- Usage in publication:
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- Calmar Bentonite Bed
- Modifications:
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- Original reference
- Dominant lithology:
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- Bentonite
- AAPG geologic province:
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- Iowa shelf
Summary:
Pg. 49. Calmar Bentonite Bed of Rivoli Member of Dunleith Formation, and Calmar Bentonite Bed of Loves Park Member of Dunleith Formation (in Illinois). Present in Iowa, Illinois, and Minnesota. At type section, consists of bentonite clay, 0.05 m thick; overlies and underlies limestone units of Rivoli Member. Age is Middle Ordovician.
Type section: Engineers Old Cut section, stream diversion channel, 2.4 km west of Decorah, in SE/4 NE/4 sec. 18, T. 98 N., R. 8 W., [approx. Lat. 43 deg. 18 min. 24 sec. N., Long. 91 deg. 49 min. 32 sec. W., Decorah 7.5-min quadrangle], Winneshiek Co., northeast IA.
Named from town of Calmar, 14.5 km south of type section, [Calmar 7.5-min quadrangle], Winneshiek Co., northeast IA.
Source: US geologic names lexicon (USGS Bull. 1564, p. 26).
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 ([ ]).