Therefore, the towering eastern hemlocks, the Canada yew and the yellow and black birch tell of a cool period 10,000 years ago. Upon their retreat, this condition persisted only in a few places such as the deep gorges of Hocking County. The glaciers changed the climate of all Ohio to a moist, cool environment. Finally, the huge slump blocks of rock littering the streams tumble from near by cliffs when cracks widen to the extent that the block is no longer supported by the main cliff.Īlthough the glaciers never reached the park areas, their influence is still seen here in the form of the vegetation growing in the gorges.
They are formed by differential weathering which comes about when water, moving down through the permeable sandstone, washes out small pockets of loosely cemented sand grains. Honeycomb weathering looks like the small holes in a beehive comb. It is actually the cross section of an ancient sand bar in the delta and was caused by changing ocean currents. The first is noticeable as diagonal lines in the rock intersecting horizontal ones. Other features of the rock include cross-bedding, honeycomb weathering and slump blocks. Weathering and erosion widened cracks found in the middle layer of sandstone at the Rock House to create that unusual formation. The recess caves at Ash Cave, Old Man's Cave and Cantwell Cliffs are all carved in the softer middle zone. The sandstone varies in composition and hardness from softer, loosely cemented middle zone to harder top and bottom layers. Subsequent millions of years of uplift and stream erosion created the awesome beauty seen today. This bedrock was deposited more than 350 million years ago as a delta in the warm shallow sea which covered Ohio at that time. The scenic features of the six areas of the Hocking Hills State Park complex are carved in the Blackhand sandstone. Here, in these sandstones and shales, one can read Ohio's history from the rocks. The natural history of this region is as fascinating as the caves are beautiful.
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