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), the uppermost stage, is named for Richmond, Indiana.
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.
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.
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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