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National Geologic Map Database

Geologic Unit: Colchester

Usage:

Colchester (No. 2) Coal Member of Carbondale Formation (IL)
Colchester (No. 2) Coal Member of Linton Formation of Carbondale Group (IN)


Geologic age:

Middle Pennsylvanian (Desmoinesian)


Type section, locality, area and/or origin of name:

Type locality: in secs. 12 and 13, T. 5 N., R. 4 W., Colchester quadrangle, McDonough Co., western IL (Kosanke and others, 1960; coal named by Worthen, 1868, IN Geology and Paleontology, v. 3, Illinois Geol. Survey).
Reference section (subsurface): Indiana Geol. Survey drillhole SDH 306, in SW/4 NE/4 sec. 2, T. 2 S., R. 7 W., Pike Co., southern IN (Hasenmueller and Ault, 1991).


AAPG geologic province:

Illinois basin


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).