446 



RAFTS AND SNAGS. 



[Ch. XIX. 



and Abbot, formed 

 River between 



dam in 1860, which backed the Red 



- 



miles, and threw about 



three-quarters of its water through two natural outlets into 

 Soda Lake, affording a navigation round the right bank of 



the raft * 



Mississipp 



HalL ' some 



cast down from the position on which they grew, get their 



bottom 



mud. The force of the 



current naturally gives their tops a tendency downwards, and, 

 by its flowing past, soon strips them of their leaves and 

 branches. These fixtures, called snags, or planters, are ex- 



em 

 earn 



to 



steam 



neath the water, with their sharp ends pointed directly against 

 the bows of the vessels coining up. For the most part these 

 formidable snags remain so still, that they can be detected 

 only by a slight ripple above them, not perceptible to inexpe- 

 rienced eyes. Sometimes, however, they vibrate up and 

 down, alternately showing their heads above the surface, and 

 bathing them beneath it.'f So imminent was the danger 

 caused by these snags, that a steamboat was constructed and 

 provided with machinery by which the greater number ol 

 these trunks of trees were drawn out of the mud. 



The prodigious quantity of wood annually drifted down by 



Mississippi 



inei 



as illustrating the manner in 



which 



abundance of vegetable matter becomes, in the ordinary course 



imbedded 



as attesting the constant destruction of soil and transporta- 

 tion of matter to lower levels by the tendency of rivers to 

 shift their courses. Each of these trees must have required 

 many years, some of them centuries, to attain their fall size ; 

 the soil, therefore, whereon they grew, after remaining un- 

 disturbed for long periods, is ultimately torn up and swep 



away. 



* Humphreys and Abbot, Report of 

 Mississippi Survey, 1861. 



t Travels in N. America, vol. iii. P- 



362. 





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