Usage:
Derby Formation (IL*,MO*)
Derby and Doe Run Formations, undifferentiated (MO*)
/Derby-Doerun Dolomite (usage of the MO Geol. Survey, 1979) (MO*)
/Derby-Doerun Dolomite of Elvins Group (MO)
/Derby-Doerun Dolomite of Knox Group (IL-notably in southern part)
/Derby-Doerun Member of Franconia Formation (IL)
[The use of a hyphen between undifferentiated formations is not considered proper notation (CSN, 1933).]
Geologic age:
Late Cambrian (Croixan; Millardan; Sunwaptan)*
Type section, locality, area and/or origin of name:
Type locality: on Harris Branch near Derby Mine (Federal Mine No. 2), about 1 mi south of railroad stations at Elvins, [Flat River 7.5-min quadrangle], St. Francois Co., eastern MO. Named from Derby Mine (Buckley, 1909).
AAPG geologic province:
Illinois basin*
Ozark uplift*
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 ([ ]).