Bilyeu Member

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Lithostratigraphy: Mammoth Cave Limestone Megagroup >>Borden Siltstone >>Bilyeu Member
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Valmeyeran Series
Allostratigraphy: Kaskaskia Sequence

Primary source

Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.

Contributing author(s)

Elwood Atherton, Charles Collinson, and Jerry A. Lineback


Original description

The Bilyeu Member of the Borden Siltstone (Lineback, 1968a, p. 5).


Named for Bilyeu Cemetery, Christian County, about 2 miles north of the type section.

Other names


Type section

Type location

The type section of the Bilyeu Member is in the National Petroleum Company No. 1-A Bilyeu, Haldon et al., south well (NW NW SW 10, 13N-1E), where the member is 102 feet thick, extending from 1616 to 1718 feet deep.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

Extent and thickness

The Bilyeu is 0-150 feet thick and extends in the subsurface through Piatt, De Witt, Macon, Christian, Montgomery, Sangamon, and parts of adjacent counties in central Illinois. The Bilyeu Member extends westward beyond the eastern pinchout of the Burlington and Keokuk Limestones and, therefore, in that area is a member of the Warsaw Shale.


The Bilyeu consists of siltstone that is coarser than most of the Borden and also of fine sandstone.




Well log characteristics


Age and correlation

Environments of deposition

Economic importance



LINEBACK, J. A., 1968a, Subdivisions and depositional environments of New Albany Shale (Devonian-Mississippian) in Indiana: American Association of Petroleum Geologists Bulletin, v. 52, p. 1291-1303.

ISGS Codes

Stratigraphic Code Geo Unit Designation