Named upper member of Coralville Formation (rank raised), 1 of 4 formations of Cedar Valley Group (revised). Name used across most of IA (Iowa shelf). Absent in southeast IA and adjacent parts of northeast MO, west IL. Type locality in Hutchinson Quarry, SE SE NE sec 9, T79N, R6W, Iowa City, Johnson Co, IA. Is 4 m thick at type; ranges 8-17 m across IA. Absent 12 km southeast of type where entire Coralville made up only of Cou Falls Member (new). Characterized by diverse lithology. Includes thin, locally carbonaceous shale, intraclastic, brecciated, or oncolitic limestone, laminated and pelleted calcilutites with birdseye ooids and stylolites, dolomites, dolomitic limestone. Thickest development of gypsum and anhydrite in central IA. Map shows east edge of Iowa City Member and east edge of evaporites in Iowa City. Nomenclature chart; graphic sections. Overlies Gizzard Creek Member (new) of Coralville in northern IA, and Cou Falls Member (new) of Coralville in eastern IA. Disconformably overlain by State Quarry Member (rank reduced) of Lithograph City Formation (new), upper formation of Cedar Valley in east-central IA. Overlies Osage Springs Member (new) of Lithograph City in northern IA. Sparsely fossiliferous (less diverse upwards)--algae, foraminifers, ostracods, gastropods, burrows, favositid corals and/or branching stromatoporoids, brachiopods, crinoids, rostroconchs. Of late Givetian, Middle Devonian age.

Source: GNU records (USGS DDS-6; Denver GNULEX).