Popular Science Monthly/Volume 23/September 1883/The Little Missouri Bad Lands II
By Professor T. H. McBRIDE.
"Knew you what silence was before?
HOWEVER interesting the Bad Lands may be in their scenery and in their conditions purely physical, it is only when we consider them in their relation to life and its progress on the earth that they become most attractive, most engaging.
To describe the present flora and especially the fauna of this region would require no very long chapter, and yet the list of species would be longer than some might suspect. Where erosion less interrupted by the fires has been allowed to do its perfect work, there are level areas of considerable extent sparsely covered with short grass, on which the prong-horn, the elk, the deer, and the big-horn sheep, have been wont to graze. The valleys, and even the flat tops of the buttes in May, are said to abound with flowers. Cottonwood-groves occur along the banks of the river, and occasionally a thicket of low box-elders, plums, and various kinds of thorny shrubs, divides with the sage-brush the occupancy of some sheltered ravine; while up the northern faces of some of the higher and more sloping buttes, where the snow of winter lingers longest, low, ragged cedars creep in straggling file. But, where the fires have done their part, the desolation is extreme. Even the vegetation which the spring-time may have brought seems to vanish from the earth, the precipitated alkali whitens the valleys, and from all the naked hills comes up a glare of dazzling light as from a desert absolute. Far as you can look or listen there conies not the faintest sign or whisper of living thing. No bird visits those forgotten hills, no insect stirs about your feet or beats with humming wings the air; the very wind is silent, and from the glowing buttes, as from a furnace, the heated atmosphere rises in shimmering columns. It seems as if it had never rained, or, if it has rained, it seems as though it would never rain again. Here is the trail by which, in 1863, passed General Sully and his train when all these hill-tops were alive with hostile Sioux. The Indians are long since gone, but the trail remains unchanged, and can be easily followed after a lapse of twenty years. Yonder, along that other trail still so clearly visible over the distant buttes, went Custer and his band when they marched away to the west and disappeared from human sight forever. The climate is an arid one, and the process of erosion slow. Looking out over the landscape as we now see it, none would imagine that all this territory was at one time favored with a climate perhaps nearly semi-tropical, that over all this wide area were waving forests of perpetual green, stretching away to the north, south, east, and west, almost to the limits of the so-called "Plains." Yet such is the case, and this complete transition from the wealth of primeval woods to the poverty of semi-desert has been brought about not by the devastation of short-sighted man, but by the orderly procedure of all those indefinite forces which for convenient description men sum up as Nature. The evidence of this transition is not far to seek. Scattered over the grassy low-lands, crowning many an isolated pillar of sandstone or clay, lying here and there on all the high hills, are remnants of gigantic trees, remnants more or less perfectly silicified, stumps, boles, and branches. In some localities these "petrified stumps" cover the whole face of
the country, and scores have been carried away on flat-cars to decorate the lawns of those able to pay freight on such unwieldy "curiosities." Scientists are frequently disposed to doubt petrifactions, and are often compelled to disappoint popular expectation in regard to forms most fairly outlined; but that these stumps and logs and splinters have been wood there can be no possible doubt. Our microscope settles the question once for all by revealing the very form and markings of the original wood-cells now replaced by silex. In Fig. 1 we have the microscopic view of a section taken from a log lying on the summit of one of the buttes. The medullary rays are plainly seen, as well as wood-cells bearing series of peculiar concentric circles, which every botanist instantly recognizes as characteristic of the Coniferæ, the cone-bearing trees, pines, cedars, firs, sequoias, so that we may not only safely pronounce the petrifaction on the hill-top a fossil log, but we have determined without doubt the vegetable order to which it belongs. For the silicifying of such masses of organic material long submergence was doubtless necessary, but to which of the beds of the series exposed these relics belong it is difficult to determine. Such fossils come to light only by erosion, and erosion leaves them always at the lowest levels.
