SANTA CLARA VALLEY : TORREY-EUREKA-TAPO FIELDS. 85 
the Santa Susana lying a little farther north than the east end of Oak 
Ridge. The topographic relation of the mountain ridges may be due 
to the development en echelon of successive anticlines, but the anoma¬ 
lies of stratigraphy suggest the presence of a strike fault a little south 
of the Tapo syncline. For instance, in the northern slope of Oak 
Ridge between the Eureka and Tapo drainages, the apparent succes¬ 
sion of beds is quite the reverse of the normal. Both the siliceous 
shale of the Modelo and the chocolate-colored shale and sandstone of 
the Vaqueros maintain a northerly dip, and the inference is that the 
latter are the younger. It is probable, however, that along the line 
indicated there has been displacement, the strata south of the fracture 
plane having been depressed, though to what extent is yet undeter¬ 
mined. This would agree with the explanation already suggested of 
the positions assumed by beds about the head of Smith Canyon. 
South of the Santa Susana Mountains the line of the fault is marked by 
great complexity of strata, it being impossible to recognize horizons 
and, in consequence, the relations of the beds. The fault plane from 
Tapo Canyon eastward appears to lie somewhat diagonal to the gen¬ 
eral trend of the formations; the area of siliceous shale, a prominent 
feature to the west, is diminished almost to disappearance, and the 
difficulty of correctly interpreting the structure is even further 
enhanced by the approach of the line of unconformity between the 
Vaqueros and Modelo beds and the Fernando formation. The Vaque¬ 
ros beds are, however, chiefly involved in the crushing south of the 
range crest. The breadth of the zone of severely crushed and folded 
strata is hardly less than a mile, while its continuity can be traced for 
a distance of at least 10 miles. 
The axis of a somewhat prominent anticline, trending a little south 
of east, passes through the knoll at the southeastern extremity of Oak 
Ridge, about three-fourths of a mile north of the parallel 34° 20' N. 
and 2 miles west of the meridian 118° 40' W. The eastern half of the 
fold involves the Fernando formation, but the western half lies almost 
wholly within the area of siliceous shale, though not far from the north¬ 
ern edge of the Fernando. The general trend of the axis is more 
nearly east and west than the direction assumed by the zone of crum¬ 
pling. These two features therefore diverge toward the west, the zone 
of crushing and fracture turning to the north of Oak Ridge, the anti¬ 
cline passing to the south. 
In addition to the foregoing, there are many other minor crumples 
of greater or less breadth and linear extent, particularly within the 
area of siliceous shale. All have a general direction of S. 70°-85° E., 
but their continuity has not been traced out. 
The formation in the middle fork of Tapo Canyon from which oil 
is derived is a succession of sandstone and shale. The sandstone is 
generally thin bedded, and its proportion to the shale diminishes 
Bull. 309—07-7 
