stand first in appealing strangely and strongly 

 to the imagination. 



All the Rocky Mountain lakes are glacier lakes. 

 There are more than a thousand of these. The 

 basins of the majority of them were excavated 

 by ice from solid rock. Only a few of them have 

 more than forty acres of area, and, with the ex- 

 ception of a very small number, they are situ- 

 ated well up on the shoulders of the mountains 

 and between the altitudes of eleven thousand and 

 twelve thousand feet. The lower and middle 

 slopes of the Rockies are without lakes. 



The lower third of the mountains, that is, the 

 foothill section, is only tree-dotted. But the mid- 

 dle portion, that part which lies between the al- 

 titudes of eight thousand and eleven thousand 

 feet, is covered by a heavy forest in which lodge- 

 pole pine, Engelmann spruce, and Douglas spruce 

 predominate. Fire has made ruinous inroads into 

 the primeval forest which grew here. 



A large portion of the summit-slopes of the 

 mountains is made up of almost barren rock, in 

 old moraines, glaciated slopes, or broken crags, 

 granite predominating. These rocks are well 



235 



