Pg. 14-18, 43-44 (table VIII), pl. 1. Crow Creek zone. Sand and marl (chalk) zone at base of Sully member (new) of Pierre formation. Thickness about 6 feet. Name replaces term Gregory marl (chalk) of Searight (1938, 1939). Correlates with the upper of two calcareous zones in the Gregory County section rather than the lower zone which is the marl (chalk) at base of Gregory member. Lies below the Oacoma and Agency zones in Sully member; overlies Gregory member of Pierre formation. [Age is Late Cretaceous.]
Named from characteristic exposures at and south of mouth of Crow Creek, [between Missouri River and Bedashosha Lake], in secs. 23 and [24], T. 106 N., R. 71 W., [Bedashosha Lake 7.5-min quadrangle], southwestern Buffalo Co., [Crow Creek Indian Reservation], central SD.

Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 993).

Pg. 2340 (table 10), 2341, 2343. Crow Creek member of Pierre shale. Rank raised to member of Pierre shale. Defined to include sandstone and calcareous shale and marl beds lying between noncalcareous shales of Gregory member below and DeGrey member (new) above, both of Pierre shale. Thickness ranges from a few feet to 15 feet. Type locality designated. [Age is Late Cretaceous.]
Type locality: at and south of mouth of Crow Creek, [between Missouri River and Bedashosha Lake], in secs. 23 and [24], T. 106 N., R. 71 W., [Bedashosha Lake 7.5-min quadrangle], southwestern Buffalo Co., [Crow Creek Indian Reservation], central SD.

Source: US geologic names lexicon (USGS Bull. 1200, p. 993).

Member of Pierre shale, central SD and northeastern NE in Williston and Salina basins. Shows ammonite zonation and correlation with other stratigraphic units in the Western Interior region. Late Cretaceous (Campanian) in age.

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

A grain-size distribution study of the basal siltstone of Crow Creek member of Pierre shale along the Missouri River trench in SD suggests that the detrital mineral grains in it were derived from the east. The influx of calcium carbonate contemporaneous with the first appearance of siltstone and the foreset bedding of the siltstone suggest that deposition of [underlying] Gregory member of Pierre was interrupted by uplift of the sea bottom in central and south-central SD. It is proposed that an area in the east-central part of SD that corresponds in general with the outcrop area of Sioux quartzite was uplifted at the same time. Reworking of sediments that previously had been deposited over this area provided the coarser material that forms the basal siltstone of Crow Creek member. [Of Late Cretaceous age.]

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