76 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [Apr. 20, 



at the close of that period. In the Yalley of the Severn we find two 

 distinct shingle-beaches, one in a position 450 feet above the base 

 of the Bunter Sandstone, and the other about 500 feet higher. If 

 these beds be reduced to their original horizontal position, and 

 the whole brought below the sea-level, it would lead one to believe 

 that all the area below 2000 feet at least was under the sea. The 

 subsidence continued, with occasional pauses, throughout the Triassic 

 epoch; and the extreme fineness of the sediment of the Keuper 

 sandstones and marls proves the remoteness of the land from which 

 it had been drifted. During the earlier stages of the Bunter series, 

 the siliceous sediment appears to have been drifted over the plain of 

 Central England, through the channel formed by the mountains of 

 Westmoreland on the north and those of Caernarvon and Denbigh on 

 the south, filling in all the old channels and valleys ; and, as the 

 later periods of the Keuper and Lias progressed, these old headlands 

 gradually became more contracted both in area and elevation. 



At the close of the period of the Bunter Sandstone, the low- 

 lying tracts of England were probably elevated into dry land, 

 and remained so during the deposition of the Muschelkalk in 

 Germany. I have arrived at this conclusion from the following con- 

 siderations. 



B. Subaerial conditions during the formation of the German 

 Muschelkalk. — The base of the Keuper is almost invariably a 

 breccia or conglomerate, the pebbles of which can be identified with 

 those Palaeozoic formations in the neighbourhood which at the close 

 of the Bunter period formed the coast. This breccia is, in fact, a 

 shingle-beach ; and, if we suppose the flat tracts of the Bunter to 

 have been re-submerged at the commencement of the Keuper period, 

 such a shingle-bed would be the inevitable result of the waves 

 acting along a newly formed, and sometimes a bold, line of coast. 

 Shallow seas and intertidal conditions prevailed throughout the 

 higher stages of the Lower Keuper Sandstone ; for we frequently 

 find the footprints of Beptiles, sun-cracks, and rain-prints, showing 

 that during the ebb of the tide the sea-bed was left dry. 



C. Unconformity of the Keuper and Bunter. — There are evidences 

 which appear to me irresistible that the strata of the Bunter and 

 Keuper are unconformable. I have already shown the probability 

 of this being the case in Germany, from the occurrence of pebbles 

 of Bunter Sandstone in the Lower Keuper Sandstone of the Oclen- 

 wald*, and the evidences in this country are equally strong. In the 

 district of Alton, in Staffordshire, the base of the Keuper is formed 

 of a white conglomeratic sandstone, resting on red shale ; and its 

 pebbles can only be referred to the reconstructed materials of the 

 Bunter. They consist of the well-known, rounded, and coloured 

 quartz of which we have no examples in England except from the 

 conglomerate -beds of that formation. The Bunter conglomerates 

 climb up the flanks of the Carboniferous rocks of Derbyshire ; and, 

 if this be the correct interpretation of their reappearance, they have 



* Quart. Journ. Geol. Soc. vol. siv. p. 224. 



