94 The American Geologist. Vebruary, 2a 
both systems to approximately the same period of erosion, but 
the personal element enters too largely into this opinion to give 
it much value as a basis for correlation. 
There are not in the great valley bordering on the Sierra 
Nevada province nor in the mountain region itself any fos- 
siliferous sedimentary deposits between the lone and a middle 
Pleistocene formation by which to fix paleontologically the 
time of the great uplift. Furthermore, at the present we can- 
not positively identify its equivalent in the Coast Range re- 
gion and our supposition that it was contemporaneous with the 
uplift and truncation of the Merced formation—the latest Pli- 
ocene recognized on the Pacific coast—is based on little more 
than theoretical deduction. 
All that we can be reasonably certain of is that the incep- 
tion of the cafien cutting in the Sierra Nevada region ante- 
dated the opening of the Glacial period as that term is used in 
the eastern states and hence the Sierran period was contempo- 
raneous in part, at least, with the Ozarkian; for it will hardly 
be disputed that such profound canons must have been the 
work of a longer period than the Glacial division of the Pleis- 
tocene. 
The erosion of the cafions is supposed to have continued 
uninterrupted to the time of the glaciation of the upper courses 
of the main streams. As a matter of fact, the glaciation of the 
high Sierras had very little effect on the cafion cutting lower 
down. The erosion is in progress today, perhaps as vigorous- 
ly as ever. 
Under LeConte’s definition, Sierran apparently covers at 
least part of the Ozarkian or pre-glacial portion of the Pleis- 
tocene and nearly the whole of the Glacial period as the latter 
has been established in the eastern states and Europe. Many 
Pacific coast geologists do not seem to appreciate the com- 
plexity and length of the Glacial period. They refer to the 
short and comparatively recent glaciation in the Sierra Nevada 
region as though it were approximately equivalent to the 
whole series of events in eastern glaciation. Sierra Nevada 
glaciation is extremely interesting because of its Alpine fea- 
tures ; but when it comes to a matter of time, it is hardly worth 
mentioning. In the Klamath region, I have not seen a trace 
of any Glacial action older than the Wisconsin epoch, and I 
