290 THE ILLINOIS GLACIAL LOBE. 



having generally an elevation of 640 to 650 feet. Possibly a shore line 

 may be found south and east of the dunes at an elevation corresponding to 

 that of the Onarga Ridge, but as yet it has not been discovered. It seems 

 probable that this ridge marks the south shore of a temporary lake which 

 discharged westward through the east fork of Vermilion River. If there 

 were no obstructions at the north, a northward discharge from the Iroquois 

 1 iasii i would seem to be more natural, for the country descends in that direc- 

 tion. The only known former obstruction is that caused by the presence 

 of the ice sheet, in which case this beach may be interpreted as the shore 

 of a glacial lake. The writer's studies have not been sufficiently detailed 

 to justify a full interpretation of the phenomena. Other features of similar 

 character are discussed below (pp. 336-338). 



SECTION TV. THE COMPOSITE MORAINIC BEET OF NORTHERN 



ILLINOIS. 



Numerous references have been made in previous pages to a composite 

 belt of moraines with which the Bloomington system connects in northern 

 Kane County, and which marks the continuation of the Bloomington system, 

 together with that of later morainic systems which are there intimately 

 associated with it. This composite belt admits of but little separation into 

 distinct moraines. It seems advisable, therefore, to give it treatment inde- 

 pendent of each of the morainic systems which lead away from it, leaving 

 open to a large degree the question of precise correlation. This belt is 

 made to include a somewhat distinct moraine, called the Marengo Ridge, 

 which lies along its western border. The discussion of this ridge is first 

 taken up ; the remaining portion of the composite belt west of Fox River is 

 next considered, and this is followed by a discussion of the portion east of 

 Fox River. 



MARENGO RIDGE. 

 DISTRIBUTION. 



North from the A'illage of Hampshire in Kane County, as far at least 

 as the State line, the Marengo Ridge constitutes the outer moraine of the 

 Wisconsin series, and it probably continues to be the outer moraine to its 

 junction with the Kettle moraine of the Green Bay lobe in western Wal- 

 worth County, Wisconsin. 1 The ridge receives its name from the village of 



1 See T. C. Chaniberlin : Third Ann. Rept. U. S. Geo!. Survey, p. 322; also PL XXXI. 



