PRE-KEWEENAWAN FORMATIONS 



695 



units only to section 22, T. 47 N., R. 44 W., where a new unit 

 representing the ferruginous slates is introduced to carry their 

 combined stratigraphic horizons east to the extremity of the 

 range, although isolated patches of iron formation are correlated 

 with the Ironwood. 



The writers' studies indicate very clearly: (i) the extension of 

 the Pahns and Ironwood formations eastward 7 miles beyond the 

 point at which they are dropped as cartigraphic units from the 



STRUCTURE SECTIONS 





KCWEENAWAN 



LEGEND 



UPPER HURON1AN ANIMIKIE 



Fig. 2 



maps of the United States Geological Survey; (2) these forma- 

 tions disappear, not through lithologic gradation into ferruginous 

 slate, but through abrupt truncation by a superior unconformable 

 series; and (3) that these formations are intruded by the granite which 

 appears on these maps as Archean (Lauren tian) . 



The Palms formation. — The Palms formation west of section 22, 

 T. 47 N., R. 44 W., contains about 400 feet of graywacke and 

 slate with interbedded thin bands of quartzite which become 

 gradually more prominent in the upper horizons and grade into a 



