SANTA CLARA VALLEY : SESPE FIELDS. 
51 
SESPE FIELDS. 
LOCATION. 
The Sespe fields include that portion of the territory north of the 
Santa Clara Valley which lies adjacent to Sespe Creek in the lower 
8 or 10 miles of its course, together with the area about Little Sespe, 
Fourfork, Tar, and Bear creeks and Pine and Coldwater canyons—all 
in the Sespe drainage system. 
STRUCTURE. 
In the Sespe district the formations begin to show crumpling, at 
first gentle, then severe, at the northern border of the Camulos quad¬ 
rangle. The axis of the general fold lies just outside the quadrangle, 
while south of the fold is the edge of the broad table of Sespe red beds. 
(See PI. Ill, sec. X-Zb) In the country adjacent to the table of red 
beds on the south lies the axis of the Coldwater anticline, the lowest 
beds exposed being those at the base of the Sespe formation. The 
eastward extension of this anticline is somewhat uncertain, but it 
may prove to be continuous with or closely adj acent to the Ivers anti¬ 
cline, the axis of which is the seat of the Ivers oil wells. Both disap¬ 
pear in the folds at the gorge of Little Sespe Creek. South of the 
Coldwater anticline, confined to the narrow ridge between Coldwater 
and Pine canyons, is a sharply compressed syncline. This is nearly in 
line and may be continuous with the syncline that farther east passes 
through Oat Mountain and becomes one of the principal structural 
features of the region. In Pine Canyon, at the base of the ridge carry¬ 
ing the syncline above mentioned, the Topatopa formation reappears 
from beneath the Sespe beds and with northerly dip constitutes San 
Cayetano Mountain and Santa Paula Peak and the general mountain 
mass of which they are such conspicuous features. The structure of 
this mountain mass is monoclinal, developed, doubtless by faulting, 
from an overturned anticline whose arch could have been but little 
less than that of the main Topatopa fold farther north. The southern 
face of the monocline is a bold escarpment of 2,000 feet, in which the 
strata still show remnants of the arch. The displacement at this 
fault is probably 3,000 or 4,000 feet. 
East of Sespe Creek the more important subordinate folds on the 
flanks of the main flexure include the Oat Mountain syncline, already 
referred to; an anticline that crosses lower Pole Canyon at the sharp 
turn from south to west; and another anticline, a mile farther south, 
that passes into the valley of Sespe Creek immediately below the 
entrance of Pole Canyon. Each of these folds is a conspicuous fea¬ 
ture, but the s}mcline is perhaps the most marked, involving the strata 
from the Modelo to the red beds of the Sespe. In addition to these 
