474 THE TENOKEE IRON-BEARING SERIES. 



To give in full the reasons for the positions assigned to these various 

 series and the underlying and overlying rocks would be but to i-ej)eat the 

 discussion before referred to. In the above table the Penokee series proper, 

 including the Quartz-slate, Iron-bearing, and Upper slate members, is placed 

 as the equivalent of the Upper Huronian, Upper Marquette, Upper Ver- 

 milion, and the quartzites of Wisconsin, Minnesota, and Dakota, primarily 

 on structural and secondarily on lithological grounds, while the Cherty 

 limestone at the base of the series, being separated by a considerable erosion 

 interval from the Penokee series proper, is regarded on grounds of a 

 similar character as equivalent to some part — probably a lower part — of 

 the Lower Huronian, Lower Kaministiquia, Lower Vermilion, Lower Mar- 

 quette, and equivalent series. The position assigned to this formation Is 

 warranted because of the very considerable time break between the Cherty 

 limestone and the Penokee series proper. 



The Penokee series and those series equivalent to it constitute a part 

 of the great Algonkian system, and the Southern Complex is Archean.* 



