556 APPENDIX. 



" We lose the primitive rocks at Isle la Crosse, 

 u where there is limestone; and at Portage la Roche we 

 " cross a high sandstone ridge, covered with much sand. * 

 " The Clear-water River, at the foot of this ridge, flows 

 " over limestone, which is also seen in the Athabasca 

 " River, but under much bituminous shale. On the 

 st north side of Athabasca Lake (or Lake of the Hills), 

 " the rocks are primitive, and the Slave River flows 

 " sometimes through limestone, at other times over 

 " granite, and sometimes between the two. Its mouths 

 " open into Slave Lake between the limestone and 

 " granite. 



" river is precisely similar to that of the Thelw-ee-cho-dezeth : 

 " a series of lake-like and many- armed dilatations, connected 

 " by narrow rocky rapids, sometimes one, sometimes many, 

 " separated by high rocky islands. There are some curious 

 " islands in the Missinippi, consisting of large granite 

 " boulders, or rounded masses, piled one above the other to 

 " a great height ; and on their upper points, where they are 

 " out of the reach of the waves, they are hoary with lichens. 

 " The water immediately surrounding these islands is many 

 " fathoms deep ; and on looking at them, I was inclined to 

 " think that the soft parts of a granite rock had weathered 

 fi away, and left these rounded and harder masses so piled 

 « up." 



* The frequent occurrence and thickness of the deposits of 

 sand in this part of North America, appear, both from Dr. 

 Richardson's description of the country seen during the pre- 

 ceding expedition east of the Mackenzie, and from Captain 

 Back's notes of his journey, to be remarkable. It well deserves 

 inquiry, whether these accumulations are the deposite of the 

 (comparatively) recent seas, during their occupation of that 



continent, or belong to the secondary or tertiary groups of 

 strata. 



