Chalfin Member

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Lithostratigraphy: Mammoth Cave Limestone Megagroup >>Salem Limestone >>Chalfin Member
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Valmeyeran Series
Allostratigraphy: Kaskaskia 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)

Elwood Atherton, Charles Collinson, and Jerry A. Lineback


Original description

The Chalfin Member of the Salem Limestone (Baxter, 1960a, p. 24-27).


Named for the village of Chalfin Bridge, Monroe County.

Other names


Type section

Type location

The type section of the Chalfin Member is in the Mississippi River bluffs 1 mile southwest of the village of Chalfin Bridge (NE SW 7, 4S-10W), where the member is 39.5 feet thick.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

Extent and thickness

The Chalfin is 26-57 feet thick in the outcrop area.


The Chalfin consists of varying thicknesses of fine-grained limestone; fine- to medium-grained, fossiliferous, locally oolitic limestone; and semilithographic limestone, some of it brecciated. The lower 10 feet is predominantly a calcarenite composed of bryozoan detritus, crinoid columnals, microcrystalline pellets, and a few oolites.




Well log characteristics


Eoendothyranopsis group pressus-rarus, Koninckopora sahariensis, K. inflata, Septabrunsiina, and profuse Calcisphaera characterize the Chalfin.

Age and correlation

Environments of deposition

Economic importance



BAXTER, J. W., 1960a, Salem Limestone in southwestern Illinois: Illinois State Geological Survey Circular 284, 32

ISGS Codes

Stratigraphic Code Geo Unit Designation