of	O
92	O
samples	O
were	O
analysed	O
by	O
X-ray	O
diffraction	O
analysis	O
to	O
determine	O
their	O
clay	O
mineralogy	O
;	O
54	O
samples	O
from	O
the	O
MMG	O
;	O
35	O
samples	O
from	O
the	O
SSG	O
,	O
and	O
3	O
samples	O
from	O
the	O
Manchester	LEXICON
Marls	LEXICON
.	O

A	O
limited	O
number	O
of	O
SSG	O
samples	O
were	O
studied	O
by	O
fission-track	O
registration	O
analysis	O
to	O
examine	O
the	O
distribution	O
and	O
mobilisation	O
of	O
uranium	O
during	O
diagenesis	O
.	O

Lexan	O
polycarbonate	O
plastic	O
was	O
used	O
as	O
a	O
detector	O
and	O
placed	O
in	O
contact	O
with	O
polished	O
thin	O
sections	O
of	O
SSG	O
.	O

Whole-rock	O
geochemical	O
analyses	O
were	O
carried	O
out	O
on	O
580	O
samples	O
,	O
including	O
more	O
than	O
300	O
from	O
the	O
SSG	O
and	O
more	O
than	O
200	O
from	O
the	O
MMG	O
.	O

Thermometric	O
data	O
were	O
obtained	O
for	O
inclusions	O
in	O
baryte	O
and	O
calcite	O
cements	O
and	O
fracture	O
mineralisation	O
in	O
the	O
SSG	O
from	O
Alderley	O
Edge	O
,	O
Clive	O
Mine	O
,	O
Bickerton	O
and	O
the	O
Thornton	O
Borehole	O
.	O

Much	O
of	O
the	O
SSG	O
was	O
accessible	O
only	O
at	O
the	O
margins	O
of	O
the	O
Cheshire	O
Basin	O
,	O
where	O
samples	O
were	O
obtained	O
from	O
surface	O
exposures	O
,	O
shallow	O
mine-workings	O
borehole	O
cores	O
.	O

Because	O
these	O
minerals	O
are	O
extremely	O
soluble	O
,	O
multiple	O
phases	O
of	O
precipitation	O
,	O
dissolution	O
,	O
recrystallisation	O
and	O
redistribution	O
can	O
be	O
expected	O
,	O
and	O
it	O
is	O
in	O
this	O
context	O
that	O
interpretation	O
of	O
the	O
diagenesis	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
in	O
the	O
Cheshire	O
Basin	O
must	O
be	O
considered	O
.	O

Since	O
the	O
diagenetic	O
history	O
of	O
the	O
sandstone	O
and	O
siltstone	O
facies	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
is	O
broadly	O
similar	O
to	O
that	O
of	O
the	O
SSG	O
,	O
it	O
is	O
included	O
in	O
the	O
following	O
discussion	O
.	O

In	O
general	O
,	O
eodiagenetic	O
and	O
early	O
mesodiagenetic	O
processes	O
in	O
the	O
SSG	O
sandstones	O
tended	O
to	O
effect	O
a	O
reduction	O
of	O
the	O
primary	O
intergranular	O
pore	O
space	O
through	O
compaction	O
,	O
early	O
pressure	O
solution	O
,	O
grain	O
overgrowth	O
and	O
cementation	O
.	O

The	O
diagenetic	O
history	O
of	O
the	O
SSG	O
in	O
the	O
Cheshire	O
Basin	O
can	O
be	O
further	O
subdivided	O
within	O
a	O
relative	O
temporal	O
framework	O
of	O
eight	O
broad	O
Diagenetic	O
Episodes	O
,	O
referred	O
to	O
as	O
DE1	O
to	O
DE8	O
,	O
along	O
similar	O
lines	O
to	O
that	O
described	O
by	O
Strong	O
et	O
al.	O
for	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
of	O
west	O
Cumbria	O
.	O

This	O
summary	O
scheme	O
provides	O
a	O
useful	O
framework	O
within	O
which	O
the	O
diagenetic	O
evolution	O
of	O
the	O
SSG	O
of	O
the	O
Cheshire	O
Basin	O
can	O
be	O
described	O
,	O
interpreted	O
and	O
related	O
to	O
other	O
features	O
such	O
as	O
regional	O
mineralisation	O
and	O
structural	O
and	O
geological	O
events	O
.	O

Early	O
red-bed	O
diagenetic	O
and	O
pedogenic	O
modification	O
can	O
be	O
recognised	O
in	O
nearly	O
all	O
sandstones	O
from	O
all	O
SSG	O
formations	O
.	O

Whole-rock	O
geochemistry	O
of	O
the	O
SSG	O
shows	O
a	O
clear	O
difference	O
in	O
Fe	O
content	O
between	O
reddish	O
brown	O
oxidised	O
facies	O
and	O
grey	O
or	O
grey-green	O
reduced	O
facies	O
,	O
with	O
significantly	O
higher	O
levels	O
in	O
the	O
oxidised	O
rocks	O
.	O

Similar	O
carbonate	O
spheroids	O
have	O
been	O
described	O
by	O
Strong	O
and	O
Pearce	O
from	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sandstones	O
of	O
Cumbria	O
.	O

While	O
eodiagenetic	O
DE1b	O
dolomite	O
occurs	O
widely	O
across	O
the	O
Cheshire	O
Basin	O
in	O
all	O
SSG	O
formations	O
,	O
it	O
appears	O
to	O
be	O
most	O
extensively	O
developed	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
Helsby	LEXICON
Sandstone	LEXICON
formations	O
in	O
the	O
north	O
of	O
the	O
basin	O
.	O

Nodular	O
non-ferroan	O
calcite	O
cement	O
with	O
similar	O
paragenetic	O
and	O
morphological	O
characteristics	O
is	O
also	O
found	O
in	O
the	O
SSG	O
.	O

There	O
is	O
some	O
evidence	O
that	O
eodiagenetic	O
calcite	O
is	O
also	O
present	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
of	O
the	O
Newport	O
UDC	O
Borehole	O
,	O
but	O
it	O
is	O
difficult	O
to	O
differentiate	O
it	O
unambiguously	O
from	O
abundant	O
late	O
mesodiagenetic	O
calcite	O
.	O

The	O
dolomite	O
and	O
calcite	O
cements	O
are	O
similar	O
to	O
eodiagenetic	O
cements	O
described	O
from	O
the	O
SSG	O
in	O
other	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
and	O
are	O
interpreted	O
as	O
pedogenic	O
or	O
caliche-type	O
dolocretes	O
and	O
calcretes	O
.	O

Carboniferous	CHRONOSTRAT
Limestone	O
-RRB-	O
,	O
and	O
it	O
is	O
plausible	O
that	O
HCO3	O
derived	O
from	O
the	O
dissolution	O
of	O
detrital	O
marine	O
-LRB-	O
?	O

Carboniferous	CHRONOSTRAT
-RRB-	O
limestone	O
dominated	O
the	O
carbon	O
isotopic	O
signature	O
of	O
the	O
eodiagenetic	O
SSG	O
porewaters	O
.	O

The	O
d18O	O
values	O
are	O
heavier	O
than	O
for	O
calcrete	O
calcites	O
from	O
the	O
SSG	O
of	O
the	O
Wessex	O
Basin	O
,	O
although	O
similar	O
to	O
dolocrete	O
from	O
East	O
Yorkshire	O
and	O
Lincolnshire	O
.	O

Palaeogeographical	O
effects	O
or	O
a	O
greater	O
degree	O
of	O
evaporative	O
enrichment	O
of	O
d18Oh2o	O
in	O
near-surface	O
water	O
recharging	O
the	O
SSG	O
in	O
the	O
Cheshire	O
Basin	O
and	O
the	O
East	O
Yorkshire	O
Lincolnshire	O
Basin	O
may	O
also	O
account	O
for	O
the	O
difference	O
.	O

Surface	O
conditions	O
in	O
the	O
Cheshire	O
Basin	O
during	O
SSG	O
times	O
may	O
have	O
been	O
similar	O
to	O
those	O
observed	O
in	O
modern	O
arid	O
continental	O
environments	O
:	O
dolomite	O
precipitated	O
in	O
these	O
environments	O
has	O
typically	O
high	O
d13C	O
and	O
d18O	O
values	O
.	O

In	O
this	O
respect	O
,	O
the	O
isotopic	O
characteristics	O
of	O
the	O
nodular	O
eodiagenetic	O
dolomite	O
in	O
the	O
SSG	O
are	O
similar	O
to	O
those	O
of	O
the	O
primary	O
dolomicrite	O
in	O
the	O
overlying	O
MMG	O
.	O

MMG	O
dolomicrites	O
are	O
closely	O
associated	O
with	O
,	O
and	O
interlaminated	O
with	O
,	O
primary	O
anhydrite	O
.	O

In	O
the	O
Cheshire	O
Basin	O
,	O
the	O
diagenetic	O
zonation	O
parallels	O
the	O
drainage	O
direction	O
of	O
the	O
Lower	CHRONOSTRAT
Triassic	CHRONOSTRAT
fluvial	O
system	O
.	O

However	O
,	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
the	O
Saughall	O
Massie	O
Borehole	O
,	O
SEM-EDXA	O
indicates	O
that	O
these	O
coatings	O
are	O
Mg-rich	O
saponitic	O
,	O
smectitic	O
or	O
corrensitic	O
clay	O
.	O

Framboidal	O
pyrite	O
was	O
seen	O
very	O
rarely	O
in	O
the	O
SSG	O
and	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
.	O

It	O
occurs	O
in	O
trace	O
amounts	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
of	O
the	O
Hondslough	O
Farm	O
Borehole	O
but	O
is	O
more	O
abundantly	O
developed	O
in	O
the	O
muddier	O
sediments	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
,	O
as	O
in	O
the	O
Saughall	O
Massie	O
and	O
Marston	O
Salt	O
Union	O
boreholes	O
.	O

DE3	O
dolomite	O
and	O
DE3-recrystallised	O
early	O
dolomite	O
nodules	O
are	O
the	O
dominant	O
carbonate	O
cement	O
in	O
much	O
of	O
the	O
SSG	O
around	O
the	O
northern	O
rim	O
of	O
the	O
Cheshire	O
Basin	O
.	O

In	O
this	O
respect	O
DE3	O
dolomite	O
is	O
similar	O
to	O
early	O
mesodiagenetic	O
non-ferroan	O
dolomite	O
described	O
by	O
Burley	O
from	O
the	O
SSG	O
in	O
Lancashire	O
.	O

Burley	O
identified	O
up	O
to	O
12	O
cathodoluminescence	O
colour	O
zones	O
in	O
the	O
quartz	O
cements	O
of	O
the	O
SSG	O
of	O
the	O
Kirkham	O
Borehole	O
,	O
near	O
Preston	O
.	O

These	O
petrographic	O
relationships	O
suggest	O
that	O
the	O
SSG	O
was	O
actively	O
undergoing	O
the	O
early	O
stages	O
of	O
burial	O
during	O
DE4	O
quartz	O
feldspar	O
mesodiagenesis	O
but	O
had	O
not	O
yet	O
achieved	O
maximum	O
burial	O
compaction	O
.	O

For	O
example	O
,	O
it	O
is	O
well	O
developed	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
but	O
absent	O
in	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
the	O
Marston	O
Salt	O
Union	O
Borehole	O
.	O

Generally	O
,	O
however	O
,	O
authigenic	O
DE4	O
quartz	O
tends	O
to	O
form	O
only	O
minor	O
or	O
patchy	O
cements	O
in	O
most	O
of	O
the	O
SSG	O
from	O
around	O
the	O
north-western	O
and	O
western	O
margins	O
of	O
the	O
basin	O
.	O

It	O
is	O
particularly	O
well	O
developed	O
in	O
certain	O
sandstone	O
beds	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Much	O
of	O
the	O
intergranular	O
porosity	O
in	O
the	O
SSG	O
is	O
secondary	O
porosity	O
,	O
resulting	O
from	O
the	O
dissolution	O
of	O
an	O
earlier	O
diagenetic	O
pore-filling	O
cement	O
.	O

Burley	O
suggested	O
that	O
much	O
of	O
the	O
secondary	O
porosity	O
in	O
the	O
SSG	O
resulted	O
from	O
late	O
mesodiagenetic	O
carbonate	O
cement	O
dissolution	O
.	O

Strong	O
suggested	O
that	O
anhydrite	O
,	O
gypsum	O
and	O
possibly	O
halite	O
were	O
precursor	O
cements	O
that	O
were	O
later	O
removed	O
to	O
yield	O
secondary	O
porosity	O
in	O
SSG	O
rocks	O
of	O
the	O
Preston	O
area	O
of	O
Lancashire	O
.	O

Anhydrite	O
is	O
a	O
very	O
likely	O
candidate	O
cement	O
:	O
poikilotopic	O
anhydrite	O
is	O
observed	O
as	O
a	O
major	O
cement	O
in	O
the	O
Malpas	LEXICON
Sandstone	LEXICON
of	O
the	O
Wilkesley	O
Borehole	O
.	O

Halite	O
and	O
anhydrite	O
are	O
both	O
seen	O
cementing	O
siltstones	O
and	O
fine	O
sandstones	O
in	O
parts	O
of	O
the	O
overlying	O
MMG	O
,	O
but	O
halite	O
was	O
not	O
directly	O
observed	O
in	O
the	O
SSG	O
.	O

Anhydrite	O
cements	O
are	O
a	O
common	O
feature	O
of	O
the	O
SSG	O
in	O
many	O
UK	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
.	O

Its	O
removal	O
during	O
late	O
mesodiagenesis	O
and/or	O
during	O
telodiagenesis	O
appears	O
to	O
account	O
for	O
much	O
of	O
the	O
secondary	O
porosity	O
in	O
the	O
SSG	O
in	O
these	O
basins	O
.	O

The	O
early	O
stages	O
of	O
this	O
episode	O
are	O
evident	O
in	O
numerous	O
small	O
faults	O
in	O
the	O
the	O
SSG	O
.	O

Similar	O
features	O
can	O
be	O
seen	O
offshore	O
in	O
the	O
underlying	O
Collyhurst	LEXICON
Sandstone	LEXICON
.	O

Similar	O
late	O
fracture-mineralising	O
dolomite	O
enclosed	O
in	O
anhydrite	O
occurs	O
in	O
the	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
of	O
the	O
Crewe	O
Heat	O
Flow	O
borehole	O
.	O

In	O
contrast	O
,	O
d13C	O
is	O
similar	O
to	O
that	O
of	O
the	O
earlier	O
carbonates	O
,	O
which	O
suggests	O
that	O
the	O
carbon	O
isotopic	O
signature	O
of	O
the	O
pore	O
fluids	O
during	O
early	O
DE6b	O
was	O
still	O
largely	O
influenced	O
by	O
re-working	O
or	O
dissolution	O
of	O
detrital	O
carbonate	O
components	O
within	O
the	O
SSG	O
.	O

Within	O
the	O
SSG	O
and	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
,	O
DE6c	O
is	O
only	O
recognised	O
in	O
the	O
Malpas	LEXICON
Sandstone	LEXICON
and	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
of	O
the	O
Wilkesley	O
Borehole	O
.	O

Similar	O
anhydrite	O
veining	O
is	O
seen	O
in	O
the	O
overlying	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
.	O

This	O
suggests	O
that	O
DE6c	O
was	O
widespread	O
in	O
its	O
influence	O
,	O
affecting	O
the	O
MMG	O
in	O
addition	O
to	O
the	O
SSG	O
.	O

Copper	O
sulphides	O
and	O
pyrite	O
	O
+-	O
a	O
complex	O
assemblage	O
of	O
Pb-Zn-As-Ni-Co-Ag-Hg-Bi-Mo-Se	O
sulphides	O
are	O
found	O
in	O
the	O
SSG	O
to	O
the	O
south-east	O
of	O
the	O
Mersey	O
and	O
in	O
the	O
Wirral	O
Peninsula	O
.	O

Minor	O
galena	O
,	O
sphalerite	O
,	O
and	O
Ni-Co-As-Cd-sulphide	O
mineralisation	O
,	O
associated	O
with	O
bituminous	O
hydrocarbon	O
residues	O
containing	O
concentrations	O
of	O
uraninite	O
and	O
uranium	O
silicate	O
,	O
are	O
found	O
locally	O
within	O
the	O
underlying	O
Manchester	LEXICON
Marls	LEXICON
and	O
appear	O
to	O
belong	O
to	O
the	O
same	O
episode	O
of	O
diagenesis	O
.	O

In	O
most	O
samples	O
the	O
sulphide	O
paragenesis	O
is	O
unclear	O
,	O
but	O
in	O
siltstones	O
and	O
sandstones	O
in	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
and	O
Helsby	LEXICON
Sandstone	LEXICON
formations	O
of	O
the	O
Saughall	O
Massie	O
,	O
Hondslough	O
Farm	O
and	O
Coton	O
Fields	O
boreholes	O
,	O
minor	O
early	O
DE1	O
framboidal	O
pyrite	O
is	O
seen	O
to	O
be	O
overgrown	O
and	O
included	O
within	O
coarser	O
euhedral	O
DE6d	O
pyrite	O
which	O
,	O
in	O
turn	O
,	O
is	O
partially	O
replaced	O
and	O
overgrown	O
by	O
minor	O
chalcopyrite	O
.	O

Similar	O
sulphide	O
mineralisation	O
relationships	O
are	O
observed	O
in	O
the	O
SSG	O
in	O
the	O
Stowell	O
Park	O
Borehole	O
-LSB-	O
SP084118	O
-RSB-	O
in	O
the	O
Worcester	O
Basin	O
.	O

The	O
heavy	O
DE6e	O
calcite	O
d13C	O
signatures	O
in	O
the	O
south	O
of	O
the	O
basin	O
closely	O
resemble	O
early	O
DE1b-DE3	O
carbonate	O
signatures	O
,	O
suggesting	O
that	O
DE6	O
carbonate	O
was	O
derived	O
largely	O
by	O
re-working	O
of	O
early	O
diagenetic	O
and	O
detrital	O
carbonate	O
components	O
within	O
the	O
SSG	O
.	O

This	O
implies	O
that	O
deeper-sourced	O
fluids	O
,	O
probably	O
from	O
basement	O
Carboniferous	CHRONOSTRAT
rocks	O
undergoing	O
thermal	O
maturation	O
of	O
organic	O
matter	O
,	O
significantly	O
influenced	O
DE6e	O
carbonate	O
diagenesis	O
and	O
mineralisation	O
in	O
the	O
northern	O
and	O
north-western	O
part	O
of	O
the	O
basin	O
.	O

Carboniferous	CHRONOSTRAT
-RRB-	O
rocks	O
undergoing	O
thermal	O
maturation	O
.	O

South	O
of	O
this	O
area	O
,	O
there	O
is	O
little	O
evidence	O
of	O
deeper-sourced	O
fluids	O
having	O
influenced	O
the	O
SSG	O
.	O

Fluids	O
here	O
were	O
more	O
oxidising	O
and	O
the	O
carbon-isotope	O
composition	O
was	O
influenced	O
largely	O
by	O
fluid	O
rock	O
interactions	O
within	O
the	O
red-bed	O
SSG	O
.	O

In	O
this	O
respect	O
,	O
the	O
slightly	O
heavier	O
d18O	O
found	O
in	O
DE6	O
carbonates	O
in	O
the	O
south	O
of	O
the	O
basin	O
is	O
also	O
consistent	O
with	O
greater	O
influence	O
of	O
water	O
rock	O
interaction	O
within	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
pile	O
,	O
in	O
contrast	O
to	O
significant	O
influence	O
from	O
deeper-sourced	O
fluids	O
at	O
higher	O
temperature	O
.	O

Many	O
of	O
the	O
samples	O
are	O
enriched	O
in	O
Cu	O
,	O
Pb	O
,	O
Zn	O
,	O
MnO	O
,	O
Ba	O
,	O
Sr	O
,	O
Co	O
,	O
Ni	O
,	O
As	O
and	O
Cr	O
,	O
with	O
concentrations	O
significantly	O
above	O
the	O
median	O
values	O
for	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

SiO2	O
values	O
are	O
generally	O
greater	O
than	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
median	O
of	O
84.3%	O
on	O
the	O
lower	O
and	O
upper	O
levels	O
,	O
but	O
at	O
or	O
below	O
the	O
median	O
for	O
the	O
middle	O
level	O
.	O

Based	O
on	O
criteria	O
discussed	O
above	O
,	O
it	O
is	O
clear	O
that	O
much	O
of	O
the	O
present	O
porosity	O
in	O
the	O
SSG	O
and	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
is	O
secondary	O
.	O

Minor	O
hydrocarbon	O
shows	O
are	O
found	O
within	O
the	O
SSG	O
around	O
the	O
basin	O
margin	O
.	O

Late	O
telodiagenetic	O
effects	O
are	O
evident	O
in	O
much	O
of	O
the	O
unconcealed	O
SSG	O
and	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
from	O
around	O
the	O
basin	O
margins	O
.	O

Caution	O
is	O
therefore	O
required	O
when	O
interpreting	O
the	O
trace-element	O
characteristics	O
of	O
the	O
SSG	O
rocks	O
,	O
especially	O
with	O
respect	O
to	O
the	O
transition	O
metals	O
and	O
other	O
redox-sensitive	O
elements	O
,	O
which	O
have	O
quite	O
clearly	O
been	O
remobilised	O
and	O
redistributed	O
in	O
most	O
of	O
the	O
samples	O
examined	O
.	O

Whole-rock	O
geochemistry	O
of	O
the	O
SSG	O
shows	O
a	O
good	O
correlation	O
between	O
CaO	O
,	O
MgO	O
and	O
LOI	O
.	O

The	O
Kinnerton	LEXICON
Sandstone	LEXICON
shows	O
strong	O
calcite	O
and	O
dolomite	O
trends	O
.	O

The	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
also	O
show	O
both	O
calcite	O
and	O
dolomite	O
trends	O
.	O

As	O
in	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
,	O
higher	O
dolomite	O
values	O
are	O
restricted	O
to	O
the	O
north-west	O
of	O
the	O
basin	O
,	O
but	O
high	O
calcite	O
contents	O
occur	O
in	O
both	O
the	O
south-east	O
and	O
the	O
north-west	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
generally	O
has	O
low	O
levels	O
of	O
carbonates	O
.	O

Dolomite	O
also	O
seems	O
to	O
be	O
the	O
more	O
important	O
carbonate	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
with	O
maximum	O
levels	O
up	O
to	O
about	O
25%	O
,	O
although	O
most	O
samples	O
have	O
less	O
than	O
6%	O
.	O

There	O
appears	O
to	O
be	O
some	O
facies	O
control	O
of	O
the	O
preserved	O
carbonate	O
content	O
:	O
greater	O
quantities	O
are	O
found	O
in	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
which	O
contain	O
significant	O
fluvial	O
facies	O
,	O
than	O
in	O
the	O
Wilmslow	LEXICON
or	O
Kinnerton	LEXICON
sandstones	O
which	O
,	O
in	O
the	O
samples	O
collected	O
,	O
were	O
dominantly	O
of	O
aeolian	O
origin	O
.	O

The	O
MMG	O
shares	O
many	O
sequences	O
of	O
diagenetic	O
cements	O
and	O
vein-fills	O
in	O
common	O
with	O
those	O
found	O
in	O
the	O
underlying	O
SSG	O
.	O

The	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
shows	O
very	O
similar	O
characteristics	O
to	O
the	O
SSG	O
and	O
the	O
description	O
of	O
its	O
diagenesis	O
has	O
been	O
largely	O
included	O
with	O
that	O
of	O
the	O
SSG	O
strata	O
.	O

As	O
in	O
the	O
SSG	O
,	O
diagenetic	O
modification	O
can	O
be	O
ascribed	O
to	O
eodiagenetic	O
processes	O
.	O

The	O
most	O
visually	O
distinctive	O
diagenetic	O
feature	O
is	O
the	O
green	O
and	O
red	O
colouration	O
commonly	O
observed	O
in	O
the	O
MMG	O
.	O

In	O
the	O
laminated	O
facies	O
,	O
which	O
occurs	O
chiefly	O
in	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
and	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
,	O
there	O
are	O
alternations	O
of	O
oxidised	O
and	O
reduced	O
laminae	O
.	O

Previous	O
geochemical	O
studies	O
in	O
the	O
MMG	O
have	O
shown	O
that	O
the	O
reduced	O
laminae	O
generally	O
contain	O
less	O
ferric	O
iron	O
than	O
the	O
interbedded	O
oxidised	O
laminae	O
.	O

Examination	O
of	O
spidergrams	O
of	O
oxidised	O
and	O
reduced	O
laminae	O
in	O
the	O
MMG	O
confirms	O
that	O
in	O
most	O
sets	O
of	O
neighbouring	O
samples	O
Fe2O3	O
contents	O
are	O
lower	O
in	O
the	O
reduced	O
laminae	O
.	O

In	O
other	O
examples	O
,	O
such	O
as	O
the	O
Byley	LEXICON
Mudstones	LEXICON
of	O
Crewe	O
Borehole	O
,	O
the	O
reduced	O
samples	O
contain	O
more	O
sand	O
or	O
silt	O
than	O
the	O
neighbouring	O
oxidised	O
samples	O
and	O
hence	O
have	O
higher	O
SiO2	O
and	O
lower	O
Al2O3	O
.	O

As	O
discussed	O
in	O
connection	O
with	O
the	O
SSG	O
.	O

The	O
pyrite	O
in	O
the	O
MMG	O
is	O
clearly	O
eodiagenetic	O
and	O
can	O
be	O
seen	O
to	O
predate	O
compaction	O
,	O
as	O
demonstrated	O
by	O
compactional	O
deformation	O
of	O
sedimentary	O
laminae	O
,	O
and	O
less	O
competent	O
mica	O
grains	O
,	O
around	O
framboidal	O
aggregates	O
.	O

This	O
caused	O
expansive	O
disruption	O
of	O
sedimentary	O
fabrics	O
and	O
is	O
therefore	O
considered	O
to	O
have	O
formed	O
near-surface	O
,	O
probably	O
in	O
evaporitic	O
or	O
sabkha-type	O
environments	O
in	O
the	O
MMG	O
.	O

Patchy	O
micritic	O
non-ferroan	O
calcite	O
cement	O
is	O
also	O
locally	O
present	O
as	O
expansive	O
nodules	O
within	O
pelloidal	O
mudstones	O
in	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
Formation	O
and	O
may	O
represent	O
calcrete	O
development	O
.	O

Early	O
diagenesis	O
can	O
be	O
summarised	O
as	O
follows	O
,	O
using	O
the	O
scheme	O
adopted	O
for	O
the	O
SSG	O
:	O
DE1a	O
:	O
synsedimentary	O
development	O
of	O
red-bed	O
clay	O
and	O
iron-oxide	O
grain	O
coatings	O
.	O

