F0R3IER HIGHER LEVEL OF THE GREAT LAKES. 249 



ments, and he who can read the language may ponder there 

 the vicissitudes of the ages. 



While, during the high tides of the lakes, the erosive 

 waves were gnawing at the rocks of Mackinac and Ohio, 

 the waters of Lake Michigan, in a quieter mood, were per- 

 forming a work equally enduring and peculiar. Here we 

 find our attention challenged by the question of prairie 

 origin and prairie features, but the views to be presented 

 will be held in abeyance until a chapter on a subsidiary 

 topic shall have been interposed, 



L2 



