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THE CANADIAN NATURALIST. 



[May 



structure. The strike of these schists is, at places, quite incon- 

 stant ; they wind in all directions, and what appear, at first sight, 

 to be quartz veins, accompany their contortions. On closer 

 inspection, however, of the largest of these, they are seen to be of 

 granite, but whether twisted fragments of that rock or really veins 

 of it, is, at first glance, very uncertain. Observed superficially, 

 they have the appearance of veins, but they do not preserve a 

 straight course, and bend with the windings of the enclosing schist. 

 They often thin out to a small point and disappear, and, a few 

 feet or inches further on in the direction of the strike, reappear 

 and continue for a short distance. Sometimes a vein thins out at 

 both ends and forms a piece of granitic material of a lenticular 

 shape, always lying parallel with the lamination of the enclosing 

 slate. Figure 6 is a representation of the phenomena here 

 described. 



a. Fragments and contorted pieces of granite. 

 &. Slates enclosing same. 

 At another point of junction, on the north shore, to the east of 

 that above described, there is a large development of similar 

 basaltic greenstone. Its constituents, with the exception of iron 

 pyrites, are indistinguishable ; it has a greenish black colour, and 

 a specific gravity of 3. Its powder has a dark green colour, which 

 changes on ignition to dark brown, with a loss of 1-79 per cent, of 

 its weight. It yields to sulphuric acid 1841 per cent, of bases. 



