Usage:
Hopkinton Dolomite (IA*,WI*)
Hopkinton Formation (IL,IA)
Subunits:
Sweeney Member (IA,IL), Marcus Member (IA,IL), Farmers Creek Member (IA,IL), Picture Rock Member (IA,IL), Johns Creek Quarry Member (IA), Welton Member (IA), Buck Creek Quarry Member (IA)
Geologic age:
early Silurian (Llandovery)*
Type section, locality, area and/or origin of name:
Not designated. Named from Hopkinton, Delaware Co., eastern IA (Calvin, 1906).
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 ([ ]).