Chazyan Stage

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Lithostratigraphy: Knox Dolomite Megagroup
Chronostratigraphy: Paleozoic Erathem >>Ordovician System >>Champlainian Series >>Chazyan 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

Chazyan Stage (Emmons, 1842, p. 107; Grabau, 1989, p. 223).


Named for Chazy, New York.

Other names


Type section

Type location

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

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.





Well log characteristics


Age and correlation

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).

Environments of deposition

Economic importance



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