Karst forms when carbonate rocks (like limestone) slowly dissolve in water over thousands of years. This chemical process creates unique features:

• Sinkholes (dolines) are bowl-shaped depressions where the ground has collapsed.

• “Lost rivers” are streams that suddenly disappear underground into a hole.

• Caves are underground tunnels and rooms.

• Large springs are where underground water comes back to the surface.

In a karst area, the most noticeable thing is the lack of surface streams. Most of the rain drains into the sinkholes and disappearing streams, traveling through underground cave tunnels instead of surface rivers. This underground system is important for drinking water, but it's easily contaminated. Water flows very fast (sometimes over a mile per day) with little natural filtering, so bacteria and pollution can quickly spread.

West Virginia has several streams that run underground. The Lost River near Wardensville (Hardy County) completely disappears and reappears a mile away as the Cacapon River. Hills Creek (Pocahontas County) sinks into a cave, and its water splits up, traveling many miles before resurfacing. The Davis Spring (Greenbrier County) is the state's largest spring, draining 72 square miles of underground water.

The most extensive karst features are found in the Greenbrier Valley (Greenbrier, Monroe, and Pocahontas counties). Towns like Lewisburg are built right on top of large sinkhole plains.