Popular Science Monthly/Volume 23/August 1883/The Little Missouri Bad Lands I
| THE LITTLE MISSOURI BAD LANDS. |
By Professor T. H. McBRIDE.
BAD Lands, so called, occur in various parts of the wide plateaus adjacent to the Rocky Mountains. There are Bad Lands in Kansas, Bad Lands in Nebraska, in Dakota, and in the Territories farther west. The English name, probably because of intelligibility and brevity, seems about to supplant the old French Mauvaises Terres by which early travelers were wont to describe these remarkable regions. Either appellation is appropriate, for these lands, at ordinary estimate, are in many places nearly valueless, and yet the voyageur meant by his mauvaises probably nothing more than that the country was difficult of transit—terres mauvaises à traverser. However this may be, it is certain that these regions are full of interest and attraction for the traveler, the student, and the naturalist.
Although Bad Lands are everywhere much the same thing, and a discussion of one locality might seem applicable to all, yet there are differences—due, no doubt, to varying conditions in times long gone by. It is not intended here to discuss these differences, but to speak briefly of what may be seen in the valley of the Little Missouri River, in Northwestern Dakota.
This little stream, by courtesy a river, rolling its murky waters northward and eastward for a distance of about two hundred miles, near the line separating the Territories of Montana and Dakota, is bordered by landscapes which in detail are without parallel, and in general effect transcend the possibilities of description. As the visitor approaches from the east, there arises suddenly before him from the monotonous plain a wondrous array of myriads of hills and hillocks—hills of nearly uniform height, but of every conceivable shape and form. Some are almost rectangular, with precipitous sides; many are conical; many are dome-shaped; some have the form of a frustum of a cone, and, on the summits of some, perfectly conical heaps appear. The greater number are flat-topped, and, rising to about the same level, give the impression of some splendid rampart extending for miles and miles along the horizon; some slope up gently from a narrow valley for seventy-five or a hundred feet, and end in a lofty rotund tower of naked sandstone. To all this diversity of form there is added diversity of color. The sides of all these mounds are almost verdureless, so that the absence of green is conspicuous, but almost every other hue is represented. Colors occur in broad bands across the faces of the hills—red and gray and yellow and black, purplish-blue and ashy and pink in an unending series of shades and tints. Nothing is brilliant, but everything soft and beautiful. Here and there, from a broader base, a hill towers away above all its surroundings, and becomes a landmark visible from afar. In the parlance of the West such a landmark is called a butte,[1] and, if one has strength and patience to climb the summit of a butte, surely his reward is great. From no other point d'avantage on this continent does a man open his eyes upon a panorama wilder or more weird. In one direction a thousand motley heaps cover the plain like the tents of some wide-spread army; in another, the flat-topped mounds stretch away to meet the horizon, and seem like the steps of some Giant's Causeway leading to the sky; while, as evening comes on and the sun goes down, the play of colors, the shifting light and shadow present a scene in presence of which the most prosaic must for the nonce feel the inspiration of the poet.
But, if this weird region is thus interesting to the ordinary tourist, much more so is it to the student—to him who seeks to know the how, if not the why, of all things terrestrial. Here is a corner of the world in which the evidences of change—of transition are—so patent that a glance reveals them to the dullest beholder. It is as if Nature were here trying to impress upon her children a great object-lesson, as if the universal Dame had said: "Behold! Look! Here have I stripped all the hills and laid bare all the valleys, that you might learn my time honored methods, and once for all see something of how worlds are made." No man would say, as he looks for the first time out over these naked hills: "Such have they ever been; such shall they always be." By no means. These, at least, are not the "everlasting hills." Here is transition. Now, transition is to the student a word of magic sound—echoing the past, prefiguring the future. Let him but behold any of Nature's processes in intermediate stage, and mystery as to mode and method vanishes; the solution is easy.
