Historical:Fox Valley Member

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Handbook of Illinois Stratigraphy
Series Bulletin 95
Author H. B. Willman, Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, Jack A. Simon
Date 1975
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Lithostratigraphy: Knox Dolomite Megagroup >>Ironton Sandstone >>Fox Valley Member
Chronostratigraphy: Paleozoic Erathem >>Cambrian System >>Croixan Series >>Franconian Stage
Allostratigraphy: Sauk Sequence


T. C. Buschbach

Name Origin

The Fox Valley Member of the Ironton Sandstone (Buschbach, 1964, p. 37), which overlies the Buelter Member, is named for the Fox River Valley.

Type Section

The type section of the Fox Valley Member of the Ironton Sandstone occurs at a depth of 1168-1180 feet in the same well as the Buelter type section.

Extent and Thickness

The Fox Valley Member is commonly 10-25 feet thick.


It consists of poorly sorted medium- to coarse-grained sandstone that is consistently dolomitic. Dolomite occurs as cementing material and as stringers of light pink to buff sandy dolomite interbedded with the sandstone. Brown spheroids and oolites are present in the dolomite.


BUSCHBACH, T. C., 1964, Cambrian and Ordovician strata of northeastern Illinois: Illinois State Geological Survey Report of Investigations 218, 90 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation