IOWA ACADEMY OF SCIENCES. 



81 



Pig. 1. Effect of Expanblon of Ice at Clear Lake (After Calvin.) 



that where so slight a change in elevation of the shore would 

 change the outlet, the change might be brought about by the 

 ice action described. 



Fig. 3. Natural Rlp-rapplng on the Shore of Spirit Lake. (After Macbrlde.) 



6 



