312 THE BEAUTIES OF NATURE 



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, 



