- Usage in publication:
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- Charter member
- Modifications:
-
- Original reference
- Dominant lithology:
-
- [Sandstone]
- AAPG geologic province:
-
- Wisconsin arch
Summary:
Pg. 153 (fig. 2), 154 (fig. 3), 156. Charter member of Mount Simon formation. Name applied to the coarse-grained to conglomeratic uppermost member of formation. Type section extends from depths of 1,381 to 1,648 feet. Thickness 71 to 260 feet. Overlies Gunn member (new); underlies Eau Claire formation. Recognized in subsurface of northern Illinois. Age is Late Cambrian.
Type well: depth-interval 1,381 to 1,648 feet, McQueen No. 1 (well 6), in SW/4 NE/4 NE/4 sec. 27, T. 42 N., R. 3 E., DeKalb Co., northeastern IL. Named for Charter Oak School, 3.5 mi north of type well.
Source: US geologic names lexicon (USGS Bull. 1200, p. 726-727).
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 ([ ]).