Usage:
Modesto Formation (IL*)
Subunits:
Athensville Coal (IL), Burroughs Limestone (IL), Carlinville Limestone (IL), Chapel Coal (IL), Cramer Limestone (IL), De Graff Coal (IL), Exline Limestone (IL), Farmington Shale (IL), Gimlet Sandstone (IL), Hall Limestone (IL), Inglefield Sandstone (IL), Lake Creek Coal (IL), Lonsdale Limestone (IL), Macoupin Limestone (IL), New Haven Coal (IL), Piasa Limestone (IL), Pond Creek Coal (IL), Rock Branch Coal (IL), Scottville Limestone (IL), Trivoli Sandstone (IL), West Franklin Limestone (IL), and Womac Coal (IL) Members
Geologic age:
Pennsylvanian, Middle*
Desmoinesian*
Pennsylvanian, Late*
Missourian*
Type section, locality, area and/or origin of name:
In secs. 16 and 17, T. 12 N., R. 9 W., Macoupin Co., west-central IL. Named from town of Modesto (Kosanke and others, 1960).
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 ([ ]).