110 OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
All the sedimentary formations in the Puente Hills, at one horizon 
or another, carry petroleum or its asphaltic residue. In the region 
developed by the Puente Oil Company, near the center of the pro¬ 
ductive belt, oil is derived from sandy strata low down in the lower 
division of the Puente shale. The Puente sandstone is bituminous at 
several points, particularly along the eastern crest of the hills, 
although as yet it affords no oil. The upper shale, also unproductive, 
nevertheless carries a small content of disseminated oil. The Fer¬ 
nando formation has proved extremely rich in several localities. 
The presence of oil at the horizons mentioned is not, however, an 
argument for their productiveness at all points. The factors of 
structure and of the original occurrence or formation of petroleum 
are always to be considered. 
While it is evident that severe disturbance of the strata has been 
the chief determinant of the presence and development of the suc¬ 
cession of oil fields along the southern face of the Puente Hills, such 
occurrences as that of the Chino field, on the eastern crest of the 
hills, 5 miles southwest of the town of Chino, are evidences of the 
possibilities, under right conditions, in the regions of subordinate 
folds. As yet, however, prospecting of the secondary and lateral 
anticlines has been but slight. 
OIL FIELDS. 
The developed oil fields of the Puente Hills include the Whittier, 
immediately east of Whittier; the La Habra, on La Habra ranch, 
3 miles southeast of the Whittier field; the Puente, on the summit 
of the ridge in its most contracted portion; the Brea Canyon, 
miles southeast of the Puente field; the Olinda, on Olinda ranch, 
7 miles northeast of Fullerton, and the Chino, about 5 miles south¬ 
west of Chino. The last-mentioned field, although within the gen¬ 
eral anticline of the Puente Hills, is independent of the other 
petroleum-producing areas, which lie at intervals along the belt of 
highly disturbed strata on the south side of the hills. (PI. XII.) 
WHITTIER FIELD. 
LOCATION. 
The producing territory of the Whittier oil field lies on the south¬ 
ern slope of the Puente Hills, beginning within a mile of the town 
of Whittier and extending in a S. 65° E. direction about 2 \ miles. 
GEOLOGY. 
The field is developed along the south side of the well-defined 
Puente fault zone, in southward-dipping conglomerate, sandstone, 
and argillaceous beds of the Fernando formation, which successively 
abut against different members in the siliceous and other shales of 