But, now that our object-lesson is before us, what can we learn about it? Let us look again from the top of the butte, this time for instruction rather than for pleasure. See, there the river winds—a silver thread, shut in by long lines of banded bluffs. Into the river valley principal ravines debouch, others into these, and so on to the very base of the bluff on which we stand. And now, you say, the problem is solved; the river is the outlet, and all these strange phenomena are due to surface-drainage. Here is the water-system, and here are its effects. But this answer can be but part of the truth, else why are no Bad Lands seen along the Desmoines or the Tennessee? Why are they not of universal occurrence? Besides, the beds of all these ravines are, for the most part, flat and level as a floor, scantily covered with short grass, or white with sage-brush (Artemisia). Only here and there a gully without water, or perchance, in some larger ravine, we may find a tiny, scarcely flowing streamlet, brown with alkali. Manifestly the river-system accounts for the general features of the country, but not for that which is peculiar. But let us look at the problem in another way. Let us begin at the bottom of these hillocks, at least as low down as we may come, and study for a moment the hillocks themselves.
We have already incidentally noticed the uniform stratification which characterizes the whole country, and is revealed by the banded appearance of the hills. At the base of one of these hills we may find (Fig. 1) a stratum of pale, yellowish clay. Just above, and perfectly conformable, is a layer of lignitic coal, inferior to soft coal, of a deep-brown color, rapidly crumbling on exposure to the air, and even, when in sufficient mass, liable to spontaneous ignition. Overlying the coal is another bed of clay of an ashy hue, containing more or less sand in composition. Next comes a layer in which sand predominates, a distinct gray in color; then a bed of clay of a bluish tint, another layer of coal, a layer of yellow clay, a stratum of very soft sandstone, another bed of clay, and then a foot or two of reddish-brown sandstone, very unequally hardened and mixed with clay. Surmounting the whole is a bed of soft clay of varying thickness, mostly a sort of remnant, persisting only in mounds and the conical heaps already referred to.
Fig. 1.—Diagrammatic Section of a Single Butte.
Now, all these strata, except the uppermost sandstone, have this common characteristic: they are composed of particles excessively fine, so that, if from any of the beds a little bit be taken, it may, when dry, be reduced between the fingers to an impalpable powder as fine as ashes. Even the lignite is no exception. If, now, in connection with this fact, and remembering the arrangement of the strata, we take into account the arid climate which prevails in all these regions, we are in position to understand much of the peculiar conformation of the Bad Lands. In the winter the snows are light, and in summer the rain that falls comes in sudden, violent, but short-lived storms. For perhaps half an hour after one of these storms, torrents flood the valleys and low plains between the hills, the rushing waters heavily charged with particles of clay, but particles so fine that they do not readily leave the water or become precipitated, but are borne on to the river, thence to the Missouri proper, which latter stream parts with them only as it blends in the clearer waters of the Mississippi. If, after the storm, we examine again the face of the bluff, we find it striated with numberless tiny channels, down which have just poured little rivulets of water hardly so much as wetting the surface, while from top to bottom the erosion has been about the same, the slightly increased density of the upper layer enabling them to sustain the brunt of the storm, and yet suffer no more wear than the softer strata beneath.
It is manifest that if this process be continued, and if all the hills are like that described, the reduction of all these terraces and mounds is but a question of time, and we may look forward to the day when all this now wild and impassable country shall be but a prairie of gentle undulations and monotonous outlook, not dissimilar to the wide plains which even now stretch off far to the east to blend with the Missouri Valley. Every mountain shall be made low and every valley filled, and no force more violent be concerned than the gentle action of the wind and rain.
I have said that the detritus of the storm is non-precipitate, is borne away by the water; and yet some of the moving particles do find lodgment by the way. There is no such thing as a talus at the foot of the bluff, but after each flood a thin film of fine silt is spread over the plain, and the flat bottoms of the ravines are by imperceptible pace forever creeping up the wasting buttes, particularly of those remote from the river.
But such a butte as that described, while revealing much, does not reveal all the facts necessary to the full understanding of our subject. One of the first things to strike the attention of the tourist among the hills is the evidence of the wide-spread action of powerful heat. The bands of red which everywhere mark the landscape are certainly traces of some glowing fire. But what a fire! Here are whole beds of clay baked until they have taken on the color and character of hard-burned brick or unglazed pottery. The resonance of the dry fragments under the hammer or the wheels of our vehicle is precisely that of broken terra-cotta. Sometimes the top of the butte is bare and red; sometimes the whole mass, from top to bottom, has been burned, and at a distance seems like a brick-kiln fallen into ruin. The splintery fragments, broken as macadamizing stone, form over the entire surface a natural riprap, on which the elements spend their force in vain. Such buttes are not transient; the fire has saved them, and in this dry climate they may stand forever. Here and there, so hot has been the fire, that the clay has been not only baked but fused, and great clinkerlike masses rest upon the hill-top, thrust themselves out from the hillside, or stand naked like monuments on the plain.
