Evidence for Eolian Origin of Cross-Stratification in Sandstone of the Casper Formation, Southernmost Laramie Basin, Wyoming

Synthesis of late Paleozoic and Mesozoic eolian deposits of the Western Interior of the United States

“…Pennsylvanian eolian deposition is widespread and has been documented from the lower Casper Formation (Steidtmann, 1974), lower Tensleep Sandstone (Mankiewicz and Steidtmann, 1979;Kerr, this volume) and Quadrant Sandstone (Saperstone and Ethridge, 1984) in Wyoming and adjacent Montana and Colorado, in the lower Weber Sandstone of Utah, Wyoming and Colorado (Bissell and Childs, 1958;Driese and Dott, 1984), and from the Honaker Trail Formation of the Hermosa Group of southeastern Utah (Loope, 1984). In addition, eolian sandstone is present in the Manakacha and Wescogame Formations of the Supai Group in northern Arizona but has yet to be documented in the literature.…”

“…Figure 7A, B and C shows the Tensleep and related units in cross-section. Although the unit is renowned for exposures of large-scale, high-angle sand-flow strata that dip to the south and southeast (Steidtmann, 1974;Mankiewicz and Steidtmann, 1979), detailed sedimentologic studies have documented a broad variety of eolian stratification styles including small-scale trough and planar-tabular wind-ripple cross strata, horizontal to gently inclined wind-ripple strata, and wet and dry interdune deposits (Mankiewicz and Steidtmann, 1979;Driese and Dott, 1984;Saperstone and Ethridge, 1984;Kerr, this volume;J. Haslett, pets.…”

“…Eolian deposits have been documented in the Esplanade Sandstone (Blakey, unpublished data), Queantoweap Sandstone (Johansen, 1981), Cedar Mesa Sandstone and Elephant Canyon Formation (Loope, 1984), upper Weber Sandstone (Bissell and Childs, 1958), upper Casper Formation (Steidtmann, 1974), and upper Minnelusa Formation (Fryberger, 1984). These units likely once formed a single continuous sandstone body, which probably formed by the amalgamation of numerous ergs and dune fields.…”

“…7A and B), the erg thins from 100 m in thickness along the northnorthwest-trending Lusk embayment to an irregular-trending erosional edge across central Wyoming. Steidtmann (1974) has described the eolian characteristics and the relations with thin marine carbonates in the southern portion of the erg deposits; Fryberger (1984) has documented transgressive-regressive events and eolian, sabkha and marine relations for the northern portion of the area. Agatston (1954) provided the stratigraphic framework that documents the facies change to Wolfcampian marine carbonates and clastics (upper Minnelusa Formation and related rocks) along the western margin of the Lusk embayment.…”

“…The Casper Sandstone formed as a coastal and inland sand sea adjacent to marine deposits of the Lusk embayment and north of the Ancestral Rockies. Episodic changes in sea level caused the interdigitation of marine and eolian deposits across much of east-central Wyoming (Steidtmann, 1974;Fryberger, 1984). In the Laramie-Fort Collins area, narrow facies belts and abrupt facies changes reflect the complex interactions between uplift to the southwest, coastal dunes, and marine transgressive-regressive events to the east (Steidtmann, 1974).…”