Trempealeauan Stage

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Lithostratigraphy: Knox Dolomite Megagroup
Chronostratigraphy: Paleozoic Erathem >>Cambrian System >>Croixan Series >>Trempealeauan Stage
Allostratigraphy: Sauk Sequence

Primary source

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.

Contributing author(s)

T. C. Buschbach


Original description


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

Other names


Type section

Type location

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

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

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.

Extent and thickness





Well log characteristics


Age and correlation

Environments of deposition

Economic importance



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