Usage:
Johns Creek Quarry Member of Hopkinton Formation (IA)
Johns Creek Quarry Member of Scotch Grove Formation (IL,IA)
Geologic age:
early Silurian (Llandovery)
Type section, locality, area and/or origin of name:
Type section: Johns Creek quarry, 6.5 km south of Farley, SE/4 SW/4 sec. 36, T. 88 N., R. 2 W., Dubuque Co., IA (Johnson, 1983).
AAPG geologic province:
Iowa shelf
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 ([ ]).