Evidences of an 1fce 



parts of the country would be more easily 

 picked up and carried than in others; there- 

 fore, the drift accumulated much more rapidly 

 in some sections than in others. 



Another factor that was active in the more 

 rapid accumulation at certain points was the 

 speed at which the ice moved, and this would 

 be determined by the pressure that was behind 

 it, and there would always be lines of unequal 

 pressure existing in such a great glacier as 

 must have existed when these moraines were 

 formed. 



As an instance of the difference in the gla- 

 cial deposits that are made in different periods 

 during the time of the melting of the great ice 

 sheet we may compare the Kettle Moraines of 

 Wisconsin with the clay deposit mixed with 

 broken gravel that we find along the west coast 

 of Lake Michigan. Those whose homes are 

 situated between Winnetka and Waukegan on 

 the lake shore have the foundations of their 

 houses set in glacial drift that was shoved into 

 position by the ice during the glacial period. 



Anyone who makes an examination of the 

 bluffs along the shore of this lake will notice 

 that there is no stratification whatever to the 

 deposit such as will always be found in an un- 

 glaciated region. Going west from the bluff 

 a few miles we come down to the prairie level, 

 where we find the soil of an entirely different 

 nature. The soil of the prairies of Illinois 



