THE LOWER HURONIAN. 335 



farthest north. This suggests that the double appearance of this baud 

 is due to infolding, the closeuess of which is evidenced by the extremely 

 plicated character of the iron formation itself. East of this ridge, in the 

 low ground, the iron formation was found exposed, but so poorly that it 

 was impossible to determine its width. It is followed to the south by 

 slates, whereas the conglomerates are the nearest rocks exposed to it on the 

 north. It seems almost unquestionable that we have here an iron-bearing 

 formation of very limited thickness, which occupies a horizon between 

 the conglomerates north of and below it, and the younger slates south of 

 and above it. This iron formation could not be traced to the east or 

 the west of the area mentioned. At one place, however, on the bare 

 hill in the SE. J of sec. 16, T. 64 N., R. 9 W., overlooking the swamp 

 which runs down to the southwest end of Newfound Lake, occur good 

 exposures of a very feldspathic fragmental rock. This coarse fragmental is 

 interbanded with fine-grained slates. Here were found, in a few places, 

 interlaminated with the slates, narrow bands of black cliert up to 3 inches 

 in width. This chert is conformable with the slates, and seems to be 

 contemporaneous with them, but may possibly consist of silicified lenses 

 of carbonate-bearing rock. These bauds disaj^pear after being followed 

 for only very short distances. They occur fairly close to the greenstone 

 to the northwest, on which rest these sediments in unconformable relations 

 without intervening thick masses of conglomerate. 



KNIFE LAKE SLATES. 



One of the largest lakes on the canoe route along the international 

 boundary has been known since the time of the fur traders as Knife Lake 

 (Lac des Couteaux). The lake was so named because of the flinty con- 

 choidally fracturing' slates whicli surround it and which, with their sharp 

 knife-like edges, cause a great deal of inconvenience to the moccasined 

 traveler, and even to him with thick boots. Probably this name is but a 

 translation of one given to it by the Indians long before the advent of 

 the French voyageurs. At any rate, the name aptly describes one of the 

 characteristics of the slates, and the lake bearing the name is so prominent 

 a feature of the hydrography of the district that the name has been given 

 also to the slates. 



