Ohio River

===Upper Ohio River===
The upper Ohio River formed when one of the glacial lakes overflowed into a south-flowing tributary of the [[Teays River]]. Prior to that event, the north-flowing Steubenville River (no longer in existence) ended between [[New Martinsville, West Virginia|New Martinsville]] and [[Paden City, West Virginia]]. The south-flowing Marietta River (no longer in existence) ended between the present-day cities. The overflowing lake carved through the separating hill and connected the rivers. The floodwaters enlarged the small [[Marietta, Ohio|Marietta]] valley to a size more typical of a large river. The new large river subsequently drained glacial lakes and melting glaciers at the end of the ice ages. The valley grew during and following the ice age. Many small rivers were altered or abandoned after the upper Ohio River formed. Valleys of some abandoned rivers can still be seen on satellite and aerial images of the hills of Ohio and West Virginia between Marietta, Ohio, and [[Huntington, West Virginia]].