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Geologic Units: Delavan
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  • Usage in publication:
    • Delavan Till Member
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Till
  • AAPG geologic province:
    • Illinois basin
Publication:

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


Summary:

Pg. 68. Delavan Till Member of Wedron Formation. Gray, silty, illitic till. Thickness up to 200 feet. Overlies Morton Loess. Underlies Tiskilwa Till Member of Wedron Formation; at type section underlies Richland Loess. Presumably stratigraphically equivalent to Esmond and Lee Center Till Members of Wedron Formation. Deposited by Peoria Sublobe of Lake Michigan Lobe. Age is Pleistocene (Woodfordian Substage of Wisconsinan Stage).
Type section: roadcuts along Illinois Highway 121, 4 mi [6.4 km] east of Delavan, in SW/4 sec. 16, T. 22 N., R. 3 W., [Emden 7.5-min quadrangle], Tazewell Co., northeastern IL. Named from Delavan, Tazewell Co., northeastern IL.

Source: Publication; US geologic names lexicon (USGS Bull. 1520, p. 83).


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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