THE PETROLEUM FIELDS OF CALIFORNIA. 
By G. H. Eldridge. 
INTRODUCTORY. 
The petroleum fields of California, as at present known, lie on 
either side of the Central Valley of the State, in the Coast Range, and 
along the Pacific front. The greatest development has taken place 
south of the parallel of San Francisco, although northward from this 
are many prospects and one developed field of minor commercial 
importance — that in the vicinity of Eureka, Humboldt County. 
The Coast Range, considered as a topographic province, includes 
all the mountains lying between the great Central Valley of California 
and the Pacific Ocean. It has no well-defined axis, either topographic 
or geologic, but consists rather of a number of parallel ridges having 
a general elevation of between 3,000 and 4,000 feet, with occasional 
peaks extending to somewhat greater heights. 
Structurally the Coast Range consists of numerous parallel anti 
clines and their corresponding synclines. There is no dominant 
axial fold, the crust having been crumpled into a close succession of 
ridges of varying amplitude and height of arch. The topographic 
trend of the general range from San Louis Obispo north is about 
N. 30° W., veering westward south of this. The structural trend of' 
the folds composing it, however, is between N. 20° and 40° W. from 
the thirty-sixth parallel north, N. 50° or 60° W. in the region of San 
Luis Obispo, and from Point Conception east N. 80° to 90° W. 
Throughout the entire range it is distinctly diagonal to the coast line, 
except, perhaps, along the Santa Barbara Channel. Faults, of course, 
occur. 
The large productive oil fields of southern California include the Oil 
City, adjacent to Coalinga; the McKittrick ; the Sunset and its exten- 
sion, the Midway; the Kern River; La Graciosa; the Suminerland; 
the Santa Clara Valley; the Los Angeles; and those of the Puente 
inns. 
THE OIL FIELDS. 
COALINGA DISTRICT. 
This district extends along the eastern base of the Mount Diablo 
Range for a distance of about 30 miles, Coalinga, the small town from 
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