O12 THE BEAUTIES OF NATURE CHAP, 
ON LAKES 
The problem of the origin of Lakes is by 
no means identical with that of Valleys. 
The latter are due, primarily as a rule to 
geological causes, but so far as their present 
condition is concerned, mainly to the action 
of rain and rivers. Flowing water, however, 
cannot give rise to lakes. 
It is of course possible to have valleys with- 
out lakes, and in fact the latter are, now at 
least, exceptional. There can be no lakes if 
the slope of the valley is uniform. To what 
then are lakes due ? 
Professor Ramsay divides Lakes into three 
classes : — 
1. Those due to irregular accumulations of 
drift, and which are generally quite shallow. 
2. Those formed by moraines. 
3. Those which occupy true basins scooped 
by glacier ice out of the solid rock. 
To these must, however, I think be added 
at least one other great class and several 
minor ones, namely, — 
