Rocky Mountains. 9 



the Ohio— the great Kenhawa, whose course above the falls 

 forms an acute angle with the part below — also the Cum- 

 berland, and Tennessee, which run a long distance parallel 

 to each other, and to the Ohio. This fact seems to justify 

 the inference, that some other agent than the rivers has been 

 active in the production of the vallies between the subordi- 

 nate ridges of the Alleghany. There appears some reason 

 to believe that the rocky hills, along the immediate course of 

 the Ohio, and the larger western rivers, have received, at 

 least their present form, from the operation of streams of 

 water. They do not, like the accessary ridges of the Alle- 

 ghany, form high and continuous chains, apparently influenc- 

 ing the direction of rivers, but present groups of conic emi- 

 nences separated by water-worn vallies, and having a sort of 

 symmetric arrangement. The structure of these hills, does 

 not so much differ from that of the Alleghany mountains, as 

 their form and position. The long chains of hills, which form 

 the ascent to the Alleghany, on the western side, are based 

 either on metalliferous limestone, or some of the inclined 

 rocks belonging to the transition formation of Werner, and 

 have their summits capped with the more recent secondary 

 aggregates in strata without inclination, and greatly resem- 

 bling those found in the plains west of the Ohio. It is not 

 easy to conceive how these horizontal strata, unless origin- 

 ally continuous, should appear so similar at equal elevations 

 in different hills, and hills separated by vallies of several 

 miles in width. If that convulsion which produced the inclina- 

 tion of the strata, of the metalliferous limestone, the clay 

 slate, and the gray wacke, happened before the deposition 

 of the compact limestone, and the argillaceous sandstones, 

 why are not these later aggregates found principally in the 

 vallies where their integrant particles would be supposed 

 most readily to have accumulated? On the other hand, if the 

 secondary rocks had been deposited previous to thai suppos- 

 ed change, how have their stratifications retained the original 

 vol. i. 2 



