of Lake Superior. 237 



granular or slightly crystalline. Its colour varies from very dark 

 green to black and brownish black ; when of the two last colours 

 it often assumes a bright jet glaze. Although quite a trap in its 

 raineralogical characters, its cross fissures are not particularly 

 marked, and never divide into columns as near the crags of Michi- 

 picoton, 8^,, except once in the hill of reddish gneis-like granite, 

 near Gravel River. Four miles and a half south-east from that 

 river the greenstone is rendered sienitic by the developement of 

 its feldspar in large red grains. It every where contains calcspar. 

 I could not ascertain precisely whether these amphibolic masses 

 are stratified, as they are only exposed in the narrow margin 

 between the lake and the woods. They are frequently seen in 

 contact with the granite in a well defined and slightly-serrated line; 

 neither rock being altered in constitution or appearance. 



This granite passes in the rear of Point Gargantua : and is re- 

 placed by greenstone on the south side of the bay contained on 

 the north by Cape Choyye. 



Point Gargantua and its neighbourhood are formed of amygda- 

 loid, whose connexion with the contiguous rocks, as presented to 

 me in passing by them rapidly though closely, seem to demand 

 considerable attention. This amygdaloid is nearly the same as 

 that of the Marmoaze, and has the same geological characters, its 

 ridges having the same dimensions, aspect, direction, and inclina- 

 tion ; and the same veins and mineral contents. The zeolite is 

 finer here. It is imbedded in large masses of calcspar and quartz 

 in groups of fibres radiating from a centre, and losing themselves 

 insensibly at the circumference of the circle they create, in calc- 

 spar. I landed at three places, and at all found the same rock, 

 modified, however, by the prevalence, or want, of particular 

 foreign minerals. Ferruginous matter prevails a good deal. 

 I met with only one conformable seam of conglomerate, about 

 eight feet thick, near the water's edge on the outer island. Its 

 ' nodules are chiefly ferruginous sandstone, thickly coated with 

 calcspar, and some stilbite ; I perceived a fine carnelian 

 among them. The glossy substance resembling a baked clay, 

 noticed at Marmoaze, is interspersed in this puddingstone, 