DE2a	O
:	O
early	O
pore-filling	O
and	O
pore-lining	O
authigenic	O
corrensite	O
and	O
smectite	O
;	O
these	O
were	O
recognised	O
in	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
directly	O
as	O
authigenic	O
minerals	O
,	O
but	O
corrensite	O
identified	O
by	O
XRD	O
in	O
other	O
formations	O
is	O
consistent	O
with	O
early	O
synsedimentary	O
evaporative	O
lacustrine	O
environments	O
.	O

This	O
broadly	O
resembles	O
DE1	O
3	O
diagenesis	O
in	O
the	O
SSG	O
.	O

However	O
,	O
since	O
these	O
features	O
are	O
synsedimentary	O
in	O
origin	O
they	O
are	O
obviously	O
not	O
syngenetic	O
with	O
DE1	O
diagenesis	O
in	O
the	O
SSG	O
-RRB-	O
.	O

Burial	O
diagenesis	O
in	O
the	O
MMG	O
shows	O
many	O
similarities	O
with	O
the	O
sequences	O
of	O
cement	O
and	O
vein	O
paragenesis	O
in	O
the	O
underlying	O
SSG	O
and	O
is	O
summarised	O
in	O
Table	O
23	O
.	O

A	O
parallel	O
can	O
be	O
seen	O
between	O
this	O
and	O
the	O
DE2	O
to	O
DE3	O
stage	O
of	O
diagenesis	O
defined	O
in	O
the	O
SSG	O
.	O

Quartz	O
cements	O
clearly	O
developed	O
after	O
the	O
formation	O
of	O
dewatering	O
fabrics	O
observed	O
in	O
the	O
MMG	O
.	O

Within	O
the	O
main	O
halite	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
Formation	LEXICON
and	O
in	O
anhydrite	O
beds	O
in	O
the	O
Wych	LEXICON
Mudstone	LEXICON
Formation	LEXICON
,	O
authigenic	O
euhedral	O
porphyroblasts	O
of	O
quartz	O
are	O
developed	O
,	O
locally	O
replacing	O
the	O
evaporites	O
and	O
also	O
preserving	O
,	O
as	O
corroded	O
inclusions	O
,	O
early	O
unrecrystallised	O
and	O
largely	O
uncompacted	O
primary	O
aphanitic	O
anhydrite	O
fabrics	O
.	O

The	O
paragenetic	O
relationship	O
of	O
silicate	O
authigenesis	O
in	O
the	O
MMG	O
mirrors	O
DE4	O
in	O
the	O
SSG	O
.	O

Poikilotopic	O
anhydrite	O
cements	O
appear	O
later	O
during	O
the	O
diagenesis	O
of	O
the	O
MMG	O
.	O

Halite	O
has	O
been	O
clearly	O
remobilised	O
during	O
mesodiagenesis	O
and	O
reprecipitated	O
within	O
veins	O
and	O
as	O
poikilotopic	O
cements	O
in	O
the	O
MMG	O
.	O

These	O
fabrics	O
again	O
mirror	O
the	O
DE5	O
stage	O
evaporitic	O
cements	O
postulated	O
in	O
the	O
SSG	O
.	O

Late-stage	O
ferroan	O
dolomite	O
and	O
ankerite	O
occur	O
as	O
rhombic	O
overgrowths	O
on	O
corroded	O
mesodiagenetic	O
dolomite	O
in	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
Formation	LEXICON
.	O

However	O
,	O
in	O
the	O
Crewe	O
Heat	O
Flow	O
Borehole	O
veins	O
of	O
place	O
ferroan	O
dolomite	O
-	O
ankerite	O
authigenesis	O
in	O
the	O
MMG	O
in	O
a	O
similar	O
paragenetic	O
position	O
to	O
DE6b	O
features	O
in	O
the	O
SSG	O
.	O

The	O
framboidal	O
pyrite	O
in	O
the	O
MMG	O
is	O
commonly	O
overgrown	O
and	O
replaced	O
by	O
later	O
diagenetic	O
sulphides	O
of	O
Cu	O
,	O
Fe	O
+-	O
Zn	O
,	O
Pb	O
,	O
As	O
,	O
Co	O
,	O
Ni	O
,	O
Ag	O
,	O
Hg	O
and	O
,	O
rarely	O
,	O
traces	O
of	O
Ag-Cu-Au	O
.	O

In	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
Formation	LEXICON
chalcopyrite	O
and	O
late	O
relatively	O
coarsely	O
crystalline	O
pyrite	O
both	O
replace	O
and	O
pseudomorph	O
small	O
clustered	O
needles	O
and	O
swallow-tail	O
crystals	O
of	O
eodiagenetic	O
gypsum	O
.	O

This	O
sequence	O
:	O
early	O
framboidal	O
pyrite	O
,	O
followed	O
by	O
coarser	O
pyrite	O
,	O
overgrown	O
and	O
overprinted	O
by	O
chalcopyrite	O
,	O
corresponds	O
very	O
closely	O
with	O
the	O
paragenetic	O
relationships	O
illustrated	O
by	O
DE6d	O
in	O
the	O
SSG	O
.	O

Samples	O
from	O
oxidised	O
and	O
reduced	O
laminae	O
of	O
the	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
in	O
the	O
Crewe	O
Borehole	O
are	O
seen	O
to	O
be	O
very	O
similar	O
in	O
chemical	O
composition	O
,	O
the	O
only	O
systematic	O
differences	O
being	O
that	O
Fe	O
is	O
lower	O
and	O
Cu	O
higher	O
in	O
the	O
reduced	O
laminae	O
than	O
in	O
neighbouring	O
oxidised	O
laminae	O
.	O

In	O
a	O
suite	O
of	O
samples	O
from	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
of	O
the	O
Saughall	O
Massie	O
borehole	O
the	O
reduced	O
samples	O
contain	O
more	O
Ca	O
than	O
the	O
oxidised	O
samples	O
,	O
accompanied	O
by	O
higher	O
Mg	O
and	O
Mn	O
.	O

The	O
differences	O
between	O
the	O
oxidised	O
and	O
reduced	O
samples	O
observed	O
in	O
the	O
Byley	LEXICON
Mudstone	LEXICON
are	O
also	O
apparent	O
in	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
,	O
and	O
additionally	O
the	O
reduced	O
laminae	O
are	O
here	O
enriched	O
in	O
Co.	O
.	O

This	O
can	O
be	O
attributed	O
to	O
later	O
minor	O
to	O
trace	O
chalcopyrite	O
,	O
chalcocite	O
and	O
covellite	O
authigenesis	O
in	O
the	O
green	O
facies	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
.	O

Similarly	O
,	O
rare	O
late	O
cross-cutting	O
calcite	O
veinlets	O
carrying	O
small	O
amounts	O
of	O
baryte	O
may	O
be	O
correlated	O
with	O
DE6e	O
calcite	O
veining	O
in	O
the	O
SSG	O
.	O

Apart	O
from	O
late	O
fibrous	O
pore-lining	O
illite	O
in	O
the	O
arenaceous	O
facies	O
of	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
the	O
higher	O
stratigraphical	O
units	O
do	O
not	O
appear	O
to	O
demonstrate	O
diagenetic	O
features	O
similar	O
to	O
DE7	O
in	O
the	O
SSG	O
.	O

The	O
most	O
significant	O
telodiagenetic	O
effect	O
in	O
the	O
MMG	O
is	O
the	O
development	O
of	O
collapse	O
breccias	O
and	O
major	O
subsidence	O
associated	O
with	O
the	O
large-scale	O
dissolution	O
of	O
thick	O
halites	O
by	O
contemporary	O
groundwater	O
,	O
particularly	O
around	O
Nantwich	O
in	O
Cheshire	O
.	O

However	O
,	O
other	O
telodiagenetic	O
effects	O
include	O
the	O
hydration	O
of	O
anhydrite	O
cements	O
and	O
their	O
replacement	O
by	O
gypsum	O
in	O
near-surface	O
MMG	O
rocks	O
.	O

Sulphur-isotope	O
data	O
of	O
sulphur-bearing	O
mineral	O
species	O
may	O
be	O
used	O
to	O
place	O
constraints	O
on	O
the	O
source	O
of	O
sulphur	O
in	O
the	O
red-bed	O
mineralisation	O
in	O
the	O
SSG	O
.	O

It	O
has	O
been	O
proposed	O
earlier	O
,	O
that	O
the	O
SSG	O
may	O
have	O
had	O
significant	O
anhydrite	O
cement	O
prior	O
to	O
DE6	O
mineralisation	O
and	O
this	O
could	O
have	O
provided	O
an	O
in	O
situ	O
source	O
of	O
sulphate	O
.	O

Carboniferous	CHRONOSTRAT
basement	O
-RRB-	O
to	O
the	O
north	O
of	O
the	O
Mersey	O
and	O
in	O
the	O
Chester	O
area	O
.	O

Naylor	O
et	O
al.	O
noted	O
that	O
the	O
baryte	O
from	O
Clive	O
Grinshill	O
and	O
Bickerton	O
was	O
isotopically	O
similar	O
in	O
d34S	O
values	O
to	O
the	O
evaporites	O
within	O
the	O
MMG	O
.	O

They	O
therefore	O
concluded	O
that	O
much	O
of	O
the	O
baryte	O
sulphate	O
was	O
derived	O
ultimately	O
from	O
Triassic	CHRONOSTRAT
evaporites	O
.	O

They	O
invoked	O
the	O
involvement	O
of	O
a	O
lighter	O
sulphate	O
component	O
,	O
derived	O
by	O
oxidation	O
of	O
reduced	O
sulphide	O
from	O
the	O
underlying	O
Carboniferous	CHRONOSTRAT
,	O
to	O
account	O
for	O
the	O
lighter	O
baryte	O
in	O
the	O
Alderley	O
Edge	O
area	O
.	O

Their	O
comparisons	O
of	O
baryte	O
with	O
evaporite	O
sources	O
were	O
based	O
on	O
only	O
three	O
samples	O
of	O
anhydrite	O
and	O
gypsum	O
for	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
Formation	LEXICON
.	O

A	O
more	O
systematic	O
study	O
of	O
sulphur	O
isotope	O
variation	O
within	O
the	O
MMG	O
evaporites	O
in	O
the	O
Cheshire	O
Basin	O
was	O
undertaken	O
in	O
the	O
present	O
study	O
,	O
and	O
the	O
data	O
are	O
summarised	O
in	O
Figure	O
104	O
.	O

d34S	O
data	O
for	O
sulphates	O
were	O
obtained	O
from	O
all	O
formations	O
except	O
the	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
and	O
Northwich	LEXICON
Halite	LEXICON
Formation	LEXICON
.	O

Consequently	O
,	O
hydration	O
and	O
replacement	O
of	O
primary	O
anhydrite	O
by	O
gypsum	O
will	O
not	O
produce	O
any	O
significant	O
isotopic	O
fractionation	O
,	O
and	O
secondary	O
gypsum	O
should	O
be	O
similar	O
to	O
the	O
original	O
anhydrite	O
,	O
which	O
in	O
turn	O
should	O
closely	O
approximate	O
to	O
the	O
d34S	O
value	O
of	O
the	O
lacustro-marine	O
waters	O
from	O
which	O
the	O
MMG	O
was	O
deposited	O
.	O

The	O
data	O
show	O
that	O
below	O
the	O
Byley	LEXICON
Mudstone	LEXICON
Formation	LEXICON
,	O
d34S	O
compositions	O
of	O
MMG	O
evaporites	O
closely	O
follow	O
the	O
Triassic	CHRONOSTRAT
marine	O
sulphate	O
evolution	O
,	O
indicating	O
a	O
strong	O
influence	O
of	O
Triassic	CHRONOSTRAT
marine-derived	O
sulphate	O
in	O
the	O
evaporitic	O
and	O
sabkha	O
sediments	O
of	O
the	O
Lower	O
MMG	O
.	O

The	O
S	O
isotopic	O
compositions	O
are	O
significantly	O
depleted	O
in	O
34S	O
,	O
with	O
respect	O
to	O
the	O
Triassic	CHRONOSTRAT
sea-water	O
curve	O
,	O
in	O
the	O
Wych	LEXICON
Mudstone	LEXICON
Formation	LEXICON
and	O
again	O
in	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
Formation	LEXICON
.	O

This	O
indicates	O
a	O
strong	O
continental-derived	O
brine	O
influence	O
,	O
and	O
greater	O
isolation	O
from	O
Triassic	CHRONOSTRAT
marine	O
circulation	O
,	O
in	O
the	O
Wych	LEXICON
and	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
formations	O
.	O

The	O
lighter	O
d34S	O
sulphate	O
in	O
these	O
continental	O
brines	O
could	O
feasibly	O
have	O
been	O
dominated	O
by	O
re-working	O
of	O
earlier	O
Permian	CHRONOSTRAT
sulphates	O
.	O

Although	O
only	O
a	O
single	O
analysis	O
was	O
obtained	O
from	O
the	O
Wilklesey	LEXICON
Halite	LEXICON
Formation	LEXICON
,	O
the	O
d34S	O
value	O
of	O
primary	O
anhydrite	O
indicates	O
a	O
return	O
to	O
an	O
evaporative	O
environment	O
influenced	O
by	O
a	O
Triassic	CHRONOSTRAT
marine	O
sulphate	O
source	O
,	O
and	O
is	O
consistent	O
with	O
the	O
development	O
of	O
a	O
large	O
thickness	O
of	O
halite	O
in	O
this	O
formation	O
.	O

Figure	O
104	O
shows	O
that	O
the	O
MMG	O
sediments	O
and	O
DE1	O
evaporites	O
generally	O
became	O
progressively	O
depleted	O
in	O
34S	O
with	O
time	O
;	O
from	O
values	O
between	O
14.8	O
degrees	O
and	O
20.8	O
degrees	O
in	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
and	O
Bollin	LEXICON
Mudstone	LEXICON
formations	O
to	O
values	O
between	O
10.3	O
degrees	O
and	O
14.3	O
degrees	O
in	O
the	O
Brooks	LEXICON
Mill	LEXICON
Mudstone	LEXICON
Formation	LEXICON
.	O

Comparison	O
of	O
these	O
data	O
with	O
baryte	O
from	O
the	O
SSG	O
-	O
hosted	O
Cu-Pb-Ba	O
mineralisation	O
clearly	O
shows	O
that	O
the	O
d34S	O
values	O
for	O
baryte	O
are	O
all	O
within	O
the	O
range	O
of	O
values	O
of	O
primary	O
evaporites	O
in	O
the	O
MMG	O
.	O

Since	O
little	O
34S	O
fractionation	O
occurs	O
between	O
solution	O
and	O
mineral	O
on	O
dissolution	O
and	O
re-precipitation	O
of	O
anhydrite	O
or	O
gypsum	O
at	O
low	O
temperature	O
,	O
the	O
baryte	O
compositions	O
in	O
the	O
SSG	O
can	O
all	O
be	O
accounted	O
for	O
by	O
precipitation	O
from	O
sulphate	O
ultimately	O
derived	O
from	O
the	O
MMG	O
.	O

The	O
differences	O
in	O
d34S	O
between	O
the	O
Alderley	O
Horst	O
mineralisation	O
and	O
Cu-Pb-Ba	O
mineralisation	O
in	O
the	O
south	O
of	O
the	O
basin	O
may	O
simply	O
reflect	O
tapping	O
of	O
brines	O
or	O
sulphate	O
sources	O
from	O
different	O
parts	O
of	O
the	O
MMG	O
.	O

The	O
d34S	O
data	O
suggest	O
that	O
sulphur	O
in	O
the	O
mineralised	O
areas	O
in	O
the	O
south	O
and	O
west	O
of	O
the	O
basin	O
was	O
originally	O
derived	O
from	O
sulphate	O
brines	O
dominantly	O
tapped	O
from	O
sources	O
within	O
the	O
lower	O
part	O
of	O
the	O
MMG	O
.	O

In	O
contrast	O
,	O
the	O
Alderley	O
Horst	O
mineralisation	O
has	O
d34S	O
signatures	O
that	O
could	O
reflect	O
sulphate	O
from	O
brines	O
derived	O
throughout	O
most	O
of	O
the	O
MMG	O
sequence	O
but	O
with	O
a	O
possible	O
bias	O
towards	O
sediments	O
between	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
and	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
Formation	LEXICON
.	O

The	O
subtle	O
differences	O
in	O
metalliferous	O
mineralisation	O
between	O
the	O
different	O
areas	O
may	O
similarly	O
be	O
related	O
to	O
different	O
parts	O
of	O
the	O
MMG	O
being	O
brine-tapped	O
.	O

For	O
the	O
SSG	O
,	O
detailed	O
examination	O
of	O
more	O
than	O
30	O
sandstone	O
samples	O
failed	O
to	O
identify	O
early	O
diagenetic	O
for	O
microthermometric	O
analysis	O
in	O
the	O
quartz	O
overgrowths	O
or	O
carbonate	O
cements	O
.	O

To	O
address	O
the	O
mineralising	O
role	O
of	O
gravity	O
-	O
driven	O
evaporite	O
brines	O
from	O
the	O
MMG	O
into	O
the	O
underlying	O
SSG	O
,	O
a	O
laser	O
ablation	O
ICP-MS	O
analysis	O
was	O
carried	O
out	O
of	O
liquid	O
inclusions	O
in	O
halite	O
from	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
Formation	LEXICON
.	O

In	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
,	O
the	O
halite	O
is	O
commonly	O
intergrown	O
with	O
reddish-brown	O
mudstone	O
and	O
displays	O
relic	O
chevron	O
or	O
cornet	O
textures	O
suggesting	O
primary	O
crystallisation	O
fabrics	O
.	O

The	O
preferred	O
temperature	O
regime	O
is	O
in	O
good	O
agreement	O
with	O
the	O
estimated	O
mean	O
basin	O
temperature	O
of	O
~	O
60	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
SSG	O
for	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
.	O

Fluids	O
associated	O
with	O
fracture-controlled	O
calcite	O
pyrite	O
mineralisation	O
in	O
the	O
SSG	O
of	O
the	O
Thornton	O
Borehole	O
on	O
the	O
fringe	O
of	O
the	O
East	O
Irish	O
Sea	O
Basin	O
.	O

Data	O
for	O
the	O
stratigraphically	O
lowest	O
samples	O
in	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
Formation	LEXICON
are	O
conspicuously	O
depleted	O
in	O
K	O
,	O
Mn	O
,	O
Cu	O
,	O
Rb	O
,	O
Ba	O
and	O
Pb	O
compared	O
with	O
data	O
from	O
all	O
higher	O
samples	O
.	O

Values	O
for	O
Mg	O
and	O
K	O
are	O
in	O
good	O
agreement	O
with	O
the	O
fluid	O
data	O
for	O
massive	O
Miocene	CHRONOSTRAT
halite	O
units	O
in	O
the	O
Lorca	O
basin	O
,	O
south-east	O
Spain	O
.	O

Thus	O
the	O
evaporite	O
bitterns	O
of	O
the	O
MMG	O
constitute	O
a	O
newly	O
discovered	O
and	O
potentially	O
major	O
source	O
of	O
metals	O
for	O
sandstone-hosted	O
mineralisation	O
in	O
the	O
Cheshire	O
Basin	O
.	O

One	O
sample	O
,	O
from	O
a	O
seep	O
in	O
Westphalian	CHRONOSTRAT
strata	O
at	O
Hem	O
Heath	O
Colliery	O
just	O
outside	O
the	O
south-east	O
margin	O
of	O
the	O
basin	O
,	O
is	O
a	O
mature	O
,	O
light	O
crude	O
oil	O
,	O
showing	O
few	O
signs	O
of	O
oxidation	O
or	O
biodegradation	O
.	O

The	O
data	O
are	O
consistent	O
with	O
migration	O
of	O
hydrocarbons	O
from	O
the	O
Westphalian	CHRONOSTRAT
sequence	O
beneath	O
or	O
adjacent	O
to	O
the	O
basin	O
.	O

This	O
component	O
was	O
derived	O
from	O
organic	O
matter	O
subject	O
to	O
a	O
higher	O
degree	O
of	O
thermal	O
maturation	O
probably	O
within	O
Carboniferous	CHRONOSTRAT
strata	O
.	O

Detailed	O
petrographic	O
and	O
stable-isotopic	O
investigation	O
of	O
the	O
SSG	O
and	O
MMG	O
in	O
the	O
Cheshire	O
Basin	O
have	O
revealed	O
a	O
complex	O
sequence	O
of	O
diagenetic	O
modifications	O
.	O

Early	O
diagenesis	O
of	O
the	O
SSG	O
in	O
the	O
Cheshire	O
Basin	O
was	O
similar	O
to	O
that	O
observed	O
in	O
other	O
UK	O
Triassic	CHRONOSTRAT
basins	O
.	O

There	O
is	O
some	O
evidence	O
of	O
possible	O
zonation	O
in	O
the	O
distribution	O
of	O
calcrete	O
and	O
dolocrete	O
within	O
the	O
lower	O
part	O
of	O
the	O
SSG	O
.	O

Similar	O
early	O
diagenetic	O
processes	O
affected	O
sandy	O
facies	O
in	O
the	O
MMG	O
.	O

Sulphur-isotope	O
data	O
for	O
the	O
lower	O
MMG	O
and	O
the	O
later	O
Wilkesley	LEXICON
Halite	LEXICON
Formation	LEXICON
indicate	O
that	O
primary	O
and	O
eodiagenetic	O
evaporites	O
were	O
derived	O
largely	O
from	O
brines	O
of	O
Triassic	CHRONOSTRAT
marine	O
origin	O
.	O

However	O
,	O
evaporites	O
formed	O
during	O
the	O
middle	O
MMG	O
.	O

The	O
effect	O
was	O
to	O
produce	O
characteristic	O
reduced	O
green	O
beds	O
and	O
reduction	O
spots	O
,	O
common	O
in	O
the	O
MMG	O
and	O
seen	O
locally	O
in	O
the	O
finer-grained	O
parts	O
of	O
fluvial	O
cycles	O
in	O
the	O
SSG	O
.	O

Authigenic	O
smectitic	O
and	O
corrensitic	O
pore-lining	O
clays	O
precipitated	O
in	O
some	O
sandstones	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
and	O
Tarporley	LEXICON
Siltstone	LEXICON
formations	O
,	O
and	O
in	O
part	O
replaced	O
detrital	O
clays	O
and	O
micas	O
.	O

Corrensite	O
was	O
identified	O
in	O
most	O
MMG	O
formations	O
but	O
its	O
diagenetic	O
fabrics	O
were	O
not	O
observed	O
.	O

It	O
seems	O
likely	O
,	O
therefore	O
,	O
that	O
the	O
corrensite	O
observed	O
in	O
the	O
MMG	O
is	O
similarly	O
of	O
eodiagenetic	O
origin	O
,	O
since	O
the	O
depositional	O
environments	O
of	O
the	O
MMG	O
were	O
likely	O
to	O
have	O
been	O
hypersaline	O
.	O

Neoformation	O
and	O
overgrowth	O
of	O
idiomorphic	O
dolomites	O
and	O
the	O
formation	O
of	O
authigenic	O
quartz	O
and	O
feldspar	O
cements	O
and	O
overgrowths	O
are	O
common	O
features	O
in	O
both	O
the	O
SSG	O
and	O
the	O
MMG	O
.	O

In	O
the	O
MMG	O
,	O
evidence	O
can	O
be	O
found	O
for	O
early	O
diagenetic	O
dissolution	O
of	O
halite	O
.	O

Later	O
mesodiagenetic	O
fabrics	O
show	O
that	O
anhydrite	O
was	O
remobilised	O
and	O
redistributed	O
as	O
a	O
mesodiagenetic	O
in	O
siltstones	O
and	O
dolomicrites	O
in	O
the	O
MMG	O
.	O

Many	O
of	O
the	O
porous	O
sandstones	O
of	O
the	O
SSG	O
have	O
fabrics	O
indicating	O
that	O
the	O
porosity	O
is	O
largely	O
secondary	O
,	O
resulting	O
from	O
the	O
dissolution	O
of	O
an	O
early	O
mesodiagenetic	O
cement	O
.	O

Many	O
of	O
the	O
diagenetic	O
features	O
are	O
common	O
to	O
both	O
MMG	O
and	O
SSG	O
rocks	O
.	O

However	O
,	O
eodiagenesis	O
and	O
early	O
mesodiagenesis	O
within	O
the	O
MMG	O
and	O
SSG	O
were	O
obviously	O
diachronous	O
since	O
they	O
are	O
contemporary	O
with	O
sedimentation	O
and	O
shallow	O
burial	O
.	O

However	O
,	O
it	O
seems	O
very	O
likely	O
that	O
later	O
mesodiagenesis	O
in	O
both	O
formations	O
was	O
linked	O
and	O
related	O
to	O
brine	O
expulsion	O
along	O
permeable	O
paths	O
during	O
burial	O
dewatering	O
of	O
the	O
MMG	O
.	O

Copper	O
is	O
variably	O
enriched	O
in	O
the	O
reduced	O
beds	O
of	O
the	O
MMG	O
.	O

It	O
is	O
suggested	O
that	O
diagenetic	O
brines	O
in	O
the	O
MMG	O
mobilised	O
these	O
metals	O
in	O
solution	O
and	O
were	O
thus	O
a	O
potential	O
source	O
of	O
mineralising	O
fluids	O
''	O
as	O
is	O
also	O
seen	O
from	O
the	O
geochemical	O
compositions	O
of	O
fluid	O
inclusions	O
trapped	O
within	O
MMG	O
halites	O
.	O

The	O
quantities	O
of	O
metals	O
involved	O
are	O
not	O
great	O
,	O
possibly	O
because	O
of	O
the	O
limited	O
supply	O
of	O
reduced	O
sulphur	O
,	O
but	O
the	O
presence	O
of	O
metal	O
sulphides	O
in	O
the	O
reduced	O
laminae	O
of	O
the	O
MMG	O
illustrates	O
,	O
in	O
microcosm	O
,	O
the	O
processes	O
by	O
which	O
migrating	O
Cu-bearing	O
saline	O
solutions	O
deposit	O
their	O
load	O
of	O
Cu	O
when	O
they	O
encounter	O
reducing	O
conditions	O
.	O

Similar	O
authigenic	O
sulphide	O
paragenetic	O
assemblages	O
are	O
observed	O
in	O
the	O
SSG	O
.	O

No	O
evidence	O
could	O
be	O
found	O
for	O
the	O
migration	O
of	O
liquid	O
hydrocarbons	O
into	O
the	O
SSG	O
before	O
or	O
during	O
base-metal	O
mineralisation	O
.	O

Though	O
the	O
presence	O
of	O
gaseous	O
hydrocarbons	O
in	O
the	O
SSG	O
prior	O
to	O
mineralisation	O
can	O
not	O
be	O
discounted	O
,	O
a	O
model	O
for	O
sulphide	O
deposition	O
involving	O
light	O
hydrocarbon	O
gases	O
remains	O
unproven	O
.	O

