Part 1

UNITED STATES DEPARTMENT OF THE INTERIOR HUBERT WORK, SECRETARY

NATIONAL PARK SERVICE STEPHEN T. MATHER, DIRECTOR

FOSSIL FORESTS OF THE YELLOWSTONE NATIONAL PARK

UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON 1928

88781°—28——2

THE NATIONAL PARKS AT A GLANCE.

[Number, 19; total area, 11,817 square miles.]

National parks Location. Area in Distinctive characteristics. in order of square creation. miles.

Hot Springs Middle 1½ 46 hot springs possessing 1832 Arkansas. curative properties—Many hotels and boarding houses—20 bath-houses under public control. Yellowstone Northwestern 3,348 More geysers than in all rest 1872 Wyoming. of world together—Boiling springs—Mud volcanoes—Petrified forests—Grand Canyon of the Yellowstone, remarkable for gorgeous coloring—Large lakes—Many large streams and waterfalls—Vast wilderness, greatest wild bird and animal preserve in world—Exceptional trout fishing. Sequoia Middle 604 The Big Tree National 1890 eastern Park—Scores of sequoia trees 20 California. to 30 feet in diameter, thousands over 10 feet in diameter—Towering mountain ranges—Mount Whitney, highest peak in continental United States—Startling precipices—Cave of considerable size. Yosemite Middle 1,125 Valley of world-famed 1890 eastern beauty—Lofty cliffs—Romantic California. vistas—Many waterfalls of extraordinary height—3 groves of big trees—High Sierra—Waterwheel falls—Good trout fishing. General Grant Middle 4 Created to preserve the 1890 eastern celebrated General Grant Tree, California. 35 feet in diameter—6 miles from Sequoia National Park. Mount Rainier West central 325 Largest accessible single peak 1890 Washington. glacier system—28 glaciers, some of large size—48 square miles of glacier, 50 to 500 feet thick—Wonderful sub-alpine wild-flower fields. Crater Lake Southwestern 249 Lake of extraordinary blue in 1902 Oregon. crater of extinct volcano—Sides 1,000 feet high—Interesting lava formations—Fine fishing. Wind Cave South Dakota. 17 Cavern having many miles of 1903 galleries and numerous chambers containing peculiar formations. Platt Southern 1⅓ Many sulphur and other springs 1901 Oklahoma. possessing medicinal value. Sullys Hill North Dakota. 1⅕ Small park with woods, streams, 1904 and a lake—Is an important wild-animal preserve. Mesa Verde Southwestern 77 Most notable and best preserved 1906 Colorado. prehistoric cliff dwellings in United States, if not in the world. Glacier Northwestern 1,534 Rugged mountain region of 1910 Montana. unsurpassed Alpine character—250 glacier-fed lakes of romantic beauty—60 small glaciers—Precipices thousands of feet deep—Almost sensational scenery of marked individuality—Fine trout fishing. Rocky Mountain North middle 378 Heart of the Rockies—Snowy 1915 Colorado. range, peaks 11,000 to 14,250 feet altitude—Remarkable records of glacial period. Hawaii Hawaii. 242 Three separate areas—Kilauea 1916 and Mauna Loa on Hawaii, Haleakala on Maui. Lassen Volcanic Northern 124 Only active volcano in United 1916 California. States proper—Lassen Peak, 10,465 feet—Cinder Cone, 6,879 feet—Hot springs—Mud geysers. Mount McKinley South 2,645 Highest mountain in North 1917 central America—Rises higher above Alaska. surrounding country than any other mountain in the world. Grand Canyon North 1,009 The greatest example of erosion 1919 central and the most sublime spectacle Arizona. in the world. Lafayette Maine coast. 12 The group of granite mountains 1919 upon Mount Desert Island. Zion Southwestern 120 Magnificent gorge (Zion 1919 Utah. Canyon), depth from 1,500 to 2,500 feet, with precipitous walls—Of great beauty and scenic interest.

THE FOSSIL FORESTS OF THE YELLOWSTONE NATIONAL PARK.

By F. H. Knowlton, _United States Geological Survey._

INTRODUCTION.

