SANTA CLARA VALLEY: SANTA PAULA RIDGE. 
49 
FIELD SOUTH OF SANTA PAULA RIDGE. 
LOCATION. 
The productive oil territory immediately east of Santa Paula Can¬ 
yon lies at the foot of the steep southern face of San Cayetano Moun¬ 
tain and is the eastward extension of the Ojai, Silver Thread, and 
Sulphur Mountain districts. The general configuration of the dis¬ 
trict is shown in PI. VII, A, a panorama looking north from Santa 
Paula, in which this field appears along the face of San Cayetano 
Mountain on the right The sharply eroded ridges in the middle dis¬ 
tance on the right are composed of the Fernando conglomerate, sand¬ 
stone, and clay. 
GEOLOGY AND STRUCTURE. 
The great San Cayetano fault, along which the late Tertiaries are 
in contact with the Topatopa formation, lies at the base of the steeper 
portion of San Cayetano Mountain, at the upper edge of the lofty foot 
slopes, 2,000 feet above sea level. Along this line the oil-producing 
territory has been found, the area of yield widening somewhat with 
the appearance of other members of the fault system, in the direction 
of Santa Paula Creek. In this direction, too, the succession of strata 
and their relations become more and more complex. 
The sediments involved in the productive region east of Santa 
Paula Creek include unmistakable Topatopa beds; a small wedge of 
the rusty Eocene sandstone, shale, and Ostrea-be&rmg limestone from 
the Silver Thread field; shale of the Modelo type, and a succession of 
sandstone, conglomerates, and blue, mud-like arenaceous clays, that 
have already been referred to as probably of Fernando (Pliocene) 
age. These last are the same as those occurring in Adams, Wheeler, 
and Aliso canyons and are also to be seen in strong outcrops crossing 
Santa Paula Creek from 3 miles above the town of Santa Paula to a 
point within a mile of Sisar Creek. The Modelo is identified by the 
siliceous character of its shales and by +heir organic life. As it is, 
however, in a locality in which the rocks are badly crushed and in 
which there is a rapid succession of interfault blocks, it is impossible 
to recognize its relations to adjacent beds. 
A typical section (see PI. Ill, sec. C-C') of the field, directly across 
the strata from a point about 2 miles east of Santa Paula Creek, 
in the vicinity of the Hartford well, is as follows: On the north the 
typical Topatopa, succeeded across a fault plane by a siliceous shale 
typical of the Modelo. South of this is a large body of brown shale 
with limestone lenses, which under ordinary circumstances would be 
regarded as also a part of the Modelo, but which is less siliceous and 
