BOWLDER BELTS. 327 



It seems more probable that the belt marks the position of the ice 

 margin at some stage of advance between the formation of the Marseilles 

 and Valparaiso moraines. Were the belt accompanied throughout by a 

 moraine, or even a thin sheet of drift, this interpretation would seem well 

 supported. For a few miles in the vicinity of the point where it crosses 

 the Marseilles moraine there are low knolls accompanying the bowlders 

 which may prove to be of the same date as the bowlder deposition. They are 

 much smaller than the swells on the Marseilles moraine, being usually only 

 3 to 5 feet in height and covering a few square rods each. They inclose 

 shallow saucerdike depressions, and on the whole give the surface a fresher 

 contour than is presented by the portion of the Marseilles moraine to the 

 west, The portion of the belt from Morris northward was made a subject 

 of joint investigation by Professor Chainberlin and the writer, and to 

 each of us the surface contours appeared somewhat fresher along the line 

 of the bowlder belt than in the district to the west. But the development 

 of a new or distinct topography in connection with the bowlder belt seems 

 at best to be limited to the immediate vicinity of the Marseilles moraine, 

 and leads us to feel some doubt concerning the interpretation of the occur- 

 rence of a thin sheet of drift in connection with the bowlder belt. 



It will be observed that the course of this bowldery strip is nearly 

 parallel with the Minooka Ridge and its supposed eastern continuation along 

 the Kankakee. This parallelism has suggested the interpretation that the 

 bowlder belt may be closely related to that ridge Possibly there was a 

 temporary advance of the ice beyond the position it held while forming 

 the ridge, .or possibly the accumulation of the bowlders and the ridge 

 occurred at the same time, the former being at the extreme margin and the 

 latter a short distance back from the margin. The smoothness of the ridge 

 apparently favors the interpretation that it is a submarginal accumulation. 



Another interpretation refers the formation of the bowldery strip to an 

 advance subsequent to the formation of the Minooka Ridge. In that case 

 the smoothness of the ridge may be due to its having been overridden. 



It seems highly probable that this bowldery strip is to be correlated 

 with the Iroquois moraine and associated bowlder belts found in Iroquois 

 County, Illinois, and Benton and Warren counties, Indiana, which are 

 referred to the late Wisconsin invasion. The indefiniteness of the bowldery 

 strip in the sandy districts of eastern Kankakee and northeastern Iroquois 



