1868.] MACFARLANE — GEOLOGY OF LAKE SUPERIOR. 251 



melaphyres seem to be more plentiful here than in the other 

 areas, or at least the mines to which they give rise are more 

 extensively worked. 



At the other points in the east shore of the lake, where rocks 

 of the character of melaphyre have been observed, the area 

 occupied by them is very limited, and confined to narrow strips of 

 beach and rocky ground, between the lake and the much more 

 elevated Laurentian or Huronian rocks. In the most westerly 

 cove on the south shore of Bachewalmung Bay, red sandstone is 

 observed striking N. 12- W., and dipping 15° south-westward. 

 It is interstratified with conglomerate, the boulders of which are 

 principally of quartzite, dark green slate and red-jasper conglo. 

 merate, which have doubtless been derived from the Huronian 

 hills in the rear. They range in diameter from one to twelve 

 and even eighteen inches. The matrix is generally red sandstone, 

 but the interstices are sometimes filled out with quartz. A short 

 distance along the shore to the north-east exposures occur of a 

 reddish-brown melaphyre tuff, containing amygdules of calcspar 

 and quartz, the matrix of which is very soft and decomposed. 

 The beds appear to strike N. 8 s E., and dip 25° to 29° west- 

 ward. They would therefore seem to be conformable with the 

 sandstone and conglomerate. Further north-eastward the rock 

 becomes more compact, of a reddish-green colour, and exhibits 

 curves of igneous flow. The geodes become much less frequent 

 and consist almost exclusively of agate. The next rock to the 

 north-east is a light red sandstone, striking N. 65 Q W., and 

 dipping 35 Q to 40^ N. E. Its contact with the trap is not 

 visible, but its dip is such as to lead to the supposition that it has 

 been disturbed by that rock. There is a great thickness of this 

 sandstone exposed here, in strata frequently vertical, striking 

 generally east and west, or to the north of west, and exhibiting 

 dips varying from 35 G N. to 57 Q S v , and at least two anticlinal 

 axes. From what has been stated here and also concerning the 

 south shore of Mamainse, it would appear that there is evidence 

 of the existence of a sandstone of greater age than the bedded 

 melaphyres and conglomerates, and it would appear not unreason- 

 able to suppose that it belongs to what has been called the Lower 

 group of the Upper Copper-bearing series. 



The trap rocks which surround the south-west base of Gros 

 Cap, although comparatively seldom amygdaloidal, are readily 

 distinguished as melaphyres. They are sometimes coarse-grained, 



