QUATERNARY DEPOSITS OF BRITISH ISLES — BROOKS. 317 



bles which must have been obtained from the neighboring glacial 

 drift. The section is : 



4. Clay with angular and subangular fragments and pebbles of lime- 

 stone and pebbles of Denbighshire sandstone and grit, felstone, 

 etc., and bones of the usual cave mammalia. 



3. Stalagmitic crust up to 2 feet in thickness. 



2. Loam containing pebbles and the bones and implements described 

 above, all more or less cemented. 



1. Coarse shelly sand. 



Near the mouth, No. 4 appears to pass horizontally into a continu- 

 ation of the upper bowlder clay of Lancashire, Cheshire, and Flint- 

 shire. W. Boyd Dawkins considers it to be derived from the wash 

 of this clay. 



From these details certain generalizations can be made about the 

 raised beaches. The first is that at Selsey and Chichester there are 

 evidently two raised beaches, series of different ages, the older one 

 represented by the marine sands of Chichester, the large erratics, 

 and the clay with a Pleistocene marine fauna, though the latter, 

 being now about sea level, represents only a slight elevation. The 

 younger, the raised beach of Selsey, passes up into the " head," and 

 must be of very nearly the same age; this characteristic directly 

 connects it with the raised beach of Brighton. 



Farther west and northwest the raised beaches descend gradually 

 in height to sea level, and there is never any sign of a duplication. 

 They never pass up into " head," and are occasionally overlain as 

 at Selsey, Portland, and in North Devon by marine or aeolian sands 

 with a temperate fauna. In the Gower Caves the raised beach 

 passes up into deposits with a temperate mammalian fauna. 



Marine shells have been found in the beach itself at various lo- 

 calities; the aspect of the fauna as a whole is rather northern than 

 southern, but without any peculiarly arctic types. All the species 

 inhabit the British coasts between Shetland and Yorkshire, and 

 Jeffreys regarded the fauna as similar to that of existing Shetland 

 beaches. 



On the other hand, the beaches often contain ice-borne bowlders, 

 so that they are evidently in part contemporaneous with a glacial 

 period. A number of factors, especially the Chellean fauna of 

 Gower, the presence of Corbicula fuminalis at Selsey, and the oc- 

 currence of Acheulian-Mousterian implements in the "head," com- 

 bine to indicate this glacial period as that of the North Sea drift 

 and chalky bowlder clay. On the east coast there are raised marine 

 deposits from just before, during, and just after this glaciation, so 

 that it is probable that in south and west England the raised beach 

 represents the whole duration of the cold period. In such case, the 

 materials would be constantly sorted by the waves, and though large 



