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The Glaciated Appalachian (Allegheny) Plateaus

Although continental glaciers easily flowed across the Till Plains of western Ohio, they were not able to advance very far into the Appalachian Plateau Region where high sandstone hills provided a barrier to slow and contain the south and eastward movement of the ice. Where the glaciers were able to encroach upon the plateau, especially to the northern half, the landscape is less hilly and the glacial soils more fertile making the landscape suitable for agriculture, and therefore settlement. Reportedly, there are more people living within the Glaciated Appalachian Plateau and more industry present than within any other physiographic region in the state. This region extends up across the state from the Paint Creek Valley south of Chillicothe, north to Ashtabula County in extreme Northeastern Ohio, a distance of nearly 300 miles. The very erodible soft shale bedrock in the most northerly portion of the plateau enabled the glaciers to override the landscape with relative ease, laying down glacial deposits as far south as northern Stark and Columbiana counties before encountering the high sandstone hills of the Unglaciated Plateau. Within the extreme northeast portion of the Glaciated Appalachian or Allegheny Plateau, in an area known as the “Snow Belt”, there is a characteristic forest cover similar to the Hemlock-White Pine-Northern Hardwood Forests of the Allegheny woods of Pennsylvania and New York., including a number of Allegheny Mountain plant species that occur nowhere else in Ohio. Also within the northern portion of the plateau, two major lobes of the Wisconsian Glacier, the Killbuck Lobe and the Grand River Lobe, formed a narrow, north to south canyon between them extending from Geauga County to Stark County. Torrents of glacial meltwaters coming off each lobe deposited an enormous amount of sand, gravel clay, large cobbles and even huge blocks of glacial ice into this deep canyon corridor between the two lobes. We find most of the best kettle lake sphagnum bogs and boreal fens in Ohio situated within this same corridor.

The more southern leg of the Glaciated Appalachian Plateau follows the Appalachian Escarpment south along a narrow band where glacial ice moved eastward through valleys, among the hills, and over the lower landscape features for only a relative short distance before being blocked by the higher sandstone hills of the Unglaciated Appalachian Plateau. In the western half of this southern section of the Glaciated Appalachian Plateau, we find extensive deposits of till and ground moraine from the Wisconsian Glacier creating a rolling landscape where American Beech and Sugar Maple woodlands tend to dominate. However, the eastern half of this southern extension of the Unglaciated Appalachian Plateau is typically covered with a relatively thin layer of glacial till from the older Illinoian Glacier with more exposed and higher bedrock hills and deep gorges. Here, Oak-Hickory woodlands are more characteristic of the drier, more acidic, and much older soils. Deep cool shaded, moist sandstone and shale gorges within the Glaciated Appalachian Plateau, such as those associated with the Mohican, Chagrin and Beaver Creek rivers, harbored Ice Age relict plants and nesting birds typical of more northern latitudes. Finally, at the extreme southern tip of the Glaciated Appalachian Plateau within the Paint Creek Valley, one encounters the dolomite gorge and cave complex of the Seven Caves Region now the Highlands Nature Sanctuary. Here too, a number of more northern relict species survive, sheltered in the cool shaded, moist northern-like micro climate of the deep gorges.

Ohio Governor’s Residence and Heritage Garden
358 North Parkview Ave., Columbus, Ohio 43209