50 THE CANADIAN NATURALIST [Vol. vii. 



stated that ia this region gold and silver veins are always asso- 

 ciated with dolomitic schists. The principal vein, to the south- 

 west of Shebandowan Lake, and others, were referred to as 

 bearing out this statement. In the Hastings series of rocks 

 o'old is also associated with dolomitic schists. 



Various isolated patches of granite and syenite, some a few 

 yards and others many miles in extent, but always connected with 

 Huronian rocks, were pointed out on the map. In these masses 

 there is no stratification. 



In the Nipigon Basin, the Upper Copper-bearing rocks of 

 Lake Superior attain their maximum development in Canadian 

 territory. This area has the shape of an arrow head, with the 

 apex pointed to the true North. The basin floor consists of marls, 

 sandstones, &c., often covered with trappean outflows. The 

 lecturer was disposed to think that this trappean outburst origin- 

 ated from some point in Lake Superior. The direction of the 

 flow, as indicated by wrinkles on the surfaces of beds, is from the 

 centre outwards. The occurrence of these traps on all sides of 

 the lake, and their general arrangement, which presents an 

 appearance as if the masses had been pressed against the rocky 

 margin of the lake basin, are supposed to favour this view. The 

 overflow in the Nipigon Basin, too, becomes exhausted in recediog 

 from Lake Superior. 



Unlike the Laurentian rocks, in which, as before stated, no 

 useful minerals have been found, the Huronian beds contain ores 

 of iron, copper, lead, gold, silver and nickel. Copper is most 

 frequent in quartz veins which intersect dioritic schists of 

 Huronian ao-e. The silver and s;old veins near Shebandowan 

 occur in similar schists, and were discovered by Mr, P. McKellar 

 in the spring of 1871. A letter from Mr. McKellar to Prof. 

 Bell was then read, which gave a description of the details. The 

 principal vein Mr. McKellar writes, is of quartz, and is from 

 two to six feet in thickness. In addition to gold and silver it 

 contains ores of all the metals we have cited above as occurring 

 in Huronian rocks. At this locality, in addition to the dolomitic 

 band associated with intrusive granite, a great variety of Huron- 

 ian schists occur. A vein of calc-spar and quartz cuttiug through 

 Huronian schists on mining lot 3 A, on the North Shore of 

 Thunder Bay, and containing native silver and nickel ore, was 

 next described. 



The main silver vein of Silver Islet belongs to the Upper 



