I<v 



'tlh 





4« 



as 



ffir, 



•« fi 





olo 



wn 



^ 



'iger float. 



^^•^T solid 

 J-one 





^l"-: is drifted 



»i) 



doming 



in ]^< ^^e 

 x^'^ion floats 



I Miiokenzie 



a 



u^flT now ID 



N long, tlie 



J., ir roots, 

 tJier reSj 



1, *'■'' 



*ll 



•-\1 



nc^ 



k 



Ch. XLYI.]' 



IX SUBAQUEOUS DEPOSITS. 



527 



3 



resembling peat^ but whicli still retains more or less of the 

 fibrous structure of the wood ; and layers of this often alter- 

 nate with layers of clay and sand, the whole being penetrated, 

 to the depth of four or five yards or more, by the long fibrous 

 roots of the willows. A deposition of this kind, with the aid 

 of a little infiltration of bituminous matter, would produce an 

 excellent imitation of coal, with vegetable impressions of the 

 willow-roots. What appeared most remarkable was the hori- 

 zontal slaty structure that the old alluvial banks presented, 

 or the regular curve that the strata assumed from unequal 

 subsidence. 

 . ' It was in the rivers only that we could observe sections 

 of these deposits ; but the same operation goes on, on a much 

 more magnificent scale, in the lakes. A shoal of many miles 

 in extent is formed on the south side of Athabasca Lake, by 

 the drift timber and vegetable debris brought down by the 

 Elk Eiver; and the Slave Lake itself must in process of 

 time be filled up by the matters daily conveyed into it from 

 Slave Eiver. Vast quantities of drift-timber are buried 

 under the sand at the mouth of the river, and enormous piles 

 of it are accumulated on the shores of every part of the 

 lake.'^ 



The banks of the Mackenzie display almost everywhere 

 horizontal beds of w^ood coal, alternating with bituminous 

 clay, gravel, sand, and friable sandstone ; sections, in short, 

 of such deposits as are now evidently forming at the bottom 

 of the lakes which it traverses. 



Notwithstanding the vast forests intercepted by the lakes, 



.ss of drift-wood is found where the 



a still 



greater m 



Mackenzie reaches the sea, in lat. 69° N., ^ 

 at present except a few stunted willows. 

 the river the alluvial matter has formed 



mouths of 



of islands 



may 



a 



t 



some 



The 



abundance of floating timber 



Mackenzie 



±ne aDunaance ot tioatmsf timber on the Mackenzie is 

 owing to the direction and to the length of the course of this 



from 



* Dr. Eicharclson's Geognost. Obs. on Capt. p-anklin's Polar Expedition. 



o(\i. 



