An attempt has been made to correlate the subsurface Devonian and Silurian strata in the western Kentucky basin with equivalent beds in the generally distant outcrops. Samples from about forty wells were studied, zoned on the basis of general lithology and insoluble residues, and a tentative correlation of these zones with the outcrop material suggested. The formations recognized at the surface in southern Illinois can be traced into the subsurface in western Kentucky.

The absence of the Decatur and upper Brownsport of the Tennessee Silurian from the sections high on the flank of the Cincinnati arch, and their presence on the west side of the basin indicates some post-middle Silurian and pre-Devonian uplift and erosion. The Kentucky Lower and lower Middle Devonian strata may represent the seaward facies of the Arkansas and Texas novaculites as thickening toward the southwest suggests that the source of the thick cherts and dolomites was in that direction.

Post-Hamilton warping of the basin, perhaps as a result of relative east-west uplift occasioned by movement of the Nashville dome, served to cut off the southern end of the syncline. This resulted in the preservation of a complete section of Lower and Middle Devonian in the deepest part, and the stripping of the Hamilton and most of the Onondaga from the east, south, and west sides. All or nearly all of the Devonian sediments were removed from the region high on the Cincinnati arch side of the basin, from Hardin County south to Barren County, before deposition of the Chattanooga shale.