I will now call your attention to the last geological division which came under my observation. It is the alluvial tract, extending from the Dividing Ridge already mentioned, to the Gulf of Mexico. This Ridge is the last range of high land which I crossed on the journey to New Orleans, and lies about six hundred miles north of the Gulf of Mexico. Its course at the place I crossed it, is a little south of west. It divides the waters of the Tennessee from those which proceed directly to the gulf. Travellers always observe it. They often mentioned it to me as the southern boundary of the _stony country_. After crossing it, you see no more limestone; and, which excites more joy in the traveller, no more of the silicious gravel, with which it is associated, and which is so troublesome to the feet of horses. The soil consists of a soft clay, or light sand, on which you seldom meet with a stone of any kind. The surface of the earth is undulating and hilly, but not mountainous. The water-courses do not move rapidly and tumultuously, as in the limestone country; but form in the soft earth, deep trenches, through which they glide smoothly and silently along. The smallest rivulet often has a trench ten feet deep; and the earth over which it passes, is continually yielding to its gentle attrition. The only minerals which I observed, are sandstone, common and ferruginous; silicious pebbles in beds of creeks, and occasionally on the uplands; earthy ores of iron, particularly red oxides, and petrifactions of shells, wood, &c. In addition to these, it may here be mentioned that galena has been found in small quantities at Gibson's Port, and at Ellis's Cliffs, in the State of Mississippi: a crystal of amethyst, in the same state, by Mr. Blannerhassett; and a great variety of useful ochres, in many places on the banks of the Mississippi.