Natural Bridge

Jefferson bought it from the King; a highway still runs over the top

The arch is the roof of a cave that lost the rest of itself. Natural Bridge stands 215 feet high with a span of 90 feet, in a gorge that Cedar Creek cut through limestone in Rockbridge County, and the rock overhead is what remains of the ceiling of a tunnel the creek once ran inside. Everything else collapsed.

The stone is Ordovician, laid down about 470 million years ago. Two formations do the work: the Chepultepec makes the buttress, and the Beekmantown, deposited conformably on top of it, makes the span and the upper part. One detail gives the structure away. The beds here lie almost flat, while beds as little as 300 feet off along Highway 11 are tilted and folded, because these rocks sit at the bottom of a syncline. Exactly how the bridge formed is still argued, but every serious account leans on the same three things: the southeast dip of the strata, the ability of water to dissolve carbonate slowly, and a great many fractures. Edgar Spencer's synthesis, the most widely accepted, has the bridge as the surviving remnant of an underground river tunnel that pulled water southward, beginning by capturing the flow of Poague Run about two miles north.

It is a Virginia Historic Landmark and a National Historic Landmark, and since 2016 the Commonwealth has run it as Natural Bridge State Park.

One practical thing to know before you go, because it decides whether the visit works for everyone in your party: reaching the bridge means going down a stairway of 137 steps. The park says accommodations for accessibility can be arranged through the rangers at the visitor centre or by phone. The park is open daily from 8am to dusk.