[en] Geologic data were collected to evaluate the Brushy Basin Member of the Morrison Formation of Late Jurassic age as a potential source of uranium ore in southeastern Utah and southwestern Colorado. It was found that the member contains tuffaceous sediments that are an adequate source of uranium, mudstones that are favorable uranium host rocks, and reducing agents that favor the precipitation of uranium. Undiscovered uranium deposits in the Brushy Basin Member may be widespread and may represent appreciable potential resources of uranium ore. Most known deposits are in sandstone, but carbonaceous mudstones are more favorable for large deposits. Favorable areas for carbonaceous mudstone uranium deposits include the northern half of the San Rafael Swell and most of the western and northwestern borders of the project area. These locations correlate with the regional pinch-out of the Salt Wash fan and, specifically, with a paucity (<10%) of sandstone in the Brushy Basin Member. Recommended additional work includes an airborne radiometric survey, construction of net-sand maps, and detailed sedimentologic analysis of the Brushy Basin Member