bd 
1880. | Geology and Paleontology. 61 
Sierra Nevada,” one of the official reports of the geological 
survey of California, though issued by the Museum of Com- 
parative Zoology, because of the full description of the reported 
discoveries of man in the Pliocene Tertiary. These gravels 
arë mostly consolidated into rock and are capped by lava, con- 
stituting the Table mountains. The original river valley is 
th 
gorge be taken for the unit of measurement. As glacial deposits 
are not known on the flanks of the Sierras, Whitney relies upon 
the character of the fossils exhumed to determine thé age, and de- 
cides that the formation was the Pliocene Tertiary, anterior to the 
glacial drift of the East. The principal fossils are these: Ahinoc- 
erus, Elotherium, Mastodon americanus and M. obscurus, three 
species of horse, a wolf, a deer, Hipparion, Auchenia, etc. These 
were determined by Dr. Leidy. Lesquereux describes seventeen 
species of deciduous trees referred to the Pliocene, with sugges- 
tions of the Miocene. Various stone implements, including tools, 
pestles, mortars, platters, spear and arrowheads, are describe 
from thirty different localities in eleven counties. Human bones 
were found under Table and in Bald mountain. All these facts 
are detailed with the utmost care, and it would seem to be clearly — 
‘Proved that human bones and implements are found in these 
gravels, associated with what are universally regarded as the 
fauna and flora of the Pliocene Tertiary. This is more satisfac- 
tory than any of the reported discoveries of human flints in the 
later Tertiary of Europe. No one would doubt the correctness of 
Whitney’s conclusion if the question did not involve the age of- 
man. Now, is it clear that the California Pliocene was the equiv- 
alent of the Eastern American and European Pliocene? There was 
no true glacial period in the Sierras corresponding to the Great 
Northern Drift; hence, may not the organisms of the Western 
Pliocene period have continued to live on till post-glacial times ?- 
Two suggestions agree with Whitney’s conclusions: (1) the im- 
mense time required to excavate the deep cafions would corres- 
pond well with careful estimates of the length of the glacial period, 
and it is clear that man antedated the erosion of these valleys. 
(2) The cafion-making period in California and over the area of 
