74 THE VERMILION IKON-BEARING DISTRICT. 



rocks of other ages with which it is associated, aud gives many details 

 concerning' the associated rocks. The Copper-bearing series does not 

 include the so-called Lower group of Logan, the Animikie group of Htmt, 

 and also the horizontal sandstones known as the Eastern and Western 

 sandstones; although it includes the dolomitic sandstones, with accompany- 

 ing crystalline rocks occurring between Black and Thunder bays, in the 

 valleys of the Black Sturgeon and Nipigon rivers, and about Lake Nipigon. 

 The Keweenaw or Copper-bearing series then includes the succession of 

 interbedded traps, amygdaloids, felsitic porphyries, porphyry-conglomerates, 

 sandstones, and the conformable overlying sandstone typically developed 

 in the region of Keweenaw Point and Portage Lake. These rocks have 

 their most widespread extent about the western half of Lake Superior, 

 but also occur in the eastern part of the lake. Their entire geographic 

 extent in the immediate basin of Lake Superior is about 41,000 square 

 miles. 



The Animikie series in the Thunder Bay district is of great thickness, 

 probably upward of 10,000 feet, comprising quartzites, quartz-slates, clay 

 slates, magnetitic quartzites, sandstones, thin limestone beds, and beds of 

 cherty and jaspery material. With these are associated in great volume, in 

 both interbedded and intersecting masses, coai'se gabbro and fine-grained 

 diabase, like those well known in the Keweenaw series. A broad examination 

 of the region shows that there is little ground for the belief in one crowning- 

 overflow. The Animikie series is lithologically like the Penokee series in 

 Wisconsin; both series bear the same relations to the newer Keweenawan 

 rocks and the older gneisses, and the two groups are regarded as the same. 



The Animikie rocks have been traced by Bell and also by N. H. 

 Winchell as far west as Gunflint Lake, and are the equivalent of, if not 

 actually contimious with, the Mesabi iron range running to Pokegama 

 Falls and the slates of St. Louis River, although the latter are affected by 

 slaty cleavage. 



The iron-bearing schists of Vermilion Lake are so like the Huroniau 

 that they are regarded as a folded continuation of the Animikie beds, 

 and a generalized section showing the supposed original connection of 

 the Animikie group and the Vermilion Lake iron-bearing schists over the 

 granite of the Mesabi range is introduced. 



That the Animikie Huronian is beneath the Keweenawan rocks is 



