LOS ANGELES DISTRICT : WESTERN FIELD. 
175 
two or three blocks northwest of the second; and the fourth covers a 
few acres at the east end of the Rancho la Brea about a mile south of 
Colegrove. 
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BAPTIST COLLEGE AREA. 
A reference to the geologic map (PL XVIIIj will show that within 
the Baptist College area are the outcrops of five distinct zones, which 
are, from the base up, the oil-bearing thin-bedded shale and sandstone 
of the Puente formation, southwest of these the 150-foot oil sand of 
the central field, the white-shale zone at the top of the Puente, the 
thin-bedded sandstone of the Fernando, and over all in more or less 
scattered patches the Pleistocene gravel and sand. Oil is derived 
principally from a zone (probably corresponding with the lower oil 
zone of the central field) of interbedded clayey shale, “shell/’ and oil 
sands, the top of which lies from 200 to 400 feet below the bottom of 
Fig. 14.—North-south section on the line W-F, Pis. XVIII, XIX, along Hoover street from First 
to Sixth streets, Los Angeles, showing the structure of the western field. 
the main oil sand of the Los Angeles district. As would be expected, 
the logs of the wells in this area farthest toward the southwest give the 
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most complete records. The Fernando formation consists of sandy 
shale and fine sandstone, beneath which are the clayey shale and in¬ 
terbedded “shell" layers which lie above the thickest sandstone bed. 
This sandstone bed (first oil sand), where reached by wells south of its 
outcrop, usually gives a small yield of heavy oil. Below the sand¬ 
stone the wells penetrate about 400 feet of thin-bedded blue clayey 
shale, thin hard “ shell,” and interbedded oil-bearing sands. Between 
130 and 170 feet above the bottom of this shale is a layer of coarse, 
water-bearing sand, and at its base is a 20 to 50 foot oil sand, the 
greater thickness in wells in the southwestern part of the area, the less 
in the wells which start down north of First street. From this horizon 
down the well logs show considerable discrepancy. Blue clayey shale, 
