20 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
closely resemble those in the lower Modelo sandstone, and the asso¬ 
ciated shale is also very much like the shales of the Modelo series 
north of the river. Yet these beds south of the Santa Clara contain 
fossils similar in a measure to those of the lower members of the Vaque- 
ros in the Tar Creek, Little Sespe, and adjacent districts. This, 
with the diminished thickness south of the river, suggests a rapid and 
marked variation in conditions during the sedimentation of these 
mportant formations in the Santa Clara Valley. 
All the shales of the Modelo formation, as well as those of the Vaque- 
ros, carry at one horizon or another minute foraminiferal remains 
and fish integuments, similar in general appearance to those com¬ 
monly present in the Monterey shale in other portions of California. 
Many of the layers in the Miocene shales, whether older or younger, 
are flecked with particles of dried bitumen, indicating a general dis¬ 
tribution of petroleum throughout the shales and suggesting that it 
may have been derived from the abundant organic life once present 
in them. 
The lower Modelo sandstone also bears considerable bitumen in the 
region of Modelo Canyon, and it is said that in summer it yields numer¬ 
ous seepages of a comparatively light petroleum. 
SUPPOSED MODELO BEDS IN THE OJAI VALLEY AND SULPHUR MOUNTAIN. 
The supposed equivalent of the Modelo in the Ojai Valley and Sul¬ 
phur Mountain is confined to beds similar to those which characterize 
the upper portion of the formation in the type locality; that is, it con¬ 
sists of shale, siliceous, chalky, or earthy, in color white, gray, or 
locally maroon, carrying the customary limestone concretions and inter- 
bedded here and there with sandstone of fine grain and a thickness up 
to 10 or 15 feet. In the shale are found the usual foraminiferal remains, 
abundant pieces of fish integument, and, it is reported, even bony fish 
skeletons. The soil formed by the disintegration of the formation is 
black. The extreme silicification that is so common a feature of the 
shale immediately at and below a mountain crest in other localities 
is repeated in Sulphur Mountain. The thickness of the formation in 
the region under discussion seems to be at least 1,50D feet. 
CORRELATION OF THE UPPER SHALY PORTION OF THE MODELO WITH 
THE MONTEREY SHALE. 
In the Santa Clara district the presence of the Monterey formation 
is uncertain, although the uppermost shale of the Modelo north of the 
river and the great mass of siliceous shale and “ chalk rock” that so 
conspicuously caps the Santa Susana Mountains, Oak Ridge, and 
South Mountain, south of the river, may be a part of it. Only one 
