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National Geologic Map Database

Geologic Unit: Millbrig

Usage:

Millbrig K-bentonite Bed of Stones River Formation (northern AL*)
Millbrig K-bentonite Bed of Chickamauga Limestone (western facies, central AL*)
Millbrig K-bentonite Bed of Colvin Mountain Sandstone of Chickamauga Group (northeastern AL*)
Millbrig K-bentonite Bed of Colvin Mountain Sandstone (northeastern AL)
Millbrig K-bentonite Bed of Decorah Formation of Galena Group (IL*)
Millbrig K-bentonite Bed of Spechts Ferry Member of Decorah Formation of Galena Group (IA*)


Millbrig Bentonite Bed of Glencoe Member of Spechts Ferry Formation (IL,WI)
Millbrig Bentonite Bed of Decorah Formation (IA,MN*,MO)
Millbrig K-bentonite Bed of Eggleston Formation (TN,VA,WV)
Millbrig K-bentonite Bed of Moccasin Formation (TN,VA,WV)
Millbrig K-bentonite Bed of Tyrone Limestone (KY)
Millbrig K-bentonite Bed of Bays Formation (TN,VA)
/Millbrig K-bentonite Bed of Stones River Group (AL)
Millbrig K-bentonite Bed of Carters Limestone (AL,GA,TN)


Geologic age:

Late Ordovician (Mohawkian; earliest Chatfieldian)*


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

Type section: Millbrig Southeast section, along east bank of Galena River, 1.6 km southeast of Millbrig, in center sec. 34, T. 29 N., R. 1 E., Jo Daviess Co., IL. Named from Millbrig (Willman and Kolata, 1978).


AAPG geologic province:

Wisconsin arch
Illinois basin
Iowa shelf
Sioux uplift*
Appalachian basin
Cincinnati arch


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 ([ ]).