CHAPTER XIV. 

 GLACIAL LAKE CHICAGO. 



By Frank Leverett. 

 EARLY INVESTIGATIONS. 



The beaches of glacial Lake Chicago from the outlet near Chicago northward to the Illinois- 

 Wisconsin line on the west side of Lake Michigan and to the -vicinity of Holland, Mich., on the 

 east side, have already been described by the writer. 1 More recently studies by the writer and 

 by Mr. Taylor have been extended northward on the east side of the lake to the Straits of Mackinac, 

 and studies by Alden and by Goldthwait have covered much of the Wisconsin part of the west 

 side of the basin, Alden devoting himself chiefly to the Chicago beaches, and Goldthwait to the 

 Algonquin and Nipissing beaches. 



DISTRIBUTION OF BEACHES. 



As a result of these studies it has been determined that the two higher beaches of Lake Chi- 

 cago, the Glenwood and the Calumet, are not present in the northern part of the Lake Michigan 

 basin, at least as surface features. A readvance of ice has probably to some extent overridden 

 and buried their northern ends, making it impossible to determine their full limits. On the east 

 shore they are traceable to a gravel plain outside the Manistee moraine that passes beneath Lake 

 Michigan between Ludington and Manistee and that appears to be a part of the Port Huron 

 morainic system of the Huron basin. On the west shore traces of stream deltas and a slight 

 beach at about 60 feet were found by Alden to extend northward to a point 10 or 12 miles 

 south of Manitowoc. 



GLENWOOD BEACH. 

 GENERAL DISTRIBUTION. 



The Glenwood beach, named from Glenwood, 111., a village standing on it a few miles south 

 of Chicago, is the highest beach formed by Lake Chicago. In the Wisconsin portion it lies very 

 close to the shore of Lake Michigan; in fact it has been to some extent .cut away by the encroach- 

 ments of the modern lake and to still greater extent by the encroachments of Lakes Nipissing 

 and Algonquin. In the Illinois portion it has been cut away by the modern lake for a few miles 

 between Waukegan and Winnetka and lies near the Lake Michigan shore north of Waukegan. 

 From Winnetka southward the beach passes inland a few miles and remains some distance back 

 from the shore of Lake Michigan as far east as the vicinity of Chesterton, Ind. From near Ches- 

 terton northward into Michigan as far as Holland it lies along the west slope of Covert Ridge, 

 the tdl ridge of the Lake Border morainic system nearest the lake. In few places is it more than 

 2 miles from the shore of the modern lake, and in some places it has been cut back by the mod- 

 ern lake. From Holland northward past the Grand and Muskegon valleys it lies 6 to 20 miles 

 back from the Lake Michigan shore, being most distant south of Grand River valley. About 10 

 miles north of the mouth of Muskegon River the beach comes back to the shore of Lake Michigan. 

 From that point northward past Little Point Sable it has been largely cut away by the encroach- 

 ments of Lake Michigan. In the vicinity of Pentwater it lies back several miles from the Lake 

 Michigan shore, but has been cut away for a few miles south of Ludington. Near Ludington and 

 northward to the gravel plain and moraine that override it, it lies back several miles from the 

 shore. 



i Mon. U. S. Geol. Survey, vol. 38, 1899, pp. 427-453. 



