Usage:
St. Peter Sandstone (AR*,IL*,IN*,IA*,KY*,MI*,MN*,MO*,NE*,OH*,OK*,SD,WV,WI*)
St. Peter Sandstone of Ancell Group (IL,IN,IA,WI)
St. Peter Sandstone of Simpson Group (KS*-subsurface)
Subunits:
(alphabetical): Glenwood Member (MI,WI), Kingdom Member (MO), Kress Member (IL*,MO*,WI), Readstown Member (IA,WI), Starved Rock Member (IA,IL,MO), Tonti Member (IA,IL,MO,WI).
Geologic age:
Middle to Late Ordovician (Whiterockian to Mohawkian)*
Type section, locality, area and/or origin of name:
Type section: bluff where Minnesota River (formerly called St. Peter's River) joins Mississippi River, Hennepin Co., southern MN (Stauffer, 1934).
Reference sections in MO: (1) roadcut on U.S. Interstate Highway I-55, beginning in NW/4 NW/4 SW/4 sec. 34, and continuing into SE/4 NE/4 sec. 33, T. 40 N., R. 6 E., Selma 7.5-min quadrangle, Jefferson Co.; and (2) roadcut on east side of I-55, in center of west line of NW/4 sec. 11, T. 38 N., R. 7 E., Bloomsdale 7.5-min quadrangle, Ste. Genevieve Co. (Thompson, 1991).
AAPG geologic province:
Appalachian basin*
Arkoma basin*
Cincinnati arch*
Forest City basin*
Illinois basin*
Iowa shelf*
Nemaha anticline*
Ozark uplift*
Salina basin*
Sioux uplift*
Upper Mississippi embayment*
Williston basin*
Wisconsin arch*
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).