The Eudora Shale member of the Stanton Formation near the bottom of this section is the offshore sequence of the Stanton cyclothem. Thd Dyson Hollow bed marks the beginning of a marine regression and the Kiewitz Shale bed above shows a short pulse of deepening of the sea. It is in the Kiewitz in which greatest abundance and diversity of invertebrate fossils has been found in this cyclothem. Most of the invertebrates found in the Kiewitz Shale bed are small and have thin, unornamented shells that indicate deep, cold water. The regressive sequence is shown by the Stoner Limestone member of the Stanton Formation. The Rock Lake Formation is a red bed that is mostly a continental deposit that shows weathering and soil development. A new cyclothem begins near the top of the the Rock Lake where a sparse marine invertebrate fauna has been observed just below the Little Kaw Limestone member of the South Bend Formation. The Little Kaw is the transgressive limestone of this new cyclothem and the Gretna Shale is the offshore unit. At the very top of the section, the base of a limestone bed, the Kitaki member of the South Bend Formation can be observed. The Kitaki is the regressive limestone of this cycle. This section is the type section of the Gretna Shale member of the South Bend Formation, the Gretna having been named by Pabian and Strimple (1993). This exposure is situated at Schramm Park.

Echinoderms - Crinoids

The Kiewitz Shale bed is a localized unit that is exposed in a fairly small area along the lower Platte River Valley in southeastern Nebraska. The Kiewitz Shale bed is an off shore shale, one that was deposited in fairly deep, cold, poorly-oxygenated water according to the cyclothemic model of Heckel. Pabian and Strimple (1970, 1985) suggested that there were two kinds of crinoid assemblages in Nebraska. Deep, cold water assemblages were characterized by having smaller crinoids with thin, unornamented plates. Warm, shallow water assemblages were characterized by having larger crinoids with thick, ornamented plates. Heckel and Pabian (1981) demonstrated the compatibility of crinoids faunas with cyclic deposition models. Holterhoff (1988) carried this work on farther and demonstrated that crinoid assemblages from cold, deep, poorly-oxygenated water not only were smaller and had thinner plates but that they also had simpler arm structures and filtration fans for gathering food particles. The crinoids illustrated here have been collected over about a 50 year time span by W. D. "Ted" White, Roger Pabian, Bill Rushlau, and Pete Holterhoff.