ROCKY MOUNTAINS is • term usually applied to an extensive mountain system in North America, corresponding in a measure to that of the Andes in South America. Believing that this term has too general a signification to be with propriety applied to a particular system, some geographer, have proposed to call the North American range the Chipoeveyon Mountauu, but this designation has not come into common use. Tbongh farther lisland than the Andes, the Rocky Mountains are like them much nearer to the Pacific than to the Atlantip Ocean. It was formerly supposed that those mountaiaa were only a continuation of the Andes, thus two mountain regions being connected by • chain which traversed the Mexican Isthmus. But it is now known that two depