112 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4TH SER. 
the Etchegoin group occurring west of Midway; but this cor- 
relation is not given as final, but only as tentative. 
In lithological character the beds of the Kern River group 
resemble the Santa Margarita, especially in the parts con- 
taining the heavy-boulder conglomerates, and also in the 
gravels, and perhaps in the greenish-colored sands; but these 
criteria are not conclusive. 
Another and stronger feature of resemblance is in the oil- 
measures. It is a generally recognized fact that the oil- 
measures of the Sunset and Midway districts are in beds of 
Etchegoin age, and are principally near the bottom. The well- 
known occurrence of oil-measures in the Kern River group 
gives a means of correlation that would have great weight with 
many, and it may well be considered to have a strong strati- 
graphic if not a paleontological basis, and therefore to warrant 
serious consideration. 
The overlapping of the Kern River group upon the older 
groups is similar to that of the Etchegoin as exposed elsewhere. 
The Kern River group, however, is in the aggregate thicker 
than the Etchegoin, west of Midway, but on the other hand 
it is thinner than the Etchegoin group north of Coalinga. 
It is possible that the Kern River group is contemporaneous 
with, and equivalent to, the upper part of the Santa Margarita 
and a part of the Etchegoin, and represents a transgressional 
or progressive subsidence of the basin-floor. This view would 
harmonize many points not readily determined by direct proof 
derived from any part of the basin. 
It is less satisfactory to attempt a correlation of the Kern 
River group with any portion of the “McKittrick Formation” 
for the reason that the latter is not yet sufficiently well under- 
stood. In the published description of the McKittrick forma- 
tion it is made to include both marine and fresh-water beds 
that are readily distinguishable, and the definition is further 
complicated by the use of terms that are subject to dispute. 
The correlation of the Kern River group with any portion of 
the McKittrick formation must therefore await a fuller and 
more consistent definition. But as both the Santa Margarita 
and the Etchegoin beds are known to be petroliferous about 
McKittrick and Midway, it is likely that the equivalents of the 
Kern River group will be found to include portions of both. 
