Historical:Chazyan 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 >>Ordovician System >>Champlainian Series >>Chazyan Stage
Allostratigraphy: Tippecanoe Sequence


H. B. Willman and T. C. Buschbach

Name Origin

The Chazyan Stage (Emmons, 1842, p. 107; Grabau, 1989, p. 223) is named for Chazy, New York.


The Everton is correlated with the type Chazyan on the basis of the fauna in the Everton type area in Arkansas and by subsurface tracing (Templeton and Willman, 1963).

Extent and Thickness

In Illinois the Chazyan Stage includes only the Everton Dolomite, which is not exposed but is encountered in drilling in the southwestern part of the state.


EMMONS, EBENEZER, 1842, Geology of New York, Part 2, comprising the survey of the second geological district: Albany, 437 p.
GRABAU, A. W., 1909, Physical and faunal evolution of North America during Ordovicic, Siluric, and early Devonic time: Journal of Geology, v. 17, p. 209-252.
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