What is a Natural Arch?
With few exceptions, Ohio is not noted for its geologic features. However, the same basic processes which shaped the spectacular scenery of the Western U.S. have also been at work in Ohio. Ohio sports at least 80 natural arches that are scattered across the State.
The non-profit 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.”
The arches listed here are owned by the Ohio Department of Natural Resources and can be readily visited. Some require a free access permit from the Division of Natural Areas & Preserves.
At 95 feet Rockbridge is Ohio's longest natural bridge. It is also the only one with a town named after it- the unincorporated community of Rockbridge in Hocking County. 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 is 3 feet thick, varies from 6.5 to 26 feet in width and crosses 40 feet above the plunge pool of the waterfall behind it. The natural bridge at Rockbridge State Nature Preserve was acquired by the Division of Natural Areas and Preserves in 1978. It is open to public visitation.
Rockhouse is unique in Ohio. It is by far the longest known natural arch in the state. It is also the longest natural tunnel and the only arch with "gothic windows" opening through its side. This scenic treasure quickly attracted the interest of geologists and tourists alike, making it one of the first areas of Hocking Hills State Park to be protected.
Rockhouse was formed by the widening of a vertical crack which separated a large block of Black Hand sandstone from the main cliff above a small tributary of Laurel Run. This created a passage nearly 200 feet long, 40 feet high and 20 feet wide. Enlargement of secondary joints crossing the main one has led to the formation of the tunnel's distinctive "windows."
Ladd Natural Bridge
This natural bridge is the only one in Ohio known to have been promoted as a commercial tourist attraction. Sometime after World War I, the Ladd family, which has owned the arch for many years, charged visitors 10 cents to visit. Some of the braver tourists even drove their cars across the span, making Ladd one of the few natural bridges in Ohio which has actually carried vehicular traffic. The bridge is 40 feet long, 12 feet wide and 5 feet thick--strong enough to hold a vehicle.
In 1984, the Ladd family dedicated 35 acres containing the natural bridge as a state nature preserve. A free access permit from the Division of Natural Areas and Preserves is required.
Although it is one of the state's smallest natural arches, Raven Rock Arch boasts the most scenic location of them all. Found high atop a cliff of Mississippian sandstone capping a 500 foot high bluff, it opens out onto a spectacular view of the Ohio River valley. Raven Rock Arch is a thin remnant of stone 14 inches wide at its narrowest point and 15 feet long.
In 1996, 95 acres of Raven Rock were dedicated as a State Nature Preserve and can be visited by first obtaining a permit from the Division of Natural Areas and Preserves.
Located in the upper end of Rocky Fork Gorge, this natural bridge is found in the Peebles dolomite, a rock formation which contains many of western Ohio's natural arches. It resulted when a crevice parallel to the cliff face was widened until it cut through the roof of an alcove carved out by an intermittent waterfall.
The remaining front edge of the alcove now forms the natural bridge. It has a length of 46 feet and is found in Miller Nature Sanctuary State Nature Preserve.
This arch may not be very large, but it makes one of the grandest appearances of any arch in Ohio. An unsuspecting visitor following the Miller Sanctuary Trail comes upon it suddenly--a great, rounded frame enclosing a cameo portrait of Rocky Fork Gorge.
The resulting opening has a span of 9.5 feet and a clearance of 5 feet. Although the arch appears at first to be the remnant of a collapsed cave, it was more likely formed by the weathering away of a highly-fractured section of Peebles dolomite forming the cliff. The arch is located in Miller Sanctuary State Nature Preserve which is open to the public.
“Rainbows of Rock, Tables of Stone: The Natural Arches and Pillars of Ohio” (McDonald and Woodward Publishing Company, 2009) written by retired State Nature Preserve manager Tim Snyder.
Ohio Department of Natural Resources Division of Geological Survey, Educational Leaflet No. 18, 2011, by Tim Snyder