THE GLACIAL PERIOD. 227 



on the shores of the latter region, which, according to him, could 

 only have accumulated at a time when those maritime districts 

 were some 10 metres lower than at present, and when ice formed 

 in the rivers and upon the coast of that part of France, and 

 scattered along shore the various kinds of stone with which it 

 was charged. 1 M. Tribolet, indeed, is of opinion that small 

 glaciers actually existed in Brittany at that time, 2 and the large 

 erratics noticed by Mr. G. Doe 3 and Mr. Pengelly 4 in Devon, 

 some of which measure from 500 to more than 3800 cubic feet, 

 also testify to a former severe climate. It is true that these 

 erratics have not travelled far, but this only shows that they 

 could not have been carried by icebergs. Bearing these facts in 

 mind, and keeping in view the conditions which prevailed 

 generally throughout Northern Europe and in all the hillier 

 regions of our continent, it seems to me unnecessary to suppose 

 with Mr, Godwin-Austen that the severe climatic conditions 

 which produced the " head " on both sides of the Channel were 

 brought about by an extreme elevation of the land. It is certain 

 that at the time the " head " was formed the shores of England 

 extended farther into the sea than now, for the deposit in 

 question caps cliffs which are being assaulted by the waves. 

 But we have no reason to believe that any such excessive eleva- 

 tion as would be required to carry up the low maritime districts 

 of the Channel into regions of extreme cold has ever taken place. 

 It is also well worth remembering that the regions in which the 

 " head " occurs are just those districts which were never over- 

 flowed by the ice-sheet, and that consequently their subaerial 

 deposits have been left undisturbed, while those of glaciated 

 regions have been swept away ; the loose dShris which occurs in 

 such countries as Scotland being merely the subaerial waste 

 which has accumulated since the ice vacated the low grounds 

 and vanished from the mountain-glens. The "head," therefore, 

 is the representative, as Mr. Godwin- Austen has remarked, of 

 the glacial deposits of the north. 5 



1 Ann. de la Soc. Geol. du Nord, t. iv. p. 186. 2 Ibid., t. v. (1878). 



3 Brit. Assoc. Rep., 1876, p. 110. 4 Ibid., 1877, p. 85. 



5 For descriptions of ' ' head " see Sir H. de la Beche's Report on the Geology of 



