File:The Quarterly journal of the Geological Society of London (13205884793).jpg

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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. .DeC. 16,
ment of these rocks more nearly resembles that of Westmoreland than
that of the typical country of Siluria. I believe also that the distri-
bution of the fossils, through the subordinate divisions of these rocks
in South Wales, agrees more exactly with their distribution in West-
moreland than it does with their distribution in Siluria — proving
that (within the narrow limits of our island) the distribution of
fossils through subordinate groups depends far more on physical
conditions than on geographical latitude. The highest group (or
" Tilestone") contains, in South Wales, a very fine series of fossils,
the greatest part of which occur also among the grits, slates and
flags of Kirkby Lonsdale, and in the ridges between Kendal and the
lower valley of the Lune. 2ndly, With many points of most intimate
resemblance between the Upper Silurian groups of Westmoreland and
South Wales, there are points of specific diflference worth notice.
Thus the Cardiola interrupta has a much greater vertical range in
this part of South Wales than it has in Westmoreland. Again, in
these two widely-separated localities, the Terehratula Navicula com-
mences nearly on the same horizon. In Westmoreland it does not
ascend into the Upper Ludlow series south of Kendal ; but in this
part of South Wales the species ascends through the whole Upper
Ludlow series, and abounds even among the red flags of the " Tile-
stone," close to the base of the Old red sandstone. My limits forbid
me to follow these points of diiFerence and resemblance any farther.
Groups of the whole Cambrian Series^ including both North and
South Wales.
Westmoreland.
Carboniferous.
Old Red
Upper Silurian
Lower Silurian J
Upper Cambrian
Slates
Snowdonian Group
Tremadoc Group. .
Crystalline Slates. .
Carboniferous.
Upper Silurian.
Coniston Limestone.
Lower Silurian.
Cumbrian Slates.