MORAINES FORMED BEFORE LAKE AGASSIZ. 141 



and running in great loops, the boundaries of lobes of the ice-sheet, across 

 Illinois, Indiana, and Ohio. These are embraced within a strip of country 

 of similar width with that of Minnesota, Iowa, and the Dakotas, which, 

 though 200 or 300 miles wide, is yet only a minor part of the drift-covered 

 area of this continent. For the interior of this area the observations of 

 Bell and Low give us good assurance that nearly an equal profusion of 

 marginal moraines, recording step by step the wavering depai-ture of the 

 ice-sheet, await exploration in all the region northeast and north from 

 Minnesota and the Great Lakes to Hudson Bay, and from northern Penn- 

 sylvania, New Jersey, Long Island, Marthas Vineyard, Nantucket, and 

 Cape Cod to the Laurentide highlands, north of Montreal and Quebec. 



EARLIEIi MOIiAINES FORMED BEFOFE THE BEGINXISG OF LAKE AGASSIZ. 



When the North American ice-sheet attained its greatest area, and 

 during its later lowan and Wisconsin stages, its southern portion, from 

 Lake Erie to the Missoiiri Eiver, consisted of vast lobes, one of wdiich, at 

 the beginning of the Wisconsin stage of accumulation of moraines, reached 

 from central and western Minnesota south to central Iowa. This Minne- 

 sota lobe then ended near Des Moines, and its margin was marked bv the 

 first or Altamont moraine, lying upon the Coteau des Prairies and in part 

 forming its crest. When the second or Gary moraine was formed, it tei'- 

 minated on the south at Mineral Ridge, in Boone County, Iowa. At the 

 time of the third or Antelope moraine it had farther retreated to Forest 

 City and Pilot Mound, in Hancock County, Iowa. The fourth or Kiester 

 moraine was formed when the southern extremity of the ice-lobe had 

 retreated across the south line of Minnesota and halted a few miles from 

 it in Freeborn and Faribault counties. The fifth or Elysian moraine, cross- 

 ing southern Lesueur County, Minn., marks the next halting place of the 

 ice. At the time of formation of the fifth moraine the soiith end of the 

 ice-lobe had been melted back 180 miles from its earlier extent, shown by 

 the Altamont moraine, and its southwest side, which at first i-ested on the 

 Coteau des Prairies, had retired 30 to 50 miles to the east side of Big Stone 

 Lake and the east part of Yellow Medicine County. 



During- its next stage of retreat the Minnesota ice-lobe was melted 

 away from the whole of Lesueur County, and its southeast extremity was 



