72 McKELLAR ON THE ANIMIKIE AND 



the old rocks, sometimes half a mile or more from the general line of contact, as, for 

 example, behind Amethyst Harbour. 



Near the foot of Thunder Bay, the line of contact of the two formations trends north- 

 ward across the strike of the Huronian green schists to the granite range lying about five 

 miles back from the bay. Along this line, the two formations are dovetailed into one 

 another for miles. In some cases, the dovetailing is caused by faulting, as for example, 

 along the Blende Lake vein, and along the great Silver Lake fault. The latter causes 

 the slightly-inclined Animikie beds to overlap the vertical Huronian strata on the north 

 side of the fault, for a distance of three miles or more. The overlying Kew^eeniau beds 

 of sandstone and marl overlap the Huronian crystalline schists for over a mile. The 

 conglomerate bed at the base of the Keweenian group is well exposed on the north side 

 of the fiiult in the cutting on the Canadian Pacific Railway near the west end of Loon 

 Lake, while on the south side, the same bed is expo.sed east ef the Silver Lake Iron Mine, 

 within fifteen or twenty chains of Silver Lake. 



Contact of the Animikie and Keweenian Formations. — G-eologists have expressed 

 different views as to the correlation of these formatious I shall here give a few facts 

 relating to this c^uestion, which have come under my own observation. I have, in one 

 instance, traced the contact of the Keweenian with the Animikie, which is exposed at 

 intervals, from Lake Superior, near Silver Islet, to the great Silver Lake fault in McTavish 

 Township, a distance of about twenty miles. It starts from the water-level, u little east 

 of Silver Islet, and winds around to Sawyer's Bay ; thence, northward, along the west- 

 facing escarpment to the fault above mentioned, at a point about fifteen or twenty chains 

 west of Silver Lake. Here tjie line of contact has attained an elevation of probably five 

 hundred feet above Lake Superior. All along, it shows a bed of coarse conglomerate, 

 becoming coarser to the north and varying in thickness from a foot to thirty feet or more, 

 and lying between the gritty white sandstones of the Keweenian and the underlying 

 and much more altered strata of the Animikie group. The two formations, which are 

 apparently conformable, dip at a low angle east-south-eastward. There seems to be a 

 dislocation along the foot of the escarpment, extending probably into Thunder Bay, 

 which has brought the lower members of the Animikie group on the west side against 

 the clay-slates on the east side. The black clay-slates, seen underneath the conglomerate 

 bed, for the most of the distance thence, are replaced at Iron Lake, twenty chains south of 

 the great faiilt, by soft, grey, thin clay-slates wliich show a thickness of about seventy 

 feet, underneath the sandstones. It is caused, no doubt, by faulting of the lower forma- 

 tion at a i:)oint further south, where it is not exposed. Some three or four hundred feet to 

 the north of Iron Lake, a dislocation of Animikie age brings the ferruginous chert and 

 jasper beds into position next underneath the conglomerate and sandstone beds; and 

 they continue in this relation northward to the Silver Lake fault. At the Iron Lake fimlt, 

 which brings the jasper rocks into the above position against the clay-slates on the south 

 side of the fault, the overlying Keweenian beds continue across uninterruptedly, sho wing- 

 that a large amount of Animikie strata must have been denuded away before the depo- 

 sition of the Keweenian beds. 



About a mile or two south of Iron Lake, I saw places where deep erosions in the black 

 clay-slates were filled in and levelled up to the overlying sandstone with coarse conglo- 



