Why are caves common in limestone areas of the central and southern Appalachian Mountains?

Caves are common in the central and southern Appalachian Mountains because these regions contain extensive deposits of limestone, a sedimentary rock that is highly susceptible to chemical dissolution.12

In areas geologically referred to as "New" Appalachia, the bedrock includes significant layers of limestone that yield to the constant action of water and weak acids. When rainwater infiltrates the soil, it absorbs carbon dioxide to form a dilute solution of carbonic acid. As this acidic water percolates through fractures, joints, and bedding planes in the limestone, it gradually dissolves the calcium carbonate that composes the rock.1345

Over long periods, this chemical process enlarges these fractures into continuous conduits and sizable underground passages, forming solution caves. This process is a hallmark of karst terrain, which characterizes much of the land beneath the central and southern Appalachian regions, particularly within or bordering the Great Appalachian Valley.641