Chemical	O
analysis	O
of	O
brine	O
inclusions	O
in	O
halite	O
from	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
Formation	LEXICON
demonstrates	O
that	O
the	O
early	O
diagenetic	O
evaporite	O
fluids	O
were	O
already	O
significantly	O
enriched	O
in	O
Cu	O
,	O
Pb	O
and	O
Ba	O
prior	O
to	O
their	O
migration	O
into	O
the	O
SSG	O
.	O

Subsequent	O
leaching	O
of	O
metals	O
from	O
the	O
SSG	O
would	O
further	O
enhance	O
their	O
mineralising	O
potential	O
.	O

Sulphur	O
isotope	O
data	O
provide	O
strong	O
evidence	O
that	O
the	O
sulphur	O
in	O
DE6	O
sulphide	O
mineralisation	O
and	O
associated	O
baryte	O
mineralisation	O
was	O
derived	O
from	O
the	O
overlying	O
MMG	O
.	O

However	O
,	O
petrographic	O
evidence	O
alluded	O
to	O
above	O
indicates	O
that	O
this	O
sulphur	O
was	O
already	O
in	O
place	O
,	O
probably	O
as	O
anhydrite	O
cementing	O
the	O
SSG	O
sandstones	O
,	O
and	O
therefore	O
was	O
not	O
brought	O
into	O
the	O
SSG	O
at	O
the	O
same	O
time	O
as	O
the	O
metals	O
.	O

This	O
implies	O
that	O
anhydrite-saturated	O
brines	O
must	O
have	O
penetrated	O
from	O
the	O
MMG	O
into	O
the	O
SSG	O
during	O
DE5	O
.	O

Later	O
DE6	O
brines	O
from	O
the	O
MMG	O
may	O
have	O
been	O
low-sulphate	O
NaCl	O
brines	O
,	O
in	O
contrast	O
to	O
the	O
earlier	O
DE5	O
anhydrite-saturated	O
fluids	O
.	O

Petrographic	O
observations	O
in	O
the	O
MMG	O
show	O
that	O
anhydrite	O
is	O
corroded	O
by	O
NaCl	O
brines	O
during	O
halite	O
remobilisation	O
.	O

The	O
late	O
DE6	O
NaCl-type	O
brines	O
would	O
have	O
dissolved	O
the	O
anhydrite	O
cements	O
on	O
entering	O
the	O
SSG	O
,	O
and	O
immediately	O
any	O
Ba	O
in	O
solution	O
would	O
have	O
been	O
deposited	O
as	O
baryte	O
.	O

This	O
is	O
consistent	O
with	O
the	O
fracture-controlled	O
distribution	O
of	O
baryte	O
in	O
the	O
SSG	O
,	O
and	O
with	O
the	O
evidence	O
for	O
several	O
different	O
fluids	O
having	O
been	O
produced	O
in	O
the	O
MMG	O
at	O
different	O
times	O
.	O

Differences	O
in	O
the	O
sulphur	O
isotopic	O
signature	O
of	O
baryte	O
between	O
different	O
deposits	O
across	O
the	O
basin	O
can	O
be	O
accounted	O
for	O
by	O
differences	O
in	O
the	O
stratigraphical	O
level	O
of	O
the	O
MMG	O
from	O
which	O
the	O
DE5	O
anhydrite-mineralising	O
brines	O
were	O
originally	O
sourced	O
.	O

In	O
the	O
south	O
and	O
west	O
of	O
the	O
basin	O
,	O
DE5	O
fluids	O
have	O
affinities	O
suggesting	O
derivation	O
largely	O
from	O
the	O
lower	O
part	O
of	O
the	O
MMG	O
.	O

In	O
contrast	O
,	O
isotopic	O
signatures	O
in	O
the	O
Alderley	O
Horst	O
area	O
suggest	O
that	O
DE5	O
brines	O
were	O
derived	O
from	O
a	O
slightly	O
higher	O
stratigraphical	O
level	O
in	O
the	O
MMG	O
.	O

The	O
mechanism	O
for	O
metal-sulphide	O
precipitation	O
in	O
the	O
SSG	O
is	O
more	O
problematic	O
since	O
it	O
requires	O
reduction	O
of	O
the	O
sulphate	O
.	O

It	O
is	O
unlikely	O
that	O
this	O
component	O
was	O
introduced	O
in	O
the	O
late	O
DE6	O
metalliferous	O
brines	O
derived	O
from	O
the	O
MMG	O
because	O
the	O
reducing	O
nature	O
of	O
the	O
fluid	O
would	O
have	O
severely	O
limited	O
the	O
transport	O
of	O
Cu	O
.	O

This	O
dominance	O
may	O
be	O
related	O
to	O
geographical	O
differences	O
in	O
the	O
nature	O
of	O
the	O
basement	O
underlying	O
the	O
basin	O
,	O
and/or	O
to	O
fluids	O
interacting	O
with	O
different	O
parts	O
of	O
the	O
Carboniferous	CHRONOSTRAT
sequence	O
due	O
to	O
variations	O
in	O
the	O
nature	O
of	O
the	O
subsurface	O
plumbing	O
system	O
.	O

This	O
comprehensive	O
publication	O
was	O
used	O
to	O
follow	O
the	O
development	O
of	O
the	O
Cheshire	O
Basin	O
from	O
Permian	CHRONOSTRAT
times	O
to	O
the	O
present	O
day	O
.	O

Early	CHRONOSTRAT
Permian	CHRONOSTRAT
deposition	O
in	O
the	O
Cheshire	O
Basin	O
area	O
was	O
characterised	O
by	O
aeolian	O
sands	O
and	O
sand	O
dunes	O
in	O
a	O
desert	O
environment	O
.	O

During	O
the	O
late	O
Permian	CHRONOSTRAT
,	O
the	O
Zechstein	O
Sea	O
encroached	O
from	O
the	O
east	O
and	O
the	O
Bakevellia	O
Sea	O
extended	O
into	O
Lancashire	O
as	O
far	O
as	O
Manchester	O
but	O
did	O
not	O
cover	O
the	O
Cheshire	O
Basin	O
.	O

In	O
the	O
early	O
Triassic	CHRONOSTRAT
sandy	O
conglomeratic	O
deposits	O
continued	O
to	O
be	O
laid	O
down	O
,	O
the	O
sediments	O
being	O
derived	O
from	O
the	O
south	O
.	O

By	O
the	O
mid	O
-	O
Triassic	CHRONOSTRAT
,	O
the	O
system	O
drained	O
into	O
a	O
shallow	O
hypersaline	O
sea	O
to	O
the	O
north	O
of	O
the	O
Wirral	O
.	O

In	O
late	O
Triassic	CHRONOSTRAT
times	O
,	O
the	O
Cheshire	O
Basin	O
area	O
was	O
again	O
an	O
area	O
of	O
alluvial	O
deposition	O
and	O
a	O
shallow	O
fresh	O
groundwater	O
system	O
was	O
probably	O
established	O
,	O
while	O
saline	O
water	O
probably	O
persisted	O
at	O
depth	O
.	O

During	O
the	O
latest	O
Triassic	CHRONOSTRAT
,	O
shallow	O
seas	O
covered	O
the	O
area	O
and	O
saline	O
water	O
would	O
probably	O
have	O
displaced	O
any	O
fresh	O
groundwater	O
as	O
the	O
sea	O
encroached	O
over	O
the	O
land	O
.	O

Jurassic	CHRONOSTRAT
sediments	O
were	O
deposited	O
and	O
eroded	O
sequentially	O
in	O
the	O
Cheshire	O
Basin	O
throughout	O
the	O
period	O
,	O
though	O
few	O
are	O
now	O
preserved	O
.	O

During	O
the	O
early	O
Jurassic	CHRONOSTRAT
the	O
Cheshire	O
Basin	O
area	O
was	O
inundated	O
,	O
and	O
the	O
surrounding	O
area	O
contained	O
several	O
land	O
masses	O
.	O

In	O
mid	O
-	O
Jurassic	CHRONOSTRAT
times	O
which	O
extended	O
to	O
the	O
southern	O
Irish	O
Sea	O
.	O

The	O
sea	O
varied	O
in	O
extent	O
throughout	O
the	O
mid	O
-	O
Jurassic	CHRONOSTRAT
but	O
did	O
not	O
inundate	O
the	O
Cheshire	O
Basin	O
until	O
c.	O
158Ma	O
.	O

During	O
the	O
remainder	O
of	O
the	O
mid	O
-	O
Jurassic	CHRONOSTRAT
and	O
into	O
the	O
late	O
Jurassic	CHRONOSTRAT
the	O
area	O
remained	O
submerged	O
but	O
the	O
sediments	O
deposited	O
there	O
have	O
been	O
subsequently	O
eroded	O
.	O

The	O
Cheshire	O
Basin	O
was	O
again	O
emergent	O
as	O
part	O
of	O
the	O
largely	O
low-relief	O
Anglo	O
-	O
Welsh	O
land	O
mass	O
in	O
late	O
Jurassic	CHRONOSTRAT
times	O
.	O

During	O
the	O
early	O
Cretaceous	CHRONOSTRAT
the	O
Cheshire	O
Basin	O
was	O
an	O
area	O
of	O
low	O
relief	O
;	O
the	O
Pennine	O
land	O
mass	O
lay	O
to	O
the	O
north-east	O
and	O
the	O
Welsh	O
land	O
mass	O
to	O
the	O
south-west	O
.	O

Fresh	O
groundwater	O
in	O
the	O
Triassic	CHRONOSTRAT
sandstones	O
would	O
probably	O
have	O
been	O
replaced	O
by	O
saline	O
water	O
.	O

Most	O
of	O
the	O
British	O
Isles	O
was	O
land	O
throughout	O
the	O
Tertiary	CHRONOSTRAT
,	O
although	O
the	O
coastline	O
moved	O
considerably	O
during	O
the	O
period	O
.	O

In	O
mid	O
to	O
late	O
Oligocene	CHRONOSTRAT
times	O
a	O
south-west-flowing	O
river	O
in	O
the	O
southern	O
Irish	O
Sea	O
is	O
postulated	O
.	O

Sea-level	O
fluctuations	O
during	O
the	O
Quaternary	CHRONOSTRAT
would	O
have	O
resulted	O
in	O
coastlines	O
moving	O
and	O
base	O
drainage	O
levels	O
changing	O
.	O

The	O
palaeo-hydrogeological	O
reconstruction	O
suggests	O
that	O
the	O
Cheshire	O
Basin	O
would	O
have	O
been	O
filled	O
with	O
highly	O
saline	O
brines	O
during	O
Permian	CHRONOSTRAT
and	O
Triassic	CHRONOSTRAT
times	O
except	O
during	O
the	O
later	O
Triassic	CHRONOSTRAT
when	O
a	O
shallow	O
fresh	O
groundwater	O
system	O
may	O
have	O
been	O
established	O
.	O

With	O
alternating	O
inundation	O
and	O
emergence	O
during	O
the	O
latest	O
Triassic	CHRONOSTRAT
and	O
in	O
Jurassic	CHRONOSTRAT
and	O
Cretaceous	CHRONOSTRAT
times	O
,	O
shallow	O
fresh	O
groundwater	O
systems	O
would	O
be	O
periodically	O
established	O
and	O
then	O
replaced	O
by	O
encroaching	O
saline	O
water	O
.	O

The	O
density	O
of	O
this	O
water	O
would	O
,	O
however	O
,	O
be	O
less	O
than	O
that	O
of	O
the	O
Triassic	CHRONOSTRAT
brines	O
,	O
some	O
of	O
which	O
could	O
be	O
present	O
at	O
depth	O
to	O
this	O
day	O
.	O

Since	O
the	O
last	O
major	O
inundation	O
of	O
the	O
Cheshire	O
Basin	O
in	O
the	O
Cretaceous	CHRONOSTRAT
,	O
uplift	O
and	O
erosion	O
has	O
established	O
shallow	O
,	O
fresh	O
groundwater	O
systems	O
superimposed	O
on	O
deeper	O
saline	O
and	O
brine	O
groundwater	O
systems	O
,	O
particularly	O
where	O
the	O
arenaceous	O
aquifers	O
are	O
unconfined	O
.	O

With	O
removal	O
of	O
Cretaceous	CHRONOSTRAT
and	O
Jurassic	CHRONOSTRAT
sediments	O
,	O
these	O
systems	O
would	O
have	O
evolved	O
into	O
the	O
present	O
system	O
.	O

On	O
a	O
local	O
scale	O
,	O
the	O
SSG	O
consists	O
of	O
several	O
aquifer	O
units	O
with	O
varying	O
rest	O
water	O
levels	O
over	O
short	O
distances	O
.	O

Along	O
the	O
south-east	O
margins	O
of	O
the	O
SSG	O
outcrop	O
the	O
potentiometric	O
surface	O
is	O
up	O
to	O
100m	O
above	O
OD	O
,	O
though	O
40	O
to	O
50m	O
above	O
OD	O
is	O
more	O
common	O
.	O

The	O
mudstones	O
of	O
the	O
Manchester	LEXICON
Marls	LEXICON
,	O
which	O
separate	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
from	O
the	O
Triassic	CHRONOSTRAT
aquifers	O
,	O
form	O
a	O
significant	O
barrier	O
to	O
groundwater	O
flow	O
in	O
the	O
north	O
of	O
the	O
basin	O
as	O
they	O
dip	O
southward	O
beneath	O
the	O
Mersey	O
.	O

These	O
groundwater	O
flow	O
regimes	O
are	O
the	O
present-day	O
active	O
systems	O
where	O
the	O
SSG	O
is	O
not	O
overlain	O
by	O
the	O
MMG	O
.	O

Most	O
recharge	O
reaches	O
the	O
SSG	O
via	O
the	O
thick	O
cover	O
of	O
drift	O
.	O

In	O
the	O
west	O
of	O
the	O
basin	O
,	O
the	O
SSG	O
is	O
in	O
contact	O
with	O
Lower	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
Limestone	O
through	O
a	O
series	O
of	O
en-echelon	O
faults	O
with	O
throws	O
up	O
to	O
300m	O
locally	O
.	O

A	O
long	O
history	O
of	O
over-pumping	O
from	O
boreholes	O
on	O
both	O
sides	O
of	O
the	O
Mersey	O
estuary	O
,	O
particularly	O
at	O
Liverpool	O
and	O
along	O
the	O
Manchester	O
Ship	O
Canal	O
,	O
has	O
resulted	O
in	O
saline	O
intrusion	O
into	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
aquifer	O
.	O

Geophysical	O
logs	O
from	O
NCB	O
boreholes	O
indicate	O
high-salinity	O
groundwater	O
in	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
in	O
the	O
north	O
of	O
the	O
basin	O
.	O

This	O
salinity	O
is	O
found	O
to	O
the	O
base	O
of	O
the	O
aquifer	O
at	O
850m	O
where	O
it	O
overlies	O
the	O
Carboniferous	CHRONOSTRAT
.	O

Similar	O
profiles	O
are	O
found	O
in	O
several	O
boreholes	O
;	O
in	O
some	O
the	O
salinity	O
rapidly	O
increases	O
beneath	O
the	O
Manchester	LEXICON
Marls	LEXICON
,	O
which	O
restricts	O
groundwater	O
flow	O
and	O
has	O
isolated	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
aquifer	O
from	O
overlying	O
sandstone	O
units	O
.	O

Further	O
evidence	O
of	O
saline	O
groundwater	O
at	O
depth	O
was	O
obtained	O
from	O
a	O
sample	O
collected	O
near	O
Chester	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
underlying	O
the	O
Triassic	CHRONOSTRAT
at	O
a	O
depth	O
of	O
about	O
500m	O
.	O

The	O
spring	O
issues	O
from	O
Drift	O
underlain	O
by	O
the	O
Erbistock	LEXICON
Beds	LEXICON
of	O
the	O
Coal	LEXICON
Measures	LEXICON
,	O
which	O
form	O
an	O
inlier	O
to	O
the	O
south	O
of	O
Chester	O
.	O

The	O
driving	O
force	O
required	O
to	O
cause	O
the	O
saline	O
water	O
to	O
rise	O
to	O
the	O
surface	O
may	O
originate	O
in	O
the	O
outcrop	O
of	O
Coal	LEXICON
Measures	LEXICON
to	O
the	O
west	O
or	O
from	O
the	O
density-driven	O
system	O
beneath	O
the	O
MMG	O
to	O
the	O
east	O
.	O

Where	O
the	O
SSG	O
underlies	O
the	O
MMG	O
,	O
however	O
,	O
the	O
aquifer	O
has	O
not	O
been	O
exploited	O
and	O
the	O
only	O
information	O
available	O
is	O
from	O
a	O
few	O
deep	O
wells	O
drilled	O
for	O
research	O
or	O
hydrocarbon	O
exploration	O
.	O

Temperature	O
gradients	O
in	O
the	O
MMG	O
are	O
around	O
23	O
degrees	O
C/km	O
and	O
in	O
the	O
SSG	O
are	O
about	O
14	O
degrees	O
C/km	O
.	O

The	O
source	O
of	O
the	O
brine	O
was	O
assumed	O
to	O
be	O
the	O
MMG	O
,	O
where	O
extensive	O
halite	O
beds	O
are	O
found	O
.	O

The	O
freshwater	O
calculations	O
were	O
run	O
as	O
a	O
steady-state	O
simulation	O
while	O
the	O
brine-driven	O
flows	O
were	O
followed	O
in	O
transient	O
mode	O
from	O
an	O
initial	O
condition	O
in	O
which	O
all	O
water	O
was	O
fresh	O
,	O
except	O
in	O
the	O
source	O
zone	O
of	O
the	O
MMG	O
,	O
until	O
an	O
apparent	O
steady	O
state	O
was	O
achieved	O
.	O

In	O
addition	O
,	O
the	O
MMG	O
forms	O
a	O
confining	O
layer	O
to	O
the	O
Triassic	CHRONOSTRAT
sandstone	O
aquifers	O
,	O
which	O
are	O
under	O
artesian	O
conditions	O
in	O
this	O
calculation	O
.	O

Flow	O
rates	O
in	O
the	O
sandstone	O
layers	O
are	O
typically	O
of	O
the	O
order	O
of	O
5.0	O
e	O
10	O
m/s	O
from	O
east	O
to	O
west	O
,	O
while	O
those	O
in	O
the	O
MMG	O
are	O
of	O
the	O
order	O
of	O
3.0	O
e	O
11	O
m/s	O
.	O

The	O
second	O
calculation	O
that	O
was	O
performed	O
assumed	O
that	O
saturated	O
brines	O
with	O
a	O
density	O
of	O
1200	O
kg/m3	O
form	O
a	O
continuous	O
band	O
in	O
the	O
lower	O
part	O
of	O
the	O
MMG	O
.	O

It	O
is	O
seen	O
that	O
the	O
flow	O
is	O
now	O
generally	O
downwards	O
in	O
the	O
central	O
part	O
of	O
the	O
basin	O
under	O
the	O
influence	O
of	O
the	O
dense	O
brines	O
originating	O
in	O
the	O
MMG	O
,	O
reversing	O
the	O
artesian	O
conditions	O
suggested	O
by	O
the	O
freshwater	O
calculation	O
.	O

Flow	O
rates	O
in	O
the	O
sandstone	O
layers	O
are	O
typically	O
of	O
the	O
order	O
of	O
7.0	O
e	O
11	O
m/s	O
,	O
while	O
those	O
in	O
the	O
MMG	O
are	O
of	O
the	O
order	O
of	O
5.0	O
e	O
11	O
m/s	O
.	O

Flow	O
rates	O
in	O
the	O
MMG	O
are	O
reduced	O
to	O
about	O
2.0	O
e	O
11	O
m/s	O
.	O

The	O
mixing	O
vortex	O
on	O
the	O
eastern	O
margin	O
has	O
now	O
expanded	O
to	O
cover	O
about	O
half	O
the	O
basin	O
,	O
and	O
the	O
upper	O
part	O
of	O
it	O
introduces	O
lower-density	O
fluid	O
to	O
much	O
of	O
the	O
upper	O
SSG	O
.	O

The	O
densest	O
fluid	O
is	O
now	O
restricted	O
to	O
a	O
descending	O
plume	O
whose	O
location	O
may	O
be	O
determined	O
by	O
the	O
shape	O
of	O
the	O
lower	O
boundary	O
of	O
the	O
MMG	O
.	O

The	O
groundwater	O
flow	O
in	O
the	O
MMG	O
is	O
no	O
longer	O
uniformly	O
up	O
or	O
down	O
but	O
may	O
vary	O
from	O
place	O
to	O
place	O
,	O
and	O
the	O
flow	O
rates	O
are	O
reduced	O
to	O
the	O
order	O
of	O
5.0	O
e	O
12	O
m/s	O
.	O

Second	O
,	O
the	O
central	O
basin	O
,	O
covered	O
by	O
the	O
MMG	O
,	O
where	O
flow	O
is	O
strongly	O
influenced	O
by	O
the	O
density	O
variations	O
arising	O
from	O
halite	O
dissolution	O
and	O
mixing	O
with	O
fresh	O
water	O
near	O
the	O
margins	O
.	O

Red	LEXICON
beds	LEXICON
play	O
a	O
fundamental	O
part	O
in	O
the	O
genesis	O
and	O
spatial	O
distribution	O
of	O
natural	O
resources	O
,	O
being	O
important	O
hosts	O
of	O
hydrocarbon	O
accumulations	O
and	O
deposits	O
of	O
metalliferous	O
minerals	O
worldwide	O
.	O

Waters	O
from	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
red	O
beds	O
in	O
the	O
Wessex	O
Basin	O
reach	O
temperatures	O
of	O
more	O
than	O
75	O
degrees	O
C	O
and	O
can	O
be	O
considered	O
diagenetic	O
waters	O
.	O

Most	O
deep	O
waters	O
in	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
red	O
beds	O
of	O
the	O
UK	O
are	O
of	O
Na-Cl	O
type	O
;	O
salinities	O
are	O
highly	O
variable	O
,	O
but	O
may	O
approach	O
halite	O
saturation	O
.	O

Most	O
of	O
the	O
salinity	O
appears	O
to	O
come	O
from	O
halite	O
dissolution	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
,	O
and	O
it	O
seems	O
likely	O
that	O
this	O
process	O
has	O
been	O
a	O
major	O
control	O
of	O
water	O
salinity	O
throughout	O
diagenesis	O
.	O

Edmunds	O
et	O
al.	O
found	O
that	O
invasion	O
of	O
meteoric	O
waters	O
into	O
the	O
SSG	O
had	O
flushed	O
any	O
pre-existing	O
Na-Cl-dominated	O
saline	O
waters	O
from	O
the	O
aquifer	O
,	O
and	O
that	O
the	O
groundwater	O
chemistry	O
was	O
dominated	O
by	O
reactions	O
with	O
carbonate	O
cement	O
,	O
detrital	O
dolomite	O
and	O
sulphate	O
minerals	O
.	O

In	O
the	O
SSG	O
of	O
the	O
east	O
Midlands	O
,	O
pH	O
increased	O
from	O
about	O
7	O
to	O
about	O
8	O
at	O
greater	O
distances	O
from	O
the	O
outcrop	O
.	O

Burial	O
depths	O
during	O
ore	O
deposition	O
in	O
many	O
sedimentary	O
basins	O
such	O
as	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
of	O
the	O
UK	O
often	O
suggest	O
maximum	O
formation-water	O
temperatures	O
between	O
100	O
degrees	O
C	O
and	O
200	O
degrees	O
C	O
,	O
which	O
are	O
higher	O
than	O
temperatures	O
estimated	O
for	O
Alderley	O
Edge	O
.	O

Campbell	O
described	O
the	O
permeability	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sandstones	O
of	O
the	O
lower	O
Mersey	O
basin	O
,	O
using	O
data	O
from	O
boreholes	O
at	O
High	O
Croft	O
Farm	O
,	O
Padgate	O
,	O
Halewood	O
and	O
Kenyon	O
Junction	O
.	O

In	O
addition	O
,	O
two	O
recent	O
studies	O
describe	O
the	O
hydrochemistry	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
aquifer	O
in	O
the	O
northern	O
part	O
of	O
the	O
Cheshire	O
Basin	O
,	O
near	O
the	O
Mersey	O
.	O

Accordingly	O
,	O
the	O
observation	O
wells	O
are	O
generally	O
in	O
areas	O
underlain	O
by	O
sediments	O
of	O
the	O
SSG	O
,	O
which	O
form	O
the	O
major	O
groundwater	O
aquifers	O
.	O

There	O
are	O
very	O
few	O
wells	O
located	O
on	O
areas	O
underlain	O
by	O
the	O
MMG	O
,	O
since	O
this	O
generally	O
acts	O
as	O
an	O
acquiclude	O
.	O

SJ/56/61	O
-RRB-	O
and	O
a	O
water	O
analysis	O
is	O
available	O
for	O
a	O
sample	O
from	O
the	O
SSG	O
at	O
305m	O
depth	O
in	O
this	O
borehole	O
.	O

Additionally	O
,	O
a	O
groundwater	O
sample	O
from	O
a	O
borehole	O
near	O
Chester	O
,	O
from	O
a	O
depth	O
of	O
approximately	O
500m	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
,	O
was	O
analysed	O
for	O
major	O
,	O
minor	O
and	O
trace	O
elements	O
,	O
and	O
for	O
18O/16O	O
and	O
2H/1H	O
isotopes	O
.	O

A	O
similar	O
decrease	O
in	O
heavy-isotope	O
abundances	O
with	O
increasing	O
depths	O
has	O
been	O
described	O
from	O
the	O
East	O
Midlands	O
Triassic	CHRONOSTRAT
aquifer	O
and	O
has	O
been	O
interpreted	O
as	O
a	O
palaeoclimatic	O
effect	O
,	O
with	O
the	O
most	O
depleted	O
samples	O
reflecting	O
recharge	O
during	O
Pleistocene	CHRONOSTRAT
glacial	O
episodes	O
.	O

He	O
pointed	O
out	O
that	O
the	O
saline	O
waters	O
did	O
not	O
necessarily	O
arise	O
through	O
evaporite	O
dissolution	O
during	O
the	O
Pleistocene	CHRONOSTRAT
.	O

The	O
water	O
sample	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
borehole	O
near	O
Chester	O
gave	O
d18O	O
=	O
6.9	O
degrees	O
and	O
d2H	O
=	O
43	O
degrees	O
,	O
suggesting	O
that	O
the	O
basement	O
waters	O
in	O
this	O
borehole	O
are	O
meteoric	O
in	O
origin	O
,	O
like	O
the	O
inland	O
waters	O
sampled	O
by	O
Lucey	O
from	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

Mean	O
Br	O
concentrations	O
for	O
a	O
number	O
of	O
groundwater	O
samples	O
from	O
the	O
Cheshire	O
Basin	O
are	O
plotted	O
against	O
corresponding	O
Cl	O
concentrations	O
in	O
Figure	O
132	O
,	O
together	O
with	O
similar	O
data	O
from	O
other	O
UK	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
aquifers	O
.	O

