It is a subunit of the Golconda Formation in Kentucky and is correlative with the Fraileys Shale to which it grades to in southern Illinois. The Big Clifty and Golconda are part of the Chesterian Series of late Mississippian age.
The Big Clifty and Golconda formations are parts of the Chesterian Series, a group of rocks from the late Mississippian period. They are found in Kentucky and transition into the Fraileys Shale in southern Illinois.