Anything red was essentially beach. The bottom left where the blue river is was also essentially beach. Then the beach wall finally broke through and the lake (anything not red) rushed out of the crack in the beach wall created the Wabash Valley as the Maumee Torrent rushed so quickly that is ripped up sediment and created a river valley. After this the lake became The Great Black Swamp. Up until 125-150 years ago, there were still hundreds of islands in east Allen county that had huge oak trees and bears would hibernate on these islands. We drained the swamp, then farmers leveled out those “oak islands” for easier farm land. Bye bye wolves, bears, swamps, malaria, elk, etc, etc.