

CHAP. XIII.] PLEISTOCENE EPOCH. 271 



nected with the mainland of Dorsetshire and having a 

 much further extension to the southward. 



All the raised beaches of the southern and south-western 

 coasts of England appear to belong to an early Pleistocene 

 period, though it is remarkable that the shells they contain 

 do not indicate a low temperature, but, on the contrary, 

 one rather higher than now prevails on the coast. Thus 

 .among the shells of the Selsea deposits, several belong to 

 species which are now confined to the Mediterranean. In 

 Cornwall and Devon the height of the raised beaches is much 

 less than those of Dorset, Hants, and Sussex, but Mr. Ussher 

 has given good reasons for considering them to be older than 

 the stony loam (" Head ") and the submerged forests. 1 



Fluviatile and Terrestrial Deposits. All the Glacial de- 

 posits, including the " plateaux gravels " last described, are 

 now trenched by valleys, in which are found river-formed 

 .gravels of various ages and at various heights above the 

 level of the modern stream. 



Some of the oldest of these gravels contain two molluscs 

 which are now extinct in England, namely, Cyrena flumi- 

 .nalis and Unio littoralis, together with bones of Elephas 

 >antiquus, Rhinoceros tichorhinus, Rh. leptorhinus, and other 

 extinct mammalia, and the stone implements of Palaeo- 

 lithic man. Such gravels are, however, confined to the 

 southern and south-eastern counties, outside the limits of 

 the area in which the later Boulder-clays occur. 



The Palaeolithic river-gravels are, therefore, only post- 

 glacial in the sense that they are later than the Glacial 

 deposits of the counties in which they occur, 2 but these 



1 " The Post- Tertiary Geology of Cornwall," 1879, p. 43. 



2 The Glacial age of the brick-earths near Brandon, which contain 

 'flint implements, has not yet been proved, for detailed evidence has never 

 ibeen published ; the statement rests on the simple assertion of Mr. 

 Skertchly, and is not universally accepted, in spite of its adoption by 

 Professor James Geikie in " Prehistoric Europe," p. 263. 



