104 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



of its drainage area in great bends at each change of course entering a 

 little deeper into its bed rock. At present it now forms grea't loops 

 or bends, some returning so close upon the other as to make almost 

 complete islands. The present position of the course of the river with 

 regard to its drainage area within the Basin is by no means of a very 

 high antiquity. This can be seen by a study of its channel and the 

 bottom lands lying along it, when it will be seen that it has moved in 

 various ways and shifted its position many times before it assumed 

 its present course. Of course we cannot tell how often it has changed, 

 but we can trace the limits of its latest movements since assuming its 

 present level. During the rainy season the stream is highly charged 

 with fine particles of matter which form a clayey sediment when al- 

 lowed to settle. Part of this sediment is deposited along the bed and 

 banks of the river in the shape of mud banks and in bars, and part of 

 it is carried to the Ohio River where quite an extensive deposit has 

 been formed within the last few years. This bankforming at the 

 mouth of the Cumberland has rendered the town of Smithland, for- 

 merly a river port, quite inaccessible from the river for navigation 

 purposes. 



In the central district the Duck River has worked in the same 

 manner as the Cumberland, but not upon such an extensive scale, as 

 its drainage area is not quite so large. In the southern division the 

 Elk River has not covered so much ground as either of the other two, 

 but still its work has been in the same direction. 



There can be no doubt but the movements of these streams have 

 been the cause of the deepening of the Basin to its present condition, 

 while the numerous smaller streams flowing over the escarpment have 

 been the chief agents in former times, as they are at present, in the 

 widening of the Basin. 



Thus we see that the Central Basin'of Tennessee was formed by 

 simple causes operating through a great length of time, and that it is 

 not at all necessary to call in the aid of any unknown factors in per- 

 forming the operation. Any assumption that some gigantic unknown 

 agency had anything to do with the case is pui'ely gratuitous and 

 unnecessary. 



It may be argued that there has not existed a sufficient length of 

 time in which to perform the work. To this it may be answered that 



