238 On the Geography and Geology 



in thin slips. The southern islet of this small group is a clifF, 

 apparently of the sandstone changed and disturbed, near Mar- 

 moaze, but as I could not land, I cannot say positively. The 

 shores of the main a few miles south abound in debris of sand- 

 stone. The main opposite to this isle I believe to be granite. 

 Landing rather more than a league to the south of this I found 

 in the laminar form of the granite, above described, an imbedded 

 or interleaved mass, several hundred yards broad along shore, of a 

 shaly brick-red rock, extremely ferruginous, containing green 

 earth, calcspar, and green and purple fluor (the fluor was detected 

 by Major Delafield). This rock is greatly weathered, the surface 

 scaling off in thin plates ; and abounding in empty vesicular 

 cavities, and bowls formed by the waves, as is common in the 

 amygdaloids of Lake Superior. It appears to me to be a decom- 

 posing trap, almost a ferruginous clay. At its well marked 

 contact with the gneis-like granite neither rock is altered. The 

 latter passes E.N.E. and N.E., dipping S.S.E. at angles of 70°. and 

 45°. Certain fissures in the red rock incline me to believe it to be 

 conformable. 



At its north end the amygdaloid of Gargantua seems to pass 

 into granite — a fact for which I was not prepared, and in which 

 I may be mistaken. The steps in this transition are those (as they 

 appeared to me) : — It first loses its almonds ; and is then a trap, 

 simply, for a few hundred yards, but not in the extremely crum- 

 bling state usual to amygdaloid. Then feldspar, mixed with quartz 

 is added, the mass assuming the shape of thick leaves going east 

 and west, and having veins one foot thick of a red jaspery matter. 

 Finally, at the point next to Gargantua on the north the rock is 

 the perfectly compound granite of Hiiggewong. 



The greenstone alluded to, as first touching upon the lake 

 near the bottom of the south side of the bay of which Cape 

 Choyye is the north headland, overspreads the whole of Micliipi- 

 coton Bay and crags, except a small space west of Point Perqua- 

 quia. Its actual junction with the granite on the south has not 

 been visited. This greenstone is fine granular and compact ; both 

 massive and slaty in the large, at intervals, by gradual passage. 



