232 NAVIGABILITY OF THE MISSOURI. 



are very numerous, and some of them several miles in extent. They do not, as higher up the 

 river, appear to owe in part their existence to the entrance of tributaries. They have nearly 

 all a rich soil, but are kept by the action of the current in a transition state, either increasing in 

 size from the constant deposition of new material, or undergoing destruction in consequence of 

 the current driving against the islands through changes in the channel of the river. 



Those changes are very marked in this river, which may be observed in nearly all streams, 

 and which are or arise from the detrition of the banks on one side, and the formation of new ones 

 at corresponding points generally on the opposite side. The detrition principally takes place 

 on the side of the main channel, as along the outer circle of bends. The current is only effectunlly 

 checked when, after it has encroached in one direction for some time, it encounters the rocky bluffs 

 which border the river valley. The growth of timber only delays its action ; for there were 

 noticed, in a great many instances, large and flourishing trees, roots and all, which, with the 

 earth they grew in, had fallen into the river, and were floating down to sink or be caught on 

 some sand-bar, and thus to become a snag or sawyer, or perhaps a nucleus around which should 

 be formed an island. The first settlers must have suffered very much from these causes ; others, 

 as those who have located below and in the vicinity of Council Bluff city, have avoided their ill 

 effects by placing their improvements as far from the river as practicable. 



The destruction of the banks is not in all cases gradual, for I saw many instances to the con- 

 trarv, and had reliable information that often an extent of several acres of land disappeared in a 

 moment. 



During a great part of our voyage, those changes, of which mention has been made, were much 

 more marked on the right than on the left bank of the river ; which may be accounted for by the 

 fact that, while the river is confined in its course between two nearly parallel ranges of bluffs, it 

 appears tending to approach the more westerly, and, as a consequence, must encroach principally 

 on that side. It was noticed that many of the principal bends were turned towards the west. 



I was informed that at some points the banks disappear more in low than in high water ; and 

 this may be explained by supposing that the strong current, while it loosens the mass, supports 

 it in its position as long as the water is high. One good effect resulting from the formation of these 

 obstructions is, that it tends to give the river a sinuous course, which diminishes the velocity. As 

 in the case of the Mississippi, so in this, if the river were straight the velocity would be too great 

 for the purposes of navigation. 



It results from the continually recurring changes to which the Missouri is liable, that at nearly 

 every bend there is a sand-bar or island, and a series of snags and sawyers. These also generally 

 occur wherever from any cause the water is still, or there is a counter current, and where there 

 are eddies or whirlpools. The difficulty in navigation is to discover in season a continuous 

 unobstructed channel. Concealed snags and sawyers are liable to occur in any part of the river. 



The average velocity of this portion of the Missouri is a little over five miles an hour. By 

 a rough measurement, made at Howard s Landing, not far above Boonville, I found the width 

 to be about half a mile. 



Some of the characteristics which I have not mentioned of this portion of the valley of the Mis 

 souri are, that the tributaries have generally much clearer water than the river itself, and are, 

 from the depositions which there take place, narrower at their mouths than elsewhere ; that the 

 smaller of the tributaries lie, for the most part, within the two parallel ranges of bluffs ; that, in many 

 instances, the bottoms may be said to be swamp-land, being occupied by numerous marshes, lakes, 

 ponds, and sloughs, which diminish the value of the exceedingly rich land, and must cause the 

 intermittent and other fevers to prevail to some extent ; that the banks of the river are heavily 

 wooded from the mouth of the Kansas to the Mississippi, there having been observed by myself 

 but one locality, and that near the mouth of Grand river, which could be called a prairie ; and that 

 the two ranges of hills which limit the valley of the Missouri were judged to be from seven to 

 lifteen miles distant from each other the eastern range touching the river at St. Charles, Port- 



