142 SOUTHWESTERN NEVADA AND EASTERN CALIFORNIA. 
STRUCTURE. 
The rhyolite of Tolicha Peak is complexly cut by normal faults 
with displacements of 10 to 50 feet. These faults in some places 
are less than 100 yards apart. The rhyolite is also intensely jointed. 
ECONOMIC GEOLOGY. 
The rhyolite around Monte Cristo Springs is kaolinized or silici- 
fied. Prospect holes arc located on quartz veins in altered rhyolite, 
the ore being quartz and silicified rhyolite stained by limonite. 
Quartz Mountain Camp, on the northern slope of Quartz Mountain, 
was not visited, but the conditions, according to the reports of pros- 
pectors, are similar to those at Monte Cristo Springs. The altered 
masses, which resemble those of Silverbow and are faulted like those 
of Bullfrog, are outlined on the economic map (fig. 4, p. 43). 
MOUNTAINS SOUTHEAST OF PAHUTE MESA. 
Southeast of Pahute Mesa are a number of small groups of moun- 
tains with cresl lines of varying trend, although a uumber have an 
eastward extension. These include Shoshone. Skull, Yucca, Timber, 
and Bare mountains and the Specter Range. Geologically they are 
characterized by the important development of the early Miocene 
rhyolite. 
SHOSHONE AND SKILL MOUNTAINS AND THE HILLS J X THE VICINITY. 
TOPOGRAPHY AND GEOGRAPHY. 
Shoshone and Skull mountains lie to the north of the Specter Range 
and the Skeleton Hills and to the east of Fortymile Canyon. Sho- 
shone Mountain i- joined to the Belted Range by a low gap, hut from 
its east-wesl trend it more properly belongs with the other ridges in 
the vicinity. Shoshone (7,540 Peet) and Skull (6,100 feet) mountains 
are each capped by horizontal lava flows, and in consequence from a 
distance appear as mesas. The other hills and ridges vary in form 
from the jagged ridges of Carboniferous rocks to the smooth de- 
pressed domes of the Sieberl lake bed-. The various ridges and hills 
are in many instances separated from one another by opposed valleys 
which are filled with desert gravels. 
A fairly heavy growth of juniper and piiion is found on the north 
slope of Shoshone Mountain above Tippipah Spring, but other por- 
tions of this mountain and the other ridges are bare except for sparse 
groves of the tree yucca and here and there a Spanish bayonet ( Yucca 
aloifoliaf). Scarcely a -pear of grass grows throughout these hills. 
Of the four springs in these hills, Cane Spring flows about 1,500 gal- 
lons a day; Tippipah contains from :>() to 100 gallons of standing 
water; Topopah (or Blackrock) flows from \:> to 25 gallons a day. 
