Geologic Unit: Pierre

Usage:

Pierre Shale (CO*,KS*,MN,NE*,NM*,ND*,SD*,WY*)
Pierre Shale of Montana Group (KS,MT*,ND,SD)
Called Fort Pierre a very long time ago.

Subunits:

(alphabetical): Apache Creek Sandstone Member (CO*), Ardmore Bentonite Beds (MT,NE), Beecher Island Member (CO*,KS*), Carter Sandstone Member (CO*), Crow Creek Member (NE,SD*), DeGrey Member (ND*,SD*), Elk Butte Member (NE*,ND*,SD*), Gammon Member (NE*,SD*) or /Gammon Ferruginous Member (CO*,MT*,WY*), Gregory Member (NE*,ND*,SD*), Gunsight Pass Member (CO*), Hygiene Sandstone Member (CO*,WY*), Lake Creek Member (KS*), /Kara Bentonitic Member (WY*), Kremmling Sandstone Member (CO*), Larimer Sandstone Member (CO*,WY*), Mitten Member (CO*,MT*,SD*), Mobridge Member (NE*,ND*,SD*), /Monument Hill Bentonitic Member (MT*,SD*,WY*), Muddy Buttes Sandstone Member (CO*), Oacoma Member (SD), Odanah Member (ND*,SD*), Pembina Member (ND*), Red Bird Silty Member (MT*,SD*,WY*), Richard Sandstone Member (CO*,WY*), Rocky Ridge Sandstone Member (CO*,WY*), Salt Grass Member (KS*), Sharon Springs Member (CO*,KS*,MT*,NE*,SD*,WY*), Sully Member (SD), Terry Sandstone Member (CO*), Virgin Creek Member (ND*,SD*), Verendrye Member (NE,ND*,SD*), Wesken Member (KS*).

Geologic age:

Late Cretaceous (Campanian to Maastrichtian)*

Type section, locality, area and/or origin of name:

Named by Meek and Hayden (1862) from exposures at old Fort Pierre, in either Stanley or Hughes Co., SD. The exact location of the old fort is not known (US geologic names lexicon, USGS Bull. 896, p. 1657).
Fort Pierre No. 1 (est. 1832): once located along western bank of Missouri River, Lat. 44 deg. 23 min. 16 sec. N., Long. 100 deg. 22 min. 58 sec. W., Oahe Dam 7.5-min quadrangle, Stanley Co., SD (US Board Geog. Names citing Hist. Comm. Brown Co. Mus. and Hist. Soc., 1980, Brown Co. Hist., Aberdeen, SD, North Plains Press, p. 246).
Fort Pierre No. 2 (est. 1859): once located along western bank of Missouri River (north of No. 1), Lat. 44 deg. 25 min. 22 sec. N., Long. 100 deg. 23 min. 10 sec. W., Oahe Dam 7.5-min quadrangle, Stanley Co., SD (US Board Geog. Names citing R.H. Mattison, 1962, South Dakota Hist. Collns., v. 31, p. 246).
See also Vereingte Staaten von Nord Amerika, 1879. Map of forts, rivers, settlements in Dakota. Available online from the South Dakota State Archives (http://www.sdhistory.org/arc/military/Forts/fort_pierre.htm).
Reference sections (incomplete; Gill and Cobban, 1965):
(1) measured in roadcuts along State Highway 46 near Little Yellowstone Park, about 20 mi south of Valley City, in sec. 31, T. 137 N., R. 57 W., and in secs. 35 and 36, T. 137 N., R. 58 W., Barnes Co., ND;
(2) measured in roadcut 0.5 mi north of North Valley City, in NE/4 sec. 9, T. 140 N., R. 58 W., Barnes Co., ND;
(3) measured on Olson Farm, in NE/4 sec. 25, T. 161 N., R. 57 W., and at spillway cut for Tongue River retention dam T-3-5, in SE/4 NE/4 sec. 24, and along State Highway 5, in NW/4 NE/4 sec. 24, T. 161 N., R. 57 W., Cavalier Co., ND;
(4) measured in roadcut west of Pembina River, in SW/4 sec. 30, T. 163 N., R. 57 W., Cavalier Co., ND.
Reference section (Gill and Cobban, 1966): in northern Great Plains, 1.5 to 2.5 mi northeast of Red Bird store, and 1 to 2.5 mi east of U.S. Highway 85, in secs. 13, 14, 23, and 24, T. 38 N., R. 62 W., Niobrara Co., WY.

AAPG geologic province:

Anadarko basin
Chadron arch*
Denver basin*
Las Vegas-Raton basin*
North Park basin*
Powder River basin*
Salina basin*
Sioux uplift*
Williston basin*
Wind River basin*