DESCRIPTIVE GEOLOGY, REGION ABOUT GOLDFIELD. 
LONE MOUNTAIN FOOTHILLS. 
TOPOGRAPHY AND GEOGRAPHY. 
Lone Mountain is a prominent craggy peak 9,121 Peel high, situated 
immediately north of the northwest corner of the area mapped. 
While this mountain and its foothills are cut off from the Silver 
Peak Range to the southwest by the detritus-filled pass 7 miles north- 
west of Montezuma, the two mountain masses are geologically and 
topographically closely related. For convenience, the long ridge in 
which General Thomas Camp is situated will also be described here. 
The Lone Mountain foothills reach a maximum elevation of 7,000 
feet. They have rather steep slopes and show a tendency to elonga- 
tion parallel to the strike of the Paleozoic rocks. The eastern ridge 
has a serrated crest line, due to the alternation of steeply dipping 
resistant limestones and soft shales. The Lone Mountain foothills 
are bare of timber and without water, although both are present on 
the mountain itself. 
GENERAL GEOLOGY. 
Lone Mountain is a batholith of granite which intrudes Cambrian 
sedimentary rocks, the predominant rocks of the foothills. The 
formations are as follows, the oldest being named first : Cambrian 
sedimentary rocks, post- Jurassic granite, pre-Tertiary diorite and 
diorite porphyry and associated serpentine, and older alluvium. 
SEDIMENTARY ROCKS. 
Cambrian. — The predominant formation of these hills is a series of 
limestones and shales which appears to consist of a lower shale mem- 
ber, at least 1,000 feet thick, and an upper limestone, several thousand 
feet thick, which in turn is probably overlain by a second shale 
member. 
The limestone is compact and rather fine grained. It is dark gray or 
:>luish gray in color, although in places weathered surfaces are stained 
yellow or brown by limonite. It is for the most part probably dolo- 
nitic, since an analysis of a limestone from the westward extension 
)f the area, in the Silver Peak quadrangle," shoAved 19 per cent of 
nagnesia, Layers of black flint, from a few inches to 2 feet thick, 
ire interbedded with the limestones near General Thomas Camp. 
ti the same vicinity the limestone has been altered to a white cherty 
luartz and all gradations exist between this and the unsilicified lime- 
tones. White calcite veins traverse the limestone in all direction-, 
rhile quartz veins are less common. These veins are not folded, and 
J re doubtless younger than the folding. 
a Turner, II. W., Silver Teak folio ; unpublished. 
