Vou. III] ANDERSON—NEOCENE DEPOSITS OF KERN RIVER 111 
were unfavorable for the continued accumulation of any class 
of sediments. 
But another aspect of sedimentation may well be considered 
in this connection, and that is the climatic conditions of the 
time. The Monterey epoch appears to have been one of dry, 
if not arid, climate. This is shown not only by the class of 
detrital sediments which are characteristic of this group, but 
also by the organic deposits, and by the class of organisms 
that were dominant in this basin at the time, namely Diatom- 
aceae, etc. 
In the various descriptions of the Monterey deposits that 
have been given from time to time, it will be recalled that 
among the materials considered as essential in its composition 
are diatomaceous and other organic shales, foraminiferal 
limestones, volcanic ash, gypsiferous clays, and disseminated 
bituminous matter more or less pervading the whole group. 
All of these materials are not only compatible with, but are 
characteristic of, arid conditions of climate. Furthermore, 
there is a generally acknowledged absence in most places of 
detrital or terrigenous materials. The enormous deposits built 
up of remains of diatoms and of foraminifera not only indi- 
cate, but they require, undisturbed and clear water, conditions 
that are found only under calm and clear skies. But under 
arid climatic conditions there would be slight denudation of 
land areas, and therefore but little sedimentation of terri- 
genous materials along a low and stationary shore line, such 
as bounded the Temblor basin on the east. 
THE KERN RIVER GROUP 
The correlation of the Kern River group with any occurring 
in the Mt. Diablo Range cannot now be made on paleontolog- 
ical ground, for the reason that as far as known it is without 
any determinative fossils. The beds of the Kern River group, 
however, can be followed south to the Tejon valley, and prob- 
ably can be connected toward the west with similar beds 
extending around the south end of the Great Valley and to 
the Sunset and Midway oil districts. In this way the Kern 
River group can, perhaps, be connected with the lower part of 
