Review of Recent Geological Literature. 265 
The Carnbriafi rocks, 7,700 feet in thickness, are divided into five 
epochs. The lower, middle and upper Cambrian are all exposed. 
Conformable over the Cambrian are the Silurian rocks. In the 
midst of the Silurian (i. e. between the Eureka quartzite and the Lone 
Mountain limestone) is an unconformity. Both the Trenton and the 
Niagara formations are included within the Lone Mountain epoch, the 
latest of the recognized Silurian. 
The Devonian follows, with imperceptible gradations from the 
limestones of the Lone Mountain epoch, and has a total thickness of 
8.000 feet, and consists of two epochs, the Nevada limestone and the 
White Pine shale. The black shale is characterized by a fragmentary 
upper Devonian flora. 
The Carboniferous, with a thickness of 9,300 feet, is made up of rocks 
of four epochs, fossils occurring in the limestones. Three salient fea- 
tures mark the life of the lower Coal Measures: first, the occurrence 
near the base of the limestone of a fresh water fauna; second, the varied 
development of the lamellibranchiates, a class which has heretofore 
been but sparingly represented in the collections of fossils from the Cor- 
dillera; third, the mingling near the base of the horizon, of Devo- 
nian, lower Carboniferous and Coal Measure species in gray limestone 
directly overlying beds characterized by a purely Coal Measures fauna. 
Coal seams occur in the first range east of the Eureka mountains. 
Each orographic block is described in detail, beginning with those 
composed of the oldest rocks, and the relations of the different moun- 
tain masses to each other are pointed out. 
In the general discussion of the Paleozoic rocks the author shows 
that from a pre-Cambrian continent in Nevada a vast amount of de- 
tritus was furnished to a sea which lay toward the east. The Eureka 
region lay not far from the eastern border of this land mass, as indi- 
cated by the abundance of coarse mechanical sediments in the paleo- 
zoic strata. There were alternating elevations and depressions. The 
final break-up was followed or accompanied by igneous ejections, the 
relations of which with the different orographic blocks are brought out 
by a cross-section. 
Pre-Tertiary igneous rocks play but a subordinate part. Some were 
found to cut Silurian strata, but their age cannot be fixed any more 
closely. They appear principally as dikes. 
The Eureka district affords no direct proof of the age or duration of 
volcanic energy, although evidence based upon observations elsewhere 
in the Great Basin points to the conclusion that the lavas belong to 
the Tertiary era, and probably the greater part of them to the Pliocene 
epoch. They broke out in four ways: first, through profound fissures 
along meridional lines of displacement; second, following lines of oro- 
graphic fracture, they border and encircle large uplifted masses of sedi- 
mentary strata; third, they occur as dikes penetrating the sedimentary 
rocks; fourth, they occur in one or two relatively large bodies, notably 
Richmond mountain and Pinto peak, along lines of displacement. The 
sequence of lavas was: hornblende-andesyte, hornblende-mica-andes- 