The	O
Br/Cl	O
ratio	O
in	O
the	O
water	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
borehole	O
near	O
to	O
Chester	O
requires	O
some	O
other	O
explanation	O
.	O

The	O
fact	O
that	O
the	O
salinity	O
of	O
the	O
Coal	LEXICON
Measures	LEXICON
water	O
is	O
close	O
to	O
that	O
of	O
sea	O
water	O
precludes	O
the	O
possibility	O
that	O
the	O
Coal	LEXICON
Measures	LEXICON
water	O
acquired	O
its	O
salinity	O
from	O
sea	O
water	O
and	O
its	O
isotopic	O
signature	O
through	O
mixing	O
with	O
dilute	O
meteoric	O
water	O
.	O

Instead	O
,	O
the	O
most	O
likely	O
source	O
of	O
the	O
salinity	O
is	O
halite	O
dissolution	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basin	O
fill	O
.	O

However	O
,	O
as	O
explained	O
above	O
,	O
a	O
water	O
which	O
had	O
acquired	O
its	O
salinity	O
through	O
evaporite	O
dissolution	O
would	O
be	O
expected	O
to	O
have	O
a	O
Br/Cl	O
ratio	O
significantly	O
less	O
than	O
the	O
sea-water	O
ratio	O
,	O
whereas	O
the	O
Coal	LEXICON
Measures	LEXICON
water	O
has	O
Br/Clmolar	O
=	O
2.02310	O
3	O
,	O
some	O
30%	O
higher	O
than	O
the	O
sea-water	O
value	O
.	O

A	O
possible	O
explanation	O
is	O
that	O
the	O
water	O
,	O
having	O
acquired	O
its	O
Na-Cl-dominated	O
salinity	O
through	O
halite	O
dissolution	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sequence	O
,	O
subsequently	O
gained	O
Br	O
by	O
reaction	O
with	O
organic	O
matter	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
.	O

Reactions	O
involving	O
organic	O
matter	O
have	O
been	O
postulated	O
as	O
a	O
possible	O
cause	O
of	O
high	O
Br/Clmolar	O
ratios	O
of	O
up	O
to	O
4.08310	O
3	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
of	O
north-east	O
England	O
.	O

The	O
Cheshire	O
Basin	O
groundwaters	O
are	O
generally	O
similar	O
to	O
those	O
from	O
other	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
aquifers	O
.	O

Most	O
of	O
the	O
groundwater	O
samples	O
from	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sequence	O
contain	O
less	O
than	O
1000mg/l	O
TDS	O
,	O
with	O
a	O
maximum	O
salinity	O
of	O
about	O
20000mg/l	O
TDS	O
.	O

This	O
sample	O
set	O
is	O
biased	O
towards	O
fresh	O
waters	O
,	O
since	O
most	O
samples	O
were	O
taken	O
from	O
wells	O
designed	O
to	O
monitor	O
water	O
supplies	O
for	O
domestic	O
consumption	O
,	O
located	O
in	O
areas	O
where	O
MMG	O
is	O
absent	O
,	O
but	O
there	O
is	O
other	O
evidence	O
to	O
suggest	O
that	O
the	O
groundwaters	O
throughout	O
the	O
basin	O
generally	O
have	O
low	O
salinities	O
and	O
never	O
become	O
brines	O
the	O
salinity	O
of	O
the	O
single	O
water	O
sample	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
borehole	O
near	O
Chester	O
was	O
only	O
0.85	O
3	O
sea-water	O
concentration	O
.	O

A	O
halite	O
-	O
equilibrated	O
water	O
at	O
25	O
degrees	O
C	O
would	O
have	O
a	O
salinity	O
of	O
c.	O
7.53	O
sea	O
water	O
,	O
and	O
other	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
in	O
the	O
UK	O
with	O
halite	O
-	O
bearing	O
evaporites	O
do	O
in	O
fact	O
contain	O
brines	O
.	O

Indeed	O
,	O
in	O
the	O
Wessex	O
Basin	O
,	O
formation	O
waters	O
in	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
aquifers	O
approach	O
halite	O
saturation	O
.	O

A	O
possible	O
explanation	O
is	O
that	O
the	O
meteoric	O
water	O
has	O
continued	O
to	O
flush	O
the	O
SSG	O
via	O
recharge	O
in	O
the	O
south-east	O
and	O
discharge	O
in	O
the	O
west	O
and	O
north	O
.	O

It	O
is	O
likely	O
that	O
the	O
water	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
borehole	O
near	O
Chester	O
acquired	O
its	O
salinity	O
through	O
halite	O
dissolution	O
,	O
suggesting	O
that	O
groundwater	O
has	O
passed	O
into	O
the	O
basement	O
from	O
the	O
basin	O
fill	O
:	O
there	O
are	O
no	O
known	O
evaporites	O
in	O
the	O
region	O
except	O
for	O
those	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sediments	O
of	O
the	O
Cheshire	O
Basin	O
.	O

It	O
can	O
be	O
seen	O
from	O
Table	O
34	O
that	O
the	O
modern	O
groundwaters	O
from	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
of	O
the	O
Cheshire	O
Basin	O
are	O
generally	O
oxidising	O
,	O
and	O
the	O
measured	O
Eh	O
values	O
are	O
reasonably	O
consistent	O
with	O
the	O
waters	O
having	O
being	O
influenced	O
by	O
the	O
atmosphere	O
.	O

Although	O
the	O
redox-pH	O
conditions	O
of	O
the	O
modern	O
formation	O
waters	O
from	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sequence	O
do	O
seem	O
consistent	O
with	O
some	O
possible	O
mobilisation	O
of	O
Cu	O
,	O
the	O
actual	O
measured	O
levels	O
of	O
dissolved	O
Cu	O
are	O
low	O
and	O
,	O
as	O
expected	O
,	O
these	O
dilute	O
waters	O
are	O
unlikely	O
to	O
give	O
rise	O
to	O
Cu	O
ore	O
deposits	O
.	O

As	O
in	O
the	O
case	O
of	O
Cu	O
,	O
the	O
concentrations	O
of	O
Pb	O
and	O
Zn	O
in	O
the	O
shallow	O
groundwaters	O
from	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sequence	O
are	O
low	O
and	O
hence	O
these	O
waters	O
would	O
not	O
be	O
likely	O
to	O
form	O
deposits	O
of	O
Pb	O
or	O
Zn	O
.	O

In	O
contrast	O
to	O
the	O
shallower	O
waters	O
from	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basin	O
fill	O
,	O
the	O
groundwater	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
borehole	O
near	O
Chester	O
gave	O
Eh	O
=	O
38	O
mV	O
,	O
consistent	O
with	O
basement	O
waters	O
being	O
more	O
reducing	O
than	O
waters	O
from	O
the	O
cover	O
sequence	O
.	O

This	O
result	O
is	O
to	O
be	O
expected	O
because	O
the	O
Coal	LEXICON
Measures	LEXICON
have	O
a	O
much	O
larger	O
organic	O
content	O
than	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
strata	O
,	O
and	O
the	O
sample	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
was	O
taken	O
from	O
a	O
relatively	O
great	O
depth	O
so	O
that	O
it	O
was	O
more	O
likely	O
to	O
be	O
isolated	O
from	O
the	O
atmosphere	O
than	O
shallower	O
samples	O
.	O

These	O
observations	O
suggest	O
that	O
although	O
the	O
water	O
in	O
the	O
Carboniferous	CHRONOSTRAT
basement	O
probably	O
originated	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
cover	O
,	O
it	O
has	O
been	O
resident	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
for	O
long	O
enough	O
to	O
be	O
reduced	O
through	O
water	O
rock	O
interactions	O
.	O

There	O
are	O
no	O
analyses	O
of	O
heavy	O
metals	O
for	O
the	O
groundwater	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
borehole	O
near	O
Chester	O
.	O

The	O
general	O
characteristics	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sediments	O
which	O
fill	O
the	O
Cheshire	O
Basin	O
are	O
typical	O
of	O
red	O
beds	O
.	O

Also	O
,	O
these	O
comparative	O
and	O
theoretical	O
investigations	O
suggest	O
a	O
likelihood	O
that	O
the	O
metal-bearing	O
fluids	O
which	O
gave	O
rise	O
to	O
the	O
ore	O
deposits	O
in	O
the	O
basin	O
originated	O
within	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
fill	O
as	O
saline	O
formation	O
waters	O
with	O
TDS	O
up	O
to	O
c.	O
10	O
3	O
sea-water	O
concentration	O
.	O

By	O
analogy	O
with	O
other	O
red-bed	O
basins	O
,	O
peak	O
temperatures	O
in	O
the	O
Cheshire	O
Basin	O
probably	O
lay	O
within	O
the	O
range	O
60	O
degrees	O
150	O
degrees	O
C.	O
However	O
,	O
if	O
a	O
late	O
Triassic	CHRONOSTRAT
age	O
is	O
accepted	O
for	O
the	O
Alderley	O
Edge	O
mineralisation	O
,	O
temperatures	O
are	O
likely	O
to	O
have	O
below	O
100	O
degrees	O
C	O
over	O
the	O
greater	O
part	O
of	O
the	O
basin	O
.	O

In	O
the	O
Cheshire	O
Basin	O
,	O
the	O
mineralisation	O
is	O
generally	O
related	O
to	O
structural	O
traps	O
where	O
faulting	O
juxtaposes	O
red-bed	O
aquifers	O
against	O
relatively	O
impermeable	O
mudrocks	O
,	O
particularly	O
those	O
in	O
the	O
MMG	O
.	O

The	O
possibility	O
that	O
ore	O
formation	O
might	O
be	O
due	O
to	O
migration	O
of	O
hydrocarbon	O
fluids	O
was	O
first	O
suggested	O
by	O
Warrington	O
postulated	O
that	O
methane	O
derived	O
from	O
the	O
underlying	O
Coal	LEXICON
Measures	LEXICON
was	O
the	O
reductant	O
.	O

In	O
contrast	O
,	O
any	O
reducing	O
water	O
from	O
the	O
Carboniferous	CHRONOSTRAT
is	O
unlikely	O
to	O
have	O
contained	O
proportionately	O
greater	O
amounts	O
of	O
sulphate	O
and	O
may	O
therefore	O
have	O
mobilised	O
relatively	O
large	O
quantities	O
of	O
Ba	O
.	O

The	O
presence	O
of	O
baryte	O
widely	O
distributed	O
throughout	O
the	O
SSG	O
is	O
not	O
accounted	O
for	O
by	O
the	O
theoretical	O
model	O
,	O
and	O
may	O
in	O
part	O
be	O
due	O
to	O
the	O
release	O
of	O
Ba	O
into	O
formational	O
fluids	O
during	O
feldspar	O
diagenesis	O
and	O
the	O
precipitation	O
of	O
baryte	O
when	O
these	O
fluids	O
mixed	O
with	O
waters	O
having	O
a	O
high	O
sulphate	O
content	O
derived	O
from	O
evaporite	O
dissolution	O
.	O

The	O
waters	O
from	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
aquifers	O
are	O
significantly	O
more	O
oxidising	O
than	O
the	O
water	O
from	O
the	O
underlying	O
Coal	LEXICON
Measures	LEXICON
.	O

If	O
the	O
measured	O
Eh	O
values	O
are	O
indeed	O
representative	O
of	O
in	O
situ	O
redox	O
conditions	O
,	O
and	O
if	O
the	O
water	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
did	O
indeed	O
originate	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
fill	O
of	O
the	O
basin	O
,	O
then	O
the	O
implication	O
is	O
that	O
this	O
latter	O
water	O
has	O
acquired	O
its	O
redox	O
state	O
during	O
water-rock	O
interactions	O
within	O
the	O
Coal	LEXICON
Measures	LEXICON
.	O

Since	O
the	O
deep	O
borehole	O
near	O
Chester	O
was	O
located	O
near	O
the	O
margin	O
of	O
the	O
basin	O
,	O
it	O
is	O
possible	O
that	O
the	O
waters	O
sampled	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
there	O
were	O
recharged	O
from	O
the	O
basin	O
margin	O
,	O
and	O
that	O
in	O
fact	O
fluid	O
flow	O
was	O
the	O
reverse	O
of	O
that	O
in	O
the	O
ore	O
genetic	O
mixing	O
model	O
.	O

The	O
main	O
conclusions	O
of	O
the	O
study	O
of	O
the	O
current	O
basinal	O
groundwater	O
flow	O
system	O
,	O
the	O
palaeohydrogeology	O
and	O
the	O
role	O
of	O
fluids	O
in	O
the	O
diagenesis	O
and	O
emplacement	O
of	O
minerals	O
can	O
be	O
summarised	O
as	O
follows	O
:	O
Red	LEXICON
beds	LEXICON
play	O
two	O
important	O
roles	O
in	O
the	O
occurrence	O
of	O
sedimentary-basin	O
resources	O
:	O
firstly	O
,	O
they	O
act	O
as	O
a	O
source	O
of	O
heavy	O
metals	O
,	O
which	O
are	O
bound	O
in	O
the	O
solid	O
phases	O
or	O
dissolved	O
in	O
metalliferous	O
formation	O
waters	O
;	O
and	O
,	O
secondly	O
,	O
owing	O
to	O
their	O
high	O
mean	O
porosities	O
and	O
permeabilities	O
,	O
they	O
act	O
as	O
conduits	O
for	O
groundwater	O
flow	O
during	O
basin	O
evolution	O
and	O
may	O
become	O
reservoirs	O
for	O
mineralising	O
fluids	O
,	O
hydrocarbons	O
or	O
groundwater	O
.	O

Red	LEXICON
beds	LEXICON
may	O
also	O
act	O
as	O
chemical	O
conditioning	O
agents	O
for	O
groundwaters	O
passing	O
through	O
them	O
.	O

Red	LEXICON
beds	LEXICON
thus	O
play	O
a	O
fundamental	O
part	O
in	O
the	O
genesis	O
and	O
the	O
spatial	O
distribution	O
of	O
natural	O
resources	O
,	O
and	O
they	O
are	O
important	O
hosts	O
of	O
hydrocarbon	O
accumulations	O
and	O
deposits	O
of	O
metalliferous	O
minerals	O
worldwide	O
.	O

The	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
red	O
beds	O
of	O
the	O
UK	O
host	O
:	O
major	O
oil	O
and	O
gas	O
reservoirs	O
.	O

Finally	O
,	O
the	O
prospectivity	O
of	O
the	O
Cheshire	O
Basin	O
and	O
comparable	O
settings	O
elsewhere	O
in	O
the	O
UK	O
for	O
red-bed	O
Cu	O
deposits	O
and	O
other	O
types	O
of	O
mineralisation	O
potentially	O
associated	O
with	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rifted	O
basins	O
are	O
discussed	O
.	O

The	O
mineralisation	O
comprises	O
disseminated	O
cement	O
and	O
fracture-hosted	O
baryte	O
and	O
more	O
localised	O
polymetallic	O
mineralisation	O
,	O
hosted	O
in	O
formations	O
of	O
the	O
SSG	O
.	O

Baryte	O
is	O
particularly	O
widespread	O
near	O
the	O
base	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
in	O
the	O
upper	O
part	O
of	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
around	O
the	O
basin	O
margins	O
.	O

The	O
mineralisation	O
occurs	O
mainly	O
in	O
the	O
upper	O
part	O
of	O
the	O
SSG	O
where	O
it	O
is	O
faulted	O
against	O
,	O
or	O
capped	O
by	O
,	O
the	O
now	O
relatively	O
impermeable	O
argillaceous	O
rocks	O
of	O
the	O
overlying	O
MMG	O
.	O

At	O
Alderley	O
Edge	O
the	O
mineralisation	O
occurs	O
in	O
SSG	O
rocks	O
dipping	O
south-west	O
at	O
10	O
to	O
15	O
degrees	O
,	O
in	O
faulted	O
contact	O
with	O
younger	O
formations	O
of	O
the	O
MMG	O
across	O
the	O
Kirkleyditch	O
Fault	O
in	O
the	O
east	O
,	O
and	O
the	O
Alderley	O
Fault	O
in	O
the	O
west	O
.	O

The	O
MMG	O
formerly	O
capped	O
the	O
sandstone	O
,	O
constraining	O
fluid	O
movement	O
and	O
forming	O
a	O
potential	O
trap	O
for	O
hydrocarbons	O
and	O
ore	O
fluids	O
.	O

Widespread	O
Cu	O
mineralisation	O
with	O
Pb	O
and	O
Zn	O
occurs	O
adjacent	O
to	O
fault	O
zones	O
in	O
both	O
fluvial	O
and	O
aeolian	O
sandstones	O
of	O
the	O
uppermost	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
the	O
Engine	O
Vein	O
Conglomerate	O
,	O
Wood	O
Mine	O
Conglomerate	O
and	O
West	O
Mine	O
Sandstone	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
eastern	O
group	O
,	O
comprising	O
the	O
Engine	O
Vein	O
Mine	O
and	O
Stormy	O
Point	O
workings	O
,	O
in	O
the	O
uppermost	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
basal	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
fault	O
at	O
the	O
northern	O
margin	O
of	O
Wood	O
Mine	O
is	O
the	O
western	O
extension	O
of	O
the	O
fault	O
which	O
cuts	O
the	O
lower	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
Engine	O
Vein	O
Mine	O
.	O

The	O
ore	O
body	O
is	O
in	O
the	O
upper	O
10m	O
of	O
the	O
Grinshill	LEXICON
Sandstone	LEXICON
Formation	LEXICON
immediately	O
below	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
and	O
extends	O
about	O
250m	O
along	O
the	O
fault	O
and	O
up	O
to	O
8m	O
downdip	O
into	O
the	O
hanging	O
wall	O
.	O

The	O
Mottram	O
St	O
Andrew	O
site	O
immediately	O
east	O
of	O
the	O
Alderley	O
block	O
is	O
adjacent	O
to	O
the	O
Kirkleyditch	O
Fault	O
where	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
thrown	O
down	O
east	O
against	O
the	O
older	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

At	O
Bickerton	O
in	O
the	O
west	O
of	O
the	O
basin	O
,	O
mineralisation	O
is	O
associated	O
with	O
a	O
north-east-trending	O
normal	O
fault	O
which	O
downthrows	O
the	O
MMG	O
east	O
against	O
the	O
SSG	O
;	O
the	O
mineralisation	O
is	O
hosted	O
by	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
the	O
footwall	O
.	O

At	O
Eardiston	O
in	O
the	O
south-west	O
of	O
the	O
Cheshire	O
Basin	O
,	O
a	O
north-north-east-trending	O
normal	O
fault	O
downthrows	O
east-dipping	O
MMG	O
beds	O
west	O
against	O
the	O
upper	O
SSG	O
.	O

MMG	O
deposits	O
overlying	O
the	O
SSG	O
east	O
of	O
the	O
main	O
fault	O
,	O
and	O
those	O
in	O
the	O
hanging	O
wall	O
,	O
created	O
a	O
trap	O
for	O
migrating	O
fluids	O
.	O

The	O
Pim	O
Hill	O
site	O
is	O
on	O
a	O
north	O
south	O
fault	O
to	O
the	O
west	O
of	O
a	O
small	O
graben	O
,	O
where	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
and	O
underlying	O
Grinshill	LEXICON
Sandstone	LEXICON
Formation	LEXICON
are	O
downthrown	O
east	O
against	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
geology	O
of	O
the	O
Yorton	O
site	O
,	O
which	O
is	O
also	O
on	O
a	O
north	O
south	O
fault	O
which	O
downthrows	O
MMG	O
beds	O
east	O
against	O
the	O
SSG	O
,	O
is	O
similar	O
.	O

At	O
Wixhill	O
,	O
mineralisation	O
is	O
associated	O
with	O
a	O
north-east-trending	O
normal	O
fault	O
,	O
which	O
downthrows	O
the	O
Bollin	LEXICON
Mudstone	LEXICON
Formation	LEXICON
north-west	O
against	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
mineralisation	O
is	O
likely	O
to	O
be	O
in	O
the	O
fault	O
and	O
in	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
the	O
footwall	O
.	O

Common	O
features	O
of	O
the	O
polymetallic	O
mineralisation	O
in	O
the	O
Cheshire	O
Basin	O
are	O
as	O
follows	O
:	O
The	O
deposits	O
are	O
hosted	O
in	O
formations	O
of	O
the	O
SSG	O
,	O
usually	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
but	O
sometimes	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
in	O
stratigraphical	O
or	O
structural	O
proximity	O
to	O
the	O
MMG	O
in	O
either	O
the	O
footwall	O
or	O
hangingwall	O
of	O
faults	O
.	O

The	O
MMG	O
appears	O
to	O
have	O
formed	O
the	O
main	O
aquiclude	O
,	O
but	O
mudstone	O
beds	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
are	O
also	O
important	O
locally	O
.	O

Early	O
workers	O
,	O
including	O
Hull	O
,	O
favoured	O
a	O
syngenetic	O
origin	O
,	O
with	O
detrital	O
Pb	O
and	O
Cu	O
sulphides	O
deposited	O
contemporaneously	O
with	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
host	O
rocks	O
.	O

Subsequently	O
Taylor	O
et	O
al.	O
moving	O
up	O
the	O
faults	O
;	O
Warrington	O
suggesting	O
that	O
a	O
concealed	O
Jurassic	CHRONOSTRAT
granite	O
was	O
the	O
source	O
of	O
ore	O
fluids	O
.	O

Holmes	O
et	O
al.	O
proposed	O
a	O
diagenetic	O
origin	O
for	O
the	O
mineralising	O
fluids	O
and	O
suggested	O
that	O
the	O
ore	O
solutions	O
were	O
oxidising	O
basinal	O
brines	O
of	O
moderate	O
salinity	O
with	O
trace	O
metals	O
released	O
during	O
diagenesis	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sediments	O
within	O
the	O
basin	O
.	O

A	O
basin	O
brine	O
expulsion	O
model	O
was	O
also	O
favoured	O
by	O
Naylor	O
et	O
al.	O
,	O
with	O
precipitation	O
as	O
a	O
result	O
of	O
interaction	O
with	O
methane	O
from	O
the	O
underlying	O
Coal	LEXICON
Measures	LEXICON
.	O

In	O
contrast	O
,	O
Thompson	O
suggested	O
that	O
the	O
metals	O
may	O
have	O
originated	O
in	O
the	O
black	O
shales	O
of	O
the	O
underlying	O
Coal	LEXICON
Measures	LEXICON
.	O

Prior	O
to	O
erosion	O
,	O
the	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
provided	O
a	O
regional	O
seal	O
,	O
indicating	O
that	O
the	O
predominant	O
direction	O
of	O
ore-forming	O
fluids	O
was	O
up	O
basin-margin	O
fault	O
systems	O
.	O

At	O
present	O
,	O
the	O
evaporite-bearing	O
MMG	O
lies	O
topographically	O
below	O
the	O
mineralised	O
horizons	O
in	O
the	O
SSG	O
.	O

Naylor	O
et	O
al.	O
used	O
this	O
evidence	O
,	O
together	O
with	O
sulphur-isotope	O
data	O
for	O
the	O
baryte	O
mineralisation	O
which	O
is	O
consistent	O
with	O
an	O
evaporitic	O
source	O
in	O
the	O
MMG	O
,	O
to	O
suggest	O
that	O
mineralisation	O
occurred	O
during	O
and	O
after	O
Tertiary	CHRONOSTRAT
inversion	O
of	O
the	O
basin	O
when	O
sulphate-bearing	O
fluids	O
rose	O
through	O
the	O
fault	O
systems	O
.	O

Most	O
authors	O
now	O
propose	O
ore	O
deposition	O
beneath	O
the	O
MMG	O
,	O
involving	O
reductants	O
such	O
as	O
hydrocarbon	O
gases	O
.	O

The	O
possibility	O
that	O
ore	O
deposition	O
might	O
be	O
due	O
to	O
migration	O
of	O
hydrocarbons	O
was	O
first	O
suggested	O
by	O
Warrington	O
postulated	O
that	O
methane	O
derived	O
from	O
the	O
underlying	O
Coal	LEXICON
Measures	LEXICON
was	O
the	O
reductant	O
.	O

Red	LEXICON
beds	LEXICON
are	O
important	O
as	O
a	O
source	O
of	O
heavy	O
metals	O
,	O
and	O
their	O
high	O
mean	O
porosity	O
and	O
permeability	O
enable	O
them	O
to	O
act	O
as	O
conduits	O
for	O
fluid	O
flow	O
during	O
basin	O
evolution	O
and	O
to	O
become	O
reservoirs	O
for	O
mineralising	O
fluids	O
,	O
hydrocarbons	O
or	O
groundwater	O
.	O

In	O
the	O
type	O
localities	O
in	O
Poland	O
and	O
Germany	O
,	O
Kupferschiefer	O
mineralisation	O
is	O
at	O
the	O
contact	O
between	O
Lower	CHRONOSTRAT
Permian	CHRONOSTRAT
volcanics	O
and	O
red	O
beds	O
and	O
Upper	CHRONOSTRAT
Permian	CHRONOSTRAT
marine	O
carbonates	O
and	O
evaporites	O
.	O

Petrographical	O
studies	O
of	O
the	O
SSG	O
have	O
shown	O
that	O
these	O
sandstones	O
contained	O
ferromagnesian	O
minerals	O
at	O
the	O
time	O
of	O
deposition	O
,	O
and	O
it	O
is	O
not	O
unreasonable	O
to	O
suppose	O
that	O
the	O
levels	O
of	O
OFEs	O
in	O
the	O
sediments	O
were	O
in	O
the	O
normal	O
ranges	O
for	O
sandstones	O
.	O

Most	O
of	O
the	O
detrital	O
matter	O
that	O
formed	O
the	O
MMG	O
was	O
already	O
oxidised	O
at	O
the	O
time	O
of	O
deposition	O
,	O
with	O
OFEs	O
associated	O
with	O
ferric	O
oxides	O
and	O
oxyhydroxides	O
,	O
and	O
OFE	O
levels	O
may	O
also	O
have	O
been	O
in	O
the	O
normal	O
ranges	O
for	O
organic-free	O
argillaceous	O
rocks	O
.	O

The	O
total	O
volume	O
of	O
MMG	O
and	O
SSG	O
strata	O
preserved	O
in	O
the	O
basin	O
is	O
estimated	O
,	O
from	O
the	O
interpreted	O
seismic	O
reflection	O
data	O
,	O
as	O
1300km3	O
and	O
3100km3	O
respectively	O
.	O

Making	O
an	O
allowance	O
for	O
erosion	O
,	O
the	O
original	O
depositional	O
volume	O
of	O
the	O
SSG	O
was	O
probably	O
of	O
the	O
order	O
of	O
3300km3	O
.	O

