The Michigan Lobe of the continental glacier had been stagnant for years, forming the Glenwood Shoreline. Once again, it began a general retreat northwards. The melt waters which formed Glacial Lake Chicago, had more space in which to reside. Then it began to drop. It appears that the outlet to the Illinois River, was cutting downward, keeping pace with the lowering lake. At around 620 feet (190 m), it stopped cutting downward and the lake stabilized.
The Calumet beach opens into the Chicago outlet, and is 20 feet (6.1 m) or 25 feet (7.6 m) below the Glenwood beach. It stands about 35 feet (11 m) above Lake Michigan at the southern end. Along much of the east and west shores the beach has been eroded by the lake. Along these shores, it is more than 12 miles (19 km) from the lake. It takes its name from the Calumet River in northwestern Indiana where it is well preserved. On the south shore it is from 1 mile (1.6 km) to 8 miles (13 km) from the lakeshore, continuing as far north on the west shore to near Winnetka.
^The Indiana Dunes - Legacy of Sand; Special Report 8; State of Indiana Department of Natural Resources; Geological Survey, John R. Hill, 1974
^The Pleistocene of Indiana and Michigan, History of the Great Lakes; Monographs of the United States Geological Survey, Vol. LIII; Frank Leverett and Frank B. Taylor; Washington, D.C,; Government Printing Office; 1915; Chapter XIV, Glacial Lake Chicago, F. Leverett