File:The Quarterly journal of the Geological Society of London (12646325234).jpg

1863..
SALTER UPPER OLD RED SANDSTONE.
479
stones, calcareous layers, and argillaceous shales, are only (on a
much larger scale) the limestone, shale, and sandstone we have left
in South Pembrokeshire.
Neglecting then the purple Morte slates, which, being destitute
of fossils, cannot yet be safely paralleled with any special division of
the Old Red*, I may, however, say that they pass up by insensible
gradations and loss of colour into the Marwood series.
In ascending order we have : —
1. Purple slates and sandstones of Morte Bay.
2. A band of pale, nearly white slate, with a few Bivalves,
3. A thick series of greenish-grey grits, with bands of Cu-
cullcea and Avicula Damnoniensis, in abundance, and with much
olive shale, in which a new Lingida occurs abundantly.
1 4. An alternating series of calcareous sandstone, grey shales with
thin nodular bands of limestone, and grey cleaved slate full of
fossils, and many hundred feet thick. Avicula Damnoniensis and
Hhynchonella laticosta, with numerous Lamellibranchiata, occur in
the lower part ; and Strophalosia caperata with Spirifer Barumensis
throughout.
The series No. 4 is the upper part of the "Pilton group" of
Phillips ; and its aspect in the grand coast- section of Baggy Point
and Croyde Bay is exactly like that assumed by the Carboniferous
Slates of Pembrokeshire, as they lie, in the section before noticed,
upon the fossiliferous beds of the Upper Old Bed.
So like are the two sections, and so exactly does the succession
appear to correspond, that my faith in fossil-evidence gave way, in
1854, before this apparent identity. The grey sandstone and inter-
vening Plant-beds of Baggy are so like those of West Angle (on a
larger scale), and the overlying calcareous and shaly series so like
Fig. 1. — Generalized Section in Pembrokeshire and North Ireland,
Upper Old Red
(1,2,3).
Carboniferous Slate
(4? &5).
Carboniferous
Limestone (6).
Fig. 2. — Generalized Section in Devonshire and South Ireland,
Carboniferous
Limestone (6).
(1,2)
Upper Devonian .Marwood (3) and Piltoa Group (4)..
Carboniferous
Slate (5).
the bottom part of the Carboniferous Slate of Angle — having a very
similar set of fossils and a few even identical, — that an older geologist

• Professor Jukes admits, as I do, these reddish-purple slates to be the equi-