Vot. IIT] ANDERSON—FURTHER STRATIGRAPHIC STUDY 23 
this basal conglomerate can be recognized and followed where 
other strata of the Coalinga beds can not be so easily identi- 
fied. Above the conglomerate are thick beds of gigantic 
oysters, pectens, and barnacles that form a conspicuous fea- 
ture of the formation. Usually there are two or more beds 
of shells from 6 to 20 feet thick included with 100 feet or 
more of sands. In Sec. 10, T. 19 S.; R: 15 E., the oysters 
occur in four beds extending through nearly 200 feet of sandy 
strata. The shells are usually firmly cemented together and 
weather into a bold escarpment in which little else than huge 
oysters is to be seen. These beds of fossils in which oysters 
are the most abundant are often used in tracing the oil-bearing 
strata of the Temblor through parts of the field in which the 
latter do not show plainly on the surface. The species that 
characterize these beds include: 
Ostrea titan CONRAD Chorus carisaénsis ANDERSON 
Pecten crassicardo CONRAD Chione temblorensis ANDERSON 
Pecten estrellanus CONRAD Astrodapsis tumidus REMOND 
Pecten (rel. P. islandicus Astrodapsis sp. 
MULL.) 
The basal conglomerates and the oyster beds with which 
they are associated overlie the red or variously colored shales 
described in the preceding section. There is little or no 
angular unconformity between the shales and conglomerates, 
though the abrupt change in the fauna and in the character 
of the deposits testifies to a change of considerable importance 
in the physical geography of the time. 
A short distance above the highest oyster bed is a layer of 
sandy white shale 80 feet in thickness, and a sandy stratum 
immediately overlying the shale on the west side of Sec. 20, 
T. 18 S., R. 15 E. has furnished the following species: _ 
Cytherea (callista) sp. Diplodonta harfordi ANDERSON 
Chione temblorensis ANDERSON Agasoma kernianum CooPER 
Macoma nasuta CooPER Turritella sp. 
Pecten estrellanus CoNRAD Cancellaria sp. 
Zirphea dentata Gass Solen sp. 
Lucina borealis Lam. Trophon sp. 
