334 THE ILLINOIS GLACIAL LOBE. 



resembling it in appearance are present within the limits of the sanely 

 ridges. The.se deposits are somewhat calcareous and in places carry small 

 nodules of lime. The sand appears to graduate horizontally into the loess- 

 like silt in passing- westward down the Iroquois Valley from Jasper County 

 into Newton County, Indiana, also in passing westward from the moraine 

 in eastern Iroquois County, Illinois, into the lower districts along the 

 Iroquois Valley. In a few places loess-like silt was found among the sand 

 ridges on the immediate border of the moraine. With these exceptions 

 there is but little silt or clayey material present. The flat areas are often 

 sandy, and heavy beds of peat or surface muck are rare. In one locality 

 near Reynolds, Indiana, beds of peaty muck containing vegetal remains 

 are reported to underlie the sand ridges, thus denoting an interval of emer- 

 gence or exposure to atmospheric action between the withdrawal of the ice 

 sheet and the spreading out of the sand deposits. Well authenticated 

 instances were found only along the south border of the sand area, and 

 their significance is not understood. 



INTERPRETATIONS. 



The limits of the sand area on the north, east, and southeast being 

 found in moraines, the question naturally arises whether the sand is not an 

 outwash from one or more of the ice lobes which formed these bordering 

 moraines. Furthermore, the direction of the retreat of the margin being 

 such as to gradually uncover this area from its western toward its eastern 

 and northern borders, it needs to be determined whether the sand-covered 

 area may not have been gradually extended from the southwest toward the 

 northeast. 



Upon examining into the connection between the sand deposits and the 

 moraines it is found that in the northeast part of the area the moraines have 

 a gravelly outwash, but this does not oppose the view just suggested, since 

 the gravel seems to graduate into sand upon passing from the moraines into 

 the sand-covered area. There is also a change to sand along the immediate 

 borders of the moraine, either upon passing south along the Maxinkuckee 

 moraine, or west along the Valparaiso moraine. 



Examining into the second question, it is found that the sand ridges in 

 places alternate with bowlder belts in such maimer as to lend some support 

 to the view that the sand was deposited in connection with the northeast- 



