Art. II. On the Origin of Prairies.
Art. II. On the Origin of Prairies.
St. Louis, (Missouri Ter.) March 3, 1819.
Sir,
The probable cause of the origin and continuance of prairies has been the subject of much speculation among the learned and curious. The inquiry is interesting; and many theories have arisen; but although plausible and ingenious, they are, in my opinion, unfounded in fact.
I should be glad to see the following remarks, which were called forth more particularly by the speculations of Caleb Atwater, Esq. (See [No. 2. p. 116]. of this work) appear in your valuable Journal of Science; and they are, for that purpose, at your service.
With high respect, I am, Sir, your's,
R. W. WELLS.
Benjamin Silliman, Esq.
Mr. Atwater, after describing the prairies and barrens, says, that according to the common opinion, they "were occasioned entirely by the burning of the woods," but, "erroneous information first propagated such an opinion, and blind credulity has extended it down to us." Mr. A. goes on to affirm that, "wherever prairies and barrens are found, there, for a long space of time, water once stood, but was gradually drained off." The writer of this having often visited and observed with attention the nature and appearance of the prairies on the Alleghany mountains, in the states of Ohio, Indiana, and Illinois, and having long been employed by the United States as a surveyor in the prairie country of the Missouri and Missisippi, thinks he may venture to oppose these speculations without being thought presumptuous. He is of opinion, that the vast prairies and barrens, extending over the greater part of the western states, and over nearly all Louisiana, were primitively occasioned, and have been since continued, by the combustion of vegetables, and that water had no agency in their formation.
In order to prove the high prairies of the state of Ohio to have been once covered by the waters of Lake Erie, Mr. A. maintains, that the channel of the Niagara river has been worn down "several hundred feet" by the attrition of its waters. Mr. A. should have shown, that the banks of the Niagara are, at this time, several hundred feet high, or, like the Potomac, at Harper's Ferry, has broken through a mountain "several hundred feet" high; but neither the one nor the other is the fact; the face of the country, on either side of the river, is comparatively low and champaign; and were it possible for the waters of the lake to rise considerably above their present level, they would meet with no obstruction or impediment, for many miles on either side the river, but would be precipitated over the cataract, into Ontario, and down the St. Lawrence to the Atlantic. But supposing there had been a mountain running between Lakes Erie and Ontario of sufficient height to prevent the water of the former from passing into the latter, it must evidently have found other places through which to escape, and before it would rise high enough to overflow the elevated region of Madison and Fayette counties, in Ohio, it would have passed over into the heads of the Alleghany. But it is impossible to imagine this, unless we suppose the Atlantic to have been six or seven hundred feet higher than at present, which, according to Mr. A. would have made prairie of all the Atlantic states.
The fact of shells and other marine substances having been found in a few places, by digging in the prairies, proves nothing, or proves too much, for they are found in equal or greater quantities all over America, in the sides and near the summit of the Alleghany mountains; on the Andes, in South America, and the Alps, in Europe. The resemblance which the soil, in the low prairies, and not in the high, bears to the alluvial, can justly be attributed, it is presumed, to the leaves and other vegetables and light materials of which they are composed, having been washed by heavy rains, for ages past, from the higher to the lower places. This will also account for the circumstance of trees growing upon the summits of the hills of steep ascent: being thin and poor, the grass neither grows sufficiently long or thick to kill the timber when fired. They could not have been islands in this fairy lake; because their summits are frequently much lower than high prairie flats a few miles distant. These are facts which will be recollected by those who have ever travelled through a prairie country of any extent.
But suppose it to have been proved, that the waters of Lake Erie once overspread the state of Ohio, from its present shore to Chillicothe, (a supposition which I trust has however been shown to be visionary) does it follow that the prairies were occasioned by such overflowing? If the water, by covering the country, prevented the timber from growing, should we not naturally look for the largest timber on the higher grounds which would be first forsaken by the waters, and for small timber on the low grounds, where the water remained longest? If this be true, (and it is unquestionable) we should then look for prairies on the low grounds bordering on Lakes Erie, Huron, and Michigan; and the thickly timbered country would be on the high land, near the sources of the rivers. But the contrary is absolutely the fact: we find heavy timbered land, and no prairies, in the low countries north of the lakes, and none south, either in Michigan territory or elsewhere, until we arrive near the sources of the rivers. It is true, that the water standing in ponds will prevent the timber from growing; but the difference is readily observed between prairies, properly so called, and those bogs.
But to prove farther that water had no agency in bringing the prairies into existence, we may mention those on and near the summit of the Alleghany mountains, (principally in Alleghany County.[47]) Many of those prairies are ten or twelve miles in length, and three or four in width. Will it be pretended that the sides of those mountains were also lakes? Farther—the most extensive prairies known, are the very high plains immediately west of the Rocky Mountains, and east of the mountains near the sources of the Arkansaw and Missouri rivers, extending even on the spurs of those mountains; a country the highest perhaps in North America, with a great and continued descent to the Pacific on the one side, and to the Gulf of Mexico on the other.
