MOUNTAIN RANGES 267 



regions and tend to give individuality to the mountains. 

 The peaks have been formed by erosion, and their pecu- 

 liarities are due to the different kinds and positions of the 

 rocks from which they have been carved. 



The younger mountains which have not long been sub- 

 jected to erosion do not show the peak and ridge structure. 

 All these peaks are the result, not only of original uplift, 

 but of subsequent carving. 



THE TETON RANGE, IDAHO, U. S. A. 



Mountains that have been eroded into sharp peaks. 



Mountain Ranges. As a rule mountains are found 

 in ranges. The mountains in the range are by no means 

 all the same elevation, nor is the range necessarily contin- 

 uous, there being often gaps along its course. Neither were 

 all ranges in a mountain region elevated at the same time. 

 Those which make up the mountain region of the western 

 United States differ much in the time of their elevation. 



