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.
H. B. Willman and T. C. Buschbach
The Richmondian Stage of the Cincinnatian Series (Winchell and Ulrich, 1897, p. ciii; Twenhofel et al., 1954, chart).
Named for Richmond, Indiana.
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
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.
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