Natural Tunnel State Park

Natural Tunnel

The Natural Tunnel, still in use as a railroad tunnel
Overview
Location	Natural Tunnel State Park, Scott County, Virginia, United States
Coordinates	36°42′11″N 82°44′35″W / 36.703°N 82.743°W / 36.703; -82.743
Operation
Constructed	1893
Opened	1894
Owner	Commonwealth of Virginia
Operator	Norfolk Southern Railway
Traffic	Coal Haulage
Character	Naturally formed limestone cave converted to a railroad tunnel
Technical
Length	838 feet (255 m)
Track gauge	1,435 mm (4 ft 8+1⁄2 in)
Electrified	No
Tunnel clearance	Portals: 50 feet (15 m) Max: 80 feet (24 m)

Natural Tunnel State Park is a Virginia state park, centered on the Natural Tunnel, a massive naturally formed cave that is so large it is used as a railroad tunnel. It is located in the Appalachian Mountains near Duffield in Scott County, Virginia.

The Natural Tunnel, which is up to 200 feet (61 m) wide and 80 feet (24 m) high,^[1] began to form more than a million years ago when groundwater bearing carbonic acid percolated through crevices and slowly dissolved limestone and dolomite bedrock. A small river, which is now called Stock Creek, was diverted underground and it continued to erode the tunnel over many millennia.

The walls of the tunnel show evidence of prehistoric life. Many fossils have been found in the creek bed and in the tunnel walls.^[2]