The	O
ratio	O
of	O
preserved	O
MMG	O
/	O
SSG	O
thicknesses	O
then	O
gives	O
an	O
original	O
depositional	O
volume	O
of	O
about	O
2000km3	O
for	O
the	O
MMG	O
.	O

If	O
the	O
basin	O
fill	O
originally	O
contained	O
average	O
upper-continental-crust	O
levels	O
of	O
metals	O
,	O
then	O
173	O
Mt	O
of	O
Cu	O
,	O
84	O
Mt	O
of	O
Pb	O
and	O
481	O
Mt	O
of	O
Zn	O
has	O
been	O
leached	O
from	O
the	O
SSG	O
and	O
60Mt	O
of	O
Cu	O
,	O
63	O
Mt	O
of	O
Pb	O
and	O
84	O
Mt	O
of	O
Zn	O
from	O
the	O
MMG	O
.	O

However	O
,	O
if	O
the	O
original	O
contents	O
of	O
OFEs	O
in	O
the	O
SSG	O
were	O
at	O
average	O
sandstone	O
levels	O
,	O
then	O
only	O
30	O
150	O
Mt	O
of	O
Cu	O
,	O
8Mt	O
of	O
Pb	O
and	O
132	O
326Mt	O
of	O
Zn	O
would	O
have	O
been	O
available	O
.	O

The	O
lower	O
values	O
of	O
OFEs	O
in	O
the	O
SSG	O
at	O
present	O
might	O
reflect	O
preferential	O
removal	O
of	O
Cu	O
and	O
Zn	O
by	O
fluids	O
passing	O
through	O
the	O
basin	O
,	O
with	O
greater	O
volumes	O
flowing	O
through	O
the	O
more	O
porous	O
and	O
permeable	O
SSG	O
than	O
moving	O
through	O
the	O
finer-grained	O
MMG	O
.	O

Early	O
diagenesis	O
in	O
the	O
SSG	O
involved	O
the	O
breakdown	O
of	O
detrital	O
ferromagnesian	O
minerals	O
and	O
the	O
reprecipitation	O
of	O
Fe	O
in	O
ferric	O
oxyhydroxides	O
,	O
followed	O
by	O
infiltration	O
of	O
detrital	O
clay	O
into	O
sandstones	O
and	O
the	O
deposition	O
of	O
low-ferroan	O
dolocretes	O
and	O
calcretes	O
in	O
conditions	O
of	O
high	O
pH	O
and	O
Eh	O
.	O

Sulphur-isotope	O
data	O
suggest	O
that	O
sulphate	O
was	O
derived	O
mainly	O
from	O
brines	O
of	O
Triassic	CHRONOSTRAT
marine	O
origin	O
,	O
although	O
higher	O
in	O
the	O
sequence	O
sulphate	O
is	O
isotopically	O
lighter	O
,	O
possibly	O
reflecting	O
an	O
increased	O
continental	O
component	O
or	O
derivation	O
from	O
Permian	CHRONOSTRAT
sources	O
.	O

During	O
the	O
late	O
phases	O
of	O
eodiagenesis	O
,	O
reduction	O
by	O
bacteria	O
of	O
Fe3	O
+	O
and	O
SO42	O
led	O
to	O
the	O
production	O
of	O
reduced	O
green	O
beds	O
and	O
reduction	O
spots	O
with	O
authigenic	O
pyrite	O
in	O
fine-grained	O
fluvial	O
-	O
cycle	O
sediments	O
and	O
with	O
corrensite	O
deposition	O
in	O
hypersaline	O
sections	O
of	O
the	O
MMG	O
.	O

During	O
earlier	O
phases	O
of	O
SSG	O
mesodiagenesis	O
,	O
early	O
carbonate	O
cements	O
together	O
with	O
silica	O
were	O
remobilised	O
.	O

Evidence	O
in	O
the	O
MMG	O
is	O
consistent	O
with	O
early	O
diagenetic	O
dissolution	O
of	O
halite	O
,	O
prior	O
to	O
the	O
development	O
of	O
early	O
mesodiagenetic	O
dolomite	O
.	O

It	O
is	O
suggested	O
that	O
much	O
of	O
the	O
SSG	O
was	O
cemented	O
by	O
anhydrite	O
.	O

All	O
the	O
evidence	O
suggests	O
that	O
chloride	O
and	O
sulphate	O
cements	O
and	O
vein	O
mineralisation	O
in	O
the	O
Cheshire	O
Basin	O
fill	O
were	O
derived	O
by	O
fluxes	O
of	O
fluid	O
from	O
the	O
MMG	O
into	O
the	O
SSG	O
,	O
initially	O
as	O
a	O
result	O
of	O
compaction	O
and	O
gravity	O
-	O
driven	O
brine	O
circulation	O
.	O

Diagenetic	O
evidence	O
is	O
consistent	O
with	O
early	O
anhydrite-saturated	O
fluids	O
fluxing	O
through	O
the	O
SSG	O
,	O
followed	O
by	O
later	O
low-sulphate	O
NaCl	O
brines	O
derived	O
from	O
the	O
MMG	O
.	O

The	O
MMG	O
thus	O
appears	O
to	O
have	O
generated	O
different	O
fluids	O
at	O
different	O
times	O
.	O

The	O
new	O
evidence	O
presented	O
here	O
indicates	O
that	O
mineralisation	O
in	O
the	O
known	O
sulphide	O
ore	O
deposits	O
occurred	O
when	O
high-density	O
metalliferous	O
brines	O
from	O
the	O
MMG	O
fluxed	O
through	O
the	O
basin	O
under	O
the	O
influence	O
of	O
gravity	O
and	O
encountered	O
a	O
small	O
volume	O
of	O
reducing	O
fluid	O
in	O
fault	O
systems	O
around	O
the	O
margins	O
of	O
the	O
basin	O
,	O
especially	O
in	O
the	O
north	O
.	O

Some	O
of	O
the	O
OFE	O
contents	O
of	O
the	O
fluids	O
could	O
have	O
been	O
picked	O
up	O
during	O
their	O
passage	O
through	O
the	O
SSG	O
,	O
and	O
some	O
may	O
have	O
been	O
introduced	O
with	O
the	O
deeper	O
,	O
reducing	O
fluids	O
.	O

The	O
extent	O
to	O
which	O
the	O
reducing	O
fluid	O
was	O
derived	O
from	O
the	O
East	O
Irish	O
Sea	O
Basin	O
to	O
the	O
north-west	O
or	O
the	O
Coal	LEXICON
Measures	LEXICON
sequences	O
beneath	O
the	O
northern	O
Cheshire	O
Basin	O
is	O
unclear	O
,	O
but	O
structural	O
considerations	O
favour	O
the	O
latter	O
source	O
.	O

There	O
is	O
no	O
direct	O
evidence	O
for	O
the	O
migration	O
of	O
hydrocarbons	O
into	O
the	O
SSG	O
before	O
or	O
during	O
base-metal	O
mineralisation	O
,	O
so	O
models	O
favouring	O
the	O
involvement	O
of	O
light	O
hydrocarbon	O
gases	O
remain	O
unproven	O
.	O

Complex	O
interaction	O
occurred	O
between	O
an	O
ore	O
fluid	O
sourced	O
in	O
the	O
MMG	O
,	O
transporting	O
and	O
mobilising	O
OFEs	O
as	O
it	O
flowed	O
down	O
and	O
outwards	O
towards	O
the	O
basin	O
margin	O
fault	O
systems	O
,	O
and	O
small	O
components	O
of	O
a	O
reducing	O
phase	O
,	O
possibly	O
derived	O
by	O
thermobaric	O
dewatering	O
and	O
organic	O
maturation	O
in	O
deep	O
Carboniferous	CHRONOSTRAT
basins	O
,	O
migrating	O
in	O
relation	O
to	O
fault	O
movement	O
and	O
seismic	O
pumping	O
.	O

Regional	O
considerations	O
,	O
particularly	O
evidence	O
from	O
more	O
fully	O
preserved	O
sedimentary	O
sequences	O
to	O
the	O
south	O
of	O
the	O
basin	O
,	O
indicate	O
that	O
extensional	O
basin	O
subsidence	O
continued	O
to	O
early	O
Jurassic	CHRONOSTRAT
times	O
with	O
renewed	O
extension	O
in	O
the	O
late	O
Jurassic	CHRONOSTRAT
and	O
early	O
Cretaceous	CHRONOSTRAT
associated	O
with	O
sea-floor	O
spreading	O
in	O
the	O
southern	O
part	O
of	O
the	O
North	O
Atlantic	O
region	O
.	O

It	O
seems	O
most	O
likely	O
that	O
the	O
known	O
mineralisation	O
in	O
the	O
Cheshire	O
Basin	O
occurred	O
at	O
some	O
time	O
during	O
the	O
late	O
Triassic	CHRONOSTRAT
to	O
early	O
Jurassic	CHRONOSTRAT
period	O
of	O
extension	O
.	O

Such	O
a	O
model	O
has	O
considerable	O
implications	O
for	O
Cu	O
exploration	O
in	O
the	O
Cheshire	O
Basin	O
and	O
in	O
other	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
in	O
the	O
UK	O
.	O

Evidence	O
for	O
the	O
extraction	O
of	O
large	O
quantities	O
of	O
metals	O
from	O
the	O
Cheshire	O
Basin	O
fill	O
by	O
the	O
migration	O
of	O
pervasive	O
high-density	O
brines	O
,	O
variously	O
enriched	O
in	O
sulphate	O
and	O
chloride	O
as	O
a	O
result	O
of	O
interaction	O
with	O
evaporitic	O
phases	O
especially	O
in	O
the	O
MMG	O
,	O
has	O
considerable	O
implications	O
for	O
exploration	O
for	O
SCDs	O
in	O
the	O
Cheshire	O
Basin	O
and	O
elsewhere	O
.	O

This	O
is	O
particularly	O
the	O
case	O
if	O
mineralisation	O
occurred	O
during	O
the	O
late	O
Triassic	CHRONOSTRAT
to	O
early	O
Jurassic	CHRONOSTRAT
period	O
of	O
crustal	O
extension	O
or	O
subsequently	O
.	O

The	O
MMG	O
appears	O
to	O
have	O
acted	O
as	O
a	O
major	O
source	O
of	O
ligands	O
and	O
metals	O
for	O
the	O
known	O
ore	O
deposits	O
,	O
as	O
well	O
as	O
being	O
the	O
dominant	O
control	O
on	O
ore-fluid	O
migration	O
,	O
and	O
there	O
is	O
thought	O
to	O
be	O
the	O
potential	O
for	O
the	O
discovery	O
of	O
further	O
small-tonnage	O
high-grade	O
Cu	O
deposits	O
beneath	O
the	O
MMG	O
.	O

In	O
the	O
south-west	O
of	O
the	O
basin	O
,	O
the	O
lack	O
of	O
Westphalian	CHRONOSTRAT
rocks	O
in	O
the	O
basement	O
,	O
which	O
are	O
thought	O
to	O
have	O
been	O
the	O
source	O
of	O
the	O
reducing	O
phase	O
involved	O
in	O
ore	O
deposition	O
,	O
may	O
also	O
limit	O
the	O
potential	O
for	O
continental	O
red-bed-type	O
Cu	O
deposits	O
.	O

Some	O
of	O
the	O
evidence	O
presented	O
here	O
suggests	O
that	O
Cu	O
mineralisation	O
occurred	O
in	O
the	O
Cheshire	O
Basin	O
during	O
the	O
late	O
Triassic	CHRONOSTRAT
to	O
early	O
Jurassic	CHRONOSTRAT
phase	O
of	O
crustal	O
extension	O
.	O

The	O
Blue	LEXICON
Anchor	LEXICON
Formation	LEXICON
,	O
Penarth	LEXICON
Group	LEXICON
and	O
Lias	LEXICON
Group	LEXICON
of	O
the	O
Prees	O
outlier	O
in	O
the	O
south-east	O
of	O
the	O
basin	O
,	O
and	O
rocks	O
of	O
similar	O
age	O
elsewhere	O
in	O
central	O
and	O
southern	O
Britain	O
,	O
comprise	O
dark	O
mudstones	O
and	O
limestones	O
which	O
could	O
have	O
provided	O
a	O
reducing	O
horizon	O
capable	O
of	O
precipitating	O
sulphide	O
minerals	O
from	O
ore	O
solutions	O
originating	O
in	O
the	O
red-beds	O
beneath	O
.	O

Hence	O
,	O
if	O
ore	O
formation	O
occurred	O
following	O
deposition	O
of	O
the	O
Lower	CHRONOSTRAT
Jurassic	CHRONOSTRAT
,	O
more	O
extensive	O
SCD	O
deposits	O
of	O
Kupferschiefer	O
,	O
rather	O
than	O
continental-red-bed	O
type	O
,	O
may	O
have	O
formed	O
near	O
the	O
top	O
of	O
the	O
red-bed	O
sequence	O
.	O

In	O
the	O
Cheshire	O
Basin	O
the	O
Blue	LEXICON
Anchor	LEXICON
Formation	LEXICON
,	O
Penarth	LEXICON
Group	LEXICON
and	O
Lias	LEXICON
Group	LEXICON
rocks	O
were	O
largely	O
eroded	O
during	O
the	O
Tertiary	CHRONOSTRAT
.	O

Elsewhere	O
,	O
however	O
,	O
they	O
are	O
present	O
from	O
north-east	O
England	O
to	O
Devon	O
in	O
the	O
south-west	O
,	O
overlying	O
red	O
beds	O
of	O
the	O
MMG	O
.	O

Numerous	O
minor	O
occurrences	O
of	O
epigenetic	O
Cu	O
occur	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
areas	O
of	O
England	O
.	O

At	O
Middleton	O
Tyas	O
,	O
secondarily	O
enriched	O
Cu	O
ores	O
occur	O
in	O
Carboniferous	CHRONOSTRAT
host	O
rocks	O
.	O

The	O
Lower	CHRONOSTRAT
Permian	CHRONOSTRAT
Marl	O
Slate	O
of	O
north-east	O
England	O
is	O
the	O
lateral	O
equivalent	O
of	O
the	O
Kupferschiefer	O
.	O

Mineralisation	O
offers	O
a	O
possible	O
explanation	O
for	O
a	O
zone	O
of	O
anomalous	O
values	O
for	O
Cu	O
and	O
other	O
elements	O
in	O
stream	O
sediments	O
extending	O
over	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
from	O
Teesside	O
to	O
York	O
is	O
similar	O
to	O
that	O
of	O
the	O
Cheshire	O
Basin	O
.	O

Hence	O
it	O
is	O
considered	O
that	O
there	O
may	O
be	O
the	O
potential	O
for	O
the	O
discovery	O
of	O
significant	O
SCDs	O
in	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
on	O
and	O
offshore	O
of	O
the	O
UK	O
where	O
they	O
are	O
overlain	O
by	O
reducing	O
marine	O
sequences	O
.	O

The	O
greatest	O
potential	O
for	O
such	O
deposits	O
would	O
be	O
at	O
sites	O
where	O
oxidising	O
hydrothermal	O
brines	O
circulating	O
in	O
the	O
basin	O
have	O
encountered	O
reducing	O
conditions	O
,	O
for	O
example	O
near	O
to	O
the	O
contact	O
between	O
the	O
red	O
beds	O
and	O
the	O
Coal	LEXICON
Measures	LEXICON
in	O
the	O
north	O
of	O
the	O
basin	O
.	O

BGS	O
regional	O
geochemical	O
data	O
show	O
Cu	O
anomalies	O
close	O
to	O
the	O
contact	O
between	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
the	O
underlying	O
Westphalian	CHRONOSTRAT
immediately	O
to	O
the	O
south-east	O
of	O
the	O
Cheshire	O
Basin	O
,	O
in	O
the	O
adjoining	O
Stafford	O
Basin	O
.	O

Boulder	O
clay	O
is	O
extracted	O
for	O
brickmaking	O
near	O
Warrington	O
,	O
and	O
the	O
SSG	O
is	O
worked	O
for	O
construction	O
fill	O
near	O
Warrington	O
and	O
as	O
a	O
building	O
stone	O
at	O
Grinshill	O
.	O

A	O
large	O
group	O
of	O
shallow	O
mines	O
was	O
sunk	O
nearby	O
in	O
the	O
Top	O
and	O
Bottom	O
beds	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

The	O
main	O
centres	O
of	O
wild	O
brine	O
extraction	O
were	O
at	O
Winsford	O
and	O
Northwich	O
,	O
sited	O
on	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

Wild	O
brine	O
was	O
also	O
formerly	O
extracted	O
from	O
the	O
Northwich	LEXICON
Halite	LEXICON
in	O
the	O
Heatley	O
Agden	O
Saltfield	O
near	O
Lymm	O
,	O
and	O
at	O
Lawton	O
-LSB-	O
8050	O
5727	O
-RSB-	O
.	O

Extensive	O
brining	O
was	O
formerly	O
undertaken	O
in	O
the	O
lower	O
part	O
of	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
,	O
near	O
Sandbach	O
,	O
Elworth	O
and	O
Middlewich	O
.	O

The	O
only	O
wild	O
brine	O
currently	O
produced	O
is	O
at	O
New	O
Cheshire	O
salt	O
works	O
at	O
Wincham	O
,	O
near	O
Northwich	O
,	O
from	O
the	O
lower	O
part	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
.	O

All	O
the	O
brine	O
comes	O
from	O
the	O
Northwich	LEXICON
Halite	LEXICON
Formation	LEXICON
and	O
is	O
from	O
cavities	O
some	O
100m	O
across	O
and	O
up	O
to	O
170m	O
in	O
height	O
formed	O
by	O
a	O
triple	O
tube	O
system	O
involving	O
water	O
,	O
compressed	O
air	O
and	O
a	O
brine	O
outlet	O
.	O

Both	O
sites	O
are	O
under	O
a	O
cover	O
of	O
Byley	LEXICON
Mudstones	LEXICON
,	O
overlying	O
the	O
halite	O
.	O

Mining	O
is	O
currently	O
all	O
in	O
the	O
Bottom	O
Bed	O
of	O
the	O
Northwich	LEXICON
Halite	LEXICON
in	O
galleries	O
7.5m	O
in	O
height	O
.	O

The	O
future	O
resources	O
are	O
vast	O
,	O
notably	O
in	O
the	O
virtually	O
untapped	O
area	O
of	O
the	O
Prees	O
Syncline	O
where	O
both	O
the	O
Northwich	LEXICON
and	O
Wilkesley	LEXICON
halites	O
are	O
present	O
.	O

This	O
area	O
includes	O
a	O
probable	O
eastern	O
extension	O
of	O
the	O
Wilkesley	LEXICON
Halite	LEXICON
outcrop	O
towards	O
Betley	O
,	O
near	O
Stoke-on-Trent	O
,	O
with	O
the	O
likelihood	O
there	O
of	O
Northwich	LEXICON
Halite	LEXICON
at	O
depth	O
.	O

Most	O
of	O
the	O
analytical	O
work	O
on	O
the	O
project	O
concentrated	O
on	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
,	O
since	O
the	O
primary	O
aim	O
was	O
to	O
provide	O
a	O
metallogenic	O
model	O
for	O
the	O
Cu-Pb-Ba	O
mineralisation	O
.	O

The	O
prospectivity	O
of	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
is	O
based	O
on	O
work	O
done	O
over	O
a	O
number	O
of	O
years	O
on	O
the	O
Pennine	O
Basin	O
.	O

Because	O
there	O
is	O
a	O
dearth	O
of	O
organic	O
matter	O
within	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
red	O
beds	O
,	O
samples	O
had	O
to	O
be	O
collected	O
outside	O
the	O
Cheshire	O
Basin	O
,	O
from	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

All	O
share	O
the	O
fundamental	O
property	O
that	O
hydrocarbons	O
were	O
generated	O
from	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

As	O
described	O
earlier	O
in	O
this	O
volume	O
,	O
the	O
Cheshire	O
Basin	O
contains	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
red	O
beds	O
.	O

Red	LEXICON
beds	LEXICON
are	O
important	O
hydrocarbon	O
reservoirs	O
in	O
many	O
parts	O
of	O
the	O
world	O
.	O

In	O
the	O
UK	O
,	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
are	O
important	O
hydrocarbon	O
reservoirs	O
in	O
the	O
North	O
Sea	O
,	O
Wessex	O
and	O
East	O
Irish	O
Sea	O
basins	O
.	O

Carboniferous	CHRONOSTRAT
rocks	O
provide	O
important	O
oil	O
and	O
gas-prone	O
source	O
rocks	O
in	O
the	O
East	O
Irish	O
Sea	O
,	O
southern	O
North	O
Sea	O
,	O
East	O
Midlands	O
and	O
Europe	O
generally	O
,	O
and	O
provide	O
reservoirs	O
in	O
the	O
East	O
Midlands	O
.	O

Carboniferous	CHRONOSTRAT
reservoirs	O
are	O
not	O
proven	O
in	O
the	O
Cheshire	O
Basin	O
,	O
however	O
,	O
and	O
there	O
are	O
no	O
mature	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
or	O
younger	O
source	O
rocks	O
in	O
that	O
area	O
or	O
in	O
the	O
East	O
Midlands	O
.	O

Producing	O
fields	O
from	O
Triassic	CHRONOSTRAT
reservoirs	O
in	O
basins	O
adjacent	O
to	O
Cheshire	O
,	O
at	O
Formby	O
and	O
in	O
the	O
East	O
Irish	O
Sea	O
,	O
together	O
with	O
oil	O
shows	O
in	O
the	O
Needwood	O
Basin	O
prove	O
that	O
oil	O
and	O
gas	O
have	O
been	O
generated	O
and	O
have	O
migrated	O
,	O
even	O
into	O
Recent	O
sedimentary	O
deposits	O
.	O

In	O
the	O
East	O
Irish	O
Sea	O
Basin	O
the	O
reservoir	O
for	O
all	O
the	O
hydrocarbons	O
is	O
the	O
Ormskirk	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
sealed	O
by	O
MMG	O
halites	O
and	O
mudstones	O
.	O

The	O
older	O
sandstones	O
of	O
the	O
SSG	O
and	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
are	O
not	O
productive	O
,	O
despite	O
the	O
latter	O
being	O
sealed	O
by	O
the	O
Manchester	LEXICON
Marls	LEXICON
.	O

The	O
key	O
to	O
the	O
hydrocarbon	O
prospectivity	O
lies	O
in	O
resolving	O
whether	O
migration	O
from	O
the	O
Carboniferous	CHRONOSTRAT
source	O
rocks	O
into	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
has	O
occurred	O
,	O
or	O
the	O
extent	O
to	O
which	O
hydrocarbons	O
are	O
trapped	O
within	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

There	O
are	O
only	O
about	O
a	O
dozen	O
recorded	O
hydrocarbon	O
shows	O
in	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
of	O
the	O
Cheshire	O
Basin	O
sensu	O
stricto	O
,	O
and	O
none	O
of	O
these	O
contains	O
live	O
oil	O
.	O

There	O
are	O
,	O
however	O
,	O
limited	O
developments	O
of	O
oil	O
sands	O
in	O
the	O
Triassic	CHRONOSTRAT
of	O
the	O
nearby	O
Needwood	O
Basin	O
and	O
commercial	O
oil	O
and	O
gas	O
production	O
from	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
of	O
the	O
East	O
Irish	O
Sea	O
Basin	O
.	O

In	O
addition	O
,	O
the	O
Formby	O
Oilfield	O
produced	O
from	O
a	O
Pleistocene	CHRONOSTRAT
sand	O
in	O
one	O
well	O
and	O
from	O
Triassic	CHRONOSTRAT
rocks	O
in	O
the	O
other	O
wells	O
.	O

In	O
contrast	O
,	O
hydrocarbon	O
shows	O
in	O
Carboniferous	CHRONOSTRAT
rocks	O
surrounding	O
the	O
Cheshire	O
Basin	O
and	O
beneath	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
are	O
commonplace	O
and	O
include	O
live	O
oil	O
.	O

The	O
Mere	O
Brow	O
Borehole	O
encountered	O
bitumen	O
in	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
,	O
and	O
minor	O
hydrocarbon	O
traces	O
are	O
reported	O
in	O
the	O
Mickle	O
Trafford	O
Borehole	O
,	O
and	O
at	O
the	O
Grinshill	O
and	O
Alderley	O
Edge	O
copper	O
mines	O
in	O
the	O
Cheshire	O
Basin	O
.	O

Their	O
presence	O
may	O
be	O
related	O
to	O
nearby	O
large	O
faults	O
,	O
in	O
the	O
case	O
of	O
the	O
Mickle	O
Trafford	O
and	O
Little	O
Ness	O
boreholes	O
,	O
and	O
the	O
close	O
proximity	O
to	O
the	O
main	O
area	O
of	O
Carboniferous	CHRONOSTRAT
subsurface	O
shows	O
in	O
the	O
north	O
of	O
the	O
basin	O
for	O
most	O
of	O
the	O
others	O
.	O

Ickes	O
reported	O
obtaining	O
2.5%	O
petroleum	O
by	O
the	O
use	O
of	O
solvents	O
,	O
with	O
Carboniferous	CHRONOSTRAT
oil	O
characteristics	O
.	O

A	O
Carboniferous	CHRONOSTRAT
source	O
and	O
mother	O
pool	O
were	O
suspected	O
but	O
not	O
found	O
,	O
despite	O
drilling	O
five	O
deep	O
boreholes	O
.	O

Interpretation	O
of	O
seismic	O
reflection	O
data	O
shows	O
that	O
Dinantian	CHRONOSTRAT
rocks	O
form	O
the	O
subcrop	O
stretching	O
north-east	O
from	O
the	O
seeps	O
.	O

Several	O
north	O
south	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
faults	O
have	O
tapped	O
the	O
migrating	O
oil	O
and	O
,	O
with	O
a	O
very	O
thin	O
MMG	O
seal	O
,	O
seepage	O
to	O
the	O
surface	O
has	O
occurred	O
.	O

This	O
oilfield	O
should	O
be	O
considered	O
as	O
the	O
first	O
discovery	O
in	O
the	O
East	O
Irish	O
Sea	O
Basin	O
and	O
highlights	O
how	O
the	O
interplay	O
between	O
Carboniferous	CHRONOSTRAT
source-rock	O
maturity	O
,	O
Triassic	CHRONOSTRAT
reservoirs	O
,	O
seals	O
and	O
faulting	O
may	O
be	O
the	O
key	O
to	O
further	O
successes	O
.	O

Carboniferous	CHRONOSTRAT
rocks	O
in	O
all	O
the	O
coalfields	O
surrounding	O
the	O
Cheshire	O
Basin	O
have	O
fair	O
to	O
good	O
shows	O
of	O
hydrocarbons	O
,	O
with	O
live	O
oil	O
,	O
and	O
are	O
comparable	O
in	O
this	O
respect	O
to	O
the	O
Nottinghamshire	O
Yorkshire	O
Coalfield	O
.	O

The	O
oil	O
has	O
migrated	O
to	O
the	O
extremity	O
of	O
the	O
Carboniferous	CHRONOSTRAT
basin	O
.	O

