11G OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
STRUCTURE. 
The older formations in the heart of the area lie in anticlinal posi¬ 
tion, the flanks of the fold showing sharp local crumplings, with pos¬ 
sibly a continuation of the faults that occur in the fields to the east 
and west. The prevailing strike is N. 70°-80° W. The position of 
the Puente fracture, if it be present (or of its alternative, the line of 
unconformity) is considerably nearer the axis of the general anticline 
than at points to the east, a few hundred feet only separating the two 
if, indeed, they are not locally coincident. As in other fields, there 
is here also a marked divergence between the trend of folds and the 
course assumed by the line of maximum disturbance. Along this line 
the development of oil territory has taken place. In the vicinity of 
the Union and New England wells, at the west end of the district, 
the strata show marked crumpling, with some evidence of faulting, 
although this is north of what appears to be the main anticline as 
traced from the east. The locality is one of especial confusion, owing 
to the compressed condition of the folds, to the proximity of the hori¬ 
zon of unconformity between the Fernando and older beds, and to the 
crushing that the rocks have undergone. 
Of the several flexures present the most important appears to be 
that which passes directly north of the Union wells, in apparent con¬ 
tinuation of the princpal anticline of the hills to the east. It lies con¬ 
siderably south of the point of greatest disturbance in the field,which 
is apparently in the immediate region of the New England wells. 
Farther west it possibly merges with the fold which appears south of 
the fault zone at the east end of the Whittier district. North of this 
fold are others, both anticlines and synclines, in one of which are the 
New England wells and an isolated well of the Union Oil Company. 
The rocks along the axis of this fold show severe crushing, with indi¬ 
cations of considerable displacement. 
At the head of the east fork of La Habra Canyon the structure again 
shows marked complexity. Sharp crumples, even faults, exist. 
The most conspicuous displacement is between the hills oneitherside 
of the road over the divide. The unconformity also is very marked, 
the line between the Fernando conglomerate and the siliceous shale 
of the Puente sweeping in a broad curve to the southern base of the 
hills and passing thence to the entrance to Walnut Canyon and the 
hills separating this from the entrance to Brea Canyon. Whether 
faults exist along this line is uncertain. North of the more conspicu¬ 
ous fracture the lower body of shale, beyond an interval of sharp 
minor folds, assumes a northerly dip, which is maintained by the 
succeeding formations to the northern limit of the hills. South of 
the fracture the shale, together with a small fragment of Puente sand¬ 
stone, appears to lie in a sharp syncline, which is succeeded by an anti- 