The barrens, also, found in Kentucky, are another evidence that water had no agency in their formation—they are situate, it is believed, in the elevated parts of the country exclusively.
The writer of this, deeming it unnecessary to say more, or to produce more facts, (although much more may be said, and many more facts produced) to prove that prairies were not lakes, will now endeavour to prove that they were occasioned by the combustion of vegetables.
Prairies are found in those countries only that are congenial to the growth of grass, and only where the soil is sufficiently rich to produce it luxuriantly—they are found commonly on high plains, sufficiently drained to prevent water from remaining on them the whole year; for it is by no means necessary that they should be always dry; on the contrary, if they are sufficiently level to prevent the rains from running off immediately, the grass will grow thicker and higher—but they must be sufficiently dry to burn, at least once in two or three years, during the long, dry season, called Indian summer. It has been universally remarked, that these seasons are much longer as we proceed westerly—commencing usually in October, and continuing a month and a half or two months, during which the vegetation is killed by the frosts, and dried by the sun; the wet prairies are also dried, and before the season has expired, the grass is perfectly combustible.
The Indians, it is presumed, (and the writer, from a residence in their country and with them, is well acquainted with their customs) burn the woods, not ordinarily for the purpose of taking or catching game, as suggested by Mr. A. but for many other advantages attending that practice. If the woods be not burned as usual, the hunter finds it impossible to kill the game, which, alarmed at the great noise made in walking through the dry grass and leaves, flee in all directions at his approach. Also the Indians travel much during the winter, from one village to another, and to and from the various hunting grounds, which becomes extremely painful and laborious, from the quantity of briers, vines, grass, &c. To remedy these and many other inconveniences, even the woods were originally burned so as to cause prairies, and for the same and like reasons they continue to be burned towards the close of the Indian summer.
Woodland is not commonly changed to prairie by one burning, but by several successive conflagrations; the first will kill the undergrowth, which causing a greater opening, and admitting the sun and air more freely, increases the quantity of grass the ensuing season: the conflagration consequently increases, and is now sufficiently powerful to destroy the smaller timber; and on the third year you behold an open prairie.
Ordinarily, all the country, of a nature to become prairie, is already in that state; yet the writer of this has seen, in the country between the Missouri and Mississippi, after unusual dry seasons, more than one hundred acres of woodland together converted into prairie. And again, where the grass has been prevented from burning by accidental causes, or the prairie has been depastured by large herds of domestic cattle, it will assume, in a few years, the appearance of a young forest. Numerous proofs of this fact can be adduced, but a few shall suffice. The vicinity of St. Louis and St. Charles affords instances. Both these beautiful places are situated on what are termed first and second bottoms, or flats—the former on the Missisippi, the latter on the Missouri; the second or upper bottoms, in both, are high plains, that commence within a few hundred yards of the rivers, and extend back many miles; all the old French inhabitants will tell you, that the prairies formerly came immediately up to those places. Now the surrounding country for several miles is covered with a growth of trees of four or five inches diameter, near the towns where the burning first ceased, and gradually diminishing in size as you recede, until you at length gain the open prairies. So the barrens in Kentucky; many of the first settlers of that state distinctly recollect when many of those barrens were clear prairies, now partially covered with small trees. It is deemed unnecessary to offer more proofs, or additional arguments, in support of the opinion that the prairies were occasioned by fire, and not by water. Indeed one glance at the maps of those extensive prairie countries, surveyed by order of government, where the prairies and woodland are distinguished and correctly delineated, should carry conviction. The timber will be there observed to skirt the rivers; in the country near their sources a few solitary trees are seen, close on the banks, secure from the fires, and increasing in numbers as the rivers increase in size, and the low grounds become more extensive.
The view given of the prairies by Mr. A. is correct; but was certainly painted in the winter season—they are, at that season, bleak and uncomfortable both to the feelings and sight; but a full return is made to both when the spring opens. The prairies (particularly to the west) are then covered with the richest verdure, interspersed with an immense variety of wild flowers, that send forth the most grateful odours. Ascend one of the small hills, and you have a prospect as delightful as it is possible for the imagination to conceive. Far as the eye can carry you, a delightful country extends, through which numerous streams wind their serpentine courses, with groves and clumps of trees at intervals upon their banks. On one hand, at an immense distance, the small hills and groves are seen rising above the blue horizon; on the other, the view is pleasantly terminated by the wood on the low grounds skirting the river to which the smaller streams are tributary—while herds of buffalo, elk, deer, and other animals, are frequently seen slowly travelling to and from the watering-places, or grazing on the plains. The inhabited parts of the country present a prospect still more pleasing; around the margin of those extensive rich prairies, numerous habitations are seen, withdrawn a short distance in the wood, from the winter's cold and summer's heat—their finely cultivated fields lie in the prairies, which yield at once to the plough, without the previous Herculean labour of demolishing the forest. The area between the farms is a common of pasture to the numerous herds during the spring, summer, and autumn, and a small part mowed affords hay for the winter. The farmer who takes up his habitation in the neighbourhood of the prairies, has many of the advantages of an old inhabited country, and all the advantages of the new.