FOUNTAINS AND STREAMS 261 



weathered off, boulder by boulder, in the ordi- 

 nary way, almost every talus had been formed 

 suddenly, in a single avalanche, and had not been 

 increased in size during: the last three or four 

 centuries ; for trees three or four hundred years 

 old were growing on them, some standing at the 

 top close to the wall, without a bruise or broken 

 branch, showing that scarcely a single boulder 

 had fallen among them since they were planted. 

 Furthermore, all the taluses throughout the range 

 seemed, by the trees and lichens growing on 

 them, to be of the same age. All the phenomena 

 pointed straight to a grand ancient earthquake. 

 But I left the question open for years, and went on 

 from canon to canon, observing again and again ; 

 measuring: the heights of taluses throughout 

 the range on both flanks, and the variations in 

 the angles of their surface slopes ; studying the 

 way their boulders were assorted and related 

 and brought to rest, and the cleavage joints of 

 the cliffs from whence they were derived, cautious 

 about making up my mind. Only after I had 

 seen one made did all doubt as to their formation 

 vanish. 



In Yosemite Valley, one morning about two 

 o'clock, I was aroused by an earthquake ; and 

 though I had never before enjoyed a storm of this 

 sort, the strange, wild thrilling motion and rum- 

 bling could not be mistaken, and I ran out of my 

 cabin, near the Sentinel Rock, both glad and 



