Plaines Member

Jump to navigation Jump to search

Lithostratigraphy: Hunton Limestone Megagroup >>Kankakee Formation >>Plaines Member
Chronostratigraphy: Paleozoic Erathem >>Silurian System >>Alexandrian Series
Allostratigraphy: Tippecanoe 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)

H. B. Willman and Elwood Atherton


Original description

The Plaines Member of the Kankakee Formation (Willman, 1973, p. 18).


Named for Plaines Station, a railroad switching point on the southeast side of the Des Plaines River 1.75 miles southwest of Joliet, Will County.

Other names


Type section

Type location

The type section of the Plaines Member is at the top of a small quarry, where it overlies the type section of the upper part of the Troutman Member.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

The Plaines Member is the uppermost member of the Kankakee Formation.

Extent and thickness

The Plaines Member is 2.2 feet thick in the type section but elsewhere is 1.5-3.4 feet thick. It is widely exposed along the Kankakee and Des Plaines Rivers.


The dolomite of the Plaines Member is pure, massive, medium grained, and nearly white, and the top is the smooth surface that marks the top of the formation.




Well log characteristics


The Microcardinalia Zone is largely in the Plaines Member.

Age and correlation

Environments of deposition

Economic importance



WILLMAN, H. B., 1973, Rock stratigraphy of the Silurian System in northeastern and northwestern Illinois: Illinois State Geological Survey Circular 479, 55 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation