MOHAWK LAKE BEDS. 
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faulting which Mr. J. S. Diller (III) has laid down as hav¬ 
ing formed the east escarpment of a huge orographic block. 
This block as outlined constitutes the main mass of the Sierra 
Nevada. Mr. Diller presumably bases his general scheme 
of faulting upon the previous work of Professor Le Conte 
and Mr. Gilbert, to whose papers he refers. This main 
escarpment forms the steep east slope of the Sierra Nevada, 
and is best seen west of Lakes Owen and Mono. For the ex¬ 
tension of this great line of faulting which seems well sub¬ 
stantiated by all geologists who have visited the above places, 
to the northward through Mohawk and American Valleys, 
we are, I think, indebted alone to Mr. Diller. My own 
observations substantiate the hypothesis of Mr. Diller so far 
as they relate to the existence of a line of faulting in Mohawk 
Valley. The existence of the hot springs seems to point to 
a fissure of some depth. 
Mr. Diller establishes, in the publication just referred to, 
two other lines of faulting to the east of the main fracture. 
(See also IV.) The smaller of these, which is intermediate 
in position between the other two, all three being approxi¬ 
mately parallel, extends along Little Grizzly Creek north¬ 
westerly to near Taylorville, in Indian Valley. The Grizzly 
Mountains lie between it and the main fracture to the west, 
and constitute another smaller orographic block. The other 
line of faulting is west of Honey Lake, the escarpment being 
best seen on the east side of Thompson Peak. The region 
between the Little Grizzly Creek fault and the fault west of 
Honey Lake constitutes Mr. Diller’s third and most eastern 
block of the Sierra Nevada. 
In Figure 1 these three lines of faulting are shown by black 
lines. Between Mohawk Valley and Mono Lake Valley the 
line of the main fault is indicated only by a dotted line, 
since positive evidence of faulting in this part of the Sierra 
Nevada has not, so far as I know, thus far been presented. 
To well understand the basis for Mr. Diller’s division of 
the Sierras into orographic blocks it will be necessary to take 
a brief review of the papers of Professor Le Conte and Mr. 
Gilbert, giving their important conclusions only. 