In looking for the source of heat capable of producing such phenomena men seem instinctively to revert to volcanic fires, and the burned clay is everywhere designated scoria. In one place where the railroad cuts through a hill of this material we have "Scoria Cut," and scoria constitutes for miles the favorite ballast. But probably volcanic fires were never nearer than at present. Of crater, lava, trap, or other usual volcanic concomitants, there is not the remotest sign; but to-day, while we are theorizing over the matter, some of the furnaces which have baked all these regions are still glowing, the smoke yet ascends, and our own eyes may witness something of the transformation. The lignite-beds furnish the fuel, the slow-paced erosion lays the fuel bare, spontaneous combustion supplies the torch, and the whole phenomenon is explained.
That the lignite is in some way connected with the fiery metamorphosis of the Bad Lands we might have inferred from the fact that no lignite ever appears above the burned belts, and in a hill entirely burned the lignite is entirely wanting. The burned clay also corresponds in position to beds overlying the coal in hills immediately adjacent. But, as we have said, the fires in isolated spots are still burning; in some places wholly subterranean, smoldering and smoking, at other points readily seen both in nature and effects. We may discover the coal on one side of a broad-topped hill, and on the other we may look from the hill's summit down through gaping rifts to the same horizon and see everything molten at white heat, while hot air, smoke, and coal-gas, as from a furnace, make the region almost inaccessible. The accompanying diagrams (Figs. 2, 3) illustrate a burning
Fig. 2.—Transverse Section of Burning Lignite—Thickness of Lignite-Bed exaggerated.
coal-bed, which has been photographed and dubbed "The Crater." Here the fire is burning out the lignite beneath a valley lying between two rounded ridges. As fast as the coal is removed by combustion
Fig. 3.—Longitudinal Section of Burning Lignite—Thickness of Lignite-Bed exaggerated.
the whole section of the valley sinks, creating with respect to the stratification what geologists term a, fault. At the lowest part of the valley, where the fire is nearest the surface, the entire superstratum breaks up and crumbles to ruin. When, after a summer storm, the flood comes down the valley, shoots into the crevices, and runs along the fissures, something like an explosion takes place. On every side volumes of steam ascend, but the fire is not extinguished. The loosened earth is much of it swept away, and a deep gulch forms between the ridges, and so the air comes freely to the fire, which might otherwise be smothered in its own ruin. Meanwhile the hearts of the hills themselves are baked like tiles in a close kiln, and while the fire would seem to hasten erosion, as in some places it certainly does, yet the metamorphism accomplished tends in the opposite direction, and is efficient in proportion to the completeness of the change.
And so the work goes on; one bed of lignite after another takes fire, one butte after another becomes the cover of a kiln, a furnace, and the whole country is transformed. I say the work goes on; better, has gone on, for it is nearly done. Glowing or smoldering through ages past, now hidden in darkness, now breaking forth to light, these secret fires have been burning, burning like a hidden fever, until the fair face of Nature has become an arid desert.
Thus the Bad Lands, as we know them, are the results of the action of two opposing elements, the water and the fire. Of these two the first had doubtless acted alone long before the second entered at all into the problem of disintegration. These level tops bespeak a former continuous level plain. More than this: into the highest of the buttes we may trace the same strata which make up the lower hills. The level must at one time have been higher still than we had first supposed. The changes of the past are enormous as compared with anything shown by the present, or even possible in the future of these strata. Owing to the peculiar nature of the strata, their uniformity and lack of solidity, the erosion has produced effects unique, and to these the fire has brought permanence and stability. Far as the coal beds extend erosion has been or is liable to be arrested, and the country doomed to infertility. But the coal is not universally present. Many places are free from it entirely, and here erosion may continue unchecked its peaceful processes until all is beaten down to the common plain. In other places the coal takes fire in but isolated hills, and these become permanent while all else is reduced to prairie. And now we remember that away to the east the plains sometimes show a solitary hill, whose sides, reddening beneath the sparse grass, and whose summit, glowing in the sunshine, betray its origin.
- ↑ This term is also applied to a high hill of any sort, even to a mountain-peak.