Lake Maumee - The Lake Retreats in Stages

The Lake Retreats in Stages

Two later stages of Lake Maumee, (called the "Lowest" and the "Middle," in that order) had lower water levels because the retreating ice exposed an outlet lower than the Wabash-Erie Channel. The Lowest Maumee (elevation: about 760 ft (232 m) ASL) drained westward through the Grand River in Michigan and into Glacial Lake Chicago, an ancestor of present-day Lake Michigan. Another advance of the ice blocked that outlet, raising the lake level to about 780 feet (238 m) ASL, the stage known as the Middle Maumee. A new outlet called the "Imlay Outlet" formed that connected with an unobstructed segment of the Grand River farther west. There is enough uncertainty about this sequence that some authorities think that Middle Maumee might have preceded Lowest Maumee.

Fluctuations in water level continued through more stages (Akrona, 695 feet (212 m); Whittlesey, 738 feet (225 m) ASL; Warren and Wayne, 660–685 feet (201–209 m) ASL; and Lundy, 590–640 feet (180–195 m) ASL. This see-saw pattern continued until an eastern outlet opened at Niagara, establishing the drainage pattern of modern Lake Erie (569 feet (173 m) ASL). This involved the reversal of drainage in what is now northeastern Indiana and northwestern Ohio as the Maumee River outlet developed by capturing streams that formerly drained into the Wabash. The Great Black Swamp that once occupied much of the land between Sandusky, Ohio, and New Haven, Indiana, was a remnant of the bed of Glacial Lake Maumee. Geologists call the former lake bottom the Maumee Lacustrine Plain.