68 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
Holser Canyon. Its trend is slightly north of west. It extends west¬ 
ward across the Pirn Valley, perhaps connecting with the Modelo or 
the Lyons anticline, or with both. To the east it was recognized in the 
high knoll near the Ventura-Los Angeles county line, beyond which 
observations in detail were not carried. The surficial formation 
affected by this anticline is the Fernando, consisting of conglomerate, 
sandstone, and clay. Along its axis the coarser strata have at various 
places been impregnated with petroleum, and near one of these, in 
Ramona Canyon, the Ramona Oil Company is drilling a well, the depth 
at the time of the writer’s visit being about 1,000 feet, but only the 
slightest traces of oil have been found. North of Holser Canyon is 
an abandoned dry well, known as the Crown King. 
Between the Holser and Lime Canyon anticlines there is undoubt¬ 
edly a syncline, but the details were not worked out for the region east 
of Piru Creek. To the south the Holser anticline occupies the 
space quite to the Santa Clara Valley, but on this limb of the fold 
(see PI. IV, sec. I-F), on the southern face of the outer ridge, a short 
distance below its crest, is developed a sharp pucker, by which the 
beds in the lower half of the ridge are turned past the vertical, having 
a northerly dip. 
OIL WELLS. 
The oil wells of the Hopper-Piru district comprise the San Cayetano, 
Sunset, Fortuna, Nigger Canyon, Modelo Canyon, Piru Oil and Land 
Company, and Holser Canyon wells. All but the last two groups are 
situated west of Piru Creek. 
SAN CAYETANO WELLS. 
The San Cayetano wells, three in number, lie near the forks of Hop¬ 
per Canyon about 3^ miles in a direct line above its mouth and con¬ 
stitute the uppermost development in this gorge. They are drilled in 
the upper portion of the Vaqueros shale, the northernmost well start¬ 
ing but a short distance below the lower Modelo sandstone. The 
maximum depth is 600 feet. In one or another of them, however, oil 
has been found almost from the grass roots down in streaks of sand¬ 
stone of variable thickness that are interbedded in the shale. With 
the oil has been found considerable water and gas. These wells lie in 
a region of great disturbance, which is attributable, perhaps, to the 
proximity of an anticlinal axis, in the first place, and to a sharp bend 
in the strata from a northwesterly to a northeasterly direction in the 
second place. This latter feature is repeated at the Sunset and For¬ 
tuna wells farther down the canyon. It may be reasonable to infer 
that while each of these three oil-bearing localities is that of an anti¬ 
cline, the curvature of the strata as a feature in the great Topatopa 
system of folds may also have acted favorably on the yield of petro- 
