'91 1-] STEVEXSOX— FORMATION OF COAL BEDS. 551 



rapid deposition of mud takes place around it. The surface left 

 above water produces willows, which, growing rapidly and binding 

 the mass together by their roots, protect it from the washing by sub- 

 sequent freshets. Woodruff advised removal of the raft, but, to 

 prevent renewal, he recommended that the narrow part of the river, 

 in which the raft was forming, be cleared of the willows lining the 

 banks, which obstructed the passage of large bodies of floating drift. 

 If this were done, the banks, no longer protected by the vegetable 

 growth, would cave readily, the river would be widened and the 

 formations of raft would cease. The removal of the raft was com- 

 pleted in 1872 and Woodruff afterwards gave a full history of the 

 obstruction, to which the reader is referred for other details. ^^ 



Franklin^^ found much floating timber on the Athabasca river in 

 northwestern Canada. " The river carries away yearly large por- 

 tions of soil, which increases its breadth and diminishes its depth, 

 rendering the water so muddy that it is hardly drinkable. Whole 

 forests of timber are floated down the stream and choke the channels 

 between the islands at its mouth." It is clear that, on the Athabasca 

 as on the ]\Iississippi, caving banks yield the supply of drifting 

 timber. In the same volume, Richardson'^ describes conditions ob- 

 served along some rivers and lakes within the region traversed by 

 Franklin's expedition. His statements have been cited by many 

 writers but so far as the present writer has seen, not in full. They 

 are as follows, with omission only of some details which are irrele- 

 vant here. Peace river brings much large drift timber into Slave 

 river 



" and as the trees retain their roots, which are often loaded with earth and 

 stones, they readily sink when water-soaked and, accumulating in the eddies, 

 form shoals which ultimately augment into islands. A thicket of small 

 willows covers the new-formed island as soon as it appears above water and 

 their fibrous roots serve to bind the whole firmly together. The trunks of 

 the trees gradually decay until they are converted into a blackish substance 



^ E. A. Woodruff, in App. Q, Ann. Rep. Chief of Engineers for 1873, 

 Separate, pp. 45-61. 



^^ J. Franklin, " Xarrative of a Journey to the Shores of the Polar Sea," 

 London, 1823, pp. 192, 357, 364, 374, 381. 



"J. Richardson, Ibid., p. 518. 



PROC. .-VMER. PHIL. SOC. , L. 202 KK, PRINTED NOV. 1 6, I9II. 



149 



