SCOTT IMPROVEMENT OF THE WESTERN RIVERS. 45 



Now, on the other hand, the fall from Cairo to Columbus (31 

 miles) is 4 feet more in high than in low water (12 feet in high 

 and 8 feet in low water). This fall of 12 feet in 21 miles of 

 such a volume of water, if not checked by the curves of Lucas 

 Bend and Iron Banks, would be a torrent ; but owing to those 

 two curves the current is hardly as strong as at many places 

 where there is less fall. 



Another element is the tenacity of the banks and the character of 

 the bottom of the river. The Mississippi (from Cairo to the Gulf) 

 and the lower Arkansas flow through an alluvial formation of an 

 unknown depth, and this alluvium varies in tenacity as the depos- 

 its have taken place in slacker or stronger currents, those forming 

 under or behind a bar being invariably the more tenacious, and 

 resisting the action of the current much longer than those which 

 have formed outside of or on top of a bar. The ooze that settles 

 in the old " cut-ofts " becomes in time stift' blue clay, that resists 

 the action of the current where the river has cut back to the old 

 bed, as is shown at several of the old mouths of the " cut-ofls." 



The banks are also affected by the clearing oft' of the timber 

 growing on them. 



In the early days of steamboating the banks were covered with 

 a dense growth of timber, the fibrous roots of which bound the 

 banks until they were undermined to a considerable distance, and 

 when a slide took place it frequently extended back over 100 feet, 

 and as much as 200 yards up and down the river. 



These slides carried the timber growing on them, down in the 

 same position in which it grew and carried the roots below the 

 strong current, thus protecting the banks behind the slide for 

 years, giving time for the filling up and growth of timber on the 

 opposite side, thus preserving the normal width and depth. 



At this time we have no accurate data in regard to the former 

 width and depth of the river, but an approximation may be 

 reached by knowing the low-water depths of the river at intervals 

 of (say) 10 years, and even that can only be an approximation. 

 In 1828 there were no steamboats on the Mississippi that drew 

 less than 6 feet light, or 8 feet loaded ; yet they found no difficulty 

 in coming to America landing (4 miles above Cairo) during the 

 whole year, unless stopped by ice, carrying freight and passen- 

 gers sufficient to make it profitable. 



