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National Geologic Map Database

Geologic Unit: Johns Creek Quarry

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 ([ ]).