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  • Usage in publication:
    • Barnhart formation
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Shale
    • Limestone
  • AAPG geologic province:
    • Illinois basin
Publication:

Cooper, G.A., 1956, Chazyan and related brachiopods [U.S.-Canada]: Smithsonian Miscellaneous Collections, v. 127, pt. 1, 1245 p.


Summary:

Pg. 116, chart 1 (facing p. 130). Barnhart formation. Name proposed for the "Decorah" of Missouri which overlies Plattin group and underlies Kimmswick formation. Consists of about 20 feet of greenish shale with interbedded thin limestones, all abundantly fossiliferous. [Age is Middle Ordovician (Trentonian of Twenhofel and others, 1954, GSA Bull., v. 65, p. 247-298).]
Type section: Koch Valley School on U.S. Highway 61-67, 2 mi south of Barnhart, Kimmswick 15-min quadrangle, Jefferson Co., east-central MO.

Source: US geologic names lexicon (USGS Bull. 1200, p. 218).


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 ([ ]).

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