This report contains material presented at the Uranium Leach Conference, which was held in Vail, Colo., August 25-27, 1976. The purpose of the presentation was to summarize some important geological concepts to a largely nongeological audience involved in the in situ extraction of uranium from buried uranium ore deposits. The major geological feature affecting the leaching of sandstone-type deposits is permeability. Important permeability variations may be caused by sedimentary structures, texture, structure, composition, and lithology. The effects of these features on leaching uranium are discussed. The major uranium districts of the U.S. and the various factors that would affect permeability and, consequently, uranium extraction in these districts are also discussed.