﻿8. V. Woodjj'un. — Americanand British Surface- Geology. 547 



In one part of the South of England, the gravels which in my 

 view represent the Upper Glacial range also to elevations between 

 600 and 700 feet, as at Caesar's Camp, near Aldershott, and other 

 detached hill-summits N.N.W. of it, but elsewhere, as at Headon 

 in the Isle of Wight,^ at St. George's Down in the same island, 

 at Chilworth Tower, Stony Crop, and Bramshaw Telegraph in 

 Hampshire,^ and at Swanscombe Hill in Kent, the limit of their 

 elevation ranges from 300 to 420 feet. Such of these summit 

 gravels as lie north of the Chalk district that divides the Hampshire 

 from the London Basin may be all continued by numerous other 

 gravel-topped eminences of less altitude across the counties of Berks, 

 Buckingham, and Hertford in the one direction, and across the 

 Thames Valley in another, into contiguity with the unwashed 

 moraine which the chalky clay represents. 



The elevation attained by the gravels in the Cotteswolds probably 

 affords a measure of the extent of the submergence in that direction, 

 as these are remote from the theatre of submarine disturbances 

 which have so elevated the gravels of the South of England. From 

 the description given by Mr. H. B. Woodward of the Devonshire 

 gravels, this submergence does not appear to have diminished for a 

 long distance further south-west. The elevation of the gravels 

 over the South of England (Surrey, Hampshire, etc.), however, 

 affords, in my view, no measure of the depth of the sea in that 

 direction, because these gravels attain greater and greater elevations 

 as they approach the points where the highly inclined position of 

 the chalk shows the region to have undergone great elevation rela- 

 tively to the rest of the gravel-sheet before so much of it was de- 

 stroyed by the denudation resulting from the disturbances producing 

 this exceptional elevation. A study of the position of these gravels 

 in Hampshire, Suri'ey, Berks, and Kent has convinced me that the 

 sea under which they accumulated was not deep ; and that though 

 it covered in a general sense the whole of the South of England, 

 there were many islands over that part of Britain formed by such of 

 the higher hills as had come into existence before the Glacial period, 

 and were not, as were the Hogsback ridge and the Purbeck and 

 Wight anticlinals, produced by the disturbances of this period.^ It 



^ Geol. Survey Memoir on the Isle of Wight. 



2 Codrington, Quart. Journ. Geol. Soc. vol. xxvi. p. 528. 



^ I have in various papers during twelve years past, and particularly in one on the 

 Weald Valley denudation in Quart. Joui'n. Geol. Soc. for 1871, urged that the dis- 

 turhances in which the rectilinear upcasts of the Isles of Wight and Purbeck, as 

 well as those of the Hogshack and Portsdown Hills, originated, took place at this 

 time ; viz. the close of the Glacial period and beginning of what we in England 

 have been accustomed to call the post- Glacial; and it is interesting to me to find that 

 Mr. Prestwich, in a paper read in the year 1874 (Q. J. G. S. vol. xxxi. p. 29), makes 

 out that during the Glacial period that portion of the Purbeck and Wight anticlinal 

 which is continued north of Portland Isle was submerged, and then upheaved and 

 subjected to excessive deundation, though he does not admit the general submergence 

 of the South of England. 



The section given in the Geological Survey Memoir of the Isle of Wight through 

 Headon Hill, with that in the Memoir on the London Basin through Csesar's Camp 

 (vol. iv. p. 376), are, it seems to me, not reconcilable with anything less than this 

 general submergence ; and show to my mind clearly the excessive denudation which 



