Shallenberger State Nature Preserve
More than 300 million years ago the Hocking Hills region lay under the waters of a vast inland ocean. The oceans have long since disappeared and the subsequent impact of the massive sandstone formation found in the area by water, wind and temperature extremes has resulted in gorges, overhangs, rock shelters, promontories and waterfalls. At Shallenberger State Nature Preserve, the long process of weathering produced Allen Knob, a promontory of highly resistant sandstone, and the smaller adjacent Ruble Knob. Allen Knob towers 240 feet above the surrounding countryside and provides a vista of the central Ohio lowlands to the west. While this major feature of the preserve owes its origin to an ancient marine environment, the preserve also shows the effects of the last major glacial period. More than 10,000 years ago great sheets of ice, in some places more than 1 mile thick, covered portions of Ohio. Shallenberger lies at their southeastern limit.