The West Mountain oil pool is a part of the South Mountain oil field and is the most westerly dome on the anticlinal Oak Ridge uplift in Ventura County, California. Normal faulting separates this fold into three blocks, each with different productive capacities. The oldest beds outcropping on the structure are of Oligocene (?) Sespe age. Drilling has penetrated this formation which is divisible into an upper and lower part on the basis of lithology. Saturation is confined to bottom conglomeratic portion of the "upper" division and the upper 1,500 feet of the "lower" division. A peculiarity of this "lower" division is the lenticular nature of the strata and their reaction to the waters normally used in the drilling muds. The Eocene beds have been penetrated, but the contac lacks sufficient lithological or foraminiferal character to determine the exact point of contact. Sands within this gradational zone show some saturation, but are as yet untested. At present, 27 wells drilled in this pool have proved at least 325 acres and have produced to date over 425,000 barrels of oil.

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