Auriferous Gravels of the Sierra Xevada. — Turner, 375 
period are chiefly of the pre-Cretaceous sedimentary and ig- 
neous rocks and are usually dark in color; such gravel is fre- 
quently called -'bull or bastard gravel" by the miners, as it is 
often less auriferous than the white quartz gravel, and is not 
always of economic importance. It should be noted that Les- 
quereux made no distinction in age between the leaves from 
under the Tuolumne table mountain and those from the 
probably older gravels at Chalk bluffs. 
Second Pekiod, 
Plant remains that are without doubt from materials of the 
second period are not abundant. Those collected by the writer 
consist chiefly of fossil wood from the "volcanic eement"( ande- 
site-tutf) itself. Some of these specimens have been examined 
by Prof, Knowlton, who identified Cupressinoxy/ou and Pifi/- 
oxylon. It should be noted that the materials of the second 
period are largely coarse gravels with few layers of fine sedi- 
ment calculated to preserve the leaves and stems of plants. 
The gravels of the Dogtown mine, 3 miles north of Altaville 
(Jackson folio), and those south of San Andreas belong to 
the second period as do also the Neocene shore gravels of the 
Jackson folio. 
In regard to the vertebrate remains, reported on so fully by 
Prof. Whitney, it may be noted that many of those bones came 
from deposits which are known to the writer to be later in 
age than those furnishing the plants. This is certainl}' true 
of some of the localities where mastodon remains have been 
found. Thus the gravels at Horse Shoe bend* are Pleistocene 
in age, while other localities are probably Miocene. 
The following quotation from Dr. Dallf is significant on 
this point: "Cope has pointed out that among the vertebrates 
from these gravels one [JElotheriuvt) is not Pliocene nor even 
upper Miocene, but belongs to the Eocene or lowest Miocene 
(White River group), while Mastodon ohscurus is upper Mio- 
cene.'" 
The Klotheriuui referred to by Cope was found at Douglass 
Flat (Big Trees atlas sheet) in Calaveras county, but the ma- 
terial from which it came is not deflnitel}^ described. The 
only specimen of Mastodon ohscurus reported by Whitney 
*AiiritVroiis Gravels, p. 2(51. 
f liullfiiu No. 84, U. S. Geologic-ill Survey, p. I'll. 
