MAN AND THE GLACIAL PERIOD. 661 



the flood-plain of modified drift at Brainerd has a height of 

 about 60 feet above the river ; at Little Falls, as before noted, 

 its height is 25 to 30 feet ; at St. Cloud, 60 feet ; at Clear- 

 water and Monticello, 70 to 80 feet ; at Dayton, 45 feet ; and 

 at Minneapolis, 25 to 30 feet above the river at the head of 

 St. Anthony's Falls. 



The modified drift at Little Falls lies on the till or direct 

 deposit of the ice-sheet, and forms a surface over which the 

 ice never readvanced. It lies far within the area that was ice- 

 covered in the second and latest principal epoch of glaciation, 

 and by reviewing the steps in the recession of the ice of that 

 epoch we shall be able to ascertain approximately what were 

 the outlines of its receding margin when the gravel and sand 

 plain of Little Falls was deposited, inclosing these evidences 

 of man's presence. The ice-sheet, supplying both this modi- 

 fied drift and the floods by which it was brought, still covered 

 much of the upper part of the Mississippi basin, which ouly 

 reaches about a hundred miles north of Little Falls ; and the 

 courses of massive morainic belts show the continuation of the 

 glacial boundary northwestward across Dakota and with less 

 clearness eastward across the Laurentian lakes. 



When the -latest North American ice-sheet attained its 

 greatest area, its southern portion from Lake Erie to Dakota 

 consisted of vast lobes, one of which reached from central and 

 western Minnesota south to central Iowa. This lobe in its 

 maximum extent ended near Des Moines, and its margin was 

 marked by the Altamont moraine, the first and outermost in 

 the series of eleven distinct marginal moraines of this epoch 

 which are recognizable in Minnesota. When the second or 

 Gary moraine was formed, it terminated on the south at Min- 

 eral 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, crossing southern Le 

 Sueur county. Minnesota, marks the next halting-place of the 

 ice. At the time of formation of the fifth moraine, the south 



