4. I have but one more article of curiosity to mention under this division. It is one of those artificial mounds which occur so frequently in the western country. I have seen many of them, and read of more. But never of one of such dimensions as that which I am now to describe.
It is situated in the interior of the Cherokee nation, on the north side of the Etowee, vulgarly called Hightower River, one of the branches of the Koosee. It stands upon a strip of alluvial land, called River Bottom. I visited it in company with eight Indian chiefs. The first object which excited attention was an excavation about twenty feet wide, and in some parts ten feet deep. Its course is nearly that of a semicircle; the extremities extending towards the river, which forms a small elbow. I had not time to examine it minutely. An Indian said it extended each way to the river, and had several unexcavated parts, which served for passages to the area which it encloses. To my surprise, I found no embankment on either side of it. But I did not long doubt to what place the earth had been removed; for I had scarcely proceeded two hundred yards, when, through the thick forest trees, a stupendous pile met the eye, whose dimensions were in full proportion to the intrenchment. I had at the time no means of taking an accurate admeasurement. To supply my deficiency, I cut a long vine, which was preserved until I had an opportunity of ascertaining its exact length. In this manner I found the distance from the margin of the summit to the base, to be one hundred and eleven feet. And judging from the degree of its declivity, the perpendicular height cannot be less than seventy-five feet. The circumference of the base, including the feet of three parapets, measured one thousand one hundred and fourteen feet. One of these parapets extends from the base to the summit, and can be ascended, though with difficulty, on horseback. The other two, after rising thirty or forty feet, terminate in a kind of triangular platform. Its top is level, and at the time I visited it, was so completely covered with weeds, bushes, and trees of most luxuriant growth, that I could not examine it as well as I wished. Its diameter, I judged, must be one hundred and fifty feet. On its sides and summit, are many large trees of the same description, and of equal dimensions with those around it. One beach-tree, near the top, measured ten feet nine inches in circumference. The earth on one side of the tree, was three and a half feet lower than on the opposite side. This fact will give a good idea of the degree of the mound's declivity. An oak, which was lying down on one of the parapets, measured at the distance of six feet from the butt, without the bark, twelve feet four inches in circumference. At a short distance to the southeast is another mound, in ascending which I took thirty steps. Its top is encircled by a breastwork three feet high, intersected through the middle with another elevation of a similar kind. A little farther is another mound, which I had not time to examine.
On these great works of art, the Indians gazed with as much curiosity as any white man. I inquired of the oldest chief, if the natives had any tradition respecting them; to which he answered in the negative. I then requested each to say what he supposed was their origin. Neither could tell: though all agreed in saying; "they were never put up by our people." It seems probable they were erected by another race, who once inhabited the country. That such a race existed, is now generally admitted. Who they were, and what were the causes of their degeneracy, or of their extermination, no circumstances have yet explained. But this is no reason why we should not, as in a hundred other instances, infer the existence of the cause from its effects, without any previous knowledge of its history.
In regard to the objects which these mounds were designed to answer, it is obvious they were not always the same. Some were intended as receptacles for the dead. These are small, and are distinguished by containing human bones. Some may have been designed as sites for public buildings, whether of a civil or religious kind; and others no doubt were constructed for the purposes of war. Of this last description, is the Etowee mound. In proof of its suitableness for such a purpose, I need only mention that the Cherokees in their late war with the Creeks, secured its summit by pickets, and occupied it as a place of protection for hundreds of their women and children. Gladly would I have spent a day in examining it more minutely; but my companions, unable to appreciate my motives, grew impatient, and I was obliged to withdraw, and leave a more perfect observation and description to some one else.
Alluvial Formation.
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.
In the geological map attached to Professor Cleaveland's Mineralogy, the alluvial country bordering on the Gulf of Mexico, is represented as terminating at Natchez. But why its termination is placed here, I am unable to understand. The country above and below Natchez, so far as it has come under my observation, presents no difference of appearance in its geology, or mineralogy. I am aware that at Natchez, when the water of the Mississippi is lowest, a soft rock is seen, from which lime has been obtained. But this rock is two hundred feet below the surface of the adjoining country; and admitting that it is a limestone rock, there is no difficulty in supposing it may constitute the basis of the alluvial deposit which rests upon it. That the incumbent earth is alluvial, can be doubted, I think, by no one who has had an opportunity of examining it. By means of a road, which has been cut obliquely down the side of the bluff, distinct layers of clay, sand, and pebbles, have been exposed for the whole distance from the summit to the base. The same character is observed at a distance from the river, where the earth has been excavated by washing, or digging. In the vicinity of the town, there is a curious exhibition of the fact. A stream of water has worn away the earth to the depth of fifteen or twenty feet, and is continually lengthening 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 deposits, 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 consequence is, that the water, which has once obtained a perpendicular 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 composed, that the river is continually undermining it, and producing effects not less to be dreaded than those of an earthquake. Several years ago, a great number of acres sunk fifty 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 will say, furnish satisfactory evidence 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 confirm the opinion.