The Ohio River Story -Part IV (GM-26)
The valley of the Ohio River along the southern margin of Indiana probably was formed in a single cataclysmic event as glacial meltwater spilled across divides and rapidly etched a major valley where only minor streams had flowed before. The valley then was partially refilled by sand and gravel associated with the melting of more recent glaciers. The latest episode of filling took place about 20,000 years ago when the Wisconsinan glacier reached almost to Cincinnati and poured debris into the valley at that point. In the great ribbon of sand and gravel that extends far down the Ohio, coarser materials are found near the source of the meltwater. Therefore gravel is abundant above Jeffersonville but is scarce downstream.

Our Hoosier State Beneath Us: Geomorphology