(54 SKETCHES OF CREATION. 



river along whose valley they have been studied, while the 

 upper is denominated the " Huronian," from the lake upon 

 whose northern shores the upper members of the series are 

 so finely exposed. The iron-bearing rocks of the northern 

 peninsula of Michigan belong to the Huronian system, as 

 well as those of Southeastern Missouri and Northern New 

 York, 



