546 



APPENDIX. 



But, though the trap formation seems to predominate 

 in Peth-the-nu-eh, the specimens from that side of 

 the island which forms the shore of Christie's Bay are 

 composed of magnesian limestone, like that of Dease's 

 River, and many other places mentioned by Dr. Rich- 

 ardson. * 



The main shore of the lake on the north and west of 

 Peth-the-nu-eh is also mountainous and rocky, consist- 

 ing chiefly of gneiss and porphyry. At a contracted part 

 of the channel, called by the natives Tal-thel-leh, it is 

 said never to freeze ; and this Captain Back's experience 

 proved to be the case during two winters. On the east 

 of this place, an island was seen, displaying a barren and 

 rounded outline to the north, but on the south distinctly 

 columnar. No specimens were obtained from it; but a 

 drawing of Captain Back's leaves no doubt as to its 

 structure, the columns being well defined and regular. 



Columns in a small Island, east of Tal-thel-leh. 



The altitude of the north shore of the lake varies but 

 little thence to the point called by the natives " The 

 Mountain" ; — so named, however, not from any remark- 

 able prominence, but to distinguish the spot where the 



* Appendix to Franklin's Second Voyage, p.xiv. 



