The river, whose current is said to be the most rapid at the period when it is about to overflow its banks, runs in its swiftest vein or portion about five miles an hour. I allude to the line of upper current, and not to the mass, which moves much slower than the surface. The average velocity of the river when not in flood is not above two miles an hour. This is easily ascertained, by the progression and regular motion of its swells, and not by its apparent motion.
In November, 1800, as before observed, the motion of the stream was so sluggish as to be scarcely perceptible. A vessel that then lay opposite the Government House, advanced against it with a light breeze. I was told by a respectable lady, Mdme. Robin, who lives about six leagues below the city, that the water of the river was so brackish that she was obliged to drink other water, and that there were an abundance of porpoises, sharks, mullet, and other sea-fish, even above her plantation, nearly one hundred miles from the Gulf. The citizens thought the water brackish opposite the town. It looked quite green like sea-water, and when held to the light was quite clear. Although I did not think it brackish, I found it vapid and disagreeable. This is a phenomenon of rare occurrence, and not satisfactorily accounted for."
XXXVI.
Geography of Mississippi—Ridges and bottoms—The Mississippi at its efflux—Pine and table lands—General features of the state—Bayous—Back-water of rivers—Springs—St. Catharine's harp—Bankston springs—Mineral waters of this state—Petrifactions—Quartz crystals—"Thunderbolts"—Rivers—The Yazoo and Pearl.
Though not much given to theorising, I have been drawn into some undigested remarks in my last letter, upon a theory, which is beginning to command the attention of scientific men, to which the result of geological researches daily adds weight, and to which time, with correct observations and farther discoveries, must add the truth of demonstration.
This letter I will devote to a subject, naturally arising from the preceding, perhaps not entirely without interest—I mean the physical geography and geology of this state. In the limits of a letter it is impossible to treat this subject as the nature of it demands, yet I will endeavour to go so far into its detail, as to give you a tolerable idea of the general features of the region.
Besides the cliffs, or great head-lands, alluded to in my last letter, frowning, at long intervals, over the Mississippi, serrated ridges, formed of continuous hills projecting from these points, extend in various directions over the state. These again branch into lower ridges, which often terminate near the river, between the great bluffs, leaving a flat space from their base to the water, from a third of a mile to a league in breadth. These flats, or "bottoms," as they are termed in western phraseology, are inundated at the periodical floods, increasing, at those places, the breadth of the river to the dimensions of a lake. The forest-covered savana, nearly forty miles across, through which the Mississippi flows, and which is bordered by the mural high lands or cliffs alluded to in my last letter, is also overflowed at such seasons; so that the river then becomes, in reality, the breadth of its valley. The grandeur of such a spectacle as a river, forty miles in breadth, descending to the ocean between banks of lofty cliffs, too far distant to be within each other's horizon, challenges a parallel. But, as this vast plain is covered with a forest, the lower half of which only is inundated, the width of the river remains as usual to the eye of the spectator on the cliffs, who will have to call in the aid of his imagination to realize, that in the bosom of the vast forest outspread beneath him rolls a river, to which, in breadth, the noble stream before him is but a rivulet. The interior hills, or ridges, mentioned above, are usually covered with pine; which is found only on such eminences, and in no other section of the south or west, except an isolated wood in Missouri, for more than fifteen hundred miles. The surface of the whole state is thus diversified with hills, with the exception of an occasional interval on the borders of a stream, or a few leagues of prairie in the north part of the state, covered with thin forests of stunted oaks. These hills rise and fall in regular undulations, clothed with forests of inconceivable majesty, springing from a rich, black loam, peculiarly fitted to the production of cotton; though, according to a late writer on this plant, "it flourishes with equal luxuriance in the black alluvial soil of Alatamaha and in the glowing sands of St. Simon's."[10]
The general features of this state have suggested the idea of an immense ploughed field, whose gigantic furrows intersect each other at various angles.—Imagine the hills, formed by these intersections, clothed with verdure, whitened with cotton fields, or covered with noble woods, with streams winding along in the deep ravines, repeatedly turning back upon their course, in their serpentine windings, before they disembogue into the Mississippi on the west, or the Pearl on the east, and you will have a rude though generally correct idea of the bolder features of this state.
A "plain," or extensive level expanse, which is not a marsh, forms, consequently, no part of its scenery, hill and hollow being its stronger characteristics. For a hilly country it presents one striking peculiarity. The surface of the forests, viewed from the bluffs, or from some superior elevation in the interior, presents one uniform horizontal level, with scarcely an undulation in the line to break the perspective. Particularly is this observable about a mile from Natchez, from the summit of a hill on the road to the village of Washington. Here an extensive forest scene lies east of the observer, to appearance a perfect level. But as he travels over hill and through ravine, anticipating a delightful prairie to lie before him, over which he may pace, (or canter, if he be a northerner) at his ease, he will find that the promised plain, like the mirage before the fainting Arabian, for ever eludes his path.