SANTA CLARA VALLEY: SESPE FORMATION. 
7 
DISTRIBUTION. 
The Topatopa formation occupies the heart of one of the greatest 
anticlines of southern California. The eastern limit of the formation 
is the eastern wall of Sespe Canyon. Westward it extends to a point 
far beyond the Ojai Ahalley—indeed, beyond Santa Barbara, a distance 
of at least 50 or 60 miles. Besides the area thus occupied there is pos¬ 
sibly a small inlier in the heart of the Coldwater anticline (see p. 8), 
although the distance beneath the lower members of the Sespe forma¬ 
tion is but slight. San Cayetano Mountain is also composed of this 
formation. 
AGE. 
Characteristic Eocene fossils have been obtained from the upper 
part of the Topatopa formation in the region north of the Silver 
Thread field. With the exception of the granite and gneisses pre¬ 
viously described, no rocks older than the Topatopa are exposed in 
the Santa Clara district. 
OCCURRENCE OF OIL. 
The Topatopa formation is oil bearing at several horizons, and from 
it come seepages and sulphur springs. While these have been observed 
more particularly from the upper portion, they are also reported from 
the lowest beds exposed at the heart of the anticline. 
SESPE FORMATION* 
GENERAL CHARACTER. 
The term Sespe has been employed a to designate a prominent and 
widely distributed mass of brownish-red sandstones and conglomer¬ 
ates, with minor layers of sandy and muddy shales, in all about 3,500 
feet thick. With these are included 400 or 500 feet of white sand¬ 
stone and greenish shale at the base and an equal amount of rust-col¬ 
ored calcareous sandstone at the top. The entire formation is exposed 
in a continuous section in the gorge of Sespe Creek near the entrance 
of Tar Creek and in the region which extends eastward between the 
waters of Tar and Little Sespe creeks. Throughout the formation the 
materials, whether fine or in the form of pebbles, are chiefly granitic. 
The coloring of the beds is in the main due to iron, but the pink feld¬ 
spar adds to the effect. 
a Waits, W. L., Bull. California State Mining Bureau, No. 11, 1897, pp. 25-2G. 
