THE LOWER HURONIAN. 297 



KNIFE LAKE AREA OF THE LOWER HURONIAIST SEDIMENTS. 



SUBDIVISIONS. 



The Lower Hurouian sediments are much better developed and more 

 extensively distributed in the eastern than in the western portion of the 

 "Vermilion district. Knife Lake, a prominent topographic feature of the 

 eastern part of the district, lies in the sediments, and therefore this portion 

 of the district in which the sediments occur will be called the Knife Lake 

 area. 



The Lower Huronian sediments of the Knife Lake area may be con- 

 veniently subdivided into (1) the basal Ogishke conglomerate, (2) the Agawa 

 formation (iron bearing), lying conformably above the conglomerate, and (3) 

 the Knife Lake slates, which overlie conformably the preceding formations. 

 Thus it will be seen that in this eastern area there is a tripartite divi- 

 sion, whereas in the Vermilion Lake or western area the Lower Huronian 

 could be subdivided into only the Ogishke conglomerate, and the Knife 

 Lake slates, time equivalents of the Ogishke conglomerate, Agawa forma- 

 tion, and the Knife Lake slates of this eastern area. The intermediate iron- 

 bearing Agawa formation of the Knife Lake area has no known stratigraphic 

 equivalent in the western part of the Vermilion district. 



DISTRIBUTION, EXPOSURES, AND TOPOGRAPHY. 



Distribution. — The eastern area of the Lower Huronian sediments 

 begins a few miles west of Ely, in sec. 4, T. 62 N., R. 13 W., and extends 

 east for a long distance beyond the international boundary, which is the 

 eastern limit of the portion of the district included in the accompany- 

 ing map (PL II). Where these sediments begin at the west the area 

 underlain by them is very narrow, and this tongue continues narrow for 

 several miles to the east, gradually, however, widening out. Finally, in 

 the vicinity of Moose Lake, the continuation of this narrow belt is found to 

 join the main Lower Huronian sedimentary area. The distribution of these 

 rocks for this part of the area will be mentioned later. To the south of the 

 east-west trending area above mentioned there lies a narrow belt of sedi- 

 ments which begins on Farm Lake, extending about east and west. This 

 belt lies along both sides of the North Branch of the Kawishiwi River, 

 extending southward below this for some distance, where it abuts against 



