72 CHICAGO ACADEMY OF SCIENCES. 



The Second or Calumet Beach. — This beach throughout 

 much of its course in Indiana and for a short distance in Ilhnois 

 follows the south border of the Calumet River, and because of this 

 close association the name Calumet seems appropriate. It stands 

 about 20 feet lower than the Upper beach, and its course in the 

 Illinois portion of the region traversed by it is indicated on the 

 accompanying map (Plate 3). From the Wisconsin line southward 

 to Chicago River it is closely associated with the Upper beach, 

 wherever that beach remains. From the Chicago to the Des 

 Plaines River it is separated from the Upper beach by an interval 

 of i-J to 3 miles. The outlet at this stage was at the Des Plaines 

 River, between the villages of Riverside and Summit, and the 

 beach gravels are well developed for a short distance below Sum- 

 mit on the east side of the outlet. The beach leads somewhat 

 directly southeastward from Summit to the north end of Blue 

 Island ridge and then southward along the east side of the ridge, 

 past Washington Heights to the Calumet River, two or three 

 miles east of Blue Island. The Sag outlet had its head at this time 

 in a wide opening between the Calumet and Thornton. Immedi- 

 ately east of Thornton the beach reappears in its customary 

 strength and passes thence eastward across Lake County, Indiana, 

 following the south border of Calumet River at an average dis- 

 tance of perhaps a mile from this stream. In western Porter 

 County, Indiana, near the line of Portage and Westchester Town- 

 ships, it crosses to the north side of the river, and its course from 

 that point eastward across Porter and northwestern LaPorte 

 Counties is nearly parallel with the present shore of Lake Michi- 

 gan and distant from it two to three miles. In Michigan it borders 

 the lake even more closely, as far north as observations were 

 carried (to latitude 42 degrees, 30 minutes), being found usually 

 within a mile or two of the lake shore. 



This beach extended a conspicuous bar out some distance into 

 the lake above Chicago. Its northern end is found at the lake 

 shore between Wilmette and Evanston, and leads thence south- 

 ward through the west part of Evanston to Rose Hill Cemetery, 

 and there turns abruptly westward and terminates at the. village 

 of Bowmanville, on the east blufif of Chicago River. It is probable 

 that this bar was attached to the old shore at some point farther 

 north than its present terminus, a portion of it having been re- 

 moved by the encroachments of Lake Michigan. The bay back 

 of this bar had a width of one to four miles and a depth of 15 to 20 

 feet in its deepest parts. Portions of it were so shallow as to be 



