Richmondian Stage

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Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Cincinnatian Series >>Richmondian Stage
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 T. C. Buschbach


Original description

The Richmondian Stage of the Cincinnatian Series (Winchell and Ulrich, 1897, p. ciii; Twenhofel et al., 1954, chart).


Named for Richmond, Indiana.

Other names


Type section

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Type author(s)

Type status

Reference section

Reference location

Reference author(s)

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Stratigraphic relationships

The Richmondian Stage is the uppermost stage of the Cincinnatian Series. In Illinois the Richmondian Stage includes the uppermost part of the Scales Shale, the Fort Atkinson Limestone, the Brainard Shale, the Neda Formation, and the Girardeau Limestone.

Extent and thickness





Well log characteristics


Age and correlation

The red shales of the Neda suggest correlation with red shales and sandstones in the Queenston and Juniata Formations at the top of the Cincinnatian Series in the Appalachian region.

Environments of deposition

Economic importance



TWENHOFEL, W. H., et al., 1954, Correlation of the Ordovician formations of North America: Geological Society of America Bulletin, v. 65, p. 247-298.
WINCHELL, N. H., and E. O. ULRICH, 1897, Lower Silurian deposits of the Upper Mississippi Province: Minnesota Geological Survey, Paleontology, v. 3, part 2, p. Ixxxiii-cxxvii.

ISGS Codes

Stratigraphic Code Geo Unit Designation