LAKE HURON CONTACT LOCALITIES. 317 



Extent of the Huronian. — 'The dark feldspathic sandstones and shales 

 of the Huronian form a triangular patch in the northern part of the 

 township of Rutherford, and are followed to the north by the vitreous 

 quartzite of the La Cloche mountains. The base of this triangle on Kil- 

 larney bay is about a mile in length, while the apex is at George lake, 

 where these rocks thin out, being replaced to the northeast by the snow- 

 white quartzite in contact with the gneiss. Mr H. G. Skill, of McGill 

 Universit}', my assistant for a time, tells me there is abundant evidence 

 of the irruption of the granitoid gneiss in the alteration and disturbance 

 of the sedimentary strata, while a band or zone of graywacke in contact 

 with the gneiss frequently shows feldspathic matter intruded parallel 

 to the strike. 



BEA VER, FOX AND BALSAM LAKES— THE HOCKS AND THEIR CONTACTS. 



The shores of Beaver, Fox and Balsam lakes on the route from Lake 

 Panache to Collins inlet, it was observed, are occupied by a dark 

 greenish-gray feldspathic sandstone or graywacke which occasionally 

 contains pebbles of a coarse, red granite. The strike of this rock is in 

 general nearly east and west, and the dip southerly at a high angle, but 

 as the rock is often massive this cannot always be determined with cer- 

 tainty. In the northeastern part of Balsam lake a small area of gran- 

 itoid gneiss is exposed, hut the immediate contact with the enclosing 

 graywacke was not seen, owing to an intervening marsh. 



CHARACTER, CONTACT AND RELATION OF THE ROCKS OF THREE-MILE LAKE. 



The Huronian rocks continue through Balsam lake and on to Three- 

 mile lake with a strike of S. 75° E. (dip S. 15° \Y. at a high angle), but 

 upon entering the latter body of water they quickly curve round first 

 to southeast, then south, and finally pinch out near their contact with 

 the gneiss, giving place at this point to the white quartzite of the 

 La Cloche mountains, the latter rock continuing in juxtaposition with 

 the gneiss as far as George lake. The graywacke in the northern part 

 of Three-mile lake shows abundant signs of disturbance ami pressure 

 and is altered into a dark-gray mica schist, with uneven or lumpy cleav- 

 age surfaces. This rock is probably the equivalent of the graywacke 

 exposed in the northern part of the township of Rutherford, having been 

 cut'out through the intervening space by the irruption of the gneiss. 

 The contact between the two rocks on Three-mile lake is seen on the 

 eastern shore nearly two miles south of the inlet from Balsam lake, tin.' 

 gneiss occupying the southeastern shore and off-lying islands, while the 

 quartzite forms the mainland to the northwest. The gneiss Is coarsely 

 crystalline, dark flesh-red in color, porphyritic ; large feldspar crystals 



