GLACIAL OR ICE-LAID DEPOSITS 



51 



valley. (Fig. 41). Lake Chicago, the axtension of Lake Michigan, 

 Lake Maumee, an extension of l^ake Erie, and other lakes at Green 

 and Saginaw Bays produced lake-laid soils and formed characteristic 

 beaches. 



The material deposited by the glaciers is of every grade from 

 the finest clay to boulders weighing many tons (Fig. 46). Its value 



Fio. 46. Granite boulder weif?hini; about 30 tons, at dopot of Northwestern R. R., 

 Waukejtan, 111. 



Fio. 47. Heap of boulders collected from a moraine in northern Illinois 

 (R. W. Dickenaon ) 