But these are not the only evidence of a former vegetable life very different from that now prevalent in the Bad Lands. All these beds
of lignite, said to exceed in area all the other coal-fields of the world, are of undoubted vegetable origin. Knowing what we do about coal in general, we can conceive of no other history for them, and although we find in these American beds no such veritable logs as characterize the braun-kohle of Northern Europe, yet the presence in the lignite of bits of carbonized wood, twigs, and bark, leaves no doubt as to the character of the primal vegetation.
But it is in the beds immediately associated with the coal that we find the most indubitable evidence at once of the presence and character of the former flora. Here, in strata of sand and clay, lie most beautiful impressions of the leaves of both deciduous and coniferous trees. We may say fossil leaves, but this is hardly the correct description, since we have preserved to us not a vestige of the original leaf, but simply a mold left in the imbedding clay, as the matter of the leaf disappeared. In fortunate cases, therefore, we have both the upper and lower surfaces of the leaf exhibited, and these impressions are perfect, so that experienced observers can determine, not the order only, but the genus, often the very species and variety, of the tree from which a given leaf has fallen! This seems astonishing to the
ordinary student or analyst of flowers, or to him who notes the great variety of form and feature which the leaves of a single tree present—a box-elder, for instance—but fails to see the hidden lines-which betray relationship. But such men as Goeppert, Heer, Saporta, and our own Lesquereux, like Tischendorf among the MSS., have a vision and an experience not possessed by many, a "special insight," Professor Lesquereux says, which, in presence of a single organ, a single leaf, can conjure forth from the dim ages past the plant entire; and men like Gray and Hooker, while acknowledging themselves not possessed of similar divining power, admit the veracity of the results obtained. I have said a leaf, an organ, sometimes a fragment, is sufficient, and that which to the ordinary observer is wholly enigmatical becomes to the paleophytologist a revelation. "These are the scattered fragments of the old book of Nature. When one sets himself to decipher them, he very soon forgets the singularity of the characters and the poor condition of the pages. Thought rises, ideas develop, the manuscript
unrolls. It is the tomb that speaks and delivers up its secret." We are reminded of the prophetess of classic fable, who wrote the burden of her prophecy on forest-leaves, and then committed the precious pages to the winds. He who would find the inspiration of her song must have the wit to rearrange.
Of these leaf-prints the finest specimens collected in the Bad Lands come from strata which have been baked by the burning coal. This burned material furnishes a matrix of sufficient hardness to preserve perfectly the mold and to endure the stroke of the hammer which brings to light the hidden image, and so the life-history of Dakota, like the history of some of the old Oriental monarchies, is revealed by the cleaving of burned bricks.
So far as I am informed, no systematic search for these fossil leaves has ever been made. They occur on the surface in isolated spots, and different localities furnish different as well as similar forms. The baking to which the fossil-bearing beds have been subjected has, in a measure, obliterated the distinction of strata, so that it is difficult in any case to determine the exact horizon, or to say whether all the leaves are from about the same level, and hence contemporaneous; it suffices our purpose to know that they are nearly so. At all events, in strata such as these, and as geology reckons time, no intervals have been very great, and we may omit discussion of the relative age of the leaves, and consider immediately their kinds and meaning. We have represented, in Figs. 3-12, leaves of the following genera:Platanus, Populus, Juglans, Corylus, Carpinus, Persea, Mens, Sequoia, Comics These names are all familiar, although we are not accustomed to see them grouped together. Platanus is represented throughout the northern Mississippi Valley by the sycamore, frequenting the water-courses and rocky banks, and often attaining grand dimensions. Two species of the genus occur in California, two in Mexico, and one in the far Levant. Populus we know from our aspens, balm of Gilead, and more than all by the cottonwood—a prairie-tree—abundant along our Western rivers, and following the Missouri and its tributaries to the very foot-hills of the Rocky Mountains. These trees all secrete about their buds more or less of fragrant wax, and possibly from the tiny pits seen at the base of the leaf of P. glandulifera exuded some such balsamic gum which spread and polished the upper surface of the young leaves. Of Corylus and Carpinus little need be said. The hazels and hornbeams are sufficiently well known as characteristic of north temperate forests everywhere. The genus Juglans we know from our invaluable walnut, once common throughout the Eastern United States. A single species is found also in Asia Minor and Europe. Cornus, the dogwood, has some northern species. But the three remaining genera are more interesting. Persea is a laurel, and laurels are especially tropical plants, extending in hardier forms as evergreens into the sheltered or milder parts of the temperate regions. This particular genus extends along the Atlantic coast from Delaware southward, and is abundant in the West Indies. Ficus is also a tropical genus, or, at least, occurs in warm climates only, as in Florida, South America, around the Mediterranean, in India, in Java; while Sequoia is limited to the mountains of California, and is to us best known through the "Big Trees" of the Mariposa.
