LATE CRETACEOUS AND EARLY TERTIARY STRATIGRAPHY AND PALYNOLOGY, HOBACK RIVER BASIN, WESTERN WYOMING

Pollen samples collected in the Hoback River basin yield Eocene, Paleocene, and Late Cretaceous dates. These dates, especially the Late Cretaceous ones, have helped redefine the stratigraphy in this area. Previously mapped Paleocene parts of the Hoback Formation can now be assigned to Upper Cretaceous Harebell Formation, Mesaverde Formation, and lenticular sandstone and shale sequence. The pollen data also confirm structural reinterpretations. Previous maps show an anticlinal fold in the Hoback Formation, which parallels the Cliff Creek thrust. The Game Hill fault has been mapped, and places Cretaceous rocks against a middle Paleocene slice of the Hoback Formation. This slice lies between the Cliff Creek thrust and Game Hill fault. Evidence suggests the Game Hill fault predates the Cliff Creek thrust. In addition to aiding structural and stratigraphic refinements in this area, the pollen samples allow comparison between early Tertiary invertebrate, vertebrate, and palynologic dates derived from identical sites.