Tlic Esmeralda Formation.- — Turner, 169 
containing coal which he kindly .placed at my disposal. In 
1899 I was detailed to make a geological map of the Silver 
Peak quadrangle and obtained additional data. The beds of the 
Esmeralda formation are inclined at most points, dipping 
usually from 10° to 40°. No absolutely continuous section of 
the entire series was obtained but the total thickness may be 
several thousand feet. 
The base of the series as seen near the coal mines is com- 
posed of sandstone chiefly, with some shale, aggregating per- 
haps 2,000 feet. In this terrane occur the coal, the dicotyledo- 
nous leaves and most of the fossil shells. 
Above the sandstones is a considerable thickness of bufif 
shales containing at a few points very abundant fossil fish. 
On the east side of Big Smoky valley in the foot-hills are 
heavy-bedded breccias and conglomerates overlying the buft 
shales. The breccia beds are chiefly made up of fragments and 
boulders of quartzyte, slate and limestone from the adjacent 
Silurian and Cambrian formations. Often a layer will be com- 
posed wholly of some one rock as slate or limestone, the latter 
usually being re-cemented, so that it has the appearance on 
the surface of being a reef of Paleozoic limestone. In some of 
the gulches, however, these breccias may be seen to be clearly 
interbedded with the sandstone of the Esmeralda formation. 
The top of the series is made up of lacustral marls and 
white shales, containing fish bones, and at some points these 
beds are capped by rhyolitic and basaltic lavas and tuffs. There 
are also some layers of rhyolitic and andesitic tuffs lower down 
in the formation, and these volcanic layers frequently contain 
silicified wood. Faulting has displaced the beds at many points 
and it is therefore dif^cult to estimate the entire thickness, of 
the formation. 
Fossil shells were collected near the coal beds, from the 
locality where Mr. Knapp obtained his specimens and also 
from a number of other points in the sandstones. These were 
referred to Dr. J.C. Merriam, whostates.'T find four species of 
shells in your collection Campeloma sp., Unio sp. Planorljis 
like spectabilis Meek, and Ancylus like undulatus Meek. The 
first three forms resemble species described from the Eocene 
of the western United States; the last form resembles a species 
described from supposed Miocene beds. Though I do not re- 
