10 District traversed by the 



small quantity of mica in thin layers. It is not improbable 

 that the waters of the St. Maurice, may in time, force for 

 themselves another channel through the clayey neck of 

 land, over which now runs the portage, and thus form a 

 third fall to the southward of the other two, and nearer the 

 Shewanahegan River. 



Another subsidence in the bed of the river occurs at 

 the falls of the Grande Mere, about eleven miles above the 

 Shewanahegan. These are near sixty feet in height, and 

 pour over a rock of sienite, forming at their foot a similar 

 basin and nearly of the same extent as that at the Shewa- 

 nahegan. Here the river, in its course to the St. Lawrence, 

 takes a turn almost at right angles ; a circumstance com- 

 mon at all the falls and most of the rapids, not only on this, 

 but many other rivers. 



The rock from hence as far as Cape le Blanc, a high 

 perpendicular precipice near seven mileshigher up theriver, 

 continues to be a sienite with hornblende in excess ; but at 

 that Cupe the hornblende diminishes in quantity, and the 

 quartz and light red felspar occur in large sized crystals. 

 This rock is much stained with the oxide of iron, particu- 

 larly near the summit. Immense fissures intersect the 

 rock in various directions, and bear evident marks of the 

 excessive violence of that awful concussion which has 

 thus torn asunder large mountains. 



The sienitic formation continues without intermission as 

 high as Wemontachinque. Occasionally, and for a short 

 distance, it passes by regular gradation into gniess and 

 very coarse granite, frequently contauiing crystals of 

 garnet. 



Large blocks of red felspar were seeen lying on the 

 shores of the river and enibeded in the rock in situ.— = 



