Trans. Wis. Acad.. Vol. XIII. 



Plate XIV. 



im^!,:..- ..n-..-^-v.'-. s;;t -..i^^^-y 



FIG. 1. 



Cracks in the ice. 



FIG. 2. 

 The ribbon like cracks have formed from the under surface and only 

 extend half way through the sheet. 



