166 BOOK OF A HUNDRED BEARS 



near. It thunders down a hundred feet to a 

 rocky shelf and, striking that, hurls itself outward 

 in a boiling smother of spray and foam, shouting 

 its triumphant descent far above its rocky walls. 



It is, perhaps, a half-mile to the Lower Falls — 

 the Falls of the Yellowstone — and, after you have 

 seen that, the Upper Fall is forgotten, for, to my 

 mind, the Falls of the Yellowstone are the most 

 beautiful I have ever seen. There are others 

 higher, wider, of greater volume, but none has 

 such a superb setting, so graciously proportioned, 

 so perfect in every way. 



The descent of the Upper Fall brings the river 

 through a gorge, some five hundred feet deep, to 

 the Lower Fall, The shelf over which it leaps is 

 of porphyry and, on each side, great porphyry 

 cliffs narrow and confine it to its perfect propor- 

 tions. It is curious, but this is the only porphy- 

 ritic formation in the Park, and you can see from 

 below how, in the incalculable ages, the river, by 

 erosion, has carried the falls back and back, leaving 

 behind the wonderful Cafion of the Yellowstone, 

 till it struck this porphyritic wall that has with- 

 stood the wear of centuries. 



