THE LOWER HURONIAN. 361 



the district the relation of the granite to the greenstone, which is shown not 

 only by the presence of these dikes but also by the effect of the granite on the 

 greenstone, may be seen, if strict attention is paid to the changes which take 

 place, as the g-ranite is approached from the north. In every instance where 

 the exposures are sufficiently numerous, as, for example, in the vicinity of 

 Ely, it will be seen that the greenstone changes its character, becoming more 

 and more schistose, and finally passing into marked amJDhibole- and mica- 

 schists in close proximity to the granite. 



S]S'OWBAKK GRAlSriTE. 



DISTRIBUTION, EXPOSURES, AND TOPOGRAPHY. 



The Snowbank granite has received its name from the fact that it is 

 typically developed around Snowbank Lake, which covers several sections 

 and parts of sections of T. 64 N., Rs. 8 and 9 W., and T. 63 N., R. 9 W. The 

 granite is confined exclusively to the immediate vicinity of the lake, being 

 best developed on the southern shores of the lake and on the islands in that 

 portion of the lake. 



The exposures are very numerous and excellent. Althovigh the granite 

 occupies the center of a structural anticline, it nevertheless does not empha- 

 size this structure by forming an area of topographically higher ground 

 than that of the surrounding country. The topography is not of marked 

 character, having the iTsual rounded gentle contours so common in the 

 glaciated granite areas of this district. 



PETROGRAPHIC CHARACTERS. 



The granite occurs in good exposures in the ^dcinity of the shores of 

 the lake, where its characters may be easily studied. It is predominantly 

 pink to red in color, although on fresh fracture it is a gray or flesh-colored 

 rock. Some facies, however, are much darker colored, as the result of a 

 higher content of the dark minerals than is contained in the normal granite. 

 The granite varies from the fine-grained to the coarse-grained form, the 

 medium-grained facies being most abundant. Porphyritic facies of the 

 granite also occur, but are not very abundant. The porphyries are developed 

 as granite-porphyries and microgranite-porphyries with feldspar, augite, and 

 qiiartz phenocrysts in a fine-grained groundmass. These porphyries, as 

 well as the very fine-grained granites, occur chiefly as ofl'shoots from the 



