GEOLOGICAL SURVEY OF THE TEREITOEIES. 



133 



strikes a number of ledges of rock, which churn it into a mass of foam. 

 A portion of the water is projected out like a broad fan, and strik- 

 ing the water below makes a sort of ricochet, while the main mass 

 of water reaches the base of the fall about 20 feet from the verti- 

 cal line let fall from the top. The water has cut out of the solid rock a 

 rouuded basin, from which the course of the river is almost at right 

 angles to the course above the fall. For some distance above the fall 



Fig. 36. 



CRYSTAL FALLS ON CASCADE CREEK, 129 FEET. 



there is a series of rapids over which the current is very swift. The 

 canon between the two falls is about half a mile long and the fall of 

 the river between these two points is 68 feet. The walls of this caiion 

 vary in height from 100 to 200 feet. 



Cascade Creek flows into the Yellowstone Eiveron the westside between 

 the falls. A short distance above its mouth we find a beautiful fall, 

 (Fig. 36,) or rather cascade, for it is made up of three distinct falls, the 



