The terrain of Kentucky has been shaped by geologic forces and the underlying rocks.Tectonic forces lifted, bent, and buckled the rocks–originally formed from sediments on shallow sea floors or swampy lowlands. Weathering and erosion shaved the hills and dissected the plains, exposing at the surface a cross section of rocks 250 to 500 million years old. The sands, gravels, silts, and clays of the Jackson Purchase Region are younger, remnants of a time when the sea lapped at the confluence of the Mississippi and Ohio Rivers.
The landforms in Kentucky are the result of the differential weathering of interbedded sandstones, siltstones, shales, and limestones. Sandstones and siltstones resist erosion, limestones dissolve along cracks and crevices, and shales break down quickly when exposed to air and water. Areas dominated by sandstones and siltstones tend to have hills with steep sides. As the shale content increases, the landscape becomes more rounded, with wide stream valleys. Areas underlain by limestone may have few surface streams (karst topography) and gently rolling land. As the shale content in the rocks increases relative to limestone, the land becomes hillier.
Natural resources–coal, oil, natural gas, soils–are the products of geologic history and vary from region to region. In turn, the ecology and economy of the different regions of Kentucky are distinctive.
To learn more about the rocks and terrain typical of your area, find the region you live in on the map and then go to the associated text and picture group for that region (color-coded frame and header block matches the map region color).
Map and Chart 187
Digital Object Identifier (DOI)
Carey, Daniel I. and Hounshell, Terry D., "Kentucky Terrain" (2008). Map and Chart--KGS. 186.