30 PLEISTOCENE OF INDIANA AND MICHIGAN. 



RETREATS AND EEADVANCES OP THE ICE. 



The Wisconsin drift, as displayed in Illinois, Indiana, and Michigan, has several complex 

 systems of moraines marking either halts or readvances of the ice border, between which are 

 nearly plane-surfaced tracts over which the ice border probably retreated somewhat rapidly. 

 In connection with the retreat of the ice sheet into and beyond the basins of the Great Lakes, large 

 glacial lakes were developed, the drainage of which differed widely from the present system of 

 drainage, being chiefly to the Mississippi and the Gulf of Mexico. 



GROUPING OP THE MORAINES. 



The moraines of the Wisconsin stage are more or less concentrated in groups. (See PL 

 XXXII, in pocket, and table opposite this page.) Several moraines, closely crowded together, 

 adjoin a few that are more widely spaced, and these in turn are succeeded by another closely 

 crowded group, and then by others more widely spaced. Thus in the Illinois district the 

 ShelbyviUe moramic system, formed at the culmination of the Wisconsin stage of glaciation, 

 consists of three ridges where most deployed and of one or two where more closely crowded. 

 North of this comes the Cerro Gordo moraine, the latest moraine of the ShelbyviUe system, 

 and three weak ridges classed as the Champaign moramic system, which are distinct for most 

 of their length, but which merge at the west into a single ridge. Thus of seven. ridges three 

 are closely combined into the great ShelbyviUe system, and four, whose aggregate bulk is less 

 than that of the ShelbyviUe system, are spread over a space several times as great. These 

 weaker ridges are succeeded to the north by four bulky, closely associated ridges known as 

 the Bloomington morainic system, which in turn is succeeded in eastern Illinois by two widely 

 spaced moraines, the Marseilles moramic system and the Minooka moraine, and .in northwest- 

 ern Indiana and southern Michigan by others known as the Maxinkuckee, the Bremen, the New 

 Paris, the Middlebury, the Lagrange, the Sturgis, and the Tekonsha, which, can be conxpared 

 with the Cerro Gordo moraine and the Champaign system, though they are as a whole somewhat 

 more bulky. Next comes another series of moraines, which comprises the Kalamazoo and 

 Valparaiso morainic systems of the Lake Michigan basin, and the Mississinawa moramic sys- 

 tem and perhaps three or four later moraines of the Huron-Erie basin. Connecting these is a 

 great series of moraines at the end of the Saginaw lobe, whose principal members pass through 

 Jackson and Charlotte and which is comparable to the Bloomington and ShelbyviUe systems. 

 It is followed by a series of weaker and more widely spaced moraines which extend back, in 

 the Saginaw and Huron basins, to the Port Huron morainic system of closely aggregated 

 ridges. This last, in turn, is followed by other wider-spaced ridges. 



The moraines of the Wisconsin drift are so numerous and in places are so intricately com- 

 bined that in this paper it is found advantageous to consider them in groups rather than to 

 attempt complete correlation of each moraine across the entire region discussed. This method 

 has nearly all the advantages of individual tracing without involving questionable correlations. 

 It is also much eimpler for the reader to follow. 



The first two groups of moraines, as noted above, include those formed in the adjustment 

 of the shrinking ice sheet to the basins that held the Lake Michigan, Saginaw, and Huron-Erie 

 lobes. With their intermorainic tracts they include an area reaching from south of Kankakee 

 River in western Indiana to south of Mississinawa River in eastern Indiana and extending 

 northward into Michigan to the vicinity of Kalamazoo and Battle Creek. 



The third group of moraines embraces the Kalamazoo and Valparaiso morainic systems 

 of the Lake Michigan lobe, the Kalamazoo and Charlotte systems of the Saginaw lobe, the 

 Mississinawa, Salamonie, Wabash, and Fort Wayne moraines of the Huron-Erie lobe, and the 

 interlobate belts between the Lake Michigan and Saginaw lobes and between the Saginaw and 

 Huron-Erie lobes. In this group all the bulky moraines of the southern haK of the southern 

 peninsula of Michigan are included. 



The fourth group of moraines embraces the Lake Border moramic system of the Lake 

 Michigan lobe, a series of weak moraines in the Saginaw basin and the moraines between the 



