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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Lake Michigan Formation
  • Modifications:
    • Named
  • Dominant lithology:
    • Clay
  • AAPG geologic province:
    • Michigan basin
Publication:

Willman, H.B., and Frye, J.C., 1970, Pleistocene stratigraphy of Illinois: Illinois Geological Survey Bulletin, no. 94, 204 p.


Summary:

Named Lake Michigan Formation for bottom sediments of Lake Michigan. Consists of 3.3 m of gray to brown silty clay of lacustrine deposits and beach sediments. Overlies till or Paleozoic bedrock. Unit is of Quaternary age.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Lake Michigan Formation*
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Michigan basin
Publication:

Colman, S.M., Keigwin, L.D., and Forrester, R.M., 1994, Two episodes of influx of meltwater from Glacial Lake Agassiz into the Lake Michigan basin; contrasts in climatic and oceanographic effects: Geological Society of America, Geology, v. 22, no. 6, p. 547-550.


Summary:

Lake Michigan Formation divided into informal lower and upper units instead of formal nomenclature. Lower unit includes Wilmette Bed, which is used formally.

Source: GNU records (USGS DDS-6; Reston GNULEX).


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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