GEOLOGY. 
33 
Vaqueros (lower Miocene) fossils from the Santa Maria district, California —Continued. 
4478. 
4504. 
4508. 
4510. 
4511. 
4512. 
4514. 
4516. 
4517. 
4519. 
4520. 
4521. 
Terebratalia kennedyi 
Dali (Pl. XVII, fig. 4a, 
4b, 4c, 4d). 
. 
X 
Purpura vaquerosensis 
Arnold (Pl. XV,figs.la, 
lb). 
X 
Turritella sp. indet. 
X 
Turritella ineziana Con¬ 
rad (Pl. XVI, fig. 3). 
X 
X 
X 
X 
Turritella variata Conrad 
(young?). 
4478. Two miles south of Santa Ynez, on knoll just east of mouth of Ballard Canyon. 
4504. Three-fourths of a mile up ridge northeast of San Julian ranch house, 1£ miles east of bench 
mark 603. 
4508. El Jaro Creek, one-fourth mile east of Salsipuedes Creek, southeast of Lompoc. 
4510. Five miles north of Concepcion, one-fourth mile west of mouth of Escondido Creek. 
4511. Float on hillside along east side of Los Amoles Creek, 1 mile above El Jaro Creek. 
4512. .Ridge between Los Amoles and Salsipuedes creeks, 10J miles S. 33° E. of Lompoc bench mark 95. 
4514. About 10 miles west of Santa Ynez, on south bend of river H miles southeast of bench mark 552. 
4516. South of Santa Ynez Mission, 2J miles up Alisal Creek, at mouth of valley on east. 
4517. Three miles north of Sudden, on'north flank of 1,912-foot hill, above locality 4518, which is Eocene. 
(See p. 29.) 
4519. On ridge 2 miles east-southeast of El Jaro Creek, bench mark 603, one-half mile west of 1,111-foot 
hill. 
4520. West side of ridge between Los Amoles and El Jaro creeks, 1 mile west of bench mark 603. 
4521. Lime quarry 5 miles southwest of Lompoc. 
MONTEREY SHALE (MIDDLE MIOCENE). 
GENERAL STATEMENT. 
A great series of fine shales, largely of organic origin, overlies con¬ 
formably the coarse and fine sedimentary deposits of the Vaqueros. 
These shales make up the Monterey formation and are probably rep¬ 
resentative of the whole of middle Miocene time. The series is of 
great thickness and is doubly important, as the probable source and 
the present reservoir of the oil. The areal extent of the Monterey is 
not adequately represented on the map. It doubtless covers as one 
continuous sheet the whole basin between the Santa Ynez and San 
Rafael mountains, as well as a large part of these ranges, but it is con¬ 
cealed over considerable areas by later deposits, which are in many 
places very thin. The character, structure, and relations of the Mon¬ 
terey have been the chief subject of the present study. 
The name Monterey was given by William P. Blake a in the early 
fifties to an organic shale formation typically developed near Mon¬ 
terey, in central California. It is very extensive in the California 
Coast Ranges, being the “bituminous shale” described by Whitney 6 
as occurring at widely separated points north and south of the Golden 
Gate. Its age is generally taken as middle Miocene. It is the source 
of much of the petroleum found in California. The shale characteristic 
of this unique formation is not similar to ordinary clay shale, but is 
composed largely of the remains of minute marine organisms. .In an 
oProc. Acad. Nat. Sci. Philadelphia, vol. 7, 1855, pp. 328-331. 
b Geological Survey of California, Geology, vol. 1, 1865, p. 137. 
