172 



MAN AND THE GLACIAL PERIOD. 



§5 £ 



" As a consequence, the only Welsh 

 ice in position to obstruct the onward 

 march of the invader would be such 

 trifling valley-glaciers as could form 

 on the western slopes of Snowdon it- 

 self. 



"The peak of Snowdon is 3,570 

 feet above sea-level, and Arenig Mawr, 

 2,817 feet high, is eighteen miles to 

 the eastward, and a broad, deep valley 

 with unobstructed access to Cardigan 

 Bay intervenes ; so, if any ice from 

 the central mass made its way over 

 the Snowdonian range, it performed 

 a much more surprising feat than that 

 involved in the ascent of Moel Tryfaen 

 from the westward. 



" The profile shows in diagrammat- 

 ic form the probable relations of the 

 foreign to the native ice at the time 

 when the Moel Tryfaen deposits were 

 laid down. 



" From what has been said regard- 

 ing the great glaciers, it would seem 

 that ice advanced upon the land from 

 the seaward in several parts of the 

 coast of England, Wales, and the Isle 

 of Man. Now, it is in precisely those 

 parts of the country, and those alone, 

 that the remains of marine animals 

 occur in the glacial deposits. If the 

 dispersal of the shells found in the 

 drift had been effected by the means 

 I have suggested, it would follow, as 

 an inevitable consequence, that wher- 

 ever shells occur there should also 



