316 THE VERMILION IRON-BEARING DISTRICT. 



present case might enable a boundary line to be drawn between the con- 

 glomerates metamorphosed by the granite only and those metamorphosed 

 by both the granite and gabbro. The effect of the gabbro seems to 

 have extended at least as far north as the northwest shore of Disappoint- 

 ment Lake. Reference has already been made to the beautiful exposures 

 of conglomerate at this place. The matrix of this conglomerate contains 

 biotite and hornblende very abundantly, and the pebbles and bowlders of 

 the conglomerate are to a great extent of a hornblendic rock in which in 

 many places large porphyritic hornblendes have been prodiiced. On the 

 weathered surface the pebbles generally decay faster than the matrix, and 

 hence are removed, leaving numerous roundish depressions. The rock has 

 not been very strongly mashed, for while the longer dimensions of the 

 pebbles are in the planes of schistosity, one could not say that the lesser 

 dimension in the other direction is not explicable as due to the original 

 shingling action of the pebbles. The rock is very irregularly veined by 

 quartz, and here and there by some granitic veins derived from the Snow- 

 bank granite. All these factors give the rock a very rough, knotty 

 appearance on the weathered surface. While in general the outlines of the 

 pebbles can be readily traced, nevertheless, when they are broken the 

 fractures extend cleanly through the pebbles and matrix alike. This shows 

 the close union between the matrix and the pebbles which has taken place 

 as the result of metamorphism. This is further shown by the fact that m 

 some cases secondary porphyritic hornblendes, which are produced in 

 certain of the pebbles and in the matrix alike, will be found to extend from 

 the pebble across the contact into the matrix. As we go southward — in 

 other words, as we get closer to the gabbro — a study of the rocks on the 

 small islands in Disappointment Lake and on the south shore shows that 

 the clastic nature of the rocks is not so apparent here. A microscopic 

 study of these rocks shows that there have been produced in them in large 

 quantity minerals — hypersthene, green and brown hornblende, brown mica, 

 augite, magnetite — whose origin is clearly due to the action of the gabbro. 

 Similar rocks may be studied in the area extending from the north shore 

 of the Kawishiwi River in sees. 16, 17, and 20, T. 63 N., R. 9 W., 

 near the shore. They are extremely metamorphosed and it is only by 

 rather close observation that one can recognize their conglomeratic nature. 

 The pebbles and the matrix of the rocks consist to a great extent of the 



