- Usage in publication:
-
- Cohn cyclothem
- Modifications:
-
- Original reference
- AAPG geologic province:
-
- Illinois basin
Summary:
Pg. 9, 18-19; J.M. Weller, 1942, Illinois Acad. Scl. Trans., v. 35, no. 2, p. 145 (table 1). Cohn cyclothem. Occurs above the LaSalle cyclothem and below the Bogota cyclothem (new). Total thickness 7.5 inches. Age is Pennsylvanian.
Type locality: about 2 mi northwest of Cohn [now Livingston], in NE/4 sec. 1, T. 11 N., R. 12 W., [Marshall 15-min quadrangle], Clark Co., eastern IL.
Source: US geologic names lexicon (USGS Bull. 1200, p. 875-876).
- Usage in publication:
-
- Cohn cyclothem
- Modifications:
-
- Revised
- AAPG geologic province:
-
- Illinois basin
Summary:
Pg. 52 (table 2), pl. 1. Cohn cyclothem. Lies above Shoal Creek cyclothem in eastern Illinois. Age is Pennsylvanian. Report presents new rock-stratigraphic classification of Pennsylvanian strata in Illinois. Cyclical classification retained but is entirely independent of rock-stratigraphic classification; includes rocks also assigned to lower part of Mattoon formation (new) of McLeansboro group.
Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 875-876).
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 ([ ]).