304 ANNUAL OF SCIENTIFIC DISCOVERY. 



becoming entirely cleared and cultivated, so that the heavy rains and 

 running waters now act with full force thereon, and displace vast 

 quantities of the soil, and other more solid matter, and run the same 

 into the river, which being now more and more restricted to its 

 channel by the leveeing process, has less opportunity of depositing 

 any of this solid matter either upon the banks or in the woods ; and 

 the consequence is, it is forced to transport all this detrital matter to 

 the ocean, or permit its channel to be filled up ; of which there is no 

 fear so long as its descending velocity is of sufficient force to agitate 

 and urge forward all such matter obstructing its passage, having no 

 more specific gravity than that with which the water of this river is 

 charged. The effect, however, of this great and increasing quantity 

 of matter so much more ponderable than the water by which it is 

 transported, having to be carried along the channel of the river, must 

 be, and is to cause extensive accumulative deposits wherever the force 

 of the water is insufficient for its agitation and transportation. These 

 deposits, in such localities, constitute, by the formation of immense 

 sand bars, such obstruction to the free flow of the water as may make 

 the river swell to a height equal to that of former years, while it is 

 really discharging a much less quantity of water. 



These obstructing deposits are likewise well calculated to make the 

 main thread of the channel more sinuous ; not only obstructing the 

 water, but by causing them to travel a greater distance, likewise 

 increasing their accumulations. These impediments to the passage of 

 the waters being of a very fluctuating character, are sometimes found 

 to disturb the relative heights of the high water at the several points 

 on the river from year to year ; so that plantations secure from the 

 high waters of one year, may not be safe against the same general 

 level of the water the following year. 



But, with all this increasing quantity of sand and other solid matters, 

 against which the waters of the river have to contend, while they are 

 beinsr more and more restricted to their channels and retarded in their 



^5 



velocity they are not perceptibly elevated in their high- water stages, 

 nor does the high water continue for any longer period than in former 

 years. Now this is certainly to be attributed to some change in the 

 general quantity requiring to be discharged annually by the river ; and 

 we know of no adequate cause of such diminution, save the increased 

 evaporation, consequent from the exposure of the lands by clearing 

 and cultivation. 



This increasing quantity of sedimentary matter subject to deposit, 

 makes river navigation somewhat more uncertain, from the more 

 extensive formation and fluctuating transfers of bars and middle 

 grounds caused by the settling of this solid matter on its descent to 

 the ocean, and on which no safe calculations can be made from one 

 year to another. Those channels which are shortest and safest for 

 Bteamers during the several stages of water one year, may not be 

 equally so the next. But over some part of the river bed, the waters 

 will always have power to wash out for themselves a channel through 

 which to descend to the ocean ; and in so doing will insure a depth 



