H. B. Willman and T. C. Buschbach
The Trentonian Stage (Vanuxem, 1838, p. 257, 276, 283; Kay, 1948, p. 1411), named for Trenton Falls in New York State, is represented in Illinois by the strata of the Galena Group.
They are correlated with the type Trentonian of New York on the bases of both faunal and lithologic similarity (Templeton and Willman, 1963).
Extent and Thickness
These rocks are present throughout most of Illinois (fig. O-21).
Trentonian strata are generally fossiliferous and the fauna contains many forms not found in the Blackriveran below or the Cincinnatian above.
KAY, MARSHALL, 1948, Summary of Middle Ordovician bordering Allegheny Synclinorium: American Association of Petroleum Geologists Bulletin, v. 32, p. 1397-1416.
TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.
VANUXEM, LARDNER, 1838, Second annual report of the geological survey of the third district of the state of New York: New York Geological Survey Annual Report 2, p. 253-286.
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