Encyclopædia Britannica, Ninth Edition/Yellowstone National Park
YELLOWSTONE NATIONAL PARK, an area situated mainly in north-western Wyoming, United States, which has been withdrawn from settlement by the United States Government and dedicated to the purposes of a public park. It is a region of hot springs and geysers, mountains and canons, lakes and waterfalls. While it is almost entirely comprised in Wyoming, a narrow strip 2 miles wide projects on the north into Montana, and on the west a strip about 5 miles in width projects into the same Territory and into Idaho. Its boundaries, which were defined at a time when the country was little known, are as follows. The northern boundary is a parallel of latitude running through the mouth of Gardiner river, a branch of the Yellowstone, 2 miles north of 45° N. The eastern boundary is a meridian 10 miles east of the most easterly point of Yellowstone Lake, which places it almost on the 110th meridian. The southern boundary is a parallel 10 miles south of the most southerly portion of the same body of water, in lat. 44° 10′ N. The western boundary is a meridian 15 miles west of the most westerly portion of Madison (now Shoshone) Lake, this meridian being approximately that of 111° 6′. The Park is therefore very nearly a rectangle in shape, its length north and south being 61·8 miles and its breadth 53·6. Its area is 3312 square miles.
The Park has an abundant rainfall, and its streams are numerous and bold. It contains many beautiful lakes and ponds. Within its area are the sources of the Yellowstone and the Madison, which go to make up the Missouri, and of the Snake, one of the forks of the Columbia. This last stream, which drains the south-western part, takes its rise in several branches, among them being Lewis Fork, which has its origin in the beautiful Shoshone Lake, and Heart river, which rises in Heart Lake, under the shadow of Mount Sheridan. The Yellowstone drains the eastern part. Rising just beyond its southern limits, it flows into and through Yellowstone Lake, a magnificent sheet of water, of very irregular shape, having an area of 150 square miles. A few miles below the lake, the river, after a succession of rapids, leaps over a cliff, making the Upper Fall, 112 feet in height. Half a mile lower down it rolls over the Lower Fall, which has a clear descent of 300 feet. The river at this point carries, at the average stage of water, about 1200 cubic feet per second. With this fall the river enters the Grand Cañon, which in many scenic effects has not its equal on the globe. Its depth is not great, at least as compared with the cañons upon the Colorado river system, ranging from 600 feet at its head to 1200 near the middle, where it passes the Washburne Mountains. Its length to the mouth of Lamar river is 24 miles. It is cut in a volcanic plateau, and its ragged broken walls, which are inclined at very steep angles, are of a barbaric richness of colouring that almost defies description. Reds, yellows, and purples predominate, and are set off very effectively against the dark green of the forests upon the plateau, and the white foam ot the rushing river which fills the bottom of the chasm. Near the foot of the Grand Cañon, Tower creek, which drains the concavity of the horseshoe formed by the Washburne Mountains, enters the Yellowstone. Just above its mouth this stream makes a beautiful fall of 132 feet into the gorge in which it joins the river. A few miles farther down the Yellowstone is joined by an eastern branch, Lamar river, which drains a large part of the Absaroka Range. Then it enters the Third Cañon, from which it emerges at the mouth of Gardiner river. The latter stream drains an area of elevated land by means of its three forks, and upon each of them occurs a fine fall in its descent toward the Yellowstone. The Madison rises in the western part of the Park and flows in a generally northward and then westward course out of the Park. Its waters are mainly collected from the rainfall upon the plateaus, and from the hot springs and geysers, most of which are within its drainage area. Upon this river and its affluents are several fine falls. Indeed all the streams of this region show evidence, in the character of their courses, of a recent change of level in the surface of the country.