42 THE BEAVER 
mentions a dam 75 feet long and three feet high on Salmon 
Brook in the Adirondacks, which made a flow about a mile 
long. 
Beavers sometimes display excellent judgment in locating 
a dam at the most suitable point to get the best results. 
At Crescent Hill, Yellowstone Park, the dam making the 
large pond previously mentioned was placed at the lower 
end of a gulch between Crescent Hill and a ridge to the east, 
SCALE 
oO fe) 2Oo IO oO SOFEET 
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Fig. 17. A Dam Wuicu CovERED AN Arc OF 225 DEGREES 
at a point where the two slopes came closest together; the 
gulch widened above where the pond was formed, while 
below the valley spread out and became flatter; this was the 
place an engineer would have selected for the same purpose. 
This dam appeared to be rather an old one. Several 
hundred feet below, along the gulch, the beaver had, in 1921, 
begun another dam at a similar spot, where the two slopes 
approached and a comparatively short dam would flood a 
