122 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
field. The formations north of the fault line, or of the line of 
unconformity, show the usual variety of flexures, the shale being 
especially crumpled, the Puente sandstone less so. Syncline and 
anticline appear with a few secondary faults, parallel to the main 
fracture. An instance of the minor faults is to be found in the 
face of the ridge between the east and west forks of Brea Canyon, 
where Puente sandstone lies vertically against slightly undulating 
beds of the lower division of the Puente shale, indicating the drag¬ 
ging down of the younger horizon in connection with the sharp fold 
from which the chief displacement has been developed. Toward the 
crest of the hills is the main axis of the general anticline, the fold 
being here somewhat modified by the radiate flexure passing to the 
northeast between the forks of Brea Canyon. 
The position assumed by the Fernando beds south of the Puente 
fault is of the greatest interest from a structural standpoint. The dip 
of the conglomerate and sandstone north of the canyon, opposite the 
wells of the Brea Canyon and Menges oil companies, is 50°-90° N. 
(See PI. XI, sec. G-H.) There appears to be a considerable differ¬ 
ence in the succession as well as in the composition of the beds on the 
two sides of the gorge, yet in the uncertainties of lithology their corre¬ 
lation can not be denied as possible. A doubt exists as to whether 
the strata immediately south of the supposed fault lie in an anticline, 
as in similar positions at several points along the hills, or whether the 
conglomerate, sandstone, and arenaceous clay have been overturned 
by dragging against the fracture plane in their downward displace¬ 
ment. At one or two points there is some evidence of the latter con¬ 
dition ; at others there is equal evidence of an anticline; elsewhere all 
is confused. If the anticline exists, its axis lies near the stream chan¬ 
nel in the lower portion of the canyon, gradually passing into the 
slopes of Brea Ridge toward the east, to become continuous or but 
slightly en echelon with that of the anticline south of the faidt in the 
Olinda field. The line of seepages in the bottom of Brea Canyon may 
mark such an axis and may possibly indicate a fracture developed 
along the crest of the fold. The most satisfactory evidence of an 
anticline aside from the unconnected northerly and southerly dips 
along the canyon exists about the head of the small lateral gulch in 
which the Menges wells are situated, the Fernando formation here 
showing the arch of a gentle fold, which, though lying close to the 
Puente fault, may prove continuous with the anticline suspected as 
coincident with the lower portion of Brea Canyon—its westernmost 
extension in fact. Moreover, it may be due to the near approach of 
anticlinal axis and fault—perhaps to the merging of one into the 
other—that the exterior ridges of the hills disappear to the west, the 
fracture alone passing thence along the base of the ridge opposite the 
wells of the Puente Oil Company. On the other hand, near the sug- 
