The Racetrack Hill anticlinal trend, approximately 7 miles east of Bakersfield, Kern County, consists of an area 10 miles long and one mile wide. On it are three oil fields of moderate economic importance--Racetrack Hill, Graham, and Jeppi--that have produced approximately 10,000,000 barrels of high-gravity oil from lower Miocene sands.

The Racetrack Hill anticlinal trend plunges approximately 500 feet per mile southwest which is almost perpendicular to the main structural trends in this part of California. It can be traced in the lower Miocene sediments as far as North Mountain View. Seismic data suggest that it probably extends southwest. The anticlinal structure, limited in general to the lower Miocene sediments, upward becomes less pronounced, and, in one place is displaced by a broad syncline in the younger sediments. Production along it is caused by actual domal closure in the Racetrack Hill oil field. Graham and Jeppi have been caused by cross-faulting in conjunction with nosing. This structure is bounded on the east by a major, possibly pre-middle Miocene fault having maximum vertical displacement of 2,000 fe t.

The lower Miocene in this area is represented by a series of sediments ranging in thickness from 1,500 feet at outcrop to at least 4,000 feet in the vicinity of the North Mountain View area. The Nozu in this area reaches a maximum thickness of more than 400 feet in the Graham area where it consists mostly of a series of very coarse conglomerates. The underlying Freeman is a dark brownish gray siltstone. Beneath this the lower Miocene productive zones occur--the Jewett consisting of a series of siltstones and permeable sands having maximum thickness of 250 feet, the Pyramid Hill sand, a 20-foot ash bed beneath this characterized by a basal grit believed to be the base of the Saucesian stage, and the underlying probably Zemorrian stage sediments that are referred to as Vedder except whe e they grade into the non-marine Walker series. The Walker is non-productive.

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