In	O
Cheshire	O
,	O
weak	O
hydrocarbon	O
shows	O
were	O
recorded	O
in	O
the	O
Blacon	O
East	O
Borehole	O
,	O
in	O
Namurian	CHRONOSTRAT
sandstones	O
.	O

The	O
Churton	O
Borehole	O
,	O
in	O
the	O
Milton	O
Green	O
Inlier	O
,	O
had	O
oil	O
shows	O
in	O
the	O
Erbistock	LEXICON
and	O
Coed-yr-Allt	LEXICON
formations	O
,	O
suggesting	O
that	O
the	O
Ruabon	LEXICON
Marl	LEXICON
seal	O
is	O
breached	O
in	O
the	O
Inlier	O
.	O

Some	O
of	O
the	O
shows	O
are	O
in	O
the	O
red	O
beds	O
,	O
but	O
most	O
are	O
in	O
the	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
sandstones	O
.	O

Philips	O
Bridge	O
Borehole	O
,	O
south	O
of	O
Stockport	O
,	O
had	O
an	O
oil	O
show	O
in	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
rocks	O
.	O

In	O
Clwyd	O
,	O
Redwood	O
reported	O
oil	O
in	O
water	O
wells	O
at	O
Rosehill	O
and	O
Erbistock	O
Lodge	O
,	O
about	O
a	O
kilometre	O
apart	O
,	O
and	O
the	O
borehole	O
at	O
Overton	O
Bridge	O
had	O
oil	O
shows	O
in	O
the	O
Coed-yr-Allt	LEXICON
and	O
Ruabon	LEXICON
Marl	LEXICON
formations	O
.	O

These	O
seeps	O
may	O
result	O
from	O
this	O
area	O
being	O
a	O
Westphalian	CHRONOSTRAT
palaeo-high	O
,	O
towards	O
which	O
migration	O
could	O
have	O
occurred	O
over	O
a	O
long	O
period	O
of	O
time	O
.	O

Cronton	O
A3/5	O
Borehole	O
penetrated	O
a	O
3m	O
oil	O
sand	O
in	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

Numerous	O
other	O
nearby	O
localities	O
also	O
experienced	O
seepages	O
,	O
indicating	O
that	O
migration	O
into	O
the	O
Westphalian	CHRONOSTRAT
D	CHRONOSTRAT
Coalport	O
Formation	O
sandstones	O
had	O
occurred	O
over	O
a	O
considerable	O
distance	O
.	O

Selley	O
,	O
in	O
a	O
cross-section	O
,	O
showed	O
the	O
relationship	O
of	O
some	O
of	O
the	O
seeps	O
to	O
the	O
basal	O
Westphalian	CHRONOSTRAT
unconformity	O
.	O

In	O
Staffordshire	O
,	O
oil-stained	O
Namurian	CHRONOSTRAT
rocks	O
were	O
found	O
where	O
the	O
Red	O
Rock	O
Fault	O
crosses	O
the	O
river	O
Dane	O
and	O
at	O
Dingle	O
Brook	O
near	O
Bosley	O
in	O
Arnsbergian	CHRONOSTRAT
mudstones	O
.	O

Nearly	O
all	O
the	O
early	O
exploration	O
wells	O
drilled	O
to	O
appraise	O
these	O
shows	O
were	O
drilled	O
north-east	O
of	O
the	O
Coalfield	O
,	O
at	O
Werrington	O
,	O
Gun	O
Hill	O
and	O
Nooks	O
Farm	O
,	O
on	O
large	O
surface	O
anticlines	O
,	O
spudded	O
into	O
Namurian	CHRONOSTRAT
rocks	O
.	O

Nooks	O
Farm	O
Borehole	O
encountered	O
sub-economic	O
gas	O
in	O
the	O
latest	O
Dinantian	CHRONOSTRAT
Onecote	LEXICON
Sandstone	LEXICON
.	O

Potential	O
hydrocarbon	O
source	O
rocks	O
include	O
Dinantian	CHRONOSTRAT
,	O
all	O
of	O
which	O
outcrop	O
on	O
the	O
periphery	O
of	O
the	O
Cheshire	O
Basin	O
.	O

They	O
are	O
well-known	O
source	O
rocks	O
in	O
other	O
oil	O
provinces	O
:	O
early	O
Namurian	CHRONOSTRAT
shales	O
.	O

The	O
Formby	O
Oilfield	O
overlies	O
Bowland	O
Shales	O
,	O
which	O
subcrop	O
beneath	O
Permian	CHRONOSTRAT
rocks	O
.	O

These	O
Westphalian	CHRONOSTRAT
source	O
rocks	O
can	O
reasonably	O
be	O
expected	O
to	O
underlie	O
the	O
Cheshire	O
Basin	O
between	O
the	O
North	O
Staffordshire	O
,	O
Lancashire	O
and	O
North	O
Wales	O
coalfields	O
.	O

The	O
latter	O
may	O
have	O
migrated	O
south-west	O
towards	O
the	O
margin	O
of	O
the	O
Carboniferous	CHRONOSTRAT
basin	O
.	O

Precambrian	CHRONOSTRAT
samples	O
were	O
from	O
the	O
Shrewsbury	O
area	O
,	O
where	O
oil	O
from	O
the	O
basal	O
Westphalian	CHRONOSTRAT
has	O
seeped	O
into	O
the	O
underlying	O
Longmyndian	CHRONOSTRAT
rocks	O
.	O

The	O
Coalport	O
Tar	O
Tunnel	O
sample	O
is	O
from	O
Westphalian	CHRONOSTRAT
rocks	O
a	O
short	O
distance	O
above	O
Silurian	CHRONOSTRAT
rocks	O
.	O

The	O
Snailbeach	O
Pb	O
mine	O
yielded	O
bitumen	O
from	O
veins	O
,	O
thought	O
to	O
be	O
Triassic	CHRONOSTRAT
in	O
age	O
,	O
in	O
Ordovician	CHRONOSTRAT
rocks	O
.	O

Five	O
of	O
the	O
Triassic	CHRONOSTRAT
samples	O
are	O
from	O
within	O
the	O
Cheshire	O
Basin	O
,	O
Burton	O
Point	O
being	O
adjacent	O
to	O
the	O
East	O
Irish	O
Sea	O
Basin	O
.	O

The	O
sample	O
from	O
well	O
110/7	O
-2	O
is	O
a	O
show	O
in	O
the	O
Permian	CHRONOSTRAT
Collyhurst	LEXICON
Sandstone	LEXICON
.	O

The	O
Ecton	O
sample	O
is	O
from	O
Dinantian	CHRONOSTRAT
rocks	O
at	O
the	O
Waterbank	O
Mine	O
dumps	O
.	O

The	O
River	O
Dane	O
sample	O
is	O
from	O
Triassic	CHRONOSTRAT
rocks	O
close	O
to	O
the	O
show	O
recorded	O
by	O
Evans	O
et	O
al.	O
.	O

The	O
five	O
most	O
biodegraded	O
samples	O
,	O
without	O
recognisable	O
alkane	O
patterns	O
,	O
are	O
from	O
the	O
Westphalian	CHRONOSTRAT
and	O
pre	O
-	O
Westphalian	CHRONOSTRAT
rocks	O
in	O
the	O
Shrewsbury	O
area	O
.	O

These	O
data	O
support	O
the	O
results	O
of	O
the	O
carbon	O
isotope	O
composition	O
of	O
the	O
late	O
carbonate	O
cement	O
,	O
indicating	O
an	O
influx	O
of	O
fluids	O
from	O
mature	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

A	O
different	O
source	O
,	O
within	O
the	O
Coal	LEXICON
Measures	LEXICON
,	O
is	O
indicated	O
by	O
the	O
high	O
Pri/Phy	O
ratios	O
of	O
the	O
Hem	O
Heath	O
,	O
Little	O
Ness	O
and	O
River	O
Dane	O
samples	O
.	O

The	O
present-day	O
geothermal	O
gradient	O
in	O
the	O
basin	O
is	O
low	O
,	O
at	O
about	O
20	O
degrees	O
C/km	O
,	O
and	O
there	O
is	O
no	O
evidence	O
for	O
significantly	O
higher	O
values	O
in	O
Permian	CHRONOSTRAT
to	O
Tertiary	CHRONOSTRAT
times	O
.	O

Thermal	O
modelling	O
of	O
the	O
basin	O
using	O
the	O
BGS	O
HotPot	O
software	O
suggests	O
that	O
the	O
basin	O
is	O
relatively	O
cool	O
,	O
with	O
mean	O
temperatures	O
ranging	O
from	O
20	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
MMG	O
to	O
37	O
degrees	O
C	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
.	O

The	O
highest	O
temperatures	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
succession	O
,	O
in	O
the	O
deeper	O
parts	O
of	O
the	O
basin	O
,	O
locally	O
exceed	O
70	O
degrees	O
C	O
in	O
parts	O
of	O
the	O
Wem	O
Audlem	O
Sub-basin	O
and	O
65	O
degrees	O
C	O
in	O
the	O
Sandbach	O
Knutsford	O
Sub-basin	O
.	O

There	O
is	O
some	O
evidence	O
from	O
the	O
East	O
Irish	O
Sea	O
Basin	O
that	O
geothermal	O
gradients	O
were	O
significantly	O
higher	O
in	O
Carboniferous	CHRONOSTRAT
times	O
.	O

Roberts	O
is	O
lower	O
than	O
that	O
in	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
of	O
well	O
112/30	O
-1	O
.	O

In	O
addition	O
,	O
there	O
is	O
a	O
downhole	O
variation	O
in	O
maturity	O
from	O
low	O
gradients	O
in	O
post	O
-	O
Carboniferous	CHRONOSTRAT
rocks	O
to	O
high	O
gradients	O
in	O
Carboniferous	CHRONOSTRAT
rocks	O
in	O
well	O
110/11	O
-1	O
.	O

This	O
may	O
result	O
from	O
a	O
geothermal	O
gradient	O
which	O
was	O
significantly	O
higher	O
during	O
the	O
Carboniferous	CHRONOSTRAT
.	O

The	O
total	O
preserved	O
thickness	O
of	O
the	O
Carboniferous	CHRONOSTRAT
in	O
the	O
Quadrant	O
109	O
Syncline	O
in	O
the	O
East	O
Irish	O
Sea	O
was	O
estimated	O
at	O
6250m	O
by	O
Jackson	O
et	O
al.	O
.	O

Coal	O
rank	O
data	O
from	O
the	O
Keele	O
1	O
Borehole	O
in	O
the	O
North	O
Staffordshire	O
Coalfield	O
suggest	O
that	O
there	O
may	O
also	O
have	O
been	O
variations	O
in	O
the	O
geothermal	O
gradient	O
during	O
the	O
Carboniferous	CHRONOSTRAT
,	O
with	O
higher	O
gradients	O
in	O
the	O
early	O
Westphalian	CHRONOSTRAT
than	O
in	O
late	O
Westphalian	CHRONOSTRAT
times	O
.	O

A	O
depth-maturity	O
plot	O
of	O
Keele	O
1	O
reveals	O
by	O
calculation	O
that	O
the	O
geothermal	O
gradient	O
may	O
have	O
been	O
as	O
high	O
as	O
81	O
degrees	O
C/km	O
in	O
early	O
Westphalian	CHRONOSTRAT
times	O
,	O
declining	O
to	O
29	O
45	O
degrees	O
C/km	O
in	O
late	O
Westphalian	CHRONOSTRAT
times	O
.	O

The	O
heat	O
flow	O
is	O
therefore	O
also	O
thought	O
to	O
have	O
been	O
higher	O
in	O
early	O
Westphalian	CHRONOSTRAT
times	O
,	O
as	O
the	O
thermal	O
conductivities	O
of	O
the	O
Westphalian	CHRONOSTRAT
rocks	O
are	O
relatively	O
constant	O
.	O

Westphalian	CHRONOSTRAT
D	CHRONOSTRAT
rocks	O
in	O
Knutsford	O
are	O
significantly	O
more	O
mature	O
than	O
the	O
highest	O
Westphalian	CHRONOSTRAT
rocks	O
in	O
Keele	O
1	O
,	O
just	O
leaving	O
the	O
oil	O
window	O
.	O

If	O
a	O
similar	O
amount	O
of	O
uplift	O
has	O
been	O
experienced	O
by	O
both	O
sites	O
,	O
this	O
implies	O
a	O
geothermal	O
gradient	O
of	O
approximately	O
34	O
degrees	O
C/km	O
since	O
Permian	CHRONOSTRAT
times	O
,	O
somewhat	O
higher	O
than	O
at	O
present	O
.	O

If	O
,	O
however	O
,	O
the	O
geothermal	O
gradient	O
has	O
been	O
approximately	O
constant	O
at	O
its	O
present	O
level	O
since	O
Permian	CHRONOSTRAT
times	O
,	O
differences	O
in	O
the	O
amount	O
of	O
Variscan	CHRONOSTRAT
uplift	O
would	O
be	O
suggested	O
.	O

Evidence	O
for	O
lateral	O
variations	O
in	O
geothermal	O
gradients	O
comes	O
from	O
coal	O
rank	O
maturity	O
data	O
from	O
North	O
Staffordshire	O
,	O
which	O
suggest	O
that	O
palaeogeothermal	O
gradients	O
during	O
Westphalian	CHRONOSTRAT
times	O
were	O
higher	O
in	O
this	O
area	O
than	O
in	O
the	O
Lancashire	O
and	O
East	O
Midlands	O
coalfields	O
,	O
perhaps	O
due	O
to	O
its	O
closer	O
proximity	O
to	O
Westphalian	CHRONOSTRAT
volcanism	O
.	O

Carboniferous	CHRONOSTRAT
source	O
rocks	O
in	O
this	O
region	O
have	O
undergone	O
two	O
phases	O
of	O
burial	O
,	O
firstly	O
during	O
Carboniferous	CHRONOSTRAT
basin	O
formation	O
and	O
secondly	O
during	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
and	O
later	O
burial	O
.	O

Thermal	O
modelling	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
fill	O
of	O
the	O
Cheshire	O
Basin	O
suggests	O
that	O
maximum	O
temperatures	O
were	O
attained	O
during	O
the	O
period	O
of	O
maximum	O
burial	O
in	O
Palaeocene	CHRONOSTRAT
times	O
.	O

Severe	O
reductions	O
in	O
average	O
porosities	O
of	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sandstones	O
,	O
resulting	O
from	O
this	O
burial	O
,	O
are	O
likely	O
towards	O
the	O
basin	O
centre	O
.	O

Average	O
temperatures	O
at	O
the	O
base	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
were	O
95	O
degrees	O
C	O
,	O
with	O
peak	O
temperatures	O
in	O
the	O
deepest	O
part	O
of	O
the	O
basin	O
of	O
140	O
degrees	O
C	O
.	O

The	O
lower	O
part	O
of	O
the	O
Permian	CHRONOSTRAT
sequence	O
entered	O
the	O
oil-maturation	O
window	O
towards	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
and	O
left	O
it	O
during	O
late	O
Palaeogene	CHRONOSTRAT
uplift	O
.	O

Peak	O
maturity	O
was	O
reached	O
in	O
early	O
Palaeogene	CHRONOSTRAT
times	O
,	O
corresponding	O
to	O
the	O
maximum	O
depth	O
of	O
burial	O
.	O

Much	O
of	O
the	O
Permian	CHRONOSTRAT
sequence	O
was	O
in	O
the	O
oil-maturation	O
zone	O
at	O
this	O
time	O
,	O
with	O
some	O
parts	O
being	O
at	O
temperatures	O
almost	O
high	O
enough	O
for	O
gas	O
maturation	O
.	O

The	O
base	O
of	O
the	O
SSG	O
was	O
in	O
the	O
oil-generating	O
window	O
from	O
early	O
Jurassic	CHRONOSTRAT
to	O
mid	O
or	O
late	O
Palaeogene	CHRONOSTRAT
times	O
,	O
and	O
the	O
base	O
of	O
the	O
MMG	O
from	O
late	O
Jurassic	CHRONOSTRAT
to	O
mid	O
Palaeogene	CHRONOSTRAT
times	O
.	O

Modelling	O
of	O
underlying	O
Carboniferous	CHRONOSTRAT
rocks	O
is	O
more	O
problematical	O
,	O
as	O
their	O
maturity	O
at	O
the	O
end	O
of	O
Carboniferous	CHRONOSTRAT
basin	O
development	O
is	O
difficult	O
to	O
estimate	O
.	O

Carboniferous	CHRONOSTRAT
strata	O
generally	O
possess	O
a	O
maturity	O
,	O
due	O
to	O
Carboniferous	CHRONOSTRAT
burial	O
and	O
Variscan	O
tectonics	O
,	O
which	O
is	O
markedly	O
higher	O
than	O
post	O
-	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

Even	O
if	O
this	O
observation	O
is	O
disregarded	O
,	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
would	O
have	O
become	O
mature	O
earlier	O
than	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
strata	O
because	O
of	O
their	O
greater	O
depth	O
.	O

They	O
probably	O
reached	O
the	O
oil	O
window	O
in	O
mid	O
to	O
late	O
Triassic	CHRONOSTRAT
times	O
,	O
and	O
they	O
remained	O
in	O
the	O
oil-generation	O
zone	O
for	O
longer	O
than	O
post	O
-	O
Carboniferous	CHRONOSTRAT
rocks	O
,	O
probably	O
until	O
early	O
Neogene	CHRONOSTRAT
times	O
.	O

They	O
would	O
also	O
have	O
attained	O
higher	O
levels	O
of	O
maturity	O
,	O
well	O
into	O
the	O
gas-generating	O
window	O
,	O
at	O
maximum	O
depth	O
of	O
burial	O
in	O
early	O
Palaeogene	CHRONOSTRAT
times	O
.	O

Hydrocarbon	O
generation	O
is	O
therefore	O
thought	O
to	O
have	O
begun	O
during	O
Carboniferous	CHRONOSTRAT
times	O
,	O
from	O
source	O
rocks	O
in	O
the	O
Pennine	O
Basin	O
depocentre	O
which	O
lay	O
to	O
the	O
north	O
of	O
the	O
area	O
now	O
occupied	O
by	O
the	O
Cheshire	O
Basin	O
.	O

It	O
is	O
likely	O
that	O
some	O
of	O
these	O
hydrocarbons	O
migrated	O
south-westwards	O
,	O
away	O
from	O
the	O
Pennine	O
depocentre	O
,	O
towards	O
the	O
margins	O
of	O
the	O
Carboniferous	CHRONOSTRAT
basin	O
,	O
into	O
the	O
area	O
now	O
underlying	O
the	O
Cheshire	O
Basin	O
.	O

As	O
subsidence	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
Cheshire	O
Basin	O
proceeded	O
it	O
is	O
likely	O
that	O
the	O
underlying	O
Carboniferous	CHRONOSTRAT
sediments	O
,	O
hitherto	O
immature	O
,	O
also	O
started	O
to	O
generate	O
hydrocarbons	O
.	O

Deep	O
saline	O
fluids	O
,	O
in	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
and	O
in	O
the	O
Coal	LEXICON
Measures	LEXICON
,	O
have	O
been	O
recorded	O
from	O
geophysical	O
log	O
interpretation	O
,	O
from	O
samples	O
from	O
a	O
deep	O
borehole	O
near	O
Chester	O
,	O
and	O
from	O
a	O
11000mg/l	O
saline	O
spring	O
at	O
Aldersey	O
.	O

Fresh	O
water	O
was	O
recovered	O
by	O
drill	O
stem	O
test	O
from	O
the	O
Coed-yr-Allt	LEXICON
Formation	LEXICON
,	O
in	O
the	O
Milton	O
Green	O
Borehole	O
.	O

Saline	O
water	O
was	O
recovered	O
from	O
Dinantian	CHRONOSTRAT
rocks	O
in	O
the	O
same	O
borehole	O
.	O

Springs	O
with	O
higher	O
than	O
average	O
temperatures	O
are	O
geographically	O
associated	O
with	O
hydrocarbon	O
shows	O
in	O
the	O
South	O
Pennine	O
Orefield	O
,	O
and	O
the	O
Ridgeway	O
Borehole	O
,	O
near	O
Sheffield	O
,	O
encountered	O
hot	O
salt	O
water	O
with	O
hydrogen	O
sulphide	O
in	O
Dinantian	CHRONOSTRAT
rocks	O
.	O

Downing	O
and	O
Howitt	O
showed	O
that	O
saline	O
concentrations	O
in	O
Namurian	CHRONOSTRAT
and	O
Westphalian	CHRONOSTRAT
groundwaters	O
,	O
in	O
the	O
East	O
Midlands	O
oilfields	O
,	O
increased	O
northwards	O
towards	O
the	O
basin	O
depocentre	O
.	O

During	O
Carboniferous	CHRONOSTRAT
times	O
,	O
it	O
is	O
likely	O
that	O
hydrocarbons	O
migrated	O
south-westwards	O
away	O
from	O
the	O
Pennine	O
Basin	O
depocentre	O
towards	O
its	O
margin	O
,	O
to	O
the	O
area	O
now	O
underlying	O
the	O
Cheshire	O
Basin	O
.	O

Late	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
structural	O
inversion	O
of	O
the	O
Pennine	O
Basin	O
would	O
have	O
caused	O
some	O
hydrocarbons	O
to	O
migrate	O
north-eastwards	O
,	O
away	O
from	O
the	O
Cheshire	O
Basin	O
area	O
,	O
but	O
erosion	O
of	O
potential	O
reservoirs	O
,	O
in	O
the	O
Pennines	O
,	O
has	O
destroyed	O
any	O
such	O
hydrocarbons	O
.	O

Migration	O
of	O
hydrocarbons	O
since	O
Carboniferous	CHRONOSTRAT
times	O
may	O
also	O
have	O
been	O
largely	O
within	O
Carboniferous	CHRONOSTRAT
rocks	O
,	O
if	O
the	O
seals	O
were	O
not	O
breached	O
.	O

Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
syn-sedimentary	O
faulting	O
is	O
,	O
however	O
,	O
likely	O
to	O
have	O
modified	O
migration	O
directions	O
.	O

The	O
most	O
prospective	O
area	O
for	O
this	O
oil	O
is	O
undoubtedly	O
to	O
the	O
south-east	O
of	O
the	O
inlier	O
,	O
because	O
there	O
is	O
probably	O
no	O
seal	O
to	O
the	O
Carboniferous	CHRONOSTRAT
at	O
outcrop	O
.	O

Hydrocarbon	O
shows	O
were	O
present	O
in	O
the	O
Carboniferous	CHRONOSTRAT
red	O
beds	O
in	O
the	O
Churton	O
Borehole	O
,	O
drilled	O
in	O
the	O
Milton	O
Green	O
Inlier	O
.	O

Madeley	O
1	O
and	O
3	O
,	O
to	O
the	O
north	O
,	O
have	O
a	O
more	O
complete	O
Westphalian	CHRONOSTRAT
succession	O
,	O
which	O
thickens	O
northwards	O
.	O

The	O
Symon	O
Unconformity	O
,	O
in	O
contrast	O
,	O
cuts	O
down	O
into	O
the	O
earlier	O
Westphalian	CHRONOSTRAT
rocks	O
,	O
removing	O
most	O
of	O
the	O
Westphalian	CHRONOSTRAT
B	CHRONOSTRAT
from	O
Madeley	O
6	O
and	O
all	O
the	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
from	O
Madeley	O
4	O
,	O
where	O
the	O
red	O
beds	O
come	O
to	O
rest	O
on	O
Wenlock	LEXICON
Shale	LEXICON
.	O

Oil	O
generated	O
from	O
the	O
coals	O
of	O
the	O
North	O
Staffordshire	O
Coalfield	O
and	O
its	O
subsurface	O
extension	O
could	O
have	O
migrated	O
toward	O
the	O
basin	O
margin	O
,	O
within	O
the	O
thinning	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
.	O

Evidence	O
of	O
migration	O
of	O
hydrocarbons	O
into	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
,	O
in	O
addition	O
to	O
the	O
few	O
,	O
poor	O
hydrocarbon	O
traces	O
,	O
comes	O
mainly	O
from	O
isotope	O
studies	O
.	O

This	O
suggests	O
fluid	O
migration	O
from	O
Carboniferous	CHRONOSTRAT
to	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
at	O
the	O
southern	O
margin	O
of	O
the	O
Lancashire	O
Coalfield	O
and	O
the	O
West	O
Lancashire	O
Basin	O
.	O

The	O
migration	O
pathways	O
for	O
fluids	O
derived	O
from	O
the	O
Carboniferous	CHRONOSTRAT
were	O
probably	O
not	O
the	O
main	O
north	O
south-trending	O
,	O
inclined	O
normal	O
faults	O
,	O
with	O
large	O
displacements	O
,	O
which	O
are	O
probably	O
sealing	O
.	O

Subvertical	O
,	O
east	O
west	O
transfer	O
faults	O
may	O
,	O
however	O
,	O
have	O
formed	O
pathways	O
for	O
upward	O
migration	O
of	O
fluids	O
from	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

Hydraulic	O
connectivity	O
between	O
the	O
Carboniferous	CHRONOSTRAT
and	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
is	O
suggested	O
by	O
the	O
chemistry	O
of	O
a	O
single	O
groundwater	O
sample	O
from	O
the	O
Coal	LEXICON
Measures	LEXICON
,	O
but	O
there	O
are	O
no	O
other	O
data	O
to	O
substantiate	O
this	O
interpretation	O
.	O

Fluid-inclusion	O
studies	O
found	O
no	O
evidence	O
of	O
migration	O
of	O
hydrocarbons	O
into	O
the	O
SSG	O
of	O
the	O
Cheshire	O
Basin	O
,	O
either	O
before	O
or	O
during	O
base-metal	O
mineralisation	O
.	O

Low-temperature	O
fluids	O
were	O
responsible	O
for	O
the	O
mineralisation	O
,	O
and	O
the	O
model	O
favoured	O
requires	O
a	O
Carboniferous	CHRONOSTRAT
fluid	O
component	O
probably	O
comprising	O
no	O
more	O
than	O
5%	O
of	O
the	O
total	O
fluid	O
budget	O
.	O

The	O
small	O
number	O
of	O
hydrocarbon	O
shows	O
in	O
post	O
-	O
Carboniferous	CHRONOSTRAT
rocks	O
invites	O
comparison	O
with	O
the	O
East	O
Midlands	O
.	O

Although	O
generation	O
of	O
hydrocarbons	O
here	O
also	O
continued	O
during	O
Permian	CHRONOSTRAT
and	O
Mesozoic	CHRONOSTRAT
times	O
,	O
there	O
was	O
no	O
significant	O
hydrocarbon	O
migration	O
into	O
post	O
-	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

It	O
is	O
possible	O
that	O
,	O
at	O
the	O
margins	O
of	O
the	O
Cheshire	O
Basin	O
,	O
hydrocarbons	O
could	O
have	O
migrated	O
into	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
.	O

