GEOLOGY. 305 



sufficient, even during the greatest depression of the -waters, for the 

 passage of steamers. When the river bed is wide, and the -waters 

 thereby much spread and shallowing, there is often but barely suffi- 

 cient water in which to make the passage ; but as these spread waters 

 subside, they concentrate in the most depressed portions of their bed, 

 thereby acquiring sufficient force from the accumulation to wash for 

 themselves a passage through which steamers can always make their 

 way. 



The lower the river periodically falls, the deeper does it reduce this 

 low water bed, thereby making more room in the channel for the pas- 

 sage of the rising waters in the ensuing spring ; which, again, when at 

 their highest stages, more or less fill up these low water passages with 

 sand, and other solid matter, as before ; thus alternately obstructing 

 and removing obstructions, by urging this impeding matter onward to 

 where the force of the current is insufficient at the time for its further 

 transportation. Such is the general rule of this river, so far as it 

 affects navigation, from its juncture with the Ohio to the bar at its 

 mouth. 



Although the increasing quantity of solid matter to be transported 

 to the ocean opposes no serious obstacle to river navigation, it neces- 

 sarily increases the difficulty at its mouth, for at high water stages, 

 when the force of the waters is urging so much of their solid matter 

 along, there must be an extensive deposit in the most depressed por- 

 tion of the bar-channel ; because the still waters of the Gulf impede 

 the force of the current by which the detrital matter is agitated and 

 carried forward, thus shallowing the channel through which ships are 

 conducted, and rendering difficult the egress to and from the ocean. 

 This will at times amount to a serious obstacle to the free commercial 

 intercourse between the Gulf and the city of New Orleans, against 

 which there is no certain remedy ; for so long as the waters of the 

 river are charged with the transport of so much solid matter, so surely 

 will they let such an amount of it fall on the bar, as will at times seri- 

 ously block up the free passage for large ships. 



This evil is progressively increasing with the changes taking place 

 above, against which the almost continual agitation of the water and 

 mud by the steamers and ships in making the passage of the channel 

 on the bar, is not at all counteractive of the disposition to deposit. 

 But the evident effects in this particular, are sufficient to indicate 

 the agitating processes the most effectual, and we may say the only 

 practical remedy for relieving the bar channel from this obstruc- 

 tion. By agitating the current the solid matter would be kept in sus- 

 pension till it passed forward into deep water. Therefore, if the usual 

 operations on the bar are at any time insufficient for the removal of 

 any excess of deposit, practical means of suoh a character, constructed 

 for the purpose, may . be beneficially applied at no considerable 

 expense. 



The following table of statistics respecting the Mississippi were 

 appended to the report of Mr. Brown, presented in 1848, and used for 

 reference in the present report. 



