34 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
Foot-of-the-Hill wells. From this locality to the top of Brush Moun¬ 
tain the series of rocks from the upper members of the red sandstones 
of the Sespe through the rusty beds at their summit and the great 
mass of shale that makes up the Vaqueros formation is unbroken. 
Three oil-bearing horizons have been found within this range—one 
either at the summit of the red beds or the base of the rusty member 
of the Sespe; another perhaps in the purple clay of the Vaqueros 
formation, and a third in the upper, earthy, and siliceous portion of 
the Vaqueros, not far below the Modelo sandstone. The wells are to 
be regarded as located on the slope of the general Topatopa anticline, 
for a careful examination of the locality reveals only minor and very 
insignificant crumples in the general sweep of the beds in an easterly, 
northeasterly, and northerly curve about the axis of the main fold. 
Brush Mountain is capped by the lower Modelo sandstone and a 
thin band of the overlying siliceous shale. The second offset in the 
general section occurs at this point. On Piru Peak very nearly the 
same formations are encountered, the only difference being a some¬ 
what greater amount of the siliceous shale at the top of the series. 
The lower Modelo sandstone outcrops immediately beneath the shale 
and at the head of Modelo Canyon is affected by the Modelo anticline, 
which is one of the most conspicuous and perfect folds of this charac¬ 
ter to be found anywhere in the region under discussion. The sand¬ 
stone here, however, appears to be at least several hundred feet thick— 
thicker, indeed, than on Brush Mountain, and yet by no means so 
extensively developed as about the head of Pfopper Canyon, farther 
north. The succession of strata on the two sides of the anticline 
varies somewhat, but this is perhaps due to crumpling and faulting. 
The presence of a fault is indicated by the abnormal succession of beds 
encountered in crossing the outcrop of the formation. It is probable 
that at the line of this section the opposing beds for some distance 
from the surface belong to the shale between the upper and lower 
Modelo sandstones, but the exact amount of throw is indeterminable, 
first, because of the uniformity of the shale in appearance; second, 
because of the rapid variation in the thickness of the strata, and third, 
because of the crushing that has taken place adjacent to the fracture. 
The Modelo anticline is one of the most productive folds north of the 
Santa Clara Valley. About midway of the folds are the wells of the 
Modelo Oil Company, attaining a maximum depth of about 1,800 feet, 
with oil at 1,400 or 1,500 feet and indications of oil at still greater 
depths below the surface. The wells are wholly in the Modelo sand¬ 
stone, which in places is so free from shale and so solid as to stand 
without casing. The wells are drilled in strata that dip 60° or more 
on both sides of the anticline, at distances varying from less than 100 
feet to 600 or 700 feet on each side of the axis. The wells of the Sun¬ 
set Oil Company in Hopper Canyon, 1J miles to the west, are also on 
