VALLEY OF THE OUIO. 1S7 



coiulaiy formations, the comparative evenness of the surface, 

 and the entire al)sence of primitive transition and ancient fleets 

 rocks in situ, would seem to render it prol)al)le that the re- 

 treat of the sea was occasioned hy the sinking of another 

 continent, and not hy the elevation of this. Which of these 

 alternatives, however, may luive occurred, I shall not fiu'- 

 ther attempt to inquire ; but assume the hypothesis, that a 

 great convulsion destroyed the relative clevatioi\ of this re- 

 gion, and that which is now covered by the Gulph of Mexico 

 and (lie Carribean sea, from Florida to Cumaria ;* in conse- 

 quence of whicli the ocean flowed lienre into its new bed, 

 in the direction of the Mississippi. The valley of that ri- 

 ver was of course the first excavation effected by the re- 

 tiring waters. To this primary canal the otiiers succeeded 

 in the order of their distance from the common embouchure. 

 These vast operations continued in all prol)al)ility for several 

 ages, during whicli the valleys constantly became deeper, 

 wider, and more symmetrical. Meanwiiile the debris of 

 the various strata, at that time perhaps more friable than at 

 present, were rolled, polished l\v attrition, intermixed, and 

 accumulated in the lowest situations. 



The currents, which I am supposing to have effected this 

 great work, seem not to havo been equally strong over eve- 

 ry part of tiie country. To the south of the river tiie val- 

 leys have less symmetry, exhibit less strikingly the impress 

 of aqueous currents, and contain but few rolled pebbles. On 

 the contrary, we observe in that region numberless excava- 

 tions which seem not referable to any action of the retiring 

 waters, or of the subsequent rains. In some parts of Ken- 

 tucky, these hollows, or ravines, are from one to two hun- 

 dred feet in depth, have fttee|) acclivities, and are so narrow 

 at l)ottom, that their transverse sections would very much 

 reseml)le in figure and magnitude the same sections of the 

 hills they separate. It is ditticult to believe these to have 



* We may xiippose this to have been either a distinct and limited convul- 

 sion, or a part of tliat geuural revolution wliicli laid bare the cxi-ting conti- 

 nents of the globe. 



