Usage:
Tonti Member of St. Peter Sandstone (IL,IA,MO,WI)
Tonti Member of St. Peter Formation (WI)
Geologic age:
Middle Ordovician
Champlainian
Type section, locality, area and/or origin of name:
Type section: exposures at Starved Rock, Lovers' Leap, and French Canyon, in W/2 NW/4 and NW/4 NW/4 SW/4 sec. 22, T. 33 N., R. 2 E., Ottawa quadrangle, Starved Rock State Park, LaSalle Co., IL. Named from Tonti Canyon in Starved Rock State Park (Templeton and Willman, 1963).
AAPG geologic province:
Iowa shelf
Lincoln anticline
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 ([ ]).