Page:The American Cyclopædia (1879) Volume XIV.djvu/395

 ROCKY MOUNTAINS while in approaching the Sierra N. and S. the highest points are as much as 8,000 ft. The well known Monte Diablo is only 3,856 ft. above the sea, although a very conspicuous ob- ject from San Francisco. The Sierra Nevada or Snowy range forms the western border of the great continental plateau, corresponding with the main Rocky chain on the east. While the base of the eastern mass is everywhere 4,000 to 5,000 ft. above sea level, and the de- scent to the sea imperceptible to the eye, the Sierra slopes rapidly, so that the sea level is reached within 100 m. So far as now known, the highest peak of the United States is in the Sierra group, viz., Mt. Whitney, 14,887 ft. The scenery of the Sierra group is of surpassing beauty and grandeur. There is not such a vast number of high peaks as in the Colorado group, but it may fairly claim the highest ; and inasmuch as the surrounding country has a much lower altitude, there is a massiveness about this magnificent range that even the Sahwatch of Colorado cannot boast. The Sierra chain is about 450 m. in length, and averages about 80 m. in width, supposing its northern terminus to be at Lassen's butte, lat. 40 30'. The central mass or core is chiefly granite, with metamorphic slates on either side, capped with basaltic and other kinds of lava and heavy beds of ashes and breccia. All these rocks are visible from the Central Pacific railroad between Truckee. and Sacramento. The evidences of very modern volcanic action are visible everywhere. Even now there are numerous hot springs and geysers, as well as occasional earthquake shocks. The height of some of the dominating peaks is as follows : Mt. Shasta, 14,442 ft. ; Mt. Tyndall, 14,386 ft. ; Mt. Kaweah, 14,000 ft.; Mt. Brewer, 13,886 ft. ; Eed Slate peak, 13,400 ft. ; Mt. Dana, 13,- 277 ft. On the mountains snow falls to the depth of 40 or 50- ft., and much of it remains all the year. Enormous glaciers exist here even at the present time, and tfie evidences of ancient glacial action are wonderful. The worn and rounded granites of the Sierra Ne- vada were well adapted to preserve the rec- ords of the old glaciers, and they everywhere testify to the intensity of their former power. These glaciers have been continued down to the present time in a modified condition. All the glaciers occur on the north side of the mountains, and are very numerous, now esti- mated at 65. The number known in the Alps is 1,100, of which about 100 may be consid- ered as primary. Some of the Sierra glaciers are nearly as large as the Alpine, as the Lyell, North Ritter, and others not yet named. Al- though the existence of glaciers in the Rocky mountains is a very modern discovery, enough is already known about them to invest the sub- ject with the highest interest. Moraines and morainal lakes occur in the Sierras in great numbers. Lake Tenaya, at the head of the Mer- ced river, or a branch of the same name, is a conspicuous example. Traces of the existence of an immense flow of ice are shown here in the valley occupied by the lake, according to Whit- ney, and the ridges on either side of the trail are so worn by glacial action that the rocks are slippery, rendering travel dangerous. Four pretty well marked belts of forest vegetation have been observed by Whitney. The lowest is the foot hills, with oaks, buckeyes, and small digger pines; the second belt lies between 4,000 and 5,000 ft., and consists of pitch pine (pinus ponderosa), bastard cedar, and Douglas spruce; the third zone, between 7,000 and 9,000 ft., is that of firs, as picea grandis and amabilis, tamarack pine, &c. ; and on the highest belt, above 9,000 ft., where vegetation begins to dwindle, a dwarf pine (pimts cris- tata) is seen up to the limit of perpetual snow. There are great numbers of beautiful lakes in the Sierras, fed by the melting of the snows, among which are Lake Tahoe and Donner lake. The Yosemite valley, so remarkable for 'its rugged scenery, and which has been set apart by legislative action as a pleasure ground, is in the Sierra. Through this valley flows the Merced river, and at its source is a fine group of peaks, 13,000 ft. high, called the Merced group. So far as structure and topography are concerned, the great mountain system extend- ing along the western borders of the western hemisphere, from the Arctic ocean to Pata- gonia, may be regarded as a unit, and due to one great cause. North America has its lofty Rocky group opposite the deep North Pacific ocean, and its small Appalachian group oppo- site the shallower North Atlantic. So South America has its still higher Andes opposite the deeper South Pacific, and the smaller Brazil- ian ranges opposite the South Atlantic. This fact, stated by Dana, is founded on a deep- seated structural cause. The elevation of a portion of the earth's crust requires in close proximity a corresponding depression. The Rocky system may be primarily divided into two portions, the Sierra Nevada and Coast ranges fronting the Pacific ocean, and the main Rocky chain which forms the great water di- vide of the continent. Each of these chains or groups is made up of a great number of smaller ranges, in the aggregate apparently possessing a considerable degree of regularity, but when studied in detail showing very little regularity or system. Sometimes, as in the Great Basin, the main ranges seem to lie par- allel for the most part, but usually the minor ridges branch off in every direction. More commonly the trend is about N. E. and S. W.-, but sometimes it is due N. and S. or E. and W. The Wahsatch range in Utah trends nearly N. and S., while the Uintah range, which seema to branch off from it, trends nearly E. and W. The area W. of the Mississippi may be divided into mountain and prairie or plain country. The belt of plains on the E. slope averages about 500 m. in width, and gradually rises to the base of the mountains. The mountain por- tion has its greatest breadth between the 36th