156 The American Geologist. March, 1901. 
zoic formations. The following table will illustrate this de- 
tail : 
Stockton, Quaternary. 
Puente, Los Angeles, and Kern Co. Pliocene. 
Ventura, Los Angeles. Kern Co.. 
Newhall. Miocene. 
Ventura, Fresno, Kern Co. Eocene. 
Colusa Co. and Sacramento Valley. Cretaceous. 
The general horizons only of the oil-bearing strata are here 
represented. Minute details are not yet attainable, nor would 
it conduce to the clearness of the outline to crowd it with de- 
tail. 
The oil-bearing strata are usually sandstones interlam- 
inated with shale as in the East, and both often show traces of 
petroleum, but the accumulations are in the sandstones. Signs 
of disturbance also are visible in many places sometimes ac- 
companied with some degree of metamorphism. 
In considering this subject we should bear in mind the 
fact that the geomorphy of California indicates intense ero- 
genic action at a very recent time. Strata of late Tertiary 
date are contorted and compressed that they stand vertical over 
large areas. The final elevation of the Sierra Nevada and 
Coast range is not apparently earlier than the Pliocene, per- 
haps even later. The proportion of living species among the 
fossil forms abundantly proves the recency of the strata. The 
energetic and extended volcanic action visible in so many 
places is evidenced b\- lavas so new that they have apparently 
only just cooled and are scarcely yet touched by erosion. 
The Anticlinal Tlicory. The accuracv of the anticlinal 
theory of the accumulation of oil and gas, as developed by 
Prof. I. C. White, in Pennsylvania, has received abundant 
confirmation from 'California. In many of the fields the line 
of development on the surface clearly coincides with the anti- 
clinal line underground, and even w^here the strata are very 
slightly disturbed exact data will probably reveal undulations 
of low angle or irregularities, such as those that govern the 
accumulations in many places in the east. 
Where the anticlinal ridges can be traced they are in most 
cases relied upon as safe guides for extending the investiga- 
tion. 
