Lake Warren

Lake Warren formed in the Lake Erie basin around 12,700 years before present (YBP) when Lake Whittlesey dropped in eleveation. Lake Warren is divided into three stages Warren I 690 feet (210 m), Warren II 680 feet (210 m) and Warren III 675 feet (206 m), each defined by the relative elevation above sea level.

Lake Warren followed Lake Wayne. It covered the basin of Lake Erie, part of Lake Huron, including Saginaw Bay and the lowland, which separates Lake Huron from Lake Erie. It included a part of the Lake Ontario basin and the lowland between Lakes Ontario and Erie. Lake Warren included the Saginaw basin and the Huron-Erie basin. Its outlet was through the Grand River to Lake Chicago. The beach stands at 680 feet (210 m) above sea level west of the hinge line, unaffected by the isostatic rebound. It is marginally above the outlet, at 670 feet (200 m). Lake Warren was preceded by a lower stage, which had its outlet through the Mohawk valley. Lake Warren came into existence its waters were raised from Lake Wayne by advancing ice front. The ice both compacted the area where the melt water could be held, raising the water level, while blocking the lower outlet from Lake Wayne.

Lake Warren was about half the size of the present day Lake Erie, lying in the southern half of the basin.

The beach rises to the north of the Grand River outlet at 2 feet (0.61 m) per mile until it reaches 800 feet (240 m) near Gladwin. It is also nearly 800 feet (240 m) on the point of the "Thumb" in Huron county north of Bad Axe. The beach is horizontal from Lenox, in St. Clair county, around the west end of Lake Erie, then along the south shore through Ohio to the Pennsylvania line, a distance of 300 miles (480 km). Between there and Batavia, New York, it rises 200 feet (61 m) in the next 150 miles (240 km).

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