Usage:
Scales Shale of Maquoketa Group (IL,IN)
Scales Formation of Maquoketa Group (IL)
Scales Member of Maquoketa Shale (WI)
Geologic age:
Late Ordovician (Cincinnatian; Maysvillian)
Type section, locality, area and/or origin of name:
Type section: railroad in Scales Mound in which 30 feet of Scales Formation overlies 10 feet of Dubuque Dolomite. Top of formation is exposed about 5 mi farther east in another railroad cut, in SW/4 SW/4 SW/4 sec. 15, T. 29 N., R. 3 E., Elizabeth quadrangle, where 20 feet of Fort Atkinson Limestone overlies 18 feet of Scales Formation. Named from town of Scales Mound, Jo Daviess Co., northwestern IL (Templeton and Willman, 1963).
AAPG geologic province:
Illinois 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 ([ ]).