66 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
beyond Pirn Creek. Its .trend is toward the Holser anticline, south 
of the Holser Canyon, but whether the Lyons or the Modelo anticline 
is continuous with the Holser is undetermined. In general, there is 
great confusion of strikes and dips in the slopes of the hills west of 
Piru Creek for the lower 2 or 3 miles of the valley, and without fur¬ 
ther details it is impossible to affirm whether or not any of the folds 
are continuous with other folds that appear to the east of the stream. 
In the Hopper Canyon section the Lyons anticline shows conspicu¬ 
ously in the middle Modelo shale. It is probable also that a fault 
has developed along the axis of the fold in this locality, the beds to 
the south having been carried downward several hundred feet. The 
maximum displacement appears to be along the east-west lateral enter¬ 
ing Hopper Canyon from the east half a mile above its mouth. The 
fracture seems to have resulted from the excessive local development 
of the anticline into an overturned or reversed fold. The attendant 
displacement accounts for the discrepancy in the distances of the 
Modelo sandstone from the apparent axis of the fold on one side and 
the other, in the line of the Hopper Canyon section. West of Hopper 
Canyon the fault is marked by a zone of highly contorted and frac¬ 
tured strata, having a width of about 400 feet. The direction 
assumed by the fault would carry it directly against the Sulphur 
Mountain fracture a mile farther west at an angle of 60°. 
A short distance south of the Lyons anticline the Modelo formation 
is unconformably succeeded by heavy conglomerates and sandstones 
of the Fernando formation. Near the contact east of Hopper Canyon 
the dip of the younger strata is southward. East of Nigger Canyon, 
however, the Fernando beds are overturned, with a steep northerly 
dip, but this probably , changes to southerly as the beds pass beneath 
the Santa Clara Valley. From this point the line of unconformity 
between the Fernando and Modelo formations passes, with a curvi¬ 
linear trend, northward above the mouth of Holser Canyon, remaining 
east of Piru Creek. 
At the line of the general section (Z-Z', PI. Ill) the Fernando 
formation is narrow of outcrop and highly inclined, but otherwise 
simple of structure. A short distance to the east, however, it is folded, 
and the folds become more pronounced and extensive across Piru Cneek, 
developing into an anticline of considerable proportions, with several 
minor crumples near by on either side. 
The Fernando and underlying beds pass beneath the Santa Clara 
Valley, but although the distance across the valley is less than 2 miles 
the Modelo formation has apparently disappeared on the south side, 
the principal formation in the hills being the Vaqueros, with Fernando 
rocks here and there resting against it above the valley level. This 
occurrence suggests possible faulting along the valley, with overlap of 
the Fernando on the older Miocene beds. 
