Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/379

 of the sea and the deposits that have already been formed ; and the upper strata all round would overlap the lower, apparently much as the Old Red Sandstone strata do in Wales and the adjoining counties. If the Caspian and other parts of the Asiatic area of inland drainage got filled with fresh water, the same general results would follow.

Neither does the unconformity mentioned by Mr. Jukes present any insuperable difficulty, assuming his Lower Old Red Sandstone to be represented in England and Scotland, of which as yet there is no absolute proof. It indicates only great disturbance and denudation, while the red colour, and the total absence of fossils till we reach the very uppermost beds of the Upper Old Red Sandstone, point to inland waters. These fossils, it is well known, are terrestrial ferns, Adiantites (Paloeopteris) hibernicus, and a freshwater shell, Anodon Jukesii, together with the fish Glyptolepis.

Permian strata. — I will now proceed to discuss the conditions under which the British Permian strata were deposited. These, it is well known, are usually divided in descending order into Magnesian Limestone or Zechstein, with subordinate Marl-slate or Kupferschiefer, and Rothliegende ; and though this division is very convenient for great part of the Continent, it is not with certainty perfectly applicable to the whole of England and some other parts of Europe. If we take the whole country from near Nottingham to Tynemouth, there is no marked line of division between the Marl-slate and the Magnesian Limestone ; and all along that range the red rocks on which the limestone series rests are now proved to be Carboniferous sandstones and shales stained by infiltration from above, which thus put on the likeness of Permian marls *. The supposed Rothliegende has, indeed, almost disappeared from the entire area.

The Permian marls, sandstones, conglomerates, and subangular breccias of Leicestershire, Warwickshire, South Staffordshire, Shropshire, and North Wales are as a rule all red, and have no visible connexion with the Magnesian Limestone. In Lancashire, in upper Permian strata, thin beds of magnesian limestone are interstratified with red marls ; and these limestones, as Mr. Binney and Mr. Hull state, may represent in time, as they do lithologically, the limestone series in the east and north of England. The latter are also interstratified with two or three occasional bands of red marl, while in Lancashire the limestones have many marl-beds intermingled with, and also both above and below them. Underneath the limestones and marls of Lancashire there are soft red sandstones, of great thickness, generally believed to represent the Rothliegende.

The Permian sandstones on the south and west coasts of the Cumbrian country are red, as are those in the Vale of Eden. In the Yale of Eden the Brockram at and near the base has no connexion with

of sand. The limestone, winch is often sandy, rests on shale, which is comparatively impermeable to water. The limestone dips east ; the carbonate of lime has been carried away in solution as bicarbonate ; and the sand remains.
 * The Yellow sands at the base of the limestone beds are generally a residue