2 The Geological Structure 



1st. Those beautiful red and spotted sandstones so well seen m 

 the excavations of the Sault St. Marie Canal, and regarded by most 

 geologists as the equivalent of the Potsdam sandstone of ISTew 

 York and Lower Canada, the base of the Silurian Series in Ame- 

 rica. 



2nd. An enormously, thick formation of Conglomerate, Sand- 

 stone, Slate, and Trap, evidently lying at the base of the red 

 Sandstone, and constituting the Huronian Series of Sir W. E. Lo- 

 gan. 



Srd. The still older Laurentian Series, represented here princi- 

 pally by Syenitic rocks, which have afforded the materials of the 

 Huronian Conglomerates. 



The two latter groups of rocks are first seen at Gros Cap. The- 

 nucleus of this lofty promontory consists of reddish Syenite, 

 here projecting to the South West of the ordinary limit of the 

 formation to which it belongs, and running down in abrupt pre- 

 cipices into the lake, while around its Western side are wreathed 

 sheets of trappean rock, similar to the cupriferous traps of other 

 parts of this coast, but here containing only veins of calc spar 

 and sulphate of barytes. 



Gros Cap is a place to be remembered by a tourist from the 

 eastward. Its bold front, against which the waves break like a 

 sea swell, the picturesque coves cut into the trap of its western 

 side, the singular and rich flora, depending in part, no doubt, on 

 the peculiar climatal conditions of the region, a,nd in part on the 

 character of the rocks, — all contribute to make it the beau ideal 

 of a voyageur's campiug ground, and a fitting introduction to 

 the bold scenery of the north shore of this great inland sea. 



Crossing Goulais Bay, which cuts deeply into the land, imme- 

 diately west of Gros Cap, we pass a low shore, presenting no 

 rock sections, but exhibiting in the bottom of the lake, red and 

 white sandstones, like those of Sault St. Marie. At the head of 

 Goulais Bay, Sir W. E. Logan has observed these to rest on the 

 continuation of the trap of Gros Cap. 



The next indentation is Batcheewanung Bay, beyond which,, 

 after passing a low gravel point, we find on the west side of the 

 small inlet, called Anse aux Crepes, a series of rocks, which, if 

 not forming an underlying member of the Potsdam sandstones,, 

 must be of Huronian age. 



They consist of imperfectly laminated red and mottled sand- 

 stone, a mottled argillo arenaceous rock, having a marly appear- 



