98 
SANTA MARIA OTL DISTRICT, CALIFORNIA. 
PINAL-FOLSOM-SANTA MARIA OIL AND GAS-ESCOLLE AREAS. 
LOCATION AND STRUCTURE. 
The area discussed in this section comprises the Folsom lease, the 
southern part of the Pinal property, the central and southern portion 
of the Santa Maria Oil and Gas lease, and the Escolle property of 
the Union Oil Company. The wells are located on the west end of 
Graciosa Ridge and in the canyons on its sides. The region is largely 
covered by the Fernando sandstone and conglomerate ‘‘cap rock,” 
although the Monterey shale is exposed in the side canyons. The 
structure underlying this part of the field is comparatively simple 
so far as known, the main Mount Solomon anticline, which plunges 
northwestward through its center, being the only fold of consequence 
immediately affecting the area. The mapping of the anticline near 
Escolle well No. 3 is based entirely on the evidence offered by the 
well logs, which is at variance with the northwesterly dips in the 
Fernando in the vicinity of Escolle wells Nos. 2 and 3. 
GEOLOGY OF THE WELLS. 
Those wells which start in the Fernando remain in this formation 
for distances ranging from a few feet to nearly 300 feet, the strata 
penetrated being sand and conglomerate. In the region of Escolle 
well No. 1 and Folsom well No. 1 the Fernando appears to be excep¬ 
tionally deep, extending nearly 300 feet below the surface, and to 
consist largely of conglomerate. One of the wells reports red con¬ 
glomerate at 30 to 90 feet below the surface; whether this is burnt 
shale so hardened as to come out of the well in fragments of consid¬ 
erable size or whether it is true water-worn material is not known. 
Asphaltum is reported at the base of the Fernando in some of the 
wells, and may also be seen at the contact between the Monterey 
shale and overlying beds at many places in this area. (See PI. 
XI, A.) The channels through which this material has escaped 
from the shale are undoubtedly joint cracks, as veins of the hardened 
asphaltum may be seen in the shale beside the road leading up to 
Santa Maria Oil and Gas (Squires) well No. 4 and at other points in 
the field. From the base of the Fernando to the bottom of the wells 
the strata penetrated are practically all shale with a few hard “shell” 
layers, under which occur accumulations of gas and locally of oil. 
A zone in which “shells” appear to be particularly abundant 
immediately overlies the first oil zone. Traces of tar and asphaltum 
are also reported in the shale at various depths. Two zones in 
which many hard limestone “shells” layers are encountered are 
reported from some of the wells; one of these is about 500 feet above 
the second oil zone (B), and the other immediately underlies it. 
