In general, 2 prerequisites are necessary for commercial Tertiary production in the Sand Wash and Washakie basins. First, favorable structure must be present with little or no faulting. Second, an advantageous facies must occur over the structural feature. One of the problems confronting workers in regional studies of the productive Tertiary formations in the Sand Wash and Washakie basins is the uncertainty of formation boundaries. Other problems which must be recognized are the different sources of clastic material involving similar or different rock types, mixed environments of deposition, and the role of unconformities. Detailed stratigraphic field studies supported by palynology have delineated the Tertiary formation boundaries in the Hiawatha and Powder Wash areas. Once the limits of the formation boundaries were established and correlated between Hiawatha and Powder Wash, certain trends related to facies were noted. These trends were extended to establish Tertiary correlations between other parts of the Sand Wash Basin and the Washakie Basin.