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Esmeralda County, Nevada.—Turner. 269 
were examined by Dr. J. C. Merriam who identified Sphaerium 
sp. similar but not s:dentical with S. idahoense from Fossil hill, 
Kawash mountains, Nevada; Melania sp. (?) and Carinfe.x, 
two species, like forms from Fossil hill. The Fossil hill forms 
have been regarded as Miocene, but Dr. Merriam does not 
consider the material sufficienc to definitely determine the age. 
lie states that they are unlike Pleistocene forms, and are also 
unlike the forms that are iound in the Esmeralda formation. 
There are also said to be fossil beds in the valley near Soda- 
ville, 
The ostracods were 1efcrred to Dr. R. H. Chapman, who 
states that some of the species are new. He identified the 
foliowing genera: 
1. Ilyocypris sp. nov., near J. gibba but distinct in important points. 
Candona sp. near C. kingsleyi. 
2. 
3. Candona sp. probably new. 
4. Candona sp. probably new. 
The Quaternary Era. 
Pleistocene. In this period there is here included all of 
geologic time from the close of the Pliocene to the Recent or 
Human period. The deposits of the Pleistocene age of Esmer- 
alda county may be censidercd under two heads, desert detri- 
tus, and lake terraces. 
There is nothing so striking in the Great Basin region as 
the numerous detrital slopes which spread out from all the 
canyous and fill extensive pertions of the valleys. Consid- 
ering the very small precipitation in this region, the forma- 
tion of these numerous alluvial fans would seem to involve a 
very long period of time. They are composed chiefly of coarse 
material, often containing bou'ders tons in weight. Where 
the older detrital fans are cut by the present water courses, 
the stratified arrangement cf these materials is clearly evident, 
(see Plate NVIT—A.) and there can be no doubt that they 
are due to the action of water. A consideration of the raanner 
in which rain falls in all this desert country suffices to explain 
the formation of these detrital slopes, for, although the pre- 
cipitation. is very small when the region as a whole is consid 
ered, it is often very great within the space of a few hours over 
a limited number of square miles. The action of the sun and 
frost on the rocks of this very dry region results in the surface 
