12 SANTA MARIA OIL DISTRICT, CALIFORNIA. 
The present writers are in agreement with these statements except 
as regards the exclusively Miocene age of The rocks, a large part of 
which are here considered as Eocene. On page 505 of Fairbanks’s 
article he speaks of “ shales and sandstones of undoubted Cretaceous 
age” between Gaviota Pass and Santa Ynez River, in the hills which 
in the present paper are considered as part of the Santa Ynez Range. 
In the very short time spent in this locality the present writers 
found no evidence of the presence of Cretaceous rocks. 
A number of asphalt deposits in northern Santa Barbara County 
are described on pages 30 to 33 of the twelfth annual report of the 
State mineralogist, cited above. The localities mentioned are on 
the Los Alamos grant, 41 miles north of Harris station; along the 
northern slope of the hills bordering the Santa Maria Valley, 10 miles 
southeast of Santa Maria; about 2 miles northeast of the Purisima 
Mission; along the southern slope of the hills between the Los Ala¬ 
mos and Santa Ynez valleys (Purisima Hills), especially on the San 
Carlos de Jonata grant; and in poorer and less known deposits at 
Gaviota Landing, at Point Arguello, near the mouth of Canada 
Honda, and at other points toward Lompoc Landing. Seepages 
out of the bituminous u slate” (shale) series are mentioned as occur¬ 
ring in the canyon of the Sisquoc, about in the center of the Sisquoc 
grant, along Labrea Creek, and near the west end of the Tinaquaic 
grant. 
By far the best observations recorded up to 1896 regarding the 
geology of this region were those of H* W. Fairbanks, published in 
his paper on the u Geology of Point Sal.” a He gives a detailed de¬ 
scription of the igneous and sedimentary formations occurring at 
the seaward end of the hills, termed in the present report the Cas- 
malia Hills. In speaking of the even summit line of the Point Sal Ridge 
he says: 
The regularity is due, in part at least, to the fact that the strata on the summit are 
nearly flat and composed of the resistant Miocene flints, while on the southern slope 
the bituminous shales are followed in descending order by a great thickness of gypsif¬ 
erous clays, in which broad valleys have been eroded. Lower down toward the 
ocean the clays are replaced by strata of volcanic ash, sandstone, and conglomerate, 
in which, because of their greater resistance, canyons have been eroded. The strata 
of volcanic ash form very striking features in the landscape on the lower slopes of the 
ridge; being interbedded with soft clays they weather out in cliffs and projecting 
ridges. 
In outlining the geology of the region of Point Sal Ridge, Fair¬ 
banks says: 
The region about the point itself has been the scene of many violent disturbances 
and repeated eruptions of basic magmas. A part of these consolidated as surface 
flows, while others have the characters of deep-seated rocks. 
The sedimentary strata comprise only the Pleistocene, Miocene, and Knoxville. 
* * * The Miocene is the most extensive formation represented. * * * It is 
a Bull. Dept. Geology Univ. California, vol. 2, No. 1, 1896, pp. 1-92. 
