Usage:
Grassy Knob Chert of New Harmony Group (IL,IN,KY)
Grassy Knob Chert (IL*)
Geologic age:
Early Devonian*
Type section, locality, area and/or origin of name:
West side of Grassy Knob, 3.5 miles southeast of Grand Tower, Jackson Co., IL (Savage, 1925).
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 ([ ]).