322 



THE VERMILION IRON-BEARING DISTRICT. 



is found witli about 9 feet of a cong-lomerate derived from it overlying it. 

 Above this follow well-banded slates and graywackes. At another point, 

 876 paces south and 700 east of the same location, is another contact 

 between the greenstone and the sediments. Here we find a baud of con- 

 glomerate formed of poorly rounded greenstone pebbles which grades up 

 by rapid alternation of conglomerate beds with finer-grained sediments 

 into the normal Knife Lake slates. The bands of fine-grained conglomerate 



vary in thickness from a few inches to 

 3 feet, the thinner ones alternating with 

 bands of the slates. The entire gradation 

 here takes place within a distance of about 

 10 paces from the greenstone on one side 

 to the normal slates, without marked con- 

 glomerate bands, on the other. The strike 

 of the beds here is N. 60° "W., with a dip 

 of 80° to the north. As may be seen from 

 the iTiap, the strike follows very closely 

 the outcrop of the greenstone. 



On the northern slope of the green- 

 stone ridge wliich forms a subordinate 

 anticline at the southwest end of Ogishke 

 Muncie Lake, another contact was found 

 between the Og'ishke conglomerate and 

 the greenstone. The contact occurs on 

 the hillside at a place 225 paces south and 

 20 paces west of a point on the shore 

 opposite and just south of the west end 

 of the westernmost island shown on the 

 map (PI. XVI, atlas). The conglomerate 

 here is fine grained and consists of greenstone pebbles with occasional jasper 

 pebbles. The conglomerate is coarsest near the eruptive greenstone and 

 grows progressively finer northward, evidently grading- upward into the 

 slates that occupy the central portion of Ogishke Muncie Lake. 



The large island northeast of the east end of this same greenstone 

 anticline well deserves examination, as it shows the relations of the green- 

 stone and the conglomerate. The large-scale sketch (fig. 20) shows the 



Kg. 20.— Sketch showing relationship of Ely green- 

 stone and overlying Ogishke conglomerate on 

 island in Ogishke Muncie Lake. 



