174 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
contain any prominent shale layers, although it is overlain and under¬ 
lain by the thin white siliceous beds. As exposed in this railroad cut 
the sand is about 50 feet thick, but the records of wells in other parts 
of the field show that it varies considerably in thickness and also in 
the number and prominence of the included shale layers. 
Above the upper coarse sandstone are some layers of thin-bedded 
white shale, which may be traced westward from the region immedi¬ 
ately north of Westlake Park toward the corner of Fifth and Hoover 
streets, and thence northwestward across Vermont avenue to Western 
avenue, which it crosses about one-fourtli of a mile south of Temple 
road. This shale, according to the well records in the region south¬ 
west of the corner of Western avenue and Temple road, probably 
averages somewhat thicker in the western field than it does in the 
central. 
The Fernando is represented in the western field by rather hard 
gray to chocolate-colored shale, exposed on a small creek southwest 
of the Baptist College. The beds dip 22° S. 25° W. Some soft, thin- 
bedded sandstone and sandy shale also occur in the formation above 
the hard beds near the base. Although there are few outcrops to cor¬ 
roborate the assertion, it is exceedingly probable that the Fernando 
overlies the Puente over the whole extent of the Los Angeles-Santa 
Monica plain, south of Temple road and at least as far west as the 
west end of Rancho la Brea. 
As previously stated, the Pleistocene deposits consist of gravel, 
sand, and clay and lie unconformably upon the older rocks from the 
foot of the Santa Monica Mountains southward across the Los An¬ 
geles-Santa Monica plain. An excellent exposure of the Pleistocene 
occurs in the ravine northwest of the Baptist College. This deposit 
consists of sand and gravel of granitic quartz, sandstone, and shale 
fragments, some of the cobbles attaining a diameter of over 6 inches. 
The whole is richly impregnated with heavy oil, which seeps from the 
underlying sandstone and shale and imparts a dark chocolate color to 
the mass. Pleistocene deposits, consisting of roughly bedded sand 
and gravel, lying in an approximately horizontal position, may also be 
seen in cuts along some of the roads west of Hoover street. 
GEOLOGY OF THE WELLS. 
For convenience of discussion, the western field will be divided into 
four areas corresponding to the four more or less distinct groups of 
wells which it comprises. The first area—the largest and by far the 
most important—embraces the territory in the vicinity of the Baptist 
College, and is bounded by Coronado street on the southeast and by 
Rosedale avenue on the west; the second area includes the region 
about the bend in the Hollywood and Cahuenga Valley Railroad at 
the corner of Western avenue and Temple road; the third is located 
