|Fox Hills - Lower Hell Creek, Powder River Basin
Maps of Fox Hills sand-body continuity are not encountered in the literature. However, generalized sand-body continuity can be inferred from maps of percent sand (Lewis and Hotchkiss, 1981) and from the regional facies distribution. The Fox Hills paleoshoreline is interpreted to have prograded from north to south in south-central Wyoming (Van Horn and Shannon, 1989). Sand body geometry in the north part of the Powder River Basin is inferred to be dominated by narrow, dip-elongate, fluvial- and distributary-channel sandstones, where the Fox Hills Sandstone grades into nonmarine deposits of the Lance Formation (Connor, 1991), whereas strike-elongate (east-west-trending), wave-dominated shoreface and delta-front Fox Hills sandstones are inferred to be present in the central part of the basin. These shorezone sandstones pinch out southward into shelf mudstones in the south part of the basin, where percent-sandstone values are commonly less than 50 percent (Lewis and Hotchkiss, 1981).
Connor, C. W., 1991, The Lance Formation—petrography and stratigraphy, Powder River Basin and nearby basins, Wyoming and Montana: U. S. Geological Survey, Bulletin 1917-I, 17p. and 8 plates.
Lewis, B. D., and Hotchkiss, W. R., 1981, Thickness, percent sand, and configuration of shallow hydrogeologic units in the Powder River Basin, Montana and Wyoming: U. S. Geological Survey, Miscellaneous Investigations Series, Map I-1317, 6 sheets.
Van Horn, M. D., and Shannon, L. T., 1989, Hay reservoir field: a submarine fan gas reservoir within the Lewis Shale, Sweetwater County, Wyoming: Wyoming Geological Association, Guidebook to 40th Field Conference, p. 155–180.