Fig. 3. Clement member of Grand Detour formation. Shown on columnar section as underlying Hely member (new) and overlying Stillman member (new). Age is Middle Ordovician.
[Notable exposures in Dixon-Oregon area, northern IL.]
Source: US geologic names lexicon (USGS Bull. 1200, p. 834).
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 ( ).
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