Usage:
Lake of Egypt member (informal) of Tradewater Formation (IL)
Informal. The rank or lithologic term should not be capitalized.
Geologic age:
Middle Pennsylvanian (Atokan)
Type section, locality, area and/or origin of name:
Not designated. Measured section in W/2 NE/4 sec. 23, T. 11 S., R. 2 E., Goreville quadrangle, Johnson Co., IL. Named from lake which straddles Williamson-Johnson Co. border (Jacobson, 1992).
AAPG geologic province:
Illinois basin
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 ([ ]).