Three abandoned postglacial beaches at the south end of Lake Michigan have been known for many years. In 1870 Dr. Edmund Andrews described them in a very elaborate paper published by the Chicago Academy of Sciences. Later, Mr. Leverett, in his monograph, “Illinois glacial lobe,” and Mr. William C. Alden, in his Chicago Folio of the U. S. Geological Survey, have collected the facts in very full measure. From these and other published observations it appears that, surrounding the south end of Lake Michigan from about the vicinity of Waukegan, on the west side, and extending indefinitely northward on the east side, there is an abandoned beach approximately 60 feet above the level of the lake. This is called the Glenwood beach.
Twenty feet lower, or about 40 feet above the present level of the lake, occurs what is called the Calumet beach. Twenty feet lower still, or approximately 20 . . .