Glenwood Shoreline

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Glacial Lake Chicago at the 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.[1]

Development[edit]

Drawing of Lake Chicago at the Glenwood Stage showing the Chicago area.

The Michigan Lobe of the continental glacier had been growing and receding since 70,000 BCE. The glacier had been static along the Valparaiso Moraine for many years before it again began to recede northward. Around 12,000 BCE the glacier began receding north of the Valparaiso Moraine. The melt waters began to form a lake between the southern front of the glacier and the moraine, which acted as a dam. The water collected until it found a low spot in the moraine, near modern Palos Hills, Illinois. Here, it topped the moraine and began cutting an outlet. At around 640 feet (200 m) above sea level, it stopped cutting downward and a stable lake formed.[2]

Where to see the shoreline[edit]

The beach name comes from Glenwood, Illinois. Beginning in Dyer, Indiana, along U.S. Route 30, the beach continues eastward from where U.S. 30 bends southward just east of U.S. 41. Just north of downtown Merrillville it ends. The next segment can be found west of State Route 51 in Hobart, along the southern flank of Deep River.

Leaving Lake County, the beach turns northward. The next visible area is along Salt Creek in Porter County. It is visible on the northern bank from just north of I-80/90, southward across State Route 149. The largest area is just south of downtown Chesterton, Indiana. It extends about 1 mile (1.6 km) east and west of Old SR 49.[3]

See also[edit]

References[edit]

  1. ^ Kenneth J. Schoon, Calumet Beginnings, 2003
  2. ^ The Indiana Dunes - Legacy of Sand; Special Report 8; State of Indiana Department of Natural Resources; Geological Survey, John R. Hill, 1974
  3. ^ The Indiana Dunes - Legacy of Sand; Special Report 8; State of Indiana Department of Natural Resources; Geological Survey, John R. Hill, 1974