GNEISSIC FOLIATION. 



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Island), the north shore of which is occupied by hornblende schist 

 and finely laminated quartzose mica schists, while the southern half 

 of it is occupied Vjy a mass of flesh-tinted rock of the composition of 

 a syenitic granite, but in which, in places, there is developed, in the 

 same rock mass, a very distinct though coarse gneissic foliation, with 

 gradations between what would be taken as a true granite and the 

 unmistakable gneiss, which preclude the possibility of any hard line 

 being drawn between them, both being in fact the same rock — a 

 granite. The gneissic foliation is due to a structural differentiation, 

 which, so far as observation would permit of judging, is more 

 especially peculiar to that portion of the mass nearest the contact 

 with the schists. The dyke on the small island shewn in the figure 

 is probably an off-shoot from this granitic mass. 



Along the junction of the Huronian hornblende schists with the 

 Laurentian gneiss on the islands 

 at the mouth of White Fish Bay, 

 may be seen some remarkable in- 

 stances of intrusions which have 

 all the 2)hysical aspect of a regular 

 gneiss. The most striking of these 

 is figured in the annexed diagram 

 (Fig. 4), which illustrates the con- 

 dition of things seen on an island 

 called the West Pointer at the 

 mouth of the bay. 



The northern and larger moiety 

 of the island is occupied by the 

 hornblende schists of the Huro- 

 nian, and the southern by coarse 

 grey gneiss. About the middle of 



the island the irregular intrusion 



of gneiss shewn in the figure ^ 'o- 4.-Scale-i inch = lo feet. 



Vjreaks through the hornblende schists. The intruded rock resembles 

 closely the regular gneiss to the south of the line of contact and its 

 foliated character is quite as well defined. The irregular nature of 

 the fissure through which this gneiss has been injected is such, that 

 it cuts across the schists at some places and runs with its strike in 

 others. The foliation of the contained gneiss is approximately 

 parallel to the walls of the fissm-e. In one place this foliation and the 



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