42 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
another the drill was stopped in a deposit of tar too heavy to pump. 
The best well is reported to have started with a yield of 50 barrels per 
day, but this was reduced to about 13 barrels at the time of the 
writer’s visit (1902), and still later is stated to have fallen off consider¬ 
ably more. The oil is black and heavy and is said to run 48 per cent 
of exceptionally pure (92 per cent) asphaltum. 
SANTA PAULA WELLS. 
Immediately west of the Sobra Vista group, at the head of the 
Upper Ojai Valley, are the two wells of the Santa Paula Oil Company. 
They penetrate the blue shale of the Modelo formation, which is here 
folded into a westward-plunging anticline. The wells derive their oil 
from interbedded sandstones, some of which yield seepages of heavy 
asphaltum. The northern well is farther down the dip and is the 
deeper of the two. It is reported that this yielded lighter oil than the 
southern well and that the latter struck oil similar to that encountered 
in one of the Sobra Vista wells, which was too heavy to pump. 
SOUTHERN SULPHUR MOUNTAIN FIELD. 
LOCATION. 
The oil areas that have been developed along the southern base of 
Sulphur Mountain lie at the heads of Aliso, Wheeler, Salt Marsh, and 
Adams canyons and along the short gulch heading against Adams 
Canyon from the Santa Paula A 7 alley. All are a short distance south 
of the northern boundary of what once constituted the San Buena¬ 
ventura Mission. The general elevation of these areas is about 1,100 
feet, Sulphur Mountain rising abruptly above to heights between 
2,500 and 2,750 feet. The canyons are of easy grade and the inter¬ 
vening ridges are comparatively low. 
GEOLOGY. 
Two and perhaps three formations are involved in this field— 
Modelo shales; Fernando conglomerate, sandstone, and clay; and 
possibly certain remnants of the Pleistocene, consisting of coarse 
gravel and gritty sand. 
The Modelo is confined to Sulphur Mountain and consists of blue 
and brown, finely laminated shale, which is either earthy or siliceous, 
here and there even slightly sandy, and thin beds of sandstone. The 
shale is the conspicuous feature, however, and is of the type variety. 
It carries the customary gray to yellow limestone concretions, which 
with the shale show an abundance of organic remains, foraminifera 
and fish integuments and their impressions. The browner variety of 
the shale is gypsiferous and carbonaceous. 
