112 J. A. Birds — Geology of the Channel Idands. 



side. In Guernsey, however, they are plentiful in all the bays on 

 the west and north-west — in Eocquaine — but especially in Vazon 

 and Cobo Bays, and Grand Havre ; while they are also to be found 

 in Bellegreve Bay on the east; and even, though sparingly, in 

 Moulin Huet and Saint's Bay on the south. They occur too in 

 Icart Bay and at Epercherie in Sark. 



Now what is the origin of all these coverings of clay and sand, 

 and of the chalk flints ? It is very improbable that any of it is true 

 Boulder-clay, belonging to the first continental period. But few 

 boulders, and no " scratched " blocks, or stones, have been observed 

 in it. Nor are there any of the other usual glacial signs to be seen 

 upon the islands. Nor again, Prof. Ansted says, ''is there any gravel 

 consisting of transported pebbles of foreign material " to be found 

 there. Much of the clay and sand may have been derived from the 

 decomposition of the underlying porphyries and syenites. Much, 

 however — especially that in the S.E. of Guernsey — has the appear- 

 ance of a genuine drift ; and, unless a more probable origin can be 

 suggested, I should be inclined to refer it to the intraglacial period 

 of submergence ; to which also I would refer the presence of the 

 chalk flints upon the shore. 



The question, however, arises : how could this be if, as exhibited 

 in the " Map of the supposed submergence of the British Isles and 

 N.W. of Europe,"^ the South of England and N.W. of France, etc., 

 had been dry land ? We might indeed suppose that ice coming from 

 the north, and loaded with clay and flints, etc., occasionally made 

 its way through the Straits of Dover, or up the Channel, and de- 

 posited its freight around the Channel Islands ; and this would 

 account for the flints now found on the shores, but it would not 

 account for the clays containing flints, as in the S.E. of Guernsey, 

 200 or 300 feet above the sea. 



Since 1846, however, when E. Forbes first expressed the opinion 

 that " the South of England and Ireland were in all probability 

 unsubmerged during the Glacial epoch," ^ a certain amount of evi- 

 dence has been gathering which seems to show that this opinion 

 must be modified, and that at all events the greater portion of the 

 South of England, as well as perhaps the N.W. of France and 

 Belgium, were submerged in the interval between the two conti- 

 nental periods. 



For example, in 1853, Mr. Trimmer, the discoverer of the drift 

 on Moel Tryfaen, pointed out that there were three sets of gravels 

 south of the Thames, viz. at Shooter's Hill, Hartford, and Eochester, 

 the northern origin of which was proved by their contents.^ Among 

 other northern stones he found a peculiar kind of quartzose pebbles, 

 which had previously been traced by Dr. Buckland from their original 

 home in a Triassic conglomerate on Cannock Chase, down the valley 

 of the Avon into Worcestershire ; and thence, over depressions in 

 the Cotteswold Hills, to Oxford, and so down the valley of the 



' Antiquity of Man, p. 276. 



2 Mem. Geol. Sury. vol. i. p. 364. 



3 Quart. Joui-n. Geol. Soc. vol. ix. 1853, part iii. of Mr. Trimmer's paper. 



