A limestone originating in the Mississippian geologic period, the Greenbrier Limestone is exposed primarily in the Greenbrier Valley and in the Potomac Highlands and neighboring areas. Throughout the rest of the state, it is buried deep beneath the Appalachian Plateau. It consists of a variety of limestone types. When the Greenbrier Limestone crops out, it forms rich valley bottoms ringed by mountains, most prominently the Greenbrier Valley and Canaan Valley. Because limestones are easily dissolved by migrating groundwater, many caves have developed in the Greenbrier Limestone; in fact it may be best-known for the large variety of caves (including Friars Hole Cave, the largest in West Virginia, as well as the Sinks of Gandy, Organ Cave, and others) that have formed within the limestone.

Limestone is a sedimentary rock, formed over very long periods by the settling of the shells of ancient sea creatures to the bottom of a body of water. The Greenbrier Limestone was deposited in a shallow ocean that flooded West Virginia in ancient times. It formed in a subsiding basin at a time when there was little mountain building activity to the east. The subsidence was greatest in southeastern West Virginia, where the Greenbrier Limestone exceeds 1,000 feet in thickness; it thins to less than 100 feet in the northwestern part of the state. The Greenbrier represents a hiatus in mountain building activity between the Devonian-Mississippian and the Pennsylvanian-Permian ages.

Deep beneath the Appalachian Plateau the Greenbrier Limestone is a source of natural gas. Some small oil fields have also been developed. The Greenbrier Limestone is an important source of crushed stone that is used in road building and in making concrete, and is quarried extensively near Elkins and Morgantown.