Historical:Allard Limestone 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: Pope Megagroup >>Menard Limestone >>Allard Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Chesterian Series >>Elviran Stage
Allostratigraphy: Kaskaskia Sequence


Elwood Atherton, Charles Collinson, and Jerry A. Lineback

Name Origin

The Allard Limestone Member of the Menard Formation (Swann, 1963, p. 38-40) is named for Allard College School, Johnson County.

Type Section

The Allard Limestone Member is located 2.2 miles southwest of Allard College School, Johnson County, in a cut at the south end of the Illinois Central Railroad tunnel (SW NW NE 1, 13S-4E).

Extent and Thickness

The Allard ranges from a little more than 30 feet in the far south to 10-12 feet in much of the northern area of the Menard.


The Allard Member is dominantly limestone.


SWANN, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation