106 NORTH AMERICA 



The western ranges have furnished, for a long time, 

 an abundant supply of timber, the yellow pine and 

 the Douglas or red fir being considered the most valu- 

 able. The Canadian portion has been little touched so 

 far, except by forest fires ; but in the United States the 

 axe and the fires have wrought immense harm to the 

 forests, and entire districts have been laid bare. This is 



FIG. 30. Aspen forest in Colorado. 



the more serious as one goes further south, where 

 drought does not allow the vegetation to recover so 

 rapidly as in the moister north, and whole chains have 

 been denuded down almost to the rock, with disastrous 

 results. ' In other parts, especially in California, where 

 mines have exhausted the surrounding districts, the 

 useless chaparral-scrub has extended considerably over 

 former timber areas. Now, however, a large number of 



