128 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
yet it is not unlike certain members of the Fernando. The writer is 
inclined to place the beds in the Puente and to regard the area as lying 
within a zone of especial disturbance that is manifest along both the 
main fracture and its northern branch, in all probability in an inter¬ 
fault block. The syncline is traceable in strike from north of east 
through north to north of west, and in a dip correspondingly variable 
from north to west and then to south around the east end of the 
trough, this being especially manifest in the heavier sandstones at 
the point occupied by the Fullerton wells, which lie close to the syn¬ 
clinal axis or a short distance off on its southern limb. Evidences of 
the syncline continue eastward to the bottoms of Soquel Creek in a 
constant repetition of the structural features of the Columbia ground 
(lease No. 1), a westerly dip along the axial line locally as high as 45° 
being especially noticeable. Bejmnd Soquel Canyon the identity of 
the syncline is lost. 
Most of the Columbia wells (lease No. 1) are located on the south 
side of the synclinal trough; some, however, are close to the axis, 
while two or three of excellent yield appear to be in strata that dip to 
the south or are intensely crushed. One of the deeper wells in which, 
up to the time of the investigation, no oil had been found penetrates 
at the collar the organic shale of the Puente. The others, which start 
in heavy sandstone, probably of the Puente formation, are highly 
productive. 
The easterly wells of the Santa Fe and those of the Fullerton and 
Columbia oil companies appear thus to have been drilled in the Puente 
formation, in ground whose structure is somewhat uncertain. Most 
of them lie a little south of the line of maximum crumpling. It may 
be inferred, therefore, that the horizon of their oils is approximately 
that of the oils of the Puente Oil Company’s wells 5 miles farther west. 
Moreover, the logs of the wells indicate the presence in depth of shale 
similar to that of the Puente oil field, whereas in other portions of the 
Sante Fe area the strata are of the more open and porous nature 
characteristic of the Fernando. This similarity of strata penetrated 
in the Puente field and the east end of the Olinda field accounts for the 
similarity of the oils of the two localities. The gravity varies between 
23° and 35° B., the oil of the Olinda field being somewhat the lighter. 
Typical Puente shale with steep dip is exposed a few feet east of the 
Columbia camp (lease No. 1) , several hundred feet south of the eastern 
wells of this company. The outcrop is in line with others of the same 
nature up Soquel Canyon, and it is probably continuous with them, 
the Fernando having here crossed to Telegraph Canyon. Loose 
shale fragments are also found over a considerable area in the same 
general region south of the wells. 
Along the middle portion of the field, in the eastern half of the 
Graham-Loftus tract, the strata occupying the face of the hills north 
