The Trapper Canyon Deposit (Battle Creek Deposit in US Bureau of Mines Monograph 12) is located on the western flank of the Bighorn Mountains approximately 30 mi (48 km) east of Greybull, Wyoming. The petroleum occurs in the upper eolian sequence of the Pennsylvanian Tensleep Sandstone which dips from 5/sup 0/ to 8/sup 0/ to the southwest. The deposit was initially reported by N.H. Darton in US Geological Survey Professional Paper 51 in 1906. A characterization study was made on the deposit which included mapping the deposit and surrounding area, measuring three stratigraphic sections in the Tensleep Sandstone, and sampling 13 outcrop localities. Thickness of the deposit ranged from 0 to 22.5 ft (6.8 m) in the 13 sample localities. Preliminary analyses of outcrop samples indicate API gravities and viscosities consistent with the definition of a tar sand. Oil properties are similar to those published for Phosphoria-sourced oils produced from the Tensleep Sandstone in fields to the west. Lateral pinch-out of the deposit, tight characteristics of upper and lower bounding units, and the lack of any apparent structural controls in the area, are all evidence for a stratigraphic trapping mechanism. Recoverable reserves are estimated at 1.96 million bbl over a 67-acre (27 ha) area.