associated with the regression that is first reflected in the increase in land-derived sediment in the upper part of the Fairport. Pelagic and benthonic faunal elements indicate water of normal or nearly normal salinity but the sparse benthos suggests turbid water and soft mud bottom that was largely inhospitable to bottom-dwelling forms. Rare small-scale oscillation ripple marks and gentle cross-laminations in siltstone, and local fish-tooth conglomerate, all in the upper part of the member, manifest shallower water during deposition of that part of the member. Blue Hill macroinvertebrates that range upward from the Fairport include Inoceramus cuvieri, I. latus, and Ostrea congesa. Of these, only Inoceramus latus ranges higher than the middle part of the Blue Hill. The bottom fauna also includes Inoceramus flaccidus White, Lucina juvenis Stanton, two species of Yoldia, five species of gastropods, a crab, and a lobster. Ammonites include Collignoniceras hyatti (Stanton), Proplacenticeras pseudo- placenta (Hyatt), Scaphites carlilensis Morrow, and Binneyites aplatus (Morrow) (rare). Forms ranging virtually throughout the Blue Hill and therefore characteristic of the member include C. hyatti and S. carlilensis. Codell Sandstone Member.- In the field-trip area the Codell ranges from 5.7 to 31 feet but over much of northern Kansas is less than 1 foot thick and is not recognized locally in the southern part of the west-central Kansas outcrop. The member is gradational vertically and laterally with upper beds of the Blue Hill. The Codell consists mostly of well-sorted fine quartzose sand and coarse quartzose silt and contains small quantities of feldspar and a limited suite of stable heavy minerals. Silty shale occurs in the Codell in some sections, including that at Stop 10. The unit is only locally cross-bedded but is extensively burrowed in some places. Fossils are poorly preserved and rare in west-central Kansas, consisting of a few shark teeth, clam molds and a small foraminiferal assemblage dominated by arenaceous species. Codell sediments indicate approach to the central Kansas area of the eastern shore- line of the Western Interior Sea which was regressing during deposition of the Carlile Shale. Figure 4.- Common macroinvertebrate fossils in Carlile and Niobrara Formations. (1) Scaphites carlilensis Morrow, Blue Hill Shale Member of Carlile, Xl; (2) Ostrea congesa Conrad, Smoky Hill Chalk Member of Niobrara, Xl (similar forms occur in Jetmore Chalk Member and Pfeifer Shale Member of Greenhorn, Fairport Chalk Member and Blue Hill Shale Member of Carlile, and Fort Hays Limestone Member of Niobrara); (3) Collignoniceras woolgari (Mantell), Fairport Chalk Member of Carlile, Xl; (4) Collignoniceras hyatti (Stanton), Blue Hill Shale Member of Carlile, X2/3; (5) Inoceramus latus Sowerby (juvenile), Fairport Chalk Member of Carlile, X2 (also occurs in Blue Hill Shale Member of Carlile); (6) Inoceramus cuvieri Sowerby, Fairport Chalk Member of Carlile, Xl (also occurs in Pfeifer Shale Member of Greenhorn and possibly in lower part of Blue Hill Shale Member of Carlile); (7) Inoceramus flaccidus White, Blue Hill Shale Member of Carlile, Xl. 18