.-/ URIFER O US GRA VEL S— INDEPENDENCE HILL FL OR A 895 



of it, bordered by parallel fault lines, sank down. This sunken 

 area is now indicated by Lake Tahoe and by its continuation 

 northward, the Sierra Valley, only separated from each other by 

 masses of Tertiary lavas. The Tahoe-Sierra Valley " Graben" 



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Fig. 2. Fault lines of the Sierra Nevada. 



or "Moat" (the later word hesitatingly proposed as an English 

 equivalent), is bordered on the west by the fault line beginning 

 at Mt. Tallac, and extending by Donner, Independence and 

 Weber lakes up towards Sierra Valley and Mohawk Valley. At 

 this latter place the investigations of Mr. Turner indicate that the 

 displacement may to a great extent at least be of Miocene Age. 

 On the east it is bordered by the very distinct fault-line extend- 

 ing along the east side of Lake Tahoe up east of Boca and 

 towards the east side of Sierra Valley. The long ridge between 



