Analysis of geologic cross sections and isopach maps of the Parachute Creek Member of the Green River Formation indicates that a 500-foot thick oil shale section, averaging 25 gallons of oil per ton and having 800 to 1,000 feet overburden, exists at three sites in the northwestern part of the Piceance Creek Basin, Colorado. These three sites are located in sec. 11, T. 1 S., R. 99 W., sec. 35, T. 1 S., R. 99 W., and sec. 12, T. 2 S., R. 99 W. These sites meet the initial geologic requirements as stated by the AEC for a Plowshare in situ nuclear experiment for recovering oil from oil shale.