Geology
From a geological standpoint, the Ohio River is young. The river formed on a piecemeal basis beginning between 2.5 and 3 million years ago. The earliest ice ages occurred at this time and dammed portions of north-flowing rivers. The Teays River was the largest of these rivers. The modern Ohio River flows within segments of the ancient Teays. The ancient rivers were rearranged or consumed by glaciers and lakes.
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