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CHAPTER XXVII. 



GLACIAL EPOCH CONTINUED. ORIGIN OF CERTAIN LAKES. 



THERE is an important subject connected with the 

 physical geography of our country, and that is, the 

 multiplicity of lakes in the mountain regions, and the 

 question thus arises To what physical operations do 

 they happen to be so numerous in some districts and 

 so scarce or altogether absent in others ? 



When glaciers descended into valleys, and depo- 

 sited their terminal moraines, it sometimes happened 

 that when a glacier declined in size its moraine still 

 remained tolerably perfect, with this result that the 

 drainage formerly represented by ice is now represented 

 by running water, which is dammed in between the 

 surrounding slopes of the solid mountain and the 

 mound formed by the terminal moraine, thus- making 

 a lake. There are such minor lakes on the Italian side 

 of the Alps below Ivrea, and there are several among 

 the mountains of Wales, which at least are partly 

 dammed in by moraines, and a few, perhaps, entirely 

 so. They are always small, and may be classed as 

 tarns, lying at the bases of cliffs in the upper recesses 

 of the mountains. Whether there are any in Scotland, 

 dammed by the terminal moraines of common valley 

 glaciers, I do not know, although they may exist in 

 parts that I have not visited. Furthermore, some- 

 times on the outer side of these moraines we find what 



