The Trapper Canyon Tar Sand Deposit is located in the eastern Bighorn Basin, approximately 25 miles east of Greybull, Wyoming. This project not only involved detailed geologic mapping of the Trapper Canyon Tar Sand Deposit, but also sampling and describing the tar zone as well as the bounding barren zones. Samples were analyzed for porosity, permeability, oil saturation, and characteristics of the oil. Thin sections from both the tar zone and barren zones were made and examined to determine textural characteristics and kinds of pore-filling cements. In addition, samples were analyzed using the scanning electron microscope to gain insight into the diagenesis of the reservoir rock and trapping mechanisms. The Trapper Canyon Tar Sand Deposit was investigated because it was considered potentially commercial, and the results of the study could aid in forming an economical plan of development for this deposit and similar deposits elsewhere in the State. Also, the area provided an excellent opportunity to examine surface exposures of a tar sand deposit. The final phase of the study involved mapping the Bush Butte quadrangle and looking for additional tar sand deposits in the quadrangle. The search for additional deposits was carried out based on a model developed by examination of the Trapper Canyon Deposit. 16 references, 14 figures, 3 tables.