The	O
Needwood	O
Basin	O
,	O
however	O
,	O
has	O
a	O
much	O
thinner	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
cover	O
than	O
Cheshire	O
,	O
and	O
it	O
would	O
be	O
easier	O
for	O
hydrocarbons	O
to	O
migrate	O
vertically	O
there	O
.	O

Potential	O
reservoirs	O
are	O
,	O
from	O
the	O
top	O
downwards	O
:	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
,	O
Wilmslow	LEXICON
Sandstone	LEXICON
and	O
Kinnerton	LEXICON
Sandstone	LEXICON
formations	O
of	O
the	O
SSG	O
;	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
Formation	LEXICON
;	O
and	O
Westphalian	CHRONOSTRAT
and	O
Namurian	CHRONOSTRAT
sandstones	O
.	O

Many	O
of	O
the	O
Silesian	CHRONOSTRAT
sandstones	O
encountered	O
in	O
the	O
Milton	O
Green	O
and	O
Blacon	O
East	O
boreholes	O
are	O
thin	O
,	O
but	O
thicker	O
equivalents	O
were	O
found	O
in	O
the	O
Erbistock	O
Borehole	O
.	O

Many	O
of	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
sandstones	O
have	O
considerable	O
secondary	O
porosity	O
due	O
to	O
dissolution	O
of	O
early	O
diagenetic	O
cements	O
of	O
non-ferroan	O
dolomite	O
,	O
anhydrite	O
and	O
possibly	O
halite	O
and	O
unstable	O
framework	O
grains	O
.	O

This	O
is	O
a	O
typical	O
feature	O
of	O
other	O
UK	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
basins	O
.	O

In	O
the	O
upper	O
part	O
of	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
porosities	O
were	O
10	O
15%	O
and	O
permeabilities	O
up	O
to	O
20mD	O
,	O
but	O
in	O
the	O
lower	O
part	O
they	O
reached	O
above	O
25%	O
and	O
up	O
to	O
1800	O
mD	O
respectively	O
.	O

In	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
the	O
porosity	O
in	O
cemented	O
parts	O
was	O
14%	O
,	O
combined	O
with	O
low	O
permeability	O
,	O
in	O
contrast	O
to	O
the	O
coarse	O
clean	O
sands	O
with	O
porosities	O
of	O
22%	O
and	O
permeabilities	O
of	O
up	O
to	O
2500mD	O
,	O
which	O
were	O
probably	O
not	O
representative	O
of	O
subsurface	O
properties	O
.	O

In	O
the	O
Wilmslow	LEXICON
Sandstone	LEXICON
geophysical	O
logs	O
gave	O
an	O
average	O
of	O
13%	O
porosity	O
.	O

A	O
decrease	O
in	O
porosity	O
with	O
depth	O
is	O
seen	O
clearly	O
in	O
the	O
sonic	O
logs	O
of	O
the	O
Knutsford	O
and	O
Prees	O
boreholes	O
,	O
below	O
the	O
top	O
Silicified	O
Zone	O
,	O
reaching	O
a	O
minimum	O
within	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
.	O

Below	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
the	O
base	O
of	O
the	O
St	LEXICON
Bees	LEXICON
Sandstone	LEXICON
.	O

Changes	O
in	O
porosity	O
in	O
the	O
upper	O
part	O
of	O
the	O
SSG	O
,	O
showing	O
no	O
systematic	O
downhole	O
increase	O
,	O
are	O
attributed	O
to	O
facies	O
control	O
.	O

The	O
fluvial	O
Delamere	LEXICON
Member	LEXICON
has	O
a	O
higher	O
sonic	O
velocity	O
than	O
the	O
Frodsham	LEXICON
and	O
Thurstaston	LEXICON
members	O
.	O

Modelling	O
of	O
the	O
burial	O
history	O
of	O
this	O
basin	O
suggests	O
that	O
compaction-induced	O
porosity	O
reduction	O
is	O
likely	O
to	O
have	O
occurred	O
towards	O
the	O
centre	O
of	O
the	O
basin	O
,	O
reducing	O
average	O
porosities	O
at	O
the	O
base	O
of	O
the	O
SSG	O
to	O
between	O
5	O
and	O
7%	O
.	O

This	O
is	O
the	O
result	O
of	O
Jurassic	CHRONOSTRAT
and	O
Cretaceous	CHRONOSTRAT
burial	O
.	O

Porosity	O
reduction	O
has	O
not	O
occurred	O
in	O
the	O
Permian	CHRONOSTRAT
sandstones	O
of	O
the	O
Prees	O
and	O
Knutsford	O
boreholes	O
.	O

A	O
downhole	O
porosity	O
reduction	O
within	O
the	O
Permian	CHRONOSTRAT
sandstones	O
is	O
apparent	O
in	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
of	O
the	O
Prees	O
Borehole	O
,	O
but	O
the	O
overlying	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
has	O
a	O
lower	O
porosity	O
.	O

The	O
Collyhurst	LEXICON
Sandstone	LEXICON
,	O
in	O
the	O
Knutsford	O
Borehole	O
,	O
shows	O
more	O
variable	O
and	O
higher	O
porosity	O
.	O

In	O
the	O
East	O
Midlands	O
oilfields	O
,	O
Coal	LEXICON
Measures	LEXICON
sandstones	O
,	O
which	O
produce	O
oil	O
,	O
have	O
porosities	O
of	O
about	O
7	O
20%	O
,	O
with	O
an	O
average	O
value	O
of	O
12%	O
.	O

Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
sandstones	O
,	O
which	O
are	O
not	O
productive	O
,	O
have	O
higher	O
porosities	O
,	O
12	O
19%	O
.	O

Permeabilities	O
range	O
from	O
0.06	O
to	O
37mD	O
,	O
locally	O
400mD	O
for	O
the	O
Productive	LEXICON
Coal	LEXICON
Measures	LEXICON
and	O
2	O
to	O
160mD	O
for	O
the	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
sandstones	O
.	O

In	O
the	O
Bothamsall	O
Oilfield	O
Hawkins	O
found	O
porosities	O
of	O
3	O
12%	O
in	O
coarser	O
grained	O
channel	O
sandstones	O
of	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
age	O
.	O

Reddening	O
of	O
Coal	LEXICON
Measures	LEXICON
sandstones	O
,	O
in	O
contrast	O
to	O
mudstones	O
,	O
has	O
occurred	O
during	O
Permian	CHRONOSTRAT
and	O
Triassic	CHRONOSTRAT
times	O
in	O
the	O
Potteries	O
Coalfield	O
,	O
indicating	O
some	O
porosity	O
and	O
permeability	O
of	O
the	O
sandstones	O
.	O

A	O
northerly	O
decrease	O
in	O
porosity	O
and	O
permeability	O
has	O
been	O
noted	O
in	O
the	O
East	O
Midlands	O
oilfields	O
,	O
which	O
is	O
interpreted	O
as	O
a	O
Carboniferous	CHRONOSTRAT
burial	O
effect	O
.	O

The	O
MMG	O
halites	O
and	O
mudstones	O
are	O
excellent	O
seals	O
,	O
where	O
sufficiently	O
thick	O
.	O

At	O
Formby	O
,	O
however	O
,	O
there	O
is	O
no	O
salt	O
and	O
the	O
MMG	O
is	O
thin	O
,	O
resulting	O
in	O
a	O
very	O
leaky	O
oilfield	O
.	O

There	O
are	O
no	O
other	O
significant	O
mudstone	O
beds	O
within	O
the	O
Triassic	CHRONOSTRAT
succession	O
.	O

The	O
Manchester	LEXICON
Marls	LEXICON
can	O
be	O
considered	O
a	O
reasonable	O
seal	O
where	O
there	O
is	O
mudstone	O
and	O
,	O
to	O
the	O
north-west	O
,	O
halite	O
,	O
but	O
this	O
formation	O
becomes	O
sandy	O
in	O
the	O
south	O
and	O
west	O
of	O
the	O
Cheshire	O
Basin	O
.	O

It	O
may	O
be	O
deduced	O
,	O
therefore	O
,	O
that	O
Carboniferous	CHRONOSTRAT
shales	O
are	O
adequate	O
to	O
seal	O
the	O
hydrocarbons	O
beneath	O
the	O
Variscan	CHRONOSTRAT
Unconformity	O
,	O
particularly	O
where	O
Ruabon	LEXICON
Marl	LEXICON
is	O
present	O
.	O

The	O
active	O
tectonics	O
of	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
times	O
in	O
the	O
Cheshire	O
Basin	O
contrast	O
with	O
the	O
relatively	O
steady	O
accumulation	O
of	O
sediments	O
on	O
the	O
gently	O
shelving	O
margin	O
to	O
the	O
southern	O
North	O
Sea	O
Basin	O
in	O
the	O
East	O
Midlands	O
.	O

The	O
East	O
Midlands	O
and	O
the	O
Cheshire	O
Basin	O
are	O
alike	O
in	O
appearing	O
to	O
have	O
few	O
hydrocarbon	O
accumulations	O
in	O
Permian	CHRONOSTRAT
and	O
later	O
rocks	O
.	O

However	O
,	O
there	O
are	O
numerous	O
oilfields	O
in	O
Carboniferous	CHRONOSTRAT
rocks	O
of	O
the	O
East	O
Midlands	O
whereas	O
,	O
to	O
date	O
,	O
there	O
have	O
been	O
no	O
commercial	O
discoveries	O
in	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
surrounding	O
the	O
Cheshire	O
Basin	O
.	O

These	O
oilfields	O
have	O
certain	O
common	O
characteristics	O
:	O
the	O
reservoirs	O
are	O
mainly	O
late	O
Namurian	CHRONOSTRAT
and	O
Westphalian	CHRONOSTRAT
A	CHRONOSTRAT
sandstones	O
,	O
and	O
are	O
sealed	O
below	O
post	O
-	O
Permian	CHRONOSTRAT
rocks	O
.	O

This	O
spectacular	O
lack	O
of	O
success	O
,	O
west	O
of	O
the	O
Pennines	O
,	O
may	O
be	O
because	O
by	O
far	O
the	O
largest	O
percentage	O
of	O
wells	O
drilled	O
in	O
the	O
west	O
of	O
the	O
Pennine	O
Basin	O
have	O
spudded	O
into	O
large	O
structures	O
at	O
stratigraphic	O
levels	O
below	O
the	O
reservoirs	O
producing	O
in	O
the	O
East	O
Midlands	O
and	O
only	O
a	O
few	O
wells	O
have	O
seals	O
below	O
post	O
-	O
Permian	CHRONOSTRAT
rocks	O
.	O

Parnell	O
has	O
tabulated	O
the	O
metal	O
enrichment	O
of	O
bitumens	O
in	O
Carboniferous	CHRONOSTRAT
-	O
hosted	O
ore	O
deposits	O
,	O
indicating	O
that	O
there	O
are	O
a	O
number	O
of	O
close	O
associations	O
between	O
ores	O
and	O
hydrocarbons	O
in	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

St	O
George	O
s	O
Land	O
formed	O
the	O
southern	O
margin	O
of	O
the	O
Carboniferous	CHRONOSTRAT
Pennine	O
Basin	O
;	O
in	O
the	O
East	O
Midlands	O
,	O
Westphalian	CHRONOSTRAT
rocks	O
overlap	O
regressive	O
Namurian	CHRONOSTRAT
rocks	O
along	O
a	O
north-east-trending	O
line	O
onto	O
this	O
former	O
landmass	O
.	O

The	O
Welton	O
Oilfield	O
was	O
discovered	O
where	O
the	O
basal	O
Westphalian	CHRONOSTRAT
sandstones	O
rest	O
unconformably	O
on	O
Dinantian	CHRONOSTRAT
rocks	O
.	O

Near	O
the	O
southern	O
margin	O
of	O
the	O
Potteries	O
Coalfield	O
and	O
beneath	O
the	O
south-east	O
Cheshire	O
Basin	O
a	O
similar	O
stratigraphical	O
situation	O
may	O
exist	O
,	O
with	O
thinning	O
of	O
the	O
Namurian	CHRONOSTRAT
rocks	O
beneath	O
the	O
Potteries	O
Coalfield	O
.	O

The	O
principal	O
difference	O
between	O
the	O
Cheshire	O
and	O
East	O
Irish	O
Sea	O
basins	O
is	O
the	O
presence	O
of	O
hydrocarbons	O
in	O
the	O
Ormskirk	LEXICON
Sandstone	LEXICON
Formation	LEXICON
of	O
the	O
East	O
Irish	O
Sea	O
Basin	O
and	O
their	O
apparent	O
absence	O
in	O
its	O
correlative	O
,	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
,	O
in	O
the	O
Cheshire	O
Basin	O
.	O

The	O
main	O
Carboniferous	CHRONOSTRAT
rift	O
is	O
orientated	O
east	O
west	O
,	O
through	O
the	O
southern	O
North	O
Sea	O
,	O
beneath	O
the	O
Cleveland	O
,	O
Craven	O
and	O
East	O
Irish	O
Sea	O
basins	O
towards	O
Ireland	O
.	O

The	O
Cheshire	O
Basin	O
is	O
more	O
peripheral	O
to	O
the	O
Carboniferous	CHRONOSTRAT
Pennine	O
Basin	O
than	O
the	O
East	O
Irish	O
Sea	O
Basin	O
and	O
is	O
therefore	O
thought	O
less	O
likely	O
to	O
be	O
underlain	O
by	O
good	O
oil-prone	O
source	O
rocks	O
at	O
depth	O
.	O

There	O
are	O
a	O
few	O
positive	O
indications	O
,	O
however	O
,	O
such	O
as	O
oil	O
shale	O
in	O
the	O
Heswall	O
Borehole	O
,	O
and	O
also	O
the	O
unproved	O
possibility	O
that	O
Dinantian	CHRONOSTRAT
basins	O
may	O
have	O
locally	O
rich	O
oil-prone	O
source	O
rocks	O
.	O

Beneath	O
the	O
East	O
Irish	O
Sea	O
Basin	O
much	O
of	O
the	O
subcrop	O
consists	O
of	O
Namurian	CHRONOSTRAT
rocks	O
.	O

This	O
long	O
delay	O
can	O
be	O
attributed	O
to	O
a	O
lack	O
of	O
interest	O
in	O
the	O
Carboniferous	CHRONOSTRAT
source	O
rocks	O
;	O
even	O
with	O
the	O
recent	O
discoveries	O
,	O
there	O
is	O
a	O
reluctance	O
to	O
extend	O
the	O
play	O
,	O
by	O
exploration	O
of	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

Significant	O
oil	O
was	O
generated	O
during	O
Jurassic	CHRONOSTRAT
times	O
,	O
but	O
gas	O
generation	O
required	O
burial	O
deeper	O
than	O
4000m	O
according	O
to	O
Hardman	O
et	O
al.	O
.	O

The	O
amount	O
of	O
Tertiary	CHRONOSTRAT
uplift	O
is	O
estimated	O
by	O
various	O
methods	O
to	O
be	O
over	O
2000m	O
.	O

The	O
SSG	O
has	O
many	O
similar	O
reservoir	O
characteristics	O
in	O
the	O
Cheshire	O
Basin	O
.	O

Porosities	O
of	O
up	O
to	O
21%	O
and	O
permeabilities	O
of	O
up	O
to	O
400mD	O
are	O
reported	O
for	O
the	O
Morecambe	O
Gasfield	O
,	O
in	O
beds	O
probably	O
equivalent	O
to	O
the	O
Frodsham	LEXICON
Member	LEXICON
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

At	O
the	O
Douglas	O
Oilfield	O
the	O
Frodsham	LEXICON
Member	LEXICON
has	O
a	O
porosity	O
of	O
17%	O
and	O
the	O
Delamere	LEXICON
Member	LEXICON
12%	O
.	O

Coal	LEXICON
Measures	LEXICON
are	O
present	O
beneath	O
almost	O
all	O
of	O
the	O
Cheshire	O
Basin	O
.	O

The	O
main	O
conclusion	O
is	O
that	O
hydrocarbons	O
generated	O
from	O
Carboniferous	CHRONOSTRAT
times	O
to	O
the	O
present	O
day	O
are	O
likely	O
to	O
be	O
trapped	O
beneath	O
the	O
base	O
Permian	CHRONOSTRAT
unconformity	O
,	O
by	O
Ruabon	LEXICON
Marl	LEXICON
seals	O
,	O
and	O
that	O
drilling	O
to	O
test	O
late	O
Namurian	CHRONOSTRAT
to	O
early	O
Westphalian	CHRONOSTRAT
reservoirs	O
,	O
although	O
deeper	O
than	O
present	O
exploration	O
,	O
can	O
be	O
justified	O
.	O

Wells	O
sited	O
on	O
the	O
crop	O
of	O
early	O
Namurian	CHRONOSTRAT
and	O
older	O
rocks	O
are	O
not	O
recommended	O
because	O
these	O
rocks	O
have	O
unfavourable	O
reservoir	O
characteristics	O
.	O

These	O
conclusions	O
are	O
at	O
variance	O
with	O
those	O
of	O
Fraser	O
et	O
al.	O
,	O
who	O
presented	O
a	O
pessimistic	O
view	O
of	O
Carboniferous	CHRONOSTRAT
basins	O
outside	O
the	O
East	O
Midlands	O
,	O
which	O
contributed	O
partly	O
to	O
the	O
evacuation	O
of	O
the	O
area	O
by	O
the	O
major	O
oil	O
companies	O
.	O

Two	O
key	O
questions	O
,	O
relevant	O
to	O
the	O
hydrocarbon	O
prospectivity	O
of	O
the	O
Cheshire	O
Basin	O
,	O
are	O
:	O
Why	O
have	O
no	O
Carboniferous	O
oilfields	O
been	O
discovered	O
in	O
north-west	O
England	O
comparable	O
to	O
those	O
in	O
the	O
East	O
Midlands	O
?	O

Why	O
is	O
the	O
Ormskirk	LEXICON
Sandstone	LEXICON
Formation	LEXICON
of	O
the	O
East	O
Irish	O
Sea	O
Basin	O
productive	O
of	O
hydrocarbons	O
whereas	O
no	O
discoveries	O
have	O
been	O
made	O
in	O
its	O
correlative	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
the	O
Cheshire	O
Basin	O
?	O

Fraser	O
et	O
al.	O
identified	O
factors	O
which	O
are	O
crucial	O
to	O
the	O
prospectivity	O
of	O
Carboniferous	CHRONOSTRAT
basins	O
in	O
northern	O
England	O
.	O

Carboniferous	CHRONOSTRAT
rocks	O
in	O
Knutsford	O
lie	O
near	O
the	O
oil	O
floor	O
at	O
3000m	O
,	O
but	O
have	O
probably	O
been	O
uplifted	O
from	O
below	O
4500m	O
in	O
Tertiary	CHRONOSTRAT
times	O
.	O

Coal-rank	O
data	O
indicate	O
that	O
present-day	O
geothermal	O
gradients	O
,	O
and	O
possibly	O
Carboniferous	CHRONOSTRAT
gradients	O
,	O
are	O
lower	O
in	O
the	O
Lancashire	O
Coalfield	O
than	O
in	O
the	O
North	O
Staffordshire	O
and	O
Nottingham	O
Yorkshire	O
coalfields	O
.	O

It	O
is	O
possible	O
that	O
Namurian	CHRONOSTRAT
pro-delta	O
shales	O
exist	O
beneath	O
the	O
Cheshire	O
Basin	O
.	O

Connections	O
between	O
the	O
Widmerpool	O
Staffordshire	O
Dinantian	CHRONOSTRAT
Basin	O
and	O
south	O
Lancashire	O
were	O
suggested	O
by	O
Collinson	O
et	O
al.	O
and	O
are	O
tentatively	O
in	O
agreement	O
with	O
seismic	O
reflection	O
interpretation	O
of	O
the	O
Carboniferous	CHRONOSTRAT
succession	O
in	O
parts	O
of	O
the	O
northern	O
Cheshire	O
Basin	O
.	O

Early	CHRONOSTRAT
Namurian	CHRONOSTRAT
sedimentation	O
may	O
,	O
therefore	O
,	O
have	O
led	O
to	O
the	O
formation	O
of	O
rich	O
source	O
rocks	O
.	O

The	O
Formby	O
Oilfield	O
is	O
an	O
example	O
of	O
the	O
probable	O
breaching	O
of	O
an	O
accumulation	O
in	O
Carboniferous	CHRONOSTRAT
rocks	O
,	O
with	O
migration	O
of	O
oil	O
into	O
Triassic	CHRONOSTRAT
and	O
Recent	O
sediments	O
.	O

Structures	O
can	O
be	O
mapped	O
in	O
Carboniferous	CHRONOSTRAT
rocks	O
beneath	O
the	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
in	O
some	O
places	O
,	O
but	O
additional	O
seismic	O
reflection	O
data	O
would	O
be	O
required	O
in	O
some	O
areas	O
prior	O
to	O
drilling	O
.	O

Westphalian	CHRONOSTRAT
reservoirs	O
,	O
beneath	O
the	O
level	O
drilled	O
at	O
Knutsford	O
,	O
lie	O
just	O
below	O
the	O
oil	O
floor	O
.	O

Oil-prone	O
Namurian	CHRONOSTRAT
and	O
Dinantian	CHRONOSTRAT
shales	O
are	O
probably	O
present	O
in	O
the	O
subsurface	O
.	O

Gas-prone	O
Westphalian	CHRONOSTRAT
coals	O
are	O
present	O
within	O
a	O
southerly	O
thinning	O
succession	O
into	O
which	O
migration	O
of	O
hydrocarbons	O
is	O
thought	O
to	O
have	O
occurred	O
.	O

Failure	O
to	O
find	O
encouraging	O
hydrocarbon	O
shows	O
in	O
post	O
-	O
Carboniferous	CHRONOSTRAT
rocks	O
and	O
subsequent	O
dry	O
commercial	O
wells	O
within	O
the	O
basin	O
are	O
seen	O
as	O
evidence	O
that	O
the	O
hydrocarbons	O
may	O
be	O
securely	O
trapped	O
in	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

Modification	O
of	O
migration	O
pathways	O
by	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
tectonism	O
is	O
obviously	O
greater	O
and	O
more	O
complex	O
than	O
in	O
the	O
East	O
Midlands	O
,	O
but	O
this	O
should	O
not	O
be	O
a	O
deterrent	O
to	O
exploration	O
.	O

If	O
hydrocarbons	O
are	O
securely	O
trapped	O
within	O
the	O
Carboniferous	CHRONOSTRAT
rocks	O
,	O
it	O
is	O
possible	O
that	O
overpressuring	O
has	O
occurred	O
.	O

Overpressuring	O
is	O
a	O
characteristic	O
of	O
the	O
deepest	O
sedimentary	O
basins	O
such	O
as	O
the	O
Anadarko	O
Basin	O
,	O
USA	O
,	O
where	O
the	O
main	O
overpressured	O
zone	O
,	O
in	O
several	O
compartments	O
,	O
encompasses	O
Devonian	CHRONOSTRAT
and	O
Carboniferous	CHRONOSTRAT
rocks	O
from	O
3	O
to	O
7km	O
deep	O
.	O

Although	O
it	O
is	O
not	O
the	O
primary	O
target	O
,	O
testing	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
should	O
not	O
be	O
ignored	O
.	O

The	O
mineralisation	O
model	O
requires	O
a	O
contribution	O
from	O
Carboniferous	CHRONOSTRAT
fluids	O
.	O

Structural	O
leads	O
can	O
be	O
identified	O
by	O
combining	O
the	O
contour	O
maps	O
of	O
the	O
top	O
SSG	O
with	O
the	O
outcrop	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

These	O
are	O
the	O
known	O
occurrences	O
of	O
Cu	O
,	O
which	O
,	O
according	O
to	O
the	O
mineralisation	O
model	O
,	O
require	O
a	O
Carboniferous	CHRONOSTRAT
fluid	O
component	O
.	O

A	O
MMG	O
seal	O
is	O
present	O
,	O
although	O
it	O
is	O
not	O
thick	O
and	O
does	O
not	O
contain	O
halite	O
.	O

A	O
nearby	O
outcrop	O
contains	O
Cu	O
mineralisation	O
in	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

The	O
top	O
Helsby	LEXICON
Sandstone	LEXICON
is	O
at	O
very	O
shallow	O
depth	O
hereabouts	O
.	O

Between	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
outcrop	O
at	O
Bickerton	O
and	O
the	O
Wem	O
Audlem	O
Sub-basinHydrocarbon	O
migration	O
up	O
the	O
tilt-block	O
towards	O
Milton	O
Green	O
may	O
have	O
occurred	O
and	O
sealing	O
by	O
a	O
MMG	O
succession	O
with	O
halite	O
is	O
assured	O
.	O

The	O
seal	O
by	O
the	O
MMG	O
is	O
good	O
.	O

Alderley	O
Edge	O
Cu	O
mines	O
are	O
situated	O
on	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
outcrop	O
to	O
the	O
north-east	O
.	O

A	O
MMG	O
seal	O
is	O
present	O
and	O
there	O
are	O
good	O
shows	O
to	O
the	O
north	O
in	O
Westphalian	CHRONOSTRAT
rocks	O
in	O
the	O
subsurface	O
and	O
at	O
outcrop	O
.	O

This	O
play	O
depends	O
on	O
the	O
presence	O
of	O
the	O
Manchester	LEXICON
Marls	LEXICON
seal	O
.	O

Halite	O
is	O
widely	O
present	O
in	O
the	O
Manchester	LEXICON
Marls	LEXICON
in	O
the	O
East	O
Irish	O
Sea	O
Basin	O
.	O

The	O
main	O
area	O
of	O
Carboniferous	CHRONOSTRAT
exploration	O
targets	O
is	O
related	O
to	O
the	O
south	O
-	O
and	O
west-thinning	O
Silesian	CHRONOSTRAT
rocks	O
.	O

The	O
Westphalian	CHRONOSTRAT
rocks	O
are	O
thinner	O
here	O
than	O
to	O
the	O
east	O
,	O
towards	O
Manchester	O
,	O
and	O
north	O
,	O
towards	O
Burnley	O
.	O

Migration	O
of	O
hydrocarbons	O
south-westwards	O
from	O
the	O
Pennine	O
Basin	O
occurred	O
during	O
Silesian	CHRONOSTRAT
times	O
.	O

Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
tectonism	O
will	O
have	O
caused	O
re-migration	O
,	O
although	O
the	O
hydrocarbons	O
may	O
still	O
be	O
retained	O
within	O
Carboniferous	CHRONOSTRAT
rocks	O
.	O

Hydrocarbons	O
within	O
Carboniferous	CHRONOSTRAT
rocks	O
,	O
west	O
of	O
the	O
King	O
Street	O
Fault	O
,	O
probably	O
migrated	O
west	O
or	O
north	O
;	O
those	O
within	O
Carboniferous	CHRONOSTRAT
rocks	O
east	O
of	O
the	O
King	O
Street	O
Fault	O
are	O
likely	O
to	O
have	O
migrated	O
north-east	O
.	O

