on 



Britten concerning the earth as modified and 

 benefited by beaver action, and I have long 

 thought that the beaver deserved at least a chap- 

 ter in Marsh's masterly book, "The Earth as 

 modified by Human Action." To " work like 

 a beaver" is an almost universal expression for 

 energetic persistence, but who realizes that the 

 beaver has accomplished anything ? Almost 

 unread of and unknown are his monumental 

 works. 



The instant a beaver-dam is completed, it has 

 a decided influence on the flow of the water, and 

 especially on the quantity of sediment which the 

 passing water carries. The sediment, instead of 

 going down to fill the channel below, or to clog 

 the river's mouth, fill the harbor, and do damage 

 a thousand miles away, is accumulated in the 

 pond behind the dam, and a level deposit is formed 

 over the entire area of the lake. By and by this 

 deposit is so great that the lake is filled with 

 sediment, but before this happens, both lake and 

 dam check and delay so much flood-water that 

 floods are diminished in volume, and the water 

 thus delayed is in part added to the flow of the 



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