326 Geology^ i^c. of Tennessee, ^e. 



ging. In the vicinity of the town, there is a curioas exhibitiou 

 of the fact. A stream of water has worn away the earth to 

 the depth of fifteen or twenty feet, and is continually length- 

 ening the chasm, in the direction opposite to its own course. 

 Thus, as the water flows from the town, the chasm approaches 

 it. In examining the cause of this fact, I perceived it was 

 owing chiefly to the difference of cohesion in the alluvial de- 

 posits, of which the earth is formed. That at the surface, 

 being a thick loam, wears away with more difficulty than the 

 deposit below it, which consists of a loose sand. The conse- 

 quence is, that-the water, which has once obtained a perpen- 

 dicular passage of a few inches through the first, washes away 

 the second with such rapidity, that it is constantly undermining 

 it. This occasions a perpetual caving in of the surface, in a 

 direction opposite to the course of the stream. The same fact 

 is observed in many parts of the country for a great distance 

 above Natchez. If there be wanting any other fact to prove 

 that the earth on which the town of Natchez stands, is alluvial, 

 it is found in the effect which the Mississippi has upon the base 

 of the Natchez bluff". In consequence of a bend in the river, 

 the whole force of its current is thrown against this base. If 

 it consisted of solid rock, the river would probably have no 

 effect upon it ; but of such loose and friable materials is it com- 

 posed, that the river is continually undermining it, and produ- 

 cing effects not less to be dreaded than those of an earthquake. 

 Several years ago, a great number of acres sunk fifl;y feet or 

 more below the general surface of the hill ; and in 1805, there 

 was another caving of that part directly over the small village 

 at the landing. Several houses were buried in consequence 

 of it, and strong fears are entertained by the inhabitants, that 

 the same cause will yet submerge in the Mississippi, the whole 

 of the present landing-place. 



These facts, I think you willsay, furnish satisfactory evi- 

 dence of the alluvial character of the country at Natchez. 

 The same character belongs to the whole extent south of the 

 Dividing Ridge. This may be safely inferred from the general 

 features of the country. But I have two facts, of a geological 

 kind, to mention, both of which go to cpnfirm the opinion. 



