Letters to a Friend 



Yosemite, 

 September 17, [1873.] 



I am again at the bottom meadow of Yosem 

 ite after a most intensely interesting bath 

 among the outer mountains. I have been ex 

 ploring the upper tributaries of the Cascade 

 and Tamarac streams. And in particular all 

 of the basin of the Yosemite Creek. The pres 

 ent basin of every stream which enters the val 

 ley on the north side was formerly filled with 

 ice, which also flowed into the valley, although 

 the ancient ice basins did not always correspond 

 with the present water basins because glaciers 

 can flow up hill. The whole of the north wall 

 of the valley was covered with an unbroken 

 flow of ice, with perhaps the single exception 

 of the crest of Eagle Cliff, and though the book 

 of glaciers gradually dims as we go lower on 

 the range, yet I fully believe that future inves 

 tigation will show that, in the earlier ages of 

 Sierra Nevada ice, vast glaciers flowed to the 

 foot of the range east of Yosemite and also 

 north and south at an elevation of 9000 feet. 

 [ 155 1 



