BEACHES, ETC., OF THE SOUTH OF ENGLAND. 325 



he believes to have been land-ice, and that, " whatever its origin 

 may be, [it] is evidently connected with the last denudation of the 

 surface." 



Mr. A. Tylor has described a series of deposits, accumulated on 

 slopes by the action of water, and " separated from the ordinary 

 aqueous action, such as is performed by rivers, lakes, and seas, as 

 well as from ordinary subaerial action." These deposits, in which 

 he includes the ' Head ' of Godwin- Austen, the ' Elephant Bed ' of 

 Mantell, and other beds equivalent to the 'Trail' of Pisher, he 

 attributed to intense pluvial action.^ 



Mr. S. Y. Wood ^ was of opinion that the Elephant Bed of 

 Brighton and the ' Head ' of Portland and other places were formed 

 by the rills of water which resulted from the periodical thawing of 

 the ice and snow, carrying with them rubble and land-shells from 

 the higher ground above over the face of the cliff, during his period 

 of ' minor glaciation.' 



Col. Godwin- Austen ^ looked upon the drift bed in the Guildford 

 railway-cutting as formed under glacial conditions, and observed 

 that " it is not necessary to suppose anything of the nature of 

 a glacier as we know them in Alpine regions ; but what would 

 result, if the cold were great enough, would be the formation of 

 frozen snow-beds on the higher grounds lasting through the heats 

 of summer, and such would be the exact counterparts of those 

 patches of ice, many square acres in extent, that are to be seen at 

 the present day on the wide level plateaux of the Chang Chingmo 

 in Thibet — that is to say, solid ice not more than 20 feet thick, with 

 a flat but much broken surface, and with a wall-like margin in most 

 places. These I noticed lasted until the winter snows began again, 

 and in very warm summers they may almost entirely disappear." 



Mr. Ussher'' thinks the Head affords evidence of a period of great 

 subaerial waste, rain-floods, and a more rigid climate. Though from 

 its general appearance it " might be regarded merely as an old talus, 



shed from the adjacent heights , in some cases fragments have 



been incorporated which could not have been derived by mere 

 weathering, but were probably carried down by torrential surface- 

 waters or melting snows from higher lands not far off . . . . The 

 appearance of stratification sometimes exhibited might be satisfac- 

 torily explained by seasonal changes." The whole marks a time 

 of greater elevation of the land, producing possibly continental 

 conditions. 



In accounting for the origin of the dry valleys in Chalk districts, 

 Mr. Clement Beid suggests that it was the debris from them that 

 went to form the Coombe Rock of Brighton. He considers that 

 during the period of great cold the ground was frozen to the depth 

 of several hundred feet, and consequently that, the Chalk being 

 thereby rendered impermeable, the surface-waters, instead of passing 



^ Quart. Journ. Geol. Soe. vol. xxv. (1869) p. 98. 



2 Ibid. vol. xxxviii. (1882) p. 721 et seq. 



3 Quart. Journ. Geol. Soc toI. xl. (1884) p. 612. 



^ ' The Post-Tertiary Geology of Cornwall,' p. 42. 



