Tyson Member

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Lithostratigraphy: Ottawa Limestone Megagroup >>Galena Group >>Decorah Subgroup >>Kings Lake Formation >>Tyson 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 Tyson Member of the Kings Lake Formation (Templeton and Willman, 1963, p. 111).


Named for Tyson Hollow, St. Louis County, Missouri, the mouth of which is 0.5 mile northeast of the type section.

Other names


Type section

Type location

The type section of the Tyson Member is located in the same section as the Mincke type section (a railroad cut in the Meramec Valley bluff (near cen. E1/2 SE SE 21, 44N-4E)) where the Tyson is 7.5 feet thick.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

The Tyson Member is the upper member of the Kings Lake Formation.

Extent and thickness

The Tyson Member thins northward to 4.3 feet in the Kings Lake type section and to 3.9 feet at New London, Missouri.


The Tyson Member is largely dolomitic, silty, argillaceous limestone that weathers buff and chalky. It occurs in medium to thick beds and contains a few thin beds of buff to reddish brown shale, coarse calcarenite, and coquinite.




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