All these genera, belonging to so many different orders, leave no doubt that the vegetation of the times when these leaves were green was abundant and varied. We may be sure that the genera mentioned
are only a few, a very few, of those to be found, that these were surrounded by their congeners and by a multitude of other and different forms, whose remains man has yet to see and understand. North Dakota was once, if not repeatedly, a land of forests.
But what a strange association of leaves we have here!—the flora of Florida, the flora of California, and the flora of our Northern woods. As we collect the leaves, we find Sequoia associated with Juglans, Persea and Ficus lie side by side, Populus and Platanus seem to affiliate, although Populus has of all the widest distribution. In the beds where they are found these leaves lie flat and smooth. Preserved just where they fell, they seem, as they lost hold upon the parent tree, to have settled once for all into quiet waters. They have never been much tossed by winds nor rolled by currents, and hence can not be said to indicate that these differing genera represent different altitudes. besides, the strata have evidently never been disturbed in such a way as to afford any great variety of altitude in this locality. We are therefore shut up to the conclusion that, at the time these leaves were green, a climate prevailed very different from any now known in the same Fig. 12.—Cornus rhamnifolia (O. Weber). The climate must have been warm and equable. Indeed, that the climate, not of Dakota only, but of the whole northern hemisphere, was at one time far milder than now seems proved, for leaves such as these of which we speak have been found in Greenland and many other circumpolar lands. What may have been the prime cause of this former high temperature in high latitudes we leave students of physical geography and surface geology to decide, but we may say this: the warm and equable climates of the world are maritime, or characteristic of islands, as the climate of Italy or the Grecian Archipelago. That a large body of fresh water may work wonders in temperature and amount of moisture, is to us a familiar fact witnessed by the climate of the peninsula of Michigan. And so, to meet the requisite climatic conditions suggested by these few leaves, we are ready to accept without doubt the statements of men who from their study of the topography of the Bad Lands declare the whole region to have been, perhaps again and again, the bed of a wide-spread inland lake or sea. On the shores and islands of this Mediterranean of the Western world stood the forests primeval whose foliage has come down to us like the sad memory of better days.
As one looks upon these fairly outlined relics of a long-forgotten age, he may catch glimpses of landscapes in presence of which all the bleakness and barrenness of the present disappear. Instead of sterile hills and buttes, far stretches the quiet sea, unvexed by storms, but filled with happy islands like the "Islands of the Blest." Over the islands the laurel blooms, abundant fig-trees spread their dense and shining foliage, and send down aerial roots in thickets impenetrable. Along the curving shores the bending willows sweep the water's surface, while hard by stands the broad-leaved plane-tree and the feathery elm, and farther back the hazel and its kindred oak. The poplar shakes its shining leaves and fills the air with fragrance. Over the cornel and the hornbeam creeps the vine, and high above all, walling the horizon like the cryptomeria in the forests of Japan, sequoias, magnificent sequoias, whose skeletons now lie white like other skeletons on the hills, lift their tufted branches. The forest-trees fall in natural decay, the mirror waters sleep in peace, while the centuries of the early Tertiary come and go.