60 OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
At the time of the writer’s visit to the locality in 1902 it was im¬ 
possible to learn the precise depth of the several wells or whether the 
source of the oil was the same in all. The position of certain wells 
on strata following the inner curve, and of others on higher strata 
following an outer curve, taken in conjunction with the actual differ¬ 
ence in elevation of about 300 feet, would indicate that possibly the 
oil zone is of considerable breadth and thickness. 
FOURFORK WELLS. 
The Fourfork wells, 15 in number, are located along one of the 
main branches of Fourfork Creek, a tributary of Little Sespe Creek. 
Fig. 8.—Sketch map showing location of the Fourfork group of wells on Fourfork Creek with relation 
to the base of the upper purple beds. Circles, wells productive in 1902. Figures indicate numbers 
of wells or dip of strata. 
They are but a little west of the divide between this stream and Tar 
Creek. The altitude of their collars varies from about 2,200 to 2,700 
feet above sea level. Their depth is between 1,200 and 1,800 feet, 
in rocks which strike in general about N. 50° E. and dip 35°-45° SE. 
The strike is, however, but a part of the broad curve which is assumed 
by the strata in their passage about the east end of the Topatopa 
anticline. Stratigraphy and structure are both regular in the vicinity 
of the wells, a complete absence of the minor flexures which form so 
common a feature in other portions of the adjacent mountains being 
noteworthy. It will be recalled that the succession of strata in this 
vicinity, from the base upward, is the red beds and rusty beds, both 
regarded as Sespe; the purple shale, gray shale, and upper purple or 
