In 1965 the Bureau of Mines with the assistance of cooperation of the Atomic Energy Commission drilled an exploratory corehole in Piceance Creek Basin, Colo., to evaluate buried oil shales that might be amenable to fracturing by a nuclear explosive and subsequenty recovery of oil by underground retorting. Preliminary results indicate continuous oil shales occurred at depths of 985 ft to the bottom of the hole at 2,600 ft and may extend another 600 ft below the sampled interval. Present plans are to deepen the hole and take boroscopic photographs of an interval exhibiting poor core recovery. A second hole will be drilled at another site in the basin to locate thinner oil-shale beds under less overburden that may be more suitable for the proposed underground tests.