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340 Million Years in the Making

The gorges, caves, and waterfalls of Hocking Hills exist because of Black Hand sandstone — a coarse-grained formation deposited roughly 340 million years ago when this region lay beneath a vast inland ocean. Ancient rivers flowing from the proto-Appalachian Mountains carried sand into the shallow sea, building up layers over 100 feet thick.

The magic happens in the middle. The sandstone has three distinct layers: a resistant upper cap, a softer porous middle, and a resistant lower base. Water infiltrates the middle layer, dissolves the cementing minerals, and carries away loosened sand grains from the inside out — a process called sapping. Over thousands of years, this creates the massive horizontal recess caves beneath the cap rock. The region was never scoured by glacial ice during the last ice age (the glacial boundary runs just to the north), which is why these formations survived while similar geology elsewhere in Ohio was ground flat.

One more thing worth knowing: the creek running through Old Man's Cave gorge is called Queer Creek — named not for any modern connotation but from an old Appalachian dialectal term meaning "strange" or "unusual," likely describing the creek's winding course through the narrow sandstone channels.