Usage:
Beecher Member of Dunleith Formation of Galena Group (IL,IA,WI)
Geologic age:
Late Ordovician (Mohawkian; Chatfieldian)
Type section, locality, area and/or origin of name:
Type section (=Dunlieth type section): exposure in Mississippi River bluffs on north side of East Dubuque, in SE/4 sec. 19, T. 29 N., R. 2 W., [approx. Lat. 42 deg. 29 min. 42 sec. N., Long. 90 deg. 38 min. 52 sec. W., Dubuque South 7.5-min quadrangle], Jo Daviess Co., northwestern IL (Templeton and Willman, 1963, Illinois Geol. Survey Bull., no. 89, p. 114; Willman and Buschbach, 1975, Illinois Geol. Survey Bull., no. 95, p. 47-87).
Named from Beecher Street in East Dubuque, Jo Daviess Co., northwestern IL (Templeton and Willman, 1963, p. 120; Willman and Buschbach, 1975).
Notable exposures in Dixon-Oregon area, northern IL (Templeton and Willman, 1952).
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 ([ ]).