STRUCTURE AND CONDITIONS AFFECTING PRESENCE OF OIL. 81 
The conditions along this anticline, especially through the eastern 
half of its length, favor the occurrence of some oil at least, as the 
axis exposes beds fairly high in the formation and the folding is 
gentle. No surface indications of petroleum were found, except a 
patch of burnt shale south of the road about 1 mile southwest of the 
highest hill (elevation 1,300 feet) and local outcrops of bituminous 
black flint and brown shale on the west side of the 800-foot hill about 
hall a mile north of the river and 1 \ miles west of the east edge of the 
Santa Rosa grant. 
MAIN PORTION OF THE SANTA YNEZ RANGE. 
The Santa Ynez Range is composed chiefly of Tejon and Yaqueros 
rocks and its structure is therefore much less important in connec¬ 
tion with the oil deposits than that of the areas underlain by the 
Monterey shale. It is dominated by a great southward-dipping 
monocline that forms a high ridge along the coast, north of which the 
strata are gently folded along curving lines that reflect two different 
structural trends. The folds that expose the Tejon-Yaqueros and 
the underlying Franciscan beneath the Monterey toward the west 
end of the range are in places abrupt and complex. The anticline 
of the Santa Rita Hills has the appearance of crossing the Santa 
Ynez Yalley and continuing in a large fold to the southeast. 
REGION BETWEEN THE SAN RAFAEL AND SANTA YNEZ MOUNTAINS. 
CASMALIA HILLS AND SAN ANTONIO TERRACE. 
Two dominant structural lines control the region of the Casmalia 
Hills and the San Antonio terrace. One is a typical fault starting 
on the coast south of Lions Head and the long area of igneous rocks 
and running southeastward. About 2 miles west of Casmalia the 
lin e is continued by an anticline, which is probably affected b}^ faults 
at least as far as Schumann Canyon. This anticline plunges more 
and more toward the southeast and loses its character as a fold, giv¬ 
ing place to the eastward-dipping monocline of the San Antonio 
terrace. 
The other structure line is one of varying character, represented 
on the map as the Schumann anticline. Northeast of the area of 
igneous rocks that meets the - sea at Lions Head Miocene strata 
form a great monocline, dipping rather steeply to the northeast. In 
the high region of Mount Lospe and northeast of the long strike 
ridges (shown in PI. IX, A, B) that extend southeastward from that 
peak, this monocline flattens out into a structural platform of very 
low dip, which on approaching the edge of the steep descent to the 
Santa Maria Yalley bends over and drops off abruptly. The axis 
along which this steepening of the dip occurs is in a way equivalent 
