Smithboro Till Member

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Lithostratigraphy: Glasford Formation >>Smithboro Till Member
Chronostratigraphy: Cenozoic Erathem >>Quaternary System >>Pleistocene Series

Primary source

Willman, H. B., and John C. Frye, 1970, Pleistocene Stratigraphy of Illinois: Illinois State Geological Survey Bulletin 94, 204 p.

Contributing author(s)

H. B. Willman and John C. Frye


Original description

The Smithboro Till Member of the Glasford Formation was informally named the Smithboro till by Jacobs and Lineback (1969, p. 9) in the south-central Illinois region.


The Smithboro Till Member was named for Smithboro, Bond County, 5 miles west of the type locality.

Other names


Type section

Type location

The type section is the Mulberry Grove Section (Jacobs and Lineback, 1969, p. 21), in borrow pits along Interstate Highway 70, SW SW Sec. 31, T. 6 N., R. 1 W., Fayette County.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

At the type section it is overlain by the Mulberry Grove Silt. As the Smithboro is the lowest till member of the Glasford Formation in south-central Illinois, it may be equivalent to the Kellerville Till Member, which is the lowest till unit of the Glasford in western Illinois. However, the tills have slightly different compositions, and separate names seem desirable until they are more directly traced between the two regions.

Extent and thickness


The till is more silty than the Vandalia Till above and is higher in expandable clay mineral content. Its character and composition have been described by Jacobs and Lineback (1969).




Well log characteristics


Age and correlation

The Smithboro Till is in the Liman Substage of the Illinoian Stage. Till fabric studies (Lineback, in press) suggest that the glacier advanced from the north, which indicates a source in the Lake Michigan Lobe.

Environments of deposition

Economic importance



JACOBS, A. M., and J. A. LINEBACK, 1969, Glacial geology of the Vandalia, Illinois, region: Illinois State Geological Survey Circular 442, 24 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation