144 
OTL DISTRICTS OF SOUTHERN CALIFORNIA. 
GENERAL STATEMENT. 
The formations involved in the geology of the region about Los 
Angeles consist of (a) black micaceous schist; ( b ) a granitic series 
embracing diorite, gneiss, and other crystalline rocks; (c) more than 
2,000 feet of Puente sandstone of lower Miocene age; (d) about 2,000 
feet of upper Puente shale and soft, thin-bedded sandstone, also of 
Miocene age, (e) basalt and diabase intruding the previous forma¬ 
tions, but older than the following: (f) 2,000 feet or more of soft, 
thin and thick bedded sandstone, thin-bedded shale, and heavy- 
bedded conglomerate of the Fernando formation, largely of Pliocene 
age, and (g) a capping of Pleistocene gravels and sands of variable 
thicknesses. (See fig. 12.) 
Feet. 
100+ Alluvium and roughly bedded gravel, sand, and clay. 
2,000 + 
Upper portion thick-bedded soft sandstone with a few lay¬ 
ers of conglomerate and thin-bedded sandy shale. Lower 
portion, largely thin-bedded soft clayey sandstone and 
sandy shale, somewhat petroliferous near the Miocene 
contact. 
(Probable unconformity, beds of both formationshaving 
;T approximately the same dip. 
Upper half, thin-bedded sandstone and sandy shale, with 
some hard siliceous members and one or two bands of 
coarse sandstone, which usually carry oil. Lower half, 
alternating bands of thin-bedded siliceous shale and 
coarse sandstone. This and all older formations in¬ 
truded by diabase and basalt. 
9 
000 +• 
Coarse, heavy-bedded brown arkose sandstone inter- 
bedded with minor quantities of argillaceous and sili¬ 
ceous shale, the shale being relatively more abundant 
toward the top and bottom of the formation. Total 
thickness unknown. 
Basement complex of diorite and other granitic rocks and 
gneiss, associated with an extensive dark-colored mica¬ 
ceous schist. 
Fig. 12.—Generalized geologic section for the immediate vicinity of the Los Angeles oil fields. 
