H. B. Willman and T. C. Buschbach
The Maysvillian Stage of the Cincinnatian Series (Foerste, 1905, p. 150; Twenhofel et al., 1954, chart), which overlies the Edenian Stage, is named for Maysville, Kentucky.
In Illinois the Maysvillian Stage consists of strata in the upper part of the Scales Formation, including the Upper Depauperate Zone and the overlying argillaceous limestone beds that contain Isotelus in abundance. The Girardeau Limestone in the extreme southwestern part of Illinois is approximately at this position, but its relation to the Upper Depauperate Zone is not known. Its fauna has long been considered to be more closely related to Silurian than to Ordovician faunas (Savage, 1917), and it therefore probably is late Richmondian in age.
FOERSTE, A. F., 1905, Classification of the Ordovician rocks of Ohio and Indiana: Science, v. 22, p. 149-152.
SAVAGE, T. E., 1917, Thebes sandstone and Orchard Creek shale and their faunas in Illinois: Illinois Academy of Science Transactions, v. 10, p. 261-275.
TWENHOFEL, W. H., et al., 1954, Correlation of the Ordovician formations of North America: Geological Society of America Bulletin, v. 65, p. 247-298.
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