The Hanna and Carbon coal basins of south-central Wyoming became structurally defined during the Laramide Orogeny. The Hanna Basin is unique among depocenters of the Rocky Mountain foreland (within the province of Laramide-style deformation) in its thick sedimentary accumulation (Upper Cretaceous through lower Eocene,> 32,000 ft) relative to its to its short map dimensions (24x40 mi). In comparison with other Wyoming foreland depressions, the Hanna Basin provides an extreme case in terms of rates of basinal subsidence, adjacent contemporaneous uplift, syntectonic deposition, and intervening episodes of major basin-margin erosion. However, temporal constraints on the depositional and structural evolution of the Hanna/Carbon basins are rudimentary. Use of vertebrate fossils linked to described sections of the Ferris and Hanna formations will provide the first detailed determinations of (1) relative age relationships within the thick sequence of uppermost Cretaceous through lower Eocene strata, (2) rates of deposition, and (3) timing and estimates of magnitude of basinal and basin-margin reverse-faulting and adjacent uplift. A temporally controlled series of interpretive geological cross-sections, extending southward into the Hanna Basin from its northerly, adjacent ranges, will be developed following completion of surifical geological description allied with analysis of cobble provenance. Additional important research components of the Hanna/Carbon basin project include (1) paleogeographic and biostratigraphic interpretations of ubiquitous shark teeth collected from Paleocene fluvial sections of the Hanna Formation, and (2) description and interpretation of vertebrate faunal changes across the Mesozoic-Cenozoic boundary. Knowledge derived from various elements of the project will allow, for the first time, quantitative comparisons of the greater Hanna Basin's evolution with other, better understood, Rocky Mountain foreland basins.
