46 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
is derived from the strata adjacent to the shallow wells (about 200 
feet deep) which are probably in the Modelo shale; but on the other 
hand, the beds are severely crushed and the oil may be derived from 
a considerable depth, rising through fissures in the shale. Of the 
wells in Salt Marsh Canyon, one yielding green oil is said to have pro¬ 
duced an average of 60 barrels a day after the head had been pumped 
off. It is said also that in the Salt Marsh wells the horizon affording 
green oil is first struck, the black variety being 100 or 200 feet lower 
down. In Wheeler Canyon the conditions are reversed, the top oil 
having a gravity of 28° B. and the lower, 400 or 500 feet below, of 30° B. 
The dip of the strata in the several productive areas of this field 
varies from 45° to 80° N. South of the axis of folding and crumpling— 
south of the productive line, therefore—the dip is usually less than 
45° S., although here and there 80° may be attained. 
SILVER THREAD OR SISAR CREEK FIELD. 
LOCATION. 
The Silver Thread field is developed on the high ground immedi¬ 
ately north of Sisar Creek, near its confluence with Santa Paula Creek, 
directly opposite the productive territory east of the latter stream. 
PI. VI, B , shows its position in relation to the surrounding country. 
STRUCTURE. 
The field is included within the area of the great fault system extend¬ 
ing from San Cayetano Mountain to the Ojai, and is therefore in struc¬ 
tural relationship with the producing fields both west and east of it. 
It lies within a short distance of the point of convergence of the sev¬ 
eral faults that form so conspicuous a feature in the geology of this, 
region. PI. Ill, sec. B-B', indicates the probable relations existing 
along this line through the field. The productive area lies in prox¬ 
imity to what is perhaps the principal fault of the Ojai system, which 
here passes along the steep slopes that form the northern walls of 
lower Sisar Canyon. The extent of the development is about a mile 
in length by 400 or 500 feet in width, the direction assumed by the 
wells being approximately S. 71° 45' E., or about the trend of the line 
between the properties of the Bard Oil and Asphalt Company on the 
south and certain others on the north. The collars of the wells are 
but a short distance below the brow of the mesa that extends back to 
the main mass of the mountains on the north, being about 1,500 feet 
above sea level, or 500 feet above the bed of Santa Paula Canyon. 
Only two or three formations outcrop in the Silver Thread field. 
The oldest of these, which occupies the northern portion of the belt, 
represents the upper part of the Topatopa and consists of a series of 
rusty conglomerate, sandstone, and shale, with interbedded quartz- 
