Historical:Capron Till Member

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Pleistocene stratigraphy of Illinois
Series Bulletin 94
Author H. B. Willman and John C. Frye
Date 1970
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Lithostratigraphy: Winnebago Formation >>Capron Till Member
Chronostratigraphy: Cenozoic Erathem >>Quaternary System >>Pleistocene Series


H. B. Willman and John C. Frye

Name origin

The Capron Till Member of the Winnebago Formation was informally named the Capron till (Frye et al., 1969, p. 26) for Capron, Boone County, from its occurrence in the prominent ridge that trends north-south through the town.

Type section

The type section is the Capron North Section, a roadcut 3 miles north of Capron, NE SE SE Sec. 23, T. 46 N., R. 4 E, where 2.25 feet of Peoria Loess overlies 1 foot of leached till, 2 feet of pink calcareous till, and 3.5 feet of calcareous sand. The till and sand are the Capron Member.

Stratigraphic relationships

The Capron Till is bounded at the base by its contact with the Plano Silt Member and at the top by its contact with the Robein Silt or overlying beds. Its spatial relations are shown diagrammatically in figure 8.

Extent and thickness

The geographic distribution of the member is shown in figure 6.


The Capron has two compositional phases, an upper sandy phase and a lower silty phase. The typical compositions of these phases are indicated in table 2.

Age and correlation

The Capron Member is within the youngest part of the Altonian Substage of the Wisconsinan Stage.


FRYE, J. C., H. D. GLASS, J. P. KEMPTON, and H. B. WILLMAN, 1969, Glacial Tills of Northwestern Illinois: Illinois State Geological Survey Circular 437, 47 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation