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Show 120 when they extended the Morrison Formation (O'Sullivan, 1984a and Peterson gypsiferous sandstones within the and Hunt et al. in the McKnight (1940) as Recapture (1953) noted that gypsum is Henry Mountains in recognized and Turner, southern Utah. onto the western 1998). Gregory (1938) described Shale Member of the Morrison Formation, in the lower half of the formation common Although some of the beds included in the Summerville Formation east of the Green River Tidwell Member sediments bedded gypsum forms a at the by are now (O'Sullivan, 1984a), he also observed that significant component of the between the Green River and the San Rafael Swell, unconformity Colorado Plateau lower Morrison Formation occurring between an angular top of the Summerville Formation and the main body of the Salt Wash Member sandstones. Lupton (1914) originally to conglomeratic Utah in the study area of this report. unconformity at the the USGS stratigraphy, originally described described by Gilluly lithologies gray coarse-grained near Green River, include gypsum in his Salt Wash Member, he also did not base of the Salt Wash Member (Peterson, and Reeside now occurs 5 to 30 m above the or recognize 1988). According the base of the Salt Wash Member in east-central Utah to as angular unconformity (1928) and Gil1uly (1929) (O'Sullivan, 1984a); these included in the Tidwell Member of the Morrison Formation 1984a and Peterson, The J-5 Although Lupton did not by Lupton (1914) intervening strata are (O'Sullivan, as sandstone beds in the upper "McElmo Formation" mudstone and siltstone an defined the Salt Wash Member unconformity cuts Swell east to western Colorado 1988). across progressively older strata from the (0' Sullivan, 1984a). San Rafael In the San Rafael Swell, the |
