Glenwood Shoreline

The Glenwood Shoreline is an ancient shoreline of the precursor to Lake Michigan, Lake Chicago. It is named after the town of Glenwood, Illinois. The shoreline was formed when the lake was higher during the last Ice Age, while ice blocked the Straits of Mackinac. After the straits were freed, the lake receded and left behind a sand ridge at an elevation of about 640 feet (200 m) where the shore resided. This ridge can be seen clearly in Glenwood, Illinois, Dyer, Indiana, and Schererville, Indiana, all south of Chicago.

The two higher beaches of Lake Chicago, the Glenwood and the Calumet, are not visible along the northern part of the Lake Michigan. The readvance of ice lobe may have buried or eroded any northern remains.

The Glenwood beach is the highest beach formed by Lake Chicago. In the Wisconsin it lies close to the shore of Lake Michigan and has been eroded by the modern lake and Lakes Nipissing and Algonquin. Southward into Illinois the remnants are broken by erosion, until reaching the area of Winnetka. From here, the beach is further inland a nearly continuous around the city of Chicago into Indiana at Chesterton. Northward into Michigan is follows the west edge of Covert Ridge into Holland. The ridge is park of the Lake Border moraine. The beach reaches back more than 2 miles (3.2 km) from the modern shoreline while in other places, the modern lake as eroded the old beach shore. North of Holland it passes through the Grand and Muskegon valleys and can be from 6 miles (9.7 km) to 20 miles (32 km) from Lake Michigan. 10 miles (16 km) north of the Muskegon River the beach returns to the shore of Lake Michigan.

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