Using	O
an	O
East	O
Midlands	O
analogue	O
,	O
there	O
may	O
also	O
be	O
a	O
play	O
where	O
the	O
basal	O
Westphalian	CHRONOSTRAT
sandstone	O
unconformably	O
overlies	O
Dinantian	CHRONOSTRAT
rocks	O
.	O

This	O
thinning	O
coincides	O
with	O
the	O
Dinantian	CHRONOSTRAT
synsedimentary	O
Bakewell	O
Fault	O
,	O
which	O
was	O
postulated	O
between	O
the	O
Eyam	O
and	O
Woo	O
Dale	O
boreholes	O
to	O
account	O
for	O
the	O
thickness	O
changes	O
in	O
the	O
Dinantian	CHRONOSTRAT
rocks	O
.	O

The	O
attractiveness	O
of	O
this	O
position	O
is	O
enhanced	O
by	O
the	O
likelihood	O
of	O
Silesian	CHRONOSTRAT
reservoirs	O
of	O
better	O
quality	O
than	O
farther	O
east	O
.	O

It	O
is	O
likely	O
,	O
therefore	O
,	O
that	O
the	O
Derbyshire	O
high	O
continues	O
north-west	O
and	O
becomes	O
progressively	O
concealed	O
by	O
Westphalian	CHRONOSTRAT
and	O
Permo	CHRONOSTRAT
-	O
Triassic	CHRONOSTRAT
rocks	O
,	O
on	O
the	O
north-east	O
margin	O
of	O
the	O
Cheshire	O
Basin	O
.	O

Other	O
possible	O
plays	O
occur	O
down-dip	O
of	O
the	O
Milton	O
Green	O
inlier	O
and	O
on	O
the	O
block	O
between	O
the	O
Wem	O
and	O
Hodnet	O
faults	O
,	O
in	O
areas	O
also	O
considered	O
propective	O
at	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
level	O
The	O
main	O
aquifer	O
units	O
in	O
the	O
Cheshire	O
Basin	O
belong	O
to	O
the	O
SSG	O
and	O
the	O
underlying	O
Permian	CHRONOSTRAT
sandstones	O
,	O
principally	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

The	O
eastern	O
boundary	O
of	O
the	O
basin	O
is	O
mainly	O
fault	O
controlled	O
,	O
which	O
has	O
resulted	O
in	O
a	O
much	O
smaller	O
area	O
of	O
sandstone	O
outcrop	O
,	O
the	O
overlying	O
MMG	O
sediments	O
being	O
faulted	O
against	O
Carboniferous	CHRONOSTRAT
rocks	O
between	O
Macclesfield	O
and	O
Newcastle-under-Lyme	O
.	O

The	O
MMG	O
overlies	O
the	O
Triassic	CHRONOSTRAT
and	O
Permian	CHRONOSTRAT
aquifers	O
and	O
attains	O
a	O
considerable	O
thickness	O
over	O
much	O
of	O
the	O
eastern	O
two-thirds	O
of	O
Shropshire	O
and	O
the	O
Cheshire	O
Plain	O
.	O

The	O
aquifers	O
of	O
the	O
SSG	O
represent	O
a	O
major	O
groundwater	O
resource	O
in	O
north-west	O
England	O
.	O

The	O
Wilmslow	LEXICON
Sandstone	LEXICON
Formation	LEXICON
tends	O
to	O
produce	O
the	O
largest	O
yields	O
because	O
of	O
its	O
higher	O
density	O
of	O
fracturing	O
and	O
less-cemented	O
matrix	O
,	O
though	O
the	O
more	O
pebbly	O
Helsby	LEXICON
Sandstone	LEXICON
and	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
are	O
also	O
very	O
productive	O
aquifers	O
.	O

The	O
saline	O
water	O
results	O
from	O
the	O
dissolution	O
of	O
halite	O
in	O
the	O
MMG	O
.	O

A	O
large	O
area	O
of	O
saline	O
water	O
of	O
this	O
origin	O
is	O
found	O
to	O
the	O
east	O
of	O
the	O
Carboniferous	CHRONOSTRAT
inlier	O
at	O
Milton	O
Green	O
.	O

Water	O
quality	O
can	O
also	O
be	O
poor	O
in	O
Drift	O
deposits	O
and	O
in	O
the	O
limited	O
water	O
resources	O
that	O
are	O
exploited	O
from	O
the	O
MMG	O
.	O

Nitrate	O
concentrations	O
in	O
groundwater	O
in	O
the	O
SSG	O
have	O
increased	O
over	O
the	O
last	O
three	O
decades	O
due	O
to	O
increased	O
use	O
of	O
nitrogenous	O
fertilisers	O
in	O
areas	O
where	O
recent	O
recharge	O
is	O
occurring	O
.	O

In	O
the	O
north	O
of	O
the	O
basin	O
,	O
the	O
two	O
units	O
are	O
separated	O
by	O
the	O
Manchester	LEXICON
Marls	LEXICON
Formation	LEXICON
,	O
which	O
is	O
thought	O
to	O
act	O
as	O
an	O
aquiclude	O
.	O

Porosities	O
are	O
high	O
,	O
especially	O
in	O
sections	O
beneath	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
and	O
close	O
to	O
outcrop	O
where	O
they	O
are	O
in	O
the	O
range	O
20	O
to	O
24%	O
.	O

These	O
conglomerates	O
and	O
pebbly	O
sandstones	O
,	O
overlying	O
the	O
Collyhurst	LEXICON
and	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formations	O
,	O
gradually	O
thicken	O
to	O
the	O
north-west	O
to	O
225m	O
in	O
the	O
Manchester	O
area	O
and	O
between	O
316	O
and	O
375m	O
in	O
the	O
Warrington	O
area	O
.	O

Hydraulic	O
conductivities	O
are	O
,	O
in	O
general	O
,	O
higher	O
in	O
the	O
south	O
of	O
the	O
basin	O
,	O
but	O
Fletcher	O
states	O
that	O
around	O
the	O
River	O
Tern	O
they	O
are	O
only	O
half	O
that	O
of	O
the	O
Collyhurst	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Of	O
the	O
three	O
members	O
of	O
the	O
formation	O
,	O
the	O
central	O
Delamere	LEXICON
Member	LEXICON
is	O
the	O
least	O
porous	O
.	O

In	O
mid-Cheshire	O
,	O
where	O
the	O
Delamere	LEXICON
Member	LEXICON
is	O
absent	O
,	O
porosity	O
and	O
hydraulic	O
conductivity	O
values	O
are	O
highest	O
,	O
attaining	O
values	O
of	O
30%	O
and	O
2.5m/d	O
respectively	O
.	O

The	O
Tarporley	LEXICON
Siltstone	LEXICON
Formation	LEXICON
,	O
at	O
the	O
base	O
of	O
the	O
MMG	O
,	O
is	O
transitional	O
between	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
the	O
overlying	O
mudstone	O
sequence	O
.	O

It	O
generally	O
has	O
low	O
values	O
of	O
hydraulic	O
conductivity	O
,	O
although	O
faulting	O
can	O
create	O
hydraulic	O
continuity	O
with	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
.	O

The	O
sand	O
and	O
gravel	O
deposits	O
act	O
as	O
an	O
important	O
source	O
of	O
recharge	O
to	O
the	O
SSG	O
and	O
also	O
as	O
a	O
means	O
of	O
discharge	O
.	O

In	O
an	O
earlier	O
project	O
concerned	O
with	O
the	O
prospectivity	O
of	O
the	O
Carboniferous	CHRONOSTRAT
basins	O
of	O
the	O
Pennines	O
for	O
metalliferous	O
minerals	O
,	O
Wadge	O
et	O
al.	O
argued	O
that	O
not	O
only	O
were	O
computers	O
necessary	O
for	O
databasing	O
and	O
modelling	O
but	O
they	O
were	O
also	O
needed	O
to	O
capture	O
the	O
knowledge	O
,	O
both	O
operative	O
and	O
interpretive	O
,	O
of	O
the	O
project	O
team	O
.	O

A	O
system	O
such	O
as	O
this	O
should	O
be	O
able	O
to	O
address	O
major	O
integrative	O
modelling	O
tasks	O
,	O
such	O
as	O
identifying	O
the	O
volumes	O
of	O
basin	O
fill	O
that	O
are	O
most	O
prospective	O
for	O
end	O
-	O
Triassic	CHRONOSTRAT
copper	O
mineralisation	O
.	O

Figure	O
151	O
shows	O
one	O
such	O
system	O
result	O
for	O
borehole	O
samples	O
from	O
the	O
Kinnerton	LEXICON
Sandstone	LEXICON
Formation	LEXICON
in	O
the	O
northern	O
part	O
of	O
the	O
basin	O
.	O

This	O
paragenesis	O
,	O
although	O
abbreviated	O
,	O
is	O
equivalent	O
in	O
overall	O
form	O
to	O
that	O
deduced	O
for	O
all	O
the	O
SSG	O
sandstones	O
.	O

Using	O
these	O
three	O
categories	O
it	O
is	O
possible	O
to	O
map	O
all	O
seven	O
possible	O
combinations	O
of	O
diagenetic	O
domains	O
,	O
and	O
Figure	O
152	O
shows	O
an	O
example	O
using	O
Thiessen	O
polygons	O
to	O
show	O
all	O
borehole	O
data	O
for	O
the	O
SSG	O
.	O

In	O
Figure	O
153	O
we	O
see	O
the	O
distribution	O
of	O
all	O
minerals	O
thought	O
to	O
be	O
associated	O
with	O
the	O
end	O
-	O
Triassic	CHRONOSTRAT
mineralisation	O
event	O
.	O

The	O
Cheshire	O
Basin	O
lay	O
in	O
low	O
latitudes	O
during	O
the	O
Triassic	CHRONOSTRAT
and	O
was	O
part	O
of	O
a	O
north	O
south	O
system	O
of	O
connecting	O
rifts	O
.	O

The	O
SSG	O
comprises	O
aeolian	O
-	O
deposited	O
arenites	O
borne	O
on	O
easterly	O
winds	O
and	O
fluvial	O
sediments	O
associated	O
with	O
rivers	O
draining	O
from	O
the	O
south	O
or	O
south-east	O
.	O

The	O
succeeding	O
MMG	O
comprises	O
mainly	O
the	O
deposits	O
of	O
a	O
continental	O
playa	O
.	O

The	O
source	O
rocks	O
for	O
the	O
detritus	O
of	O
the	O
SSG	O
probably	O
come	O
from	O
four	O
main	O
areas	O
:	O
.	O

In	O
the	O
example	O
of	O
the	O
hypothesis	O
This	O
sample	O
had	O
an	O
Armorican	O
source	O
,	O
the	O
rule	O
is	O
:	O
If	O
Monazite/Zircon	O
is	O
very	O
high	O
AND	O
If	O
Apatite/Rutile	O
is	O
high	O
AND	O
If	O
Tourmaline	O
is	O
very	O
FeO	O
rich	O
AND	O
If	O
Palaeoflow	O
Direction	O
is	O
northerly	O
AND	O
If	O
Nd/Sm	O
is	O
moderate	O
THEN	O
Hypothesis	O
is	O
True	O
The	O
result	O
of	O
the	O
application	O
of	O
this	O
rule	O
to	O
all	O
samples	O
of	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
Formation	LEXICON
is	O
shown	O
in	O
Figure	O
154	O
.	O

The	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
represent	O
one	O
of	O
the	O
notable	O
fluvial	O
excursions	O
into	O
the	O
dominantly	O
aeolian	O
sedimentation	O
regime	O
of	O
SSG	O
deposition	O
.	O

The	O
results	O
are	O
couched	O
in	O
terms	O
of	O
four	O
fuzzy	O
classes	O
,	O
from	O
low	O
to	O
very	O
high	O
possibility	O
that	O
the	O
Chester	LEXICON
Pebble	LEXICON
Beds	LEXICON
,	O
in	O
aggregate	O
at	O
a	O
certain	O
borehole	O
,	O
were	O
derived	O
from	O
an	O
Armorican	O
source	O
.	O

At	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
,	O
when	O
the	O
thermal	O
phase	O
of	O
crustal	O
extension	O
in	O
the	O
Cheshire	O
Basin	O
was	O
ending	O
.	O

The	O
metal	O
content	O
of	O
the	O
mixture	O
was	O
precipitated	O
in	O
faulted	O
sandstones	O
near	O
the	O
top	O
of	O
the	O
SSG	O
.	O

The	O
basin	O
is	O
floored	O
by	O
Upper	CHRONOSTRAT
Carboniferous	CHRONOSTRAT
rocks	O
except	O
in	O
the	O
extreme	O
south-west	O
of	O
the	O
basin	O
,	O
and	O
prospectivity	O
may	O
thus	O
be	O
lower	O
in	O
the	O
south-west	O
.	O

This	O
pattern	O
may	O
have	O
existed	O
at	O
the	O
end	O
of	O
the	O
Triassic	CHRONOSTRAT
.	O

Flow	O
vectors	O
perpendicular	O
to	O
the	O
end	O
-	O
Triassic	CHRONOSTRAT
basin	O
margins	O
.	O

Increased	O
prospectivity	O
at	O
the	O
intersection	O
of	O
these	O
with	O
the	O
top	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
.	O

Increased	O
prospectivity	O
where	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
cut	O
by	O
north	O
south	O
faults	O
.	O

Increased	O
prospectivity	O
where	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
and	O
MMG	O
mudstones	O
are	O
faulted	O
together	O
.	O

Figure	O
155	O
shows	O
the	O
results	O
of	O
one	O
such	O
simple	O
model	O
:	O
a	O
binary	O
map	O
showing	O
increased	O
prospectivity	O
where	O
the	O
top	O
of	O
the	O
Helsby	LEXICON
Sandstone	LEXICON
Formation	LEXICON
is	O
cut	O
by	O
north-south	O
faults	O
,	O
expressed	O
as	O
a	O
minimum-width	O
grid	O
scale	O
of	O
1km	O
.	O

A	O
rock-ridge	O
topography,	O
usually	O
pronounced,	O
is	O
developed	O
on	O
many	O
of	O
the	O
widespread	O
rock	O
exposures	O
in	O
shallow	O
water	O
(	O
Type	O
5	O
)	O
.	O

In	O
deeper	O
water	O
the	O
rock	O
surfaces	O
are	O
glacially	O
smoothed	O
and	O
the	O
ridges	O
less	O
pronounced	O
.	O

A	O
grooved	O
glaciated	O
pavement	O
was	O
observed	O
at	O
-29	O
m	O
off	O
Burnmouth	O
(	O
Eden	O
,	O
Carter	O
and	O
McKeown	O
,	O
1969	O
,	O
p.250	O
)	O
.	O

Indistinct	O
,	O
discontinuous	O
indications	O
of	O
ridges	O
in	O
deep	O
water	O
probably	O
denote	O
low	O
glaciated	O
exposures	O
among	O
boulder	O
clay	O
and	O
plastic	O
clay	O
deposits	O
,	O
but	O
these	O
ridges	O
have	O
yet	O
to	O
be	O
sampled	O
.	O

It	O
seems	O
probable	O
that	O
most	O
of	O
the	O
rocks	O
eroded	O
into	O
well-defined	O
strike	O
ridges	O
are	O
of	O
Carboniferous	CHRONOSTRAT
and	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
age	O
,	O
but	O
some	O
of	O
the	O
less	O
well-defined	O
strike-ridge	O
areas	O
may	O
be	O
of	O
older	O
rocks	O
.	O

Homogeneous	O
or	O
flat-lying	O
rocks	O
are	O
indicated	O
by	O
areas	O
of	O
high	O
signal	O
return	O
but	O
no	O
lineation	O
(	O
Type	O
4	O
)	O
;	O
these	O
may	O
be	O
mainly	O
of	O
Lower	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
and	O
Lower	CHRONOSTRAT
Palaeozoic	CHRONOSTRAT
age	O
.	O

A	O
characteristic	O
area	O
showing	O
Carboniferous	CHRONOSTRAT
rock-ridge	O
topography	O
was	O
examined	O
near	O
Burnmouth	O
by	O
Scuba	O
diving	O
(	O
p.t7	O
;	O
Eden	O
,	O
Carter	O
and	O
McKeown	O
,	O
1969	O
)	O
.	O

Four	O
of	O
the	O
cores	O
obtained	O
with	O
the	O
Hulltype	O
corer	O
were	O
of	O
solid	O
rock	O
;	O
three	O
(	O
Plate	O
2	O
)	O
were	O
Carboniferous	CHRONOSTRAT
(	O
stations	O
23	O
,	O
24	O
,	O
25	O
)	O
and	O
one	O
was	O
Upper	LEXICON
Old	LEXICON
Red	LEXICON
Sandstone	LEXICON
(	O
station	O
5	O
)	O
in	O
age	O
.	O

The	O
project	O
area	O
lies	O
predominantly	O
on	O
coal-bearing	O
bedrock	O
of	O
Carboniferous	CHRONOSTRAT
age	O
,	O
with	O
areas	O
of	O
older	O
strata	O
in	O
the	O
north	O
.	O

2.3	O
The	O
complex	O
mechanisms	O
involved	O
in	O
the	O
formation	O
of	O
till	O
are	O
beyond	O
the	O
scope	O
of	O
this	O
account	O
but	O
the	O
most	O
common	O
material	O
,	O
lodgement	O
till	O
,	O
is	O
the	O
product	O
of	O
basal	O
release	O
of	O
debris	O
below	O
ice	O
sheets	O
and	O
glaciers	O
.	O
'	O

Flow	O
till	O
'	O
or	O
`	O
ablation	O
till	O
'	O
is	O
produced	O
as	O
debris	O
flow	O
at	O
ice	O
margins	O
when	O
large	O
volumes	O
of	O
water	O
are	O
released	O
during	O
melting	O
of	O
the	O
ice	O
.	O

These	O
sediments	O
are	O
overlain	O
by	O
the	O
Baillieston	LEXICON
Till	LEXICON
Formation	LEXICON
which	O
formed	O
in	O
pre	O
-	O
late	O
Devensian	CHRONOSTRAT
times	O
.	O

North	O
of	O
Glasgow	O
this	O
till	O
is	O
overlain	O
by	O
sand	O
and	O
gravel	O
of	O
the	O
Cadder	LEXICON
Formation	LEXICON
.	O

The	O
sands	O
and	O
gravels	O
in	O
which	O
the	O
remains	O
were	O
found	O
were	O
possibly	O
deposited	O
as	O
outwash	O
related	O
to	O
the	O
advance	O
of	O
the	O
late	O
-	O
Devensian	CHRONOSTRAT
ice	O
sheet	O
.	O

In	O
southern	O
parts	O
of	O
the	O
city	O
,	O
muds	O
of	O
the	O
Broomhill	LEXICON
Formation	LEXICON
occur	O
discontinuously	O
above	O
the	O
Baillieston	LEXICON
Till	LEXICON
.	O

These	O
formations	O
are	O
succeeded	O
by	O
the	O
Wilderness	LEXICON
Till	LEXICON
Formation	LEXICON
,	O
which	O
was	O
deposited	O
during	O
the	O
late	O
-	O
Devensian	CHRONOSTRAT
by	O
an	O
ice	O
sheet	O
that	O
was	O
over	O
1	O
km	O
thick	O
and	O
covered	O
large	O
parts	O
of	O
Britain	O
between	O
27	O
000	O
to	O
13	O
000	O
years	O
ago	O
.	O

To	O
the	O
east	O
of	O
the	O
ice	O
dam	O
in	O
eastern	O
Glasgow	O
evidence	O
for	O
these	O
events	O
is	O
provided	O
by	O
sand	O
and	O
gravel	O
of	O
the	O
Broomhouse	LEXICON
Formation	LEXICON
,	O
in	O
which	O
there	O
are	O
indications	O
of	O
southeastward	O
transport	O
of	O
sediment	O
.	O

To	O
the	O
west	O
,	O
by	O
contrast	O
,	O
deposits	O
of	O
sand	O
and	O
gravel	O
of	O
the	O
Bridgeton	LEXICON
Formation	LEXICON
were	O
carried	O
and	O
deposited	O
by	O
downstream	O
currents	O
.	O

The	O
oldest	O
muds	O
of	O
the	O
Paisley	LEXICON
Formation	LEXICON
are	O
typically	O
finely	O
laminated	O
and	O
brightly	O
coloured	O
,	O
with	O
many	O
silt	O
layers	O
,	O
and	O
are	O
thought	O
to	O
have	O
formed	O
at	O
the	O
same	O
time	O
as	O
the	O
ice	O
was	O
melting	O
.	O

2.11	O
The	O
muds	O
of	O
the	O
succeeding	O
Linwood	LEXICON
Formation	LEXICON
are	O
relatively	O
poorly	O
laminated	O
and	O
the	O
upper	O
part	O
is	O
sulphide-rich	O
.	O

Deposits	O
of	O
sand	O
and	O
gravel	O
more	O
or	O
less	O
contemporaneous	O
with	O
the	O
Linwood	LEXICON
Formation	LEXICON
and	O
which	O
formed	O
in	O
river	O
channels	O
,	O
deltas	O
and	O
beaches	O
,	O
are	O
assigned	O
to	O
the	O
Killearn	LEXICON
Formation	LEXICON
.	O

The	O
extent	O
of	O
the	O
ice	O
is	O
marked	O
by	O
the	O
distribution	O
of	O
the	O
Gartocharn	LEXICON
Till	LEXICON
Formation	LEXICON
and	O
by	O
moundy	O
topography	O
that	O
marks	O
the	O
location	O
of	O
the	O
glacier-front	O
.	O

Periglacial	O
conditions	O
prevailed	O
,	O
as	O
evidenced	O
by	O
frost-wedge	O
casts	O
,	O
while	O
marine	O
muds	O
with	O
arctic	O
shells	O
,	O
the	O
Balloch	LEXICON
Formation	LEXICON
,	O
were	O
laid	O
down	O
in	O
the	O
western	O
Clyde	O
and	O
Leven	O
valleys	O
.	O

A	O
shelly	O
gravel	O
,	O
the	O
Inverleven	LEXICON
Formation	LEXICON
,	O
commonly	O
underlies	O
the	O
Balloch	LEXICON
Formation	LEXICON
.	O

An	O
extensive	O
ice-dammed	O
lake	O
occupied	O
the	O
Endrick	O
and	O
Blane	O
Water	O
valleys	O
,	O
and	O
here	O
sediments	O
of	O
the	O
sandy	O
Drumbeg	LEXICON
and	O
clay-dominated	O
Blane	LEXICON
Water	LEXICON
formations	O
were	O
deposited	O
.	O

2.13	O
Sea-level	O
then	O
rose	O
to	O
a	O
maximum	O
of	O
about	O
11	O
m	O
to	O
13	O
m	O
OD	O
and	O
subsequently	O
fell	O
to	O
its	O
present	O
level	O
,	O
giving	O
rise	O
to	O
sequences	O
of	O
marine	O
and	O
non-marine	O
deposits	O
,	O
as	O
detailed	O
below	O
,	O
and	O
the	O
Clippens	LEXICON
Peat	LEXICON
Formation	LEXICON
.	O

The	O
valleys	O
are	O
floored	O
by	O
a	O
gravel	O
,	O
forming	O
the	O
base	O
of	O
the	O
Longhaugh	LEXICON
Formation	LEXICON
,	O
which	O
mainly	O
consists	O
of	O
sand	O
with	O
shell	O
fragments	O
.	O

This	O
passes	O
up	O
into	O
further	O
sand	O
deposits	O
of	O
the	O
Gourock	LEXICON
Formation	LEXICON
and	O
also	O
well-bedded	O
muds	O
of	O
the	O
Erskine	LEXICON
Formation	LEXICON
.	O

In	O
Loch	O
Lomond	O
,	O
the	O
post	O
Loch	CHRONOSTRAT
Lomond	CHRONOSTRAT
Stade	CHRONOSTRAT
succession	O
opens	O
with	O
marine	O
clays	O
and	O
silts	O
of	O
the	O
Buchanan	LEXICON
Formation	LEXICON
which	O
are	O
overlain	O
by	O
non-marine	O
clays	O
and	O
silts	O
of	O
the	O
Kilmaronock	LEXICON
Formation	LEXICON
.	O

These	O
,	O
in	O
turn	O
,	O
are	O
overlain	O
by	O
fluvial	O
or	O
deltaic	O
sands	O
and	O
gravels	O
of	O
the	O
Endrick	LEXICON
Formation	LEXICON
.	O

These	O
formations	O
are	O
of	O
Flandrian	CHRONOSTRAT
age	O
.	O

2.14	O
The	O
general	O
picture	O
gleaned	O
from	O
the	O
available	O
field	O
and	O
archival	O
borehole	O
information	O
and	O
from	O
the	O
fifteen	O
fully	O
cored	O
boreholes	O
shows	O
that	O
the	O
Quaternary	CHRONOSTRAT
sequence	O
around	O
Glasgow	O
is	O
complex	O
,	O
consisting	O
of	O
dozens	O
of	O
unique	O
vertical	O
successions	O
,	O
or	O
profiles	O
.	O

Till	O
consists	O
chiefly	O
of	O
glacial	O
diamicton	O
,	O
but	O
may	O
locally	O
include	O
lenses	O
of	O
clay	O
,	O
silt	O
,	O
sand	O
or	O
gravel	O
.	O

However	O
,	O
because	O
the	O
bedrock	O
is	O
Middle	LEXICON
Coal	LEXICON
Measures	LEXICON
with	O
many	O
workable	O
coal	O
seams	O
the	O
possibility	O
of	O
undermining	O
should	O
be	O
considered	O
.	O

The	O
fact	O
that	O
the	O
bedrock	O
is	O
Upper	LEXICON
Coal	LEXICON
Measures	LEXICON
with	O
few	O
mineral	O
seams	O
of	O
any	O
note	O
means	O
that	O
the	O
site	O
is	O
likely	O
to	O
be	O
free	O
of	O
shallow	O
mining	O
.	O

The	O
original	O
settlement	O
of	O
Hunstanton	O
,	O
now	O
known	O
as	O
Old	O
Hunstanton,	O
probably	O
gained	O
its	O
name	O
from	O
the	O
River	O
Hun	O
,	O
with	O
Deri	LEXICON
and	O
Derlwyn	LEXICON
formations	O
to	O
the	O
coast	O
just	O
to	O
the	O
east	O
of	O
Dinas	O
revealing	O
Plean	LEXICON
Nos.	LEXICON
1	LEXICON
and	O
2	LEXICON
limestones	O
,	O
the	O
base	O
of	O
the	O
Passage	LEXICON
Formation	LEXICON
is	O
at	O
a	O
level	O
approximately	O
5m	O
above	O
Plean	LEXICON
No.	LEXICON
2	LEXICON
Limestone	LEXICON
.	O