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basalt of late Tertiary age. The Wasatch formation does not outcrop on the property. However, it must' be crossed by every access road reaching the area from any direction except north. The Wasatch formation is of continental origin and comprises silt- stones with .a high percentage of clay and sandstones. It underlies the oil shale formation throughout the basin. The main oil shale section is contained in the Green River formation which is comprised of three units, the Douglas Creek member, the Garden Gulch member, and the Parachute Creek member containing the oil shale, and overlain by the sands of the Uinta formation. The Douglas Creek member is formed of cross-bedded ripple-marked sandstone with some limestone and shale. It forms a prominent outcrop in Logan Wash. The Garden Gulch member overlies the Douglas Creek member and underlies the Parachute Creek member. The predominant rock type is papery shale. Barren marlstone is also common along with some oolitic algal limestone and very minor oil shale. The Garden Gulch member forms prominent gray sloping outcrops that can be confused with the overlying Parachute Creek member from a distance. The principal difference between the two members is the lack of carbonate in the Garden Gulch member compared with the Parachute Creek member which is predominantly carbonate. The Parachute Creek member is comprised of shale and marlstone and is the oil shale producing unit in the Piceance Basin. Donnell (1951) divides the Para- chute Creek member into three zones; the upper oil shale zone, a middle barren zone, and a "middle and lower oil shale zones" comprising, in essence, a lower zone. The highest grade oil shale is in the"Mahogany Ledge" in the lower part of the upper high-grade zone, and is approximately 90 ft. thick. It is underlain by Ex. D - 3