41 (JEOLOGICAL STRUCTURE OF THE 



ing high-land are confined to its eastern bank. The 

 first of these, below the mouth of the Ohio, is the 

 Mine au Fer or Iron-banks; and after a descent of 

 several hundred miles, we again perceive an occur- 

 rence of the same bank of friable materials in the four 

 successive bluffs or cliffs of the Chicasaws. As this 

 alluvium is here best developed, we shall attempt to 

 describe its appearance. These cliffs are. elevated 

 about 2 or 300 feet above the lower level of the 

 river, and are a portion of the continuous high-lands 

 which constitute the principal part of the territory. 

 They are connected with the uplands of the Walnut- 

 hills, of Natchez, Fort Adams, Grand and Petit 

 Gulf, Ellis's and Thomson's cliffs, and finally ter- 

 minate a few miles below Baton-rouge. The surface 

 often presents a ferruginous clay or gravel ; and from 

 the deep and friable nature of the materials, it is sub- 

 ject iu the vicinity of streams to be washed into deep 

 and wide ravines. The soil is but moderately fertile, 

 and requires the aid of manures. The Chicasaw 

 Bluffs, which from top to bottom, as well as at Nat- 

 chez, present nothing but friable beds immediately 

 below the surface, consist of sandy and ferruginous 

 clays, lower down often purer and whiter ; then suc- 

 ceeds, with an almost unexpected uniformity, a band 

 of bright pink-colored clay, which we also recognize 

 at the. Mine au Fer, as well as in the Pine-bluffs, 

 about 180 miles up the Arkansa. This clay is suc- 

 ceeded by another bed nearly similar to the first; a 

 carbonaceous appearance then succeeds, and com- 



