From abstract: Uranium deposits and radioactivity anomalies have been found in the eastern half of the area underlain by the Browns Park formation in northwestern Colorado, south-central Wyoming, and northeastern Utah. The deposits are in eolian, lacustrine, and fluvial sandstones, tuffaceous sandstones, and limestones all of which were deposited on two converging pediments during Miocene time. At least one eastern and one western facies of lacustrine and fluvial sedimentary rocks are separated by a belt of eolian sandstones. The faces may be distinguished in the field and by petrographic and heavy-mineral studies in the laboratory.