CHAPTER IV. 



BEAVER DAMS (CONTINUED).' 



Solid-bank Dams — Places where constructed — No Dams in deep Water — 

 Where impossible, the Beavers inhabit River Banks — Description of Solid- 

 bank Dam — Opening for Surplus Water — Pond confined to River Banks — 

 Similar Dam with Hedge — Fallen-tree Dam — Use of Tree accidental — 

 Spring Rill Dam — Series of Dams on the Carp — Dams in a Gorge — Lake 

 Outlet Dams — High Dam — Long Dam — Description of same — Manner of 

 Photographing same — Dams in other Districts of North America — Petri- 

 fied P'^aver Dams in Montana. 



The solid-bank dam, which we are next to consider, 

 although constructed upon tlie same principles as the 

 kind previously described, presents a very different 

 appearance. This difference of external form is the 

 result of the altered conditions under which it is 

 erected, occasioned by a gradual transformation in the 

 character of each particular stream in its descending 

 course. In the capacity thereby displayed of adapt- 

 ing their works to the ever-varying circumstances in 

 which they find themselves placed, instead of follow- 

 ing blindly an invariable type, some evidence of the 

 possession, on their part, of a free intelligence, is un- 

 doubtedly furnished. 



After a stream has emerged from its sources in the 

 hills, and acquired volume with its onward flow, it 

 soon begins to develop banks as well as a broader 

 channel, and these banks assume a vertical form in 

 the level areas where the soil is alluvial. Such are 

 the changes which occur on the Ely Branch of the 



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