Isolated pieces of fossil wood are of comparatively common and widespread occurrence, especially in the more recent geological deposits of the West. Not infrequently scattered logs, stumps, and roots of petrified or lignitized trees are brought to light, but only exceptionally are they so massed and aggregated as to be worthy of the designation of fossil forests. Examples of such are the celebrated fossil forests of relatively late geological age near Cairo, Egypt, the huge prostrate trunks in the Napa Valley near Calistoga, Cal., and the geologically much older and far more extensive forests now widely known as the Petrified Forest National Monument in Apache County, Ariz. But in many respects the most remarkable fossil forests known are those now to be described in the Yellowstone National Park. In the forests first mentioned the trunks and logs were all prostrated before fossilization, and it is perhaps not quite correct to designate such aggregations as veritable fossil forests, though they usually are so called. In the fossil forests of Arizona, for example, which are scattered over many square miles of what is now almost desert, all the trunks show evidence of having been transported from a distance before they were turned to stone. Most of them are not even in the position in which they were originally entombed, but have been eroded from slightly higher horizons and have rolled in the greatest profusion to lower levels. As one views these Arizona forests from a little distance, with their hundreds, even thousands, of segments of logs, it is difficult to realize that they are really turned to stone and are now exhumed from the earth. The appearance they present (see fig. 1) is not unlike a “log drive” that has been stranded by the receding waters and left until the bark had disappeared and many logs had fallen into partial decay. Trunks of many sizes and lengths are now mingled and scattered about in the wildest profusion, and the surface of the ground is carpeted with fragments of wood that have been splintered and broken from them. In the Yellowstone National Park, however, most of the trees were entombed in the upright position in which they grew, by the outpouring of various volcanic materials, and as the softer rock surrounding them is gradually worn away they are left standing erect on the steep hillsides, just as they stood when they were living: in fact, it is difficult at a little distance to distinguish some of these fossil trunks from the lichen-covered stumps of kindred living species. Such an aggregation of fossil trunks is therefore well entitled to be called a true fossil forest. It should not be supposed, however, that these trees still retain their limbs and smaller branches, for the mass of volcanic material falling on them stripped them down to bare, upright trunks.

The fossil forests of the Yellowstone National Park cover an extensive area in the northern portion of the park, being especially abundant along the west side of Lamar River for about 20 miles above its junction with the Yellowstone. Here the land rises rather abruptly to a height of approximately 2,000 feet above the valley floor. It is known locally as Specimen Ridge, and forms an approach to Amethyst Mountain. There is also a small fossil forest containing a number of standing trunks near Tower Falls, and near the eastern border of the park along Lamar River in the vicinity of Cache, Calfee, and Miller Creeks, there are many more or less isolated trunks and stumps of fossil trees, but so far as known none of these are equal in interest to the fossil forest on the slopes of Specimen Ridge.

The fossil forests are reached over a road from the Mammoth Hot Springs, or from Camp Roosevelt near Tower Falls, and they are in their way quite as wonderful and worthy of attention as many of the other features for which the Yellowstone National Park is so justly celebrated.

Recently another extensive fossil forest has been found on the divide between the Gallatin and Yellowstone Rivers in the Gallatin Range of mountains, in Park and Gallatin Counties, Mont. This forest, which lies just outside the boundary of the Yellowstone National Park, is said to cover 35,000 acres and to contain some wonderfully well preserved upright trunks, many of them very large, equaling or perhaps even surpassing in size some of those within the limits of the park. Two of the best preserved of these trunks are shown in figures 2 and 3, which are here reproduced by the kindness of Mr. E. C. Alderson, of Bozeman, Mont.

In the beds of the streams and gulches coming down into the Lamar River from Specimen Ridge and the fossil forests one may observe numerous pieces of fossil wood, which may be traced for a long distance down the Lamar and Yellowstone Rivers. The farther these pieces of wood have been transported downstream, the more they have been worn and rounded, until ultimately they become smooth, rounded “pebbles” of the stream bed. The pieces of wood become more numerous and fresher in appearance upstream toward the bluffs, until at the foot of the cliffs in some places there are hundreds, perhaps thousands of tons that have but recently fallen from the walls above. One traversing the valley of the Lamar River may see at many places numerous upright fossil trunks in the faces of nearly vertical walls. These trunks are not all at a particular level but occur at irregular heights: in fact a section cut down through these 2,000 feet of beds would disclose a succession of fossil forests (see fig. 4). That is to say, after the first forest grew and was entombed, there was a time without volcanic outburst—a period long enough to permit a second forest to grow above the first. This in turn was covered by volcanic material and preserved, to be followed again by a period of quiet, and these more or less regular alternations of volcanism and forest growth continued throughout the time the beds were in process of formation.

GEOLOGIC RELATIONS.

While these fossil forests were growing and being entombed, much of the area now within the limits of the park, as well as large adjacent areas, was the scene of tremendous geologic activities. After the Cretaceous period (see diagram p. 28), there was a time of great volcanic activity, which appears to have lasted until perhaps the beginning of the glacial epoch. There were many active volcanoes just west, north, and west of the park, and some in the park itself. From these volcanoes vast quantities of material were poured out, building up in places whole mountain ranges. Thus the major portion of the great Absaroka Range, just east of the park, as it appears to-day, was built up of volcanic material.

Mr. Arnold Hague gives the following graphic account of this and adjacent areas:

From one end to the other the Absarokas present a high, imposing plateau, with elevations ranging from 10,000 to over 12,000 feet above sea level. The entire mass is made up almost exclusively of Tertiary igneous rocks. * * * Degradation of the mass has taken place on a grand scale. Vast quantities of volcanic ejectmenta have been removed from the summit, but no reliable data exist by which the amount can be estimated even approximately. All the higher portions have been sculptured by glacial ice. Enormous amphitheaters have been carved out of the loose agglomerates, and peaks, pinnacles, and relics of great table-lands testify in some measure to the forces of erosion. The plateau is scored by a complete network of deep valleys and gorges, which dissect it in every direction, and lay bare the structure of the vast volcanic pile.[1]

Within the park there is evidence of similar volcanic activity, and it is clear that the basin between the encircling ranges was filled to its present elevation by volcanic flows, which formed the present park plateau. The area within which the fossil forests are now found was apparently in the beginning an irregular but relatively flat basin, on the floor of which after a time there grew the first forest. Then there came from some of the volcanoes, probably those to the north, an outpouring of ashes, mud flows, and other material which entirely buried the forest, but so gradually that the trees were simply submerged by the incoming material, few of them being prostrated. On the raised floor of the basin, after a time, the next forest came into existence, only to be in turn engulfed as the first had been, and so on through the period represented by the 2,000 feet or more of similar beds. The series of entombed forests affords a means of making at least a rough estimate of the time required for the upbuilding of what is now Specimen Ridge and its extensions. (See p. 27.)

During the time this 2,000 feet of material was being accumulated, and since then to the present day, there has been relatively little warping of the earth’s crust at this point; that is, the beds were then, and still are, practically horizontal, so that the fossil forests, as they are being gradually uncovered, still stand upright.

When the volcanic activities had finally ceased, the ever-working disintegrating forces of nature began to tear and wear down this accumulated material, eroding the beds on a grand scale. Deep canyons and gulches have been trenched, and vast quantities of the softer materials have been carried away by the streams and again deposited on lower levels or transported to great and unknown distances.

As the material in which the fossil forests are now entombed consist of ashes, mud flows, breccia, and the like, not all the beds are of the same texture end hardness, so that erosion has acted unevenly on them and has produced many peculiar rock forms. The grotesque so-called “hoodoos” have been carved out in this manner. The fossil trunks, being usually harder than the surrounding matrix in which they are embedded, have more firmly resisted erosion and now project to different heights above the general level. In exposed beds that are nearly or quite horizontal, disintegration has acted at nearly equal pace on the trunks and on the matrix, so that the trunks are nearly or quite on a level with the surrounding surface. On steep hillsides, however, from which all loose material is easily and quickly removed, some of the fossil trunks stand up to a height of 20 or 30 feet. If the beds had been tilted at a considerable angle, these trunks could project from the surface for only a short distance before their weight would break them off, showing again the remarkably stable conditions that have continued since the trunks were covered up.

AMETHYST MOUNTAIN.

The fossil forest that was first brought to scientific attention is on the northern slope of Amethyst Mountain, opposite the mouth of Soda Butte Creek, 12 miles southeast of Camp Roosevelt. The following account, by Dr. William H. Holmes, the discoverer of these fossil forests, shows the impression first made by them:

As we ride up the trail that meanders the smooth river bottom [Lamar River] we have but to turn our attention to the cliffs on the right hand to discover a multitude of the bleached trunks of the ancient forests. In the steeper middle portion of the mountain face, rows of upright trunks stand out on the ledges like the columns of a ruined temple. On the more gentle slopes farther down, but where it is still too steep to support vegetation, save a few pines, the petrified trunks fairly cover the surface, and were at first supposed by us to be shattered remains of a recent forest.[2]

These trunks may easily be seen from the road along the Lamar River, about a mile away. They stand upright—as Holmes has said, like the pillars of some ruined temple—and a closer view shows that there is a succession of these forests, one above another. In the foothills and several hundred feet above the valley there is a perpendicular wall of volcanic breccia, which in some places attains a height of nearly 100 feet. The fossil trunks may be seen in this wall in many places, all of them standing upright, in the position in which they grew. Some of these trunks, which are 2 to 4 feet in diameter and 20 to 40 feet high, are so far weathered out of the rock as to appear just ready to fall: others are only slightly exposed: niches mark the places from which others have already fallen: and the foot of the cliff is piled high with fragments of various sizes.

Above this cliff fossil trunks appear in great numbers and in regular succession. As they are all perfectly silicified, they are more resistant than the surrounding matrix and consequently stand above it. Most of them are only a few inches above the surface, but occasionally one rises as high as 5 or 6 feet. The largest trunk observed in the park is found in this locality. It is a little over 10 feet in diameter, a measurement that includes a part of the bark. It is very much broken down, especially in the interior, probably having been so disintegrated before it was fossilized. It projects about 6 feet above the surface.

At many places about Amethyst Mountain there are numerous fragments of fossil wood and many hollow trunks. The material in which they had been embedded has been eroded away, and they lie around in somewhat the same attitudes that are shown by all the trunks in the Arizona fossil forests, but there is little doubt that they were originally erect and have simply fallen by their own weight because of the removal of the material around them.

Many of the trunks here, as well as elsewhere in the park, had decayed in the center before they were fossilized, and some of the hollow interiors are filled with clusters and rosettes of beautiful crystals of amethyst, which doubtless suggested the name given to the adjacent mountain. Much of this finely preserved wood, as well as the trunks containing the crystals of amethyst, was broken up and carried away by collectors of minerals and curiosities before the Government control in the park was made sufficiently rigid to insure proper protection.

SPECIMEN RIDGE.

In many respects the most remarkable of the fossil forests is on the northwest end of Specimen Ridge, about a mile southeast of Junction Butte and about opposite the mouth of Slough Creek. So far as known, this forest was first brought to scientific attention by Mr. E. C. Alderson, of Bozeman, Mont., and the writer, who discovered it in August, 1887. It is found on the higher part of the ridge, and covers several acres. The trees are exposed at various heights on the very steep hillsides, and one remarkable feature of the forest is that most of them project well above the surface.

One of the largest and best preserved trees stands at the very summit of the slope (see title page). This trunk, which is that of a giant redwood, is 26½ feet in circumference without the bark and about 12 feet in height. The portion of this huge trunk preserved is the base, and it exhibits to a considerable degree the swelling or buttressing so well known in the living redwood. The roots, which are as large as the trunks of ordinary trees, are now embedded in solid rock.

On the steep hillside a short distance below the big tree just mentioned are the two trunks shown in figure 5. They are about 2 feet in diameter and 25 feet high, and stand some 20 feet apart, and we may imagine them to have formed the doorposts of the “ancient temple” of which Holmes speaks. Both these trunks are without the bark. On the left of the figure is one of the huge irregular masses of rock that has been carved out by erosion.

In figure 6 is shown another trunk about 3 feet in diameter and nearly 30 feet high. In several places along the trunk the thick bark may be noted. This tree is a pine, as are the two last described, and slightly below and behind it are two living pine trees, which are about the size it must have been when living. Another trunk, some 12 feet in height, is shown in figure 7, and in figure 8 there may be noted a standing trunk and above it another that has recently fallen.