Big Clifty Sandstone Member

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Lithostratigraphy: Pope Megagroup >>Okaw Group >>Golconda Group >>Fraileys Shale >>Big Clifty Sandstone Member
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Chesterian Series >>Hombergian Stage
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

Big Clifty Sandstone Member of the Fraileys Shale (Norwood, 1876, p. 405).


Named for Big Clifty Creek, Grayson County, Kentucky.

Other names


Type section

Type location

The type section of the Big Clifty Sandstone Member is along the Big Clifty Creek, 2 miles southwest of the village of Big Clifty.

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

It is near the middle of the Fraileys or, less commonly, near the base. In Indiana the Big Clifty occupies nearly the whole of the interval represented by the Fraileys Shale in Illinois.

Extent and thickness

The Big Clifty enters Illinois from the east and wedges out within a few tens of miles. Many wells in Lawrence, northern and eastern Jasper, and southern Cumberland Counties encounter 15-20 feet of Big Clifty. A few sporadic occurrences have been found in Marion County and east of there.





Well log characteristics


Age and correlation

Environments of deposition

Economic importance

“Big Clifty” and “Jackson” are informal names applied to producing zones in the Big Clifty Sandstone Member of the Fraileys Shale.



NORWOOD, C. J., 1876, Report on the geology of the region adjacent to the Louisville, Paducah, and Southwestern Railroad, with a section: Kentcuky Geological Survey, v. 1, p. 355-488.

ISGS Codes

Stratigraphic Code Geo Unit Designation