68 McKELLAE ON THE ANIMIKIE AND 



StratiCtRAPHICAL Structure. — lu the foregoing pages, I think I have shown that 

 there is a strongly marked lithologieal difference between the almost horizontal and 

 unaltered Animikie and the folded crystalline Huronian schists of Lake Superior. Now 

 I will endeavor to prove by stratigraphical evidence that the difference is conclusive. 



Prof Irving shows that the Animikie beds on the north shore of Lake Superior and 

 the Penokee-Gogebic beds of the south shore, in Wisconsin and Michigan, belong to the 

 same horizon and that wherever they are exposed, with the exception perhaps of the 

 Knife Lake area, as on the south shore, along their strike for some sixty miles, and on 

 the north shore in the same way, from Thunder Bay, to Mississippi River, a stretch of 

 over two hundred miles, they present a simple flat bedding with a moderate dip, always 

 towards the great basin of Lake Superior ; and that their position, as far as known, is 

 always next underneath the Keweenian group, which agrees precisely with the condi- 

 tions of the latter or overlying group in relation to the Lake Superior synclinal. He 

 shows also that the folded schists of the north shore and those of the Marquette and 

 Menominee districts are the same formation and that they are characterised by irregular, 

 steep, complex cleavage or bedding, conspicuously different from the simple flat bedding 

 of the Animikie rocks, all of which, I think, no one can doubt ; at least it agrees com- 

 pletely with my knowledge of the two formations. But when he claims in his hypothesis, 

 that this broad simple trend of the Animikie under the Lake Superior basin remained 

 undisturbed at the time of the steep folding of the Huronian, I cannot agree with him. 

 It seems clear, and I think Prof. Irviug's own showing confirms it, that the Animikie 

 and Keweenian strata must have been comparatively level during the building up of 

 the latter formation, which is now seen ou both sides of the lake dipping towards each 

 other underneath the Lake Superior basin. Therefore, the sinking of the strata in the 

 middle of the lake must have taken place after the building up of the Keweenian group, 

 and before the deposition of the now flat-lying Sault Ste. Marie sandstones. The once 

 molten matter, which constitutes the bulk of the Keweenian strata, must have presented 

 a tolerably level surface over this vast area, at the time of the solidification. It seems 

 plain that the broad geological downward bend or synclinal that forms the geological basin 

 of Lake Superior, could not have resulted concomitantly with the close folding of the 

 Huronian strata, as inferred by Prof Irving in his hypothesis. No one, I think, will 

 claim that the folding of the Archœau strata occurred after the building up of the 

 Keweenian group. 



I have traversed, in considerable detail, almost all the Huronian folded schist areas 

 lying between Michipicoteu and Lake of the Woods. I have seen the Marcjuette schist- 

 formation and spent a good deal of time in examining the folded schist-belt on the South 

 Range, south of the Keweenian or Native Copper Range lying to the south of Ontonogon, 

 Michigan. I have found the ma,jority of the strata of each of these areas to present strongly 

 the Huroniau greenish chloritic aspect previously mentioned. I have also found these 

 strata almost invariably highly inclined or nearly vertical, and associated with gneiss, 

 syenite and granite ; often interstratified with and intersected by the latter two, in which 

 relation the Animikie strata are never found. 



This belt of chloritic and greenstone schists occupies the greater part, if not the whole 

 of the south half of Town 46 N. in Range 3y and 40 W. These schists stand on edge or 

 are highly inclined, striking eastward across the middle branch of Otonagon River towards 



