Economic uranium deposits occur within tabular, arkosic sandstones of a large Eocene "wet" fan complex known as the Battle Spring Formation in the central Great Divide basin. These "roll-front"-type deposits are located where the fan complex intertongues basinward with finer-grained fluvial, paludal, and lacustrine facies of the Wasatch and Green River Formations.

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Two types of roll-front deposits have been identified: (1) essentially tabular, low-grade, disseminated deposits located along the eastern flank of a large tongue of oxidized sandstones, and (2) narrow, higher-grade C-shaped deposits located along the western flank of the same altered sandstone tongue. These uranium deposits occur at the basinward limit of a large alteration system consisting of a series of oxidation cells that extend from the northern margin of the basin 50 km southward. Behind the roll fronts, alteration is characterized by broad zones of various iron-oxidation colors which merge with mineralization on the east and diverge by as much as 1.5 km from mineralization on the west.

The grade of uranium mineralization and the corresponding alteration characteristics apparently relate to the steepness of the Eh gradient across the roll-front interface. Steeper gradients and consequently higher-grade mineralization in the western part of the area are related to the greater abundance of carbonaceous material in intertonguing Wasatch mudstones. Alteration patterns have become somewhat obscured in this western area owing to probable re-reduction of altered sandstones.

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