374 The American Geologist. June, 1895 
studied by Diller* and are thought by him to be synchronous 
with the lone formation. At several points in this fresh-water 
deposit he olitained fossil leaves, and these Prof. Lesquereux 
determined as of Miocene and probably of upper Miocene age. 
Prof. F. H. Knowlton in a recent letter expresses the opinion 
that the flora of the Auriferous gravels have upper Miocene 
affinities. He writes: ''Out of 55 species found in Alaska, 
and belonging with hardly any doubt to the Eocene, no less 
than 17 are common to the Auriferous gravels and allied for- 
mations of California, which is sufficient to grade the beds 
down at least to the Miocene. I am also finding a number of 
plants from the Yellowstone National park that are common 
to California. The park flora is in turn clearly allied to the 
Fort Union (Eocene), which also tends to bring down the Au- 
riferous gravels flora. The only thing against the Miocene 
age of the California flora is its evident close relation to the 
living, and even this might be modified by a re-study of the 
material." 
Prof. Knowlton's opinion is based on a study of leaves from 
many ditf'erent localities, but chiefly from the gravels of the 
first period. 
Intermediate Period. 
The plant beds in Mohawk valley and at the Monte Cristo 
mine in Spanish Peakf are overlain by andesitic breccia. 
They pretty certainly represent formations later in age than 
the white quartz gravels and associated deposits above de- 
scribed, but it is not certain that the}^ represent the distinctly 
later second period of the "volcanic cement" flows. The same 
is true of the deposits under the Tuolumne table mountain, 
studied by Lesquereux, which have been, covered by a flow of 
basalt, and of the Dodson mine gravel from which the fossil 
wood Arducarioxjlon was obtained. The latter deposit is 
also under basalt, the kind elsewhere called the older basalt, 
which is older than the "volcanic cement'" (andesite-tult") 
flows, but probably younger than the rh3^olite flows that are 
associated witli the earlier white quartz gravels. 
The pebbles of the gravel deposits of this intermediate 
*Eighlh Ann. Kept. U. S. Geologic;il Survey, pp. 41.'{-422: iiml .lounial 
of Geology, vol. ii, pp. 32-54. 
f Fourtcciitii Ann. Rept. U. S. Geological Survey, pp. 4()6-0r. 
