106 THE MOUNTAINS OF CALIFORNIA 



with oak and pine, but it was once a lake stretch 

 ing from wall to wall and nearly from one end of 

 the valley to the other, forming one of the most 

 beautiful cliff-bound sheets of water that ever 

 existed in the Sierra. And though never perhaps 

 seen by human eye, it was but yesterday, geologi 

 cally speaking, since it disappeared, and the traces 

 of its existence are still so fresh, it may easily be 

 restored to the eye of imagination and viewed in 

 all its grandeur, about as truly and vividly as if 

 actually before us. Now we find that the detritus 

 which fills this magnificent basin was not brought 

 down from the distant mountains by the main 

 streams that converge here to form the river, how 

 ever powerful and available for the purpose at first 

 sight they appear ; but almost wholly by the small 

 local tributaries, such as those of Indian Canon, 

 the Sentinel, and the Three Brothers, and by a 

 few small residual glaciers which lingered in the 

 shadows of the walls long after the main trunk 

 glacier had receded beyond the head of the valley. 

 Had the glaciers that once covered the range 

 been melted at once, leaving the entire surface 

 bare from top to bottom simultaneously, then of 

 course all the lakes would have come into existence 

 at the same time, and the highest, other circum 

 stances being equal, would, as we have seen, be 

 the first to vanish. But because they melted gradu 

 ally from the foot of the range upward, the lower 

 lakes were the first to see the light and the first 

 to be obliterated. Therefore, instead of finding the 

 lakes of the present day at the foot of the range, we 

 find them at the top. Most of the lower lakes van- 



