88 
SANTA MARTA OIL DISTRICT, CALIFORNIA. 
Zaca Creek-Lisque Creek anticlines, viz, the adjacent anticlines are 
en echelon with each other, each plunging down past the end of its 
neighbor. Graciosa and Harris canyons, particularly the former, 
are the superficial reflection of the syncline between the ends of the 
Mount Solomon and Schumann anticlines, and Solomon Canyon and 
Canada de los Alisos occupy analogous positions between the Mount 
Solomon and Gato Ridge and the Gato Ridge and La Zaca Creek- 
Lisque Creek anticlines, respectively. 
Asphaltum deposits .—Practically the whole top of Graciosa Ridge 
is capped by post-Monterey sandstones and conglomerates, which 
are heavily charged with asphaltum. Asphaltum also occurs as 
veins penetrating the Monterey and post-Monterey beds at the 
east end of the ridge, and a fine example of asphaltum veins and vein- 
lets filling the joint cracks in the Monterey is to be seen beside the 
road leading up to the- Santa Maria Oil and Gas (Squires) well No. 4. 
This occurrence of the asphaltum in the joint cracks of the shale 
gives a clew to the probable channels through which the oil migrated 
from the depths to the surface, and leads to the general conclusion 
that joint cracks are the reservoirs and channels of migration of the 
oil in many of the productive strata of this field. 
Conclusions regarding future development .—It is obvious from a 
glance at the contour map (PI. X, p. 92) and a perusal of the detailed 
description of the developed areas that practically all of the terri¬ 
tory covered by contour lines is productive. The only part of the 
region about which the compiler of the map has any misgivings as to 
productiveness is that occupying a general synclinal position south 
of the great bend in the Mount Solomon anticline. These misgivings 
are partially alleviated, however, by the idea that probably the 
position of the territory in question on the flanks of Graciosa Ridge, 
which is, broadly, a quaquaversal fold or dome, may exert enough 
control on the oil to cause its collection there at least in paying 
quantities, if not in the remarkable measure found in other parts of 
this field. The region adjacent to the southeast end of the axis of 
the Mount Solomon anticline ought to be productive. The beds on 
the northeastern flank dip more steeply than those on the south¬ 
western, and the first productive stratum is thought to be at a lower 
horizon in the shale on the former flank than on the latter, so that it 
is probable that the oil zone will be struck at a greater depth from 
the surface northeast of the anticline than southwest of it. 
GATO RIDGE ANTICLINE. 
Structure .—The Gato Ridge anticline extends from the top of the 
ridge just east of the mouth of Solomon Canyon to a point some¬ 
where near the middle of the triangle formed by Canada de los 
Alisos, Cuaslui Creek, and Foxen Canyon. It follows very closely 
