Historical:Trempealeauan Stage

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Handbook of Illinois Stratigraphy
Series Bulletin 95
Author H. B. Willman, Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, Jack A. Simon
Date 1975
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Lithostratigraphy: Knox Dolomite Megagroup
Chronostratigraphy: Paleozoic Erathem >>Cambrian System >>Croixan Series >>Trempealeauan Stage
Allostratigraphy: Sauk Sequence


T. C. Buschbach

Name Origin

The Trempealeauan Stage is named for Trempealeau, Trempealeau County, Wisconsin.

Type Section

The type section of the Trempealeauan Stage is located in Trempealeau, Trempealeau County, Wisconsin.

Stratigraphic Position

The Trempealeauan Stage (Howell et al., 1944, chart 1) consists of the strata from the base of the Platycolpus-Scoevogyra Zone to the top of the Plethopeltis Zone as they are represented in the type section of the Trempealeau Formation (now called the St. Lawrence Formation). However, more recent work (Raasch, 1951; Lochman-Balk and Wilson, 1958) favors placing the base of the Trempealeauan somewhat lower-- at the base of the Saukia Zone in the Franconia Formation. As the fossil zones present in other areas have not been recognized in Illinois, the exact position of the base of the Trempealeauan Stage is uncertain and is placed at the top of the Franconia Formation. The Potosi, Eminence, and Jordan Formations are included in the Trempealeauan Stage.


HOWELL, B. F., et al., 1944, Correlation of the Cambrian formations of North America: Geological Society of America Bulletin, v. 55, p. 993-1003.
LOCHMAN-BALK, CHRISTINA, and J. L. WILSON, 1958, Cambrian biostratigraphy in North America: Journal of Paleontology, v. 32, p. 312-350.
RAASCH, G. O., 1951, Revision of Croixan dikelocephalids: Illinois Academy of Science Transactions, v. 44, p. 137-151 ; Illinois State Geological Survey Circular 179.

ISGS Codes

Stratigraphic Code Geo Unit Designation