GLACIAL LAKES AND THEIR CORRELATIVE ICE-BORDERS 



IN THE SUPERIOR BASIN. 



HY FRANK LEVERETT. 



(Abstract.) 



The paper deals only -svitli tlu' final recession of the ice from tlie 

 Superior Basin^ and from what appears to be the Port Huron morainic 

 system in that basin. There seems to have been considerable ice reces- 

 sion preceding the Port Huron readvance with a corresponding enlarge- 

 ment of glacial lakes in this basin as well as in the Huron and Michigan 

 basins. The readvance overrode and completely obliterated the glacial 

 lake in tlie western Superior basin. There was probably also an inter- 

 glacial lake in the Superior basin following the Illinoiaa glaciation. 



The latest lobe of ice that occupied the Superior basin was part of 

 the Labrador ice sheet. On melting away it made a northeastward reces- 

 sion from the west end of the basin past the Keweenaw Peninsula. At 

 the same time there was northward recession of the ice border from the 

 Michigan and Huron basins across the eastern end of the Northern 

 Peninsula into the eastern part of the Superior basin. The latest hold 

 of the ice on the soil of Michigan was in the part of the shore of Lake 

 Superior between the Huron Mountains and Whitefish Point. 



The ponding of glacial waters at the west end of the Superior basin 

 was at first in a chain of small lakes, separated by higher unsubmerged 

 areas, which extended to the border of the ice. Lake Nemadji, at the 

 extreme west end of the Superior Basin, discharged past Moose Lake, 

 Minnesota, to Kettle River and thence to the St. Croix and Mississippi 

 Rivers. Lake Brule occupied a narrow strip along the Brule valley and 

 discharged southward to the St. Croix River. The next lake to the east 

 covered a lowland south of Ashland and will be termed Lake Ashland. 

 This lake discharged westward across the Bayfield Peninsula, just south 

 of Iron River, Wisconsin, to Lake Brule. The northern part of the 

 peninsula was still covered by the ice slieet. Still farther east was 

 another lake covering part of the Ontonagon drainage basin in the western 

 part of the Northern Peninsula of Michigan, and called Lake Ontonagon. 

 This discharged westward into Lake Ashland near Saxon, Wisconsin. 

 At this time the ice still covered the plain between the Copper Range 

 and Lake Superior. 



19th Mich. Acad. Sci. Kept., 1917. 



