Where Sinkholes Form in the Appalachians: The Ridge & Valley Province

Sinkhole Hotspot: Appalachian Ridge & Valley Province

Sinkholes in the Appalachians concentrate in the Ridge and Valley Province—a northeast-southwest band from Alabama to New York—where soluble bedrock creates karst terrain.

Geologic Cause

• Rock types: Limestone, dolomite, marble, gypsum, halite (evaporites).
• Process: Acidic groundwater dissolves carbonate/evaporite rock → voids → collapse.
• Structure: Folded/faulted strata from Alleghenian orogeny expose soluble layers at surface.

Key Areas

• Shenandoah Valley (VA/WV) – intense karst; Shenandoah Caverns, Grand Caverns.
• Great Valley (TN/GA/AL) – Chickamauga, Lookout Mountain caves.
• Cumberland Valley (PA/MD) – Carlisle, Chambersburg sinkhole plains.
• Greenbrier Valley (WV) – Organ Cave, Lost World Caverns.
• Helderberg Escarpment (NY) – Howe Caverns, Secret Caverns.

Notable Absence

• Blue Ridge & Piedmont: Mostly crystalline (granite, gneiss, schist) – insoluble, few sinkholes.
• Appalachian Plateau: Sandstone/shale caprock over coal; subsidence from mining, not karst.

Human Impact

• Stormwater injection, quarry dewatering, groundwater pumping accelerate collapse.
• PA, VA, WV, TN, KY, AL have karst protection ordinances.