Pg. 2340 (table 1), 2341, 2343, 2345-2346. DeGrey member of Pierre shale. Defined to include Agency-Oacoma zones of previous reports. Consists of clay, shale, and bentonite beds. Underlies Verendrye member (new); overlies Crow Creek member (new); contacts gradational. Thickness at type locality about 82 feet; thickness increases toward Pierre to about 160 feet and decreases toward Chamberlain to about 40 feet. Age is Late Cretaceous.
Type locality: west edge of NW/4, sec. 8, T. 109 N., R. 75 W., Hughes Co., central SD. Named from DeGrey Post Office and store. Type section is 2 mi southeast of DeGrey in cut-bank of Missouri River.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1075).

Member of Pierre shale, central and west-central SD and northeastern NE in Williston and Salina basins. Also called DeGrey shale member. Shows ammonite zonation and correlation with named and unnamed units in the Western Interior region. Late Cretaceous (Campanian) in age.

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

Extended name into eastern ND in Williston basin for a member of Pierre Shale. In Cheyenne River Valley, Barnes Co, ND consists of dark, flaky bentonitic shale weathering to a dark gumbo bare of vegetation; black-weathering concretions of iron-manganese are abundant; at least 40 ft thick. Thins and becomes lighter in color northward. Is 29.5 ft thick in a reference section for Pierre Shale (Pembina Mountain section) measured in secs 24 and 25, T161N, R57W, Cavalier Co, ND. Rests conformably on Gregory Member of Pierre and is conformably overlain by Odanah Member of Pierre. Lists fossils collected 9 mi south of Valley City, Barnes Co, ND. Shows ammonite zonation. Probably correlates with both the DeGrey and underlying Crow Creek Members of Pierre Shale in the Missouri River Valley, SD.

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

DeGrey Member of Pierre Shale. Samples collected from:
(1) a 15-cm-thick bentonite bed within the DIDYMOCERAS NEBRASCENSE ammonite zone, 8 m above base of DeGrey Member of Pierre Shale, in NW/4 NE/4 sec. 24, T. 161 N., R. 57 W., Cavalier Co., ND (Williston basin). K-Ar age on biotite 72.2 Ma (weighted mean). Age is Late Cretaceous (Campanian).
(2) a 6-cm-thick bentonite bed within the D. NEBRASCENSE ammonite zone, 16.5 m below top of DeGrey Member of Pierre Shale, in NW/4 sec. 26, T. 108 N., R. 76 W., Lyman Co., SD (Sioux uplift). K-Ar age on biotite 72.2 Ma (weighted mean). Age is Late Cretaceous (Campanian).

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