176 SOUTHWESTERN NEVADA AND EASTERN CALIFORNIA. 
calcite, are still forming. River bowlders are here and there inclosed 
m these veins, and stalactitic calcite hangs from them in some canyon 
walls. The bands are either parallel to the walls or at right angles to 
them, while in certain places the borders of the veins are vertically 
banded and the centers horizontally banded. Many of the later veins 
fa nit the older. 
Areas of silicified ami kaolinized rhyolite in the Amargosa Ivange 
are shown on the map (fig. t, p. 4?>). The rhyolite S miles southeast 
of Daylight Spring has been silicified, and small quartz veins cut it. 
The area has been located, but no information is at hand as to the 
value of the ore. Silicified rhyolite. with many small quartz veins, 
outcrops at several places east of Mexican Camp and 1 mile north of 
McDonald Spring. At the latter locality small quartz veins also 
occur in the biotite andesite. The quartz in this portion of the range 
is largely white or gray and compact. At Currie Well bowlders of 
silicified rhyolite. said to pan gold, occur as float, but the original posi- 
tion of the rock is not known. Silicified rhyolite stained by the yel- 
low basic ferric-alkali sulphate ( ?) already mentioned (p. 50) covers 
a considerable area to the south of Grapevine Canyon. This rhyolite 
is doubtless worthy of careful prospecting. 
BULLFROG IIILLS. a 
TOPOGRAPHY AND GEOGRAPHY. 
The Bullfrog Hills lie west of Oasis Valley, between the Amargosa 
Desert and Sarcobatus Flat. They form a spur of the Amargosa 
Range and have an east-west crest line, from which an eroded 
mesa extends northward and rather sharp ridges stretch out to the 
south. The highest peak in the hills reaches an elevation of 6,035 
feet. The Bullfrog Hills are bare of timber and are only sparsely 
covered with desert shrubs and cacti. The towns in these hills ob- 
tain water from Amargosa River (see p. 18) and from a number of 
springs in Oasis Valley and in the hills themselves. Among the lat- 
ter may be mentioned Indian (30.000 to 40,000 gallons per day), 
Crystal, and Mud springs. Hicks Hot Springs, in Oasis Valley, have 
already been described (p. 20). 
GENERAL GEOLOGY. 
The formations exposed in the Bullfrog Hills include the follow- 
ing, the oldest being named first: Pre-Silurian schist. Eureka 
quartzite, Lone Mountain limestone, post- Jurassic pegmatite, pre- 
a The geology and ore deposits of the Bullfrog district will he descrihed in detail by 
Messrs. F. L. Ransome, W. II. Emmons, and G. II. Garrey in .) forthcoming Professional 
Paper, and the geology of the area shown on the Bullfrog special sheet has heen gen- 
eralized from their map. The description here given refers more particularly to the 
area outside that covered by the special map. 
