Yellowstone Beaver 195 



length (figure 40). In spite of the great length of dam the pond is 

 not much more than 100 feet wide. It contains a medium-sized, 

 typically shaped lodge. Below this dam is another, the pond belong- 

 ing to which is nearly filled up with silt, and much of it grown up 

 to grass and willows, — a good example on a small scale of the mak- 

 ing of a beaver meadow. And below this dam, strung along the 

 creek for nearly half a mile, are no less than thirteen very old dams. 

 Some of those farthest down the stream are being partially rebuilt 

 and new ponds are forming. 



Above the large dam is another 250 feet in length. The pond 

 originally formed by this has been drained by a tunnel through the 

 dam at the level of the water in the pond below. Above this is the 

 unusual occurrence of a double series of ponds and dams. The 

 easterly one, of five ponds, takes its water from flat, swampy ground. 

 The westerly group of nine, a series of small ponds, is on the stream 

 itself. 



On the high flat between the North and South Forks is a small 

 stream along whose narrow gulley the beavers have long since 

 destroyed all the aspen nearly to its source, their disintegrating dams 

 now alone remaining. This little stream is fed by cold springs in a 

 dense old Engelmann spruce woods, along whose margin are fine 

 mature groves of aspen. The beavers have now dammed the brook- 

 let clear to the borders of the spruce bog, and a very interesting point 

 to notice here is that the evaporation from the large pond seems to 

 nearly balance the inflow, so that no water flows over the dam. If 

 the flow of water into the pond does increase, from heavy rains for 

 instance, the beavers at once build up the dam a bit higher, utilizing 

 every drop of water. This largest pond contains two lodges. Many 

 aspens have been freshly cut in a fine grove close along the shore 

 (figure 41). In the marshy ground above, several small ponds have 

 been dug out and dams built of mud during the past season, as well 

 as more typical dams. In one of these ponds a small lodge was 

 constructed between August 10 and September 4, and aspen brush 

 stored beside it. 



Beaver Ponds near Crescent Hill. These are located in the 

 beautiful region at the very head of the North Fork of Elk Creek, 

 easily reached on horseback or on foot. The largest of the ponds 

 (figure 42), at the foot of the Crescent Hill cliff's, lies in a perfect 

 setting of forested hills and open grassy valleys. Most of the nearby 

 aspen has been cut, but the beavers keep the dam in fair repair, so 



