268 PREHISTORIC EUROPE. 



in the north of Lewis, where the bottom-moraine of the ice-sheet 

 that crept over that island is abundantly charged with shelly 

 debris, derived from the bed of the Minch. 



It is the bottom-moraine of this latest great mer de glace 

 which appears at the surface all over Scotland and the north of 

 England. In the eastern counties of the latter country it has 

 been followed south as far at least as North Lincolnshire ; in the 

 west it forms, as I have said, the upper boulder-clay of Lanca- 

 shire and Cheshire, and it is the superficial till of North Wales. 

 It covers also a wide region in the central and north-eastern 

 districts of Ireland. Although much yet remains to be done 

 before the southern limits of this latest ice-sheet are definitely 

 ascertained, yet the evidence is sufficient to enable us to form a 

 rough approximation to the truth. The basin of the Irish Sea 

 was filled to overflowing by ice coming from each of the three 

 kingdoms, while at the same time the Scandinavian mer de glace 

 occupied the bed of the North Sea, and pressed back the ice 

 creeping out from Scotland and England. The high grounds of 

 Northern England were deeply buried, but when we come south 

 as far as Derbyshire traces of recent glaciation disappear, and 

 the hills begin to show fewer marks of abrasion. It is probable 

 that, during the latest glacial epoch, the Peak and other hills 

 in that part of England were not overwhelmed by the general 

 mer de glace. A broad stream of ice, however, flowed out of the 

 Irish-Sea basin into Cheshire, and was probably coalescent there 

 with ice creeping down from the Welsh mountains. Charnwood 

 Eorest appears at the same time to have supported a little ice- 

 sheet of its own, which, flowing out in all directions, carried 

 boulders north, south, east, and west. In the basin of the Irish 

 Sea the ice, being of enormous thickness, probably extended 

 south as far as Wicklow and Pembroke. 



In the south of England it is doubtful whether any true 

 glaciers existed at that time, but the angular debris which over- 

 lies the raised-beaches on both sides of the Channel, and which 

 bespeaks, as Mr. Godwin- Austen long ago pointed out, cold 

 climatic conditions, is in all probability the subaerial equivalent 



