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National Geologic Map Database

Geologic Unit: Fern Glen

Usage:

Fern Glen Formation (IL*,MO*)
Fern Glen Limestone (IL*,KS*,MO*)
Fern Glen Formation of Mammoth Cave Group (IL-notably southwestern part)


Subunits:

(alphabetical): Meppen Limestone Member (MO), Reeds Spring Limestone Member (KS), St. Joe Limestone Member (KS).


Geologic age:

Mississippian, Early*
Osagean*


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

Named from exposures near Fern Glen Station [Fern Glen], 20 mi west of St. Louis, [southwestern St. Louis Co.], central eastern MO (Weller, 1909).
Type section (composite): two railroad cuts on either side of Fern Glen on north bank of Meramec River, in center SE/4 sec. 14 and NW/4 SW/4 SW/4 sec. 13, T. 44 N., R. 4 E., Manchester 7.5-min quadrangle, St. Louis Co., central eastern MO (Thompson, 1975).


AAPG geologic province:

Ozark uplift*
Forest City basin*
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 ([ ]).