Wyota Member

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Lithostratigraphy: Ottawa Limestone Megagroup >>Galena Group >>Kimmswick Subgroup >>Dunleith Formation >>Wyota Member
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Trentonian Stage
Allostratigraphy: Tippecanoe 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)

H. B. Willman and T. C. Buschbach


Original description

The Wyota Member of the Dunleith Formation (Templeton and Willman, 1963, p. 124).


Named for Wyota Street in East Dubuque, Jo Daviess County, near the type section.

Other names


Type section

Type location

The type section of the Wyota Member is part of the Dunleith Formation type section (in an exposure in the Mississippi River bluffs on the north side of East Dubuque (SE 19, 29N-2W))(fig. O-2B), where the Wyota Member is 19.9 feet thick.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

The Wyota Member of the Dunleith Formation, the uppermost member in northern Illinois, overlies the Wall Member.

Extent and thickness

The Wyota Member is commonly 18-20 feet thick.


Most of the Wyota Member is purer than the Wall but less pure than the overlying Sinsinawa Member of the Wise Lake Formation. It is characterized by the persistence of thin beds with argillaceous flecks, particularly in the upper 10 feet, and by abundant chert nodules in well defined bands. The upper 2-4 feet is slightly argillaceous, locally shaly, and in many exposures makes a strong reentrant that marks the top of the Dunleith Formation.




Well log characteristics


Age and correlation

Environments of deposition

Economic importance



TEMPLETON, J. S., and H. B. WILLMAN, 1963, Champlainian Series (Middle Ordovician) in Illinois: Illinois State Geological Survey Bulletin 89, 260 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation