230 
IOWA ACADEMY OF SCIENCE 
to the hilltops. Nor is this an isolated case. A few pebbles and boulders 
will almost always be found in the surface clay if one but searches. 
High up in the so-called “loess” at Greenfield was found a bowlder 
the size of a man’s head. Better evidence could not be for the con- 
clusion that the material was deposited directly by the ice, and not by 
any secondary agency. 
