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Geologic Unit: Medusa
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Map showing publication footprint
  • Usage in publication:
    • Medusa member
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Limestone
    • Dolomite
  • AAPG geologic province:
    • Wisconsin arch
Publication:

Templeton, J.S., and Willman, H.B., 1952, Guidebook for the 16th annual field conference, central northern Illinois: Tri-State Annual Field Conference Guidebook, October 11-12, 1952, no. 16, 47 p., Also issued as Illinois State Geol. Survey Gdbk., 2nd ser., 1952. http://archive.org/details/guidebookforsixt02tris


Summary:

Figs. 3, 10, 15A, 16. Medusa member of Pecatonica formation. Limestone, dolomite; thickness as much as 11 feet. Shown on columnar section as underlying Oglesby member (new) and overlying New Glarus member (new). Where Oglesby member is absent, underlies Boarman member (new) of Mifflin formation. Age is Middle Ordovician.
[Notable exposures in Dixon-Oregon area, northern IL.]

Source: US geologic names lexicon (USGS Bull. 1200, p. 2449).


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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