88 LIVERPOOL BIOLOGICAL SOCIETY. 
“The Glacial Phenomena of the Eden Valley and the 
Western Part of the Yorkshire Dale District,’* and now 
vigorously supported by Professor H. Carvill Lewis of 
Philadelphia. If the views of this new school be adopted, 
the complicated system of successive glaciations with 
intervening warmer periods becomes unnecessary, nor 18 
required the great submergence of 1400 feet. According 
to this theory, advanced by Professor Lewis, there was at 
the last glacial period (as previous glaciations of a much 
earlier date are admitted)+ a subsidence of 500 feet in 
North Wales and 200 feet in the Lake district, the Irish 
Sea being filled by the glaciers that issued from the 
Cumberland hills, the Firth of Clyde and the north of 
Ireland, and the ice sheet flowing southwards glaciated 
Puffin Island and Anglesey, and deposited along its course 
boulders of greywacke and felsite from the north, flint and 
chalk from Ireland, and shells from deposits in the Irish 
Sea. The ice becoming packed against the Welsh hills, 
was forced up their flanks in one place to the height of 
800 feet, and there deposited the shell drifts of Moel 
Tryfaen. As the glacier dwindled before the approach of 
a warmer climate, which effectually repealed this ice union 
of the three kingdoms, its detritus was deposited, according 
to Professor Lewis, as a great terminal moraine which 
followed the ice sheet during its retreat northwards; 
Mr. Goodchild, however, denies the existence of any such 
moraine, and considers that the deposits were dropped 
simultaneously over a large area from the slowly melting 
ice. At the same time, in the east of England, the great 
chalky boulder clay was formed, according to Professor 
Lewis, in a great extra moraine lake which extended from 
* Quar. Jour. Geol. Soc., vol. xxxi.; and Trans. Cumberland and West- 
moreland Assoc. for Adv. of Science, no. xi., 1887. 
t+ Geol. Mag., 1837, p. 516.. 
