318 THE BEAUTIES OF NATURE CHAP, 
scoop out the rock to a certain extent at d; 
in that case if it subsequently retires say to 
c, there would be a lake lying in the basin 
thus formed between ¢ and e. 
a 
évaey ; 
Fig. 47. 
On the other hand I am not disposed to 
attribute the Swiss lakes altogether to the 
action of glaciers. In the first place it does 
not seem clear that they occupy true rock 
basins. On this point more evidence is re- 
quired. That some lakes are due to unequal 
changes of level will hardly be denied. No 
one, for instance, as Bonney justly observes,’ 
would attribute the Dead Sea to glacial ero- 
sion. 3 
The Alps,.as we have seen, are a succession 
of great folds, and there is reason to regard 
the central one as the oldest. If then the 
same process continued, and the outer fold 
was still further raised, or a new one formed, 
more quickly than the rivers could cut it 
1 Growth and Structure of the Alps. 
