A scenic view of Rockbridge with waterfall at Rockbridge State Nature Preserve in Hocking County, Ohio. The Natural Arch and Bridge Society defines a natural arch as �a rock exposure that has a hole completely through it formed by the natural, selective removal of rock, leaving a relatively intact frame.� At 92 feet Rockbridge is Ohio's longest natural bridge. The bridge originated as a typical Hocking Hills alcove carved into the soft middle layer of Black Hand Sandstone at the head of a short box canyon cut by a small tributary of the Hocking River. Three intersecting vertical fractures in the roof of the shelter were gradually enlarged until the block they surrounded was no longer supported and fell, creating a skylight. The bridge [...]
