Map showing the Cumberland Plateau in yellow as defined by Bailey's ecoregions.
The Cumberland Plateau is the southern part of the Appalachian Plateau. It includes much of eastern Kentucky, part of Tennessee, and a small portion of northern Alabama and northwest Georgia. The terms "Allegheny Plateau" and the "Cumberland Plateau" both refer to the dissected plateau lands lying west of the main Appalachian Mountains. The terms stem from historical usage rather than geological difference, so there is no strict dividing line between the two. Two major rivers share the names of the plateaus, with the Allegheny River rising in the Allegheny Plateau and the Cumberland River rising in the Cumberland Plateau.
In Kentucky, the height of the plateau's hills increases from northwest to southeast, with the westernmost areas of the plateau having a relief of around 200 feet and an appearance similar to the knobs region, whereas areas near Black Mountain have a relief exceeding 2,500 feet.
The Cumberland Plateau is contiguous with the Allegheny Plateau on the northern side, the only real difference being local naming. The sedimentary rocks that compose both plateaus are of Mississippian and Pennsylvaniangeological age, composed of near shore sediments washed westward from the old Appalachian Mountains. Some rock layers were laid down in shallow coastal waters, some, including bituminous coal seams were laid onshore in swampy environments. These are interlaced with delta formations of cross-bedded sandstones and occasionally conglomerate. There are numerous discontinuities in the beds, where they were raised high enough to be eroded, then lowered to have more sediments added on top.
The plateau contains some of the largest stretches of contiguous forest in the eastern United States. Regionally, forests are intermediate between oak (Quercus) and hickory (Carya) forest types with pines (Pinus) occurring on dry, upland sites and mesophytic species occurring in protected coves.
^ORNL Report: Druckenbrod, D.L. and V.H. Dale. 2004. Sustaining the landscape: a method for comparing current and desired future conditions of forest ecosystems in the North Cumberland Plateau and Mountains. ORNL/TM-2004/314. Oak Ridge National Laboratory, Oak Ridge, TN. 37 pages.  (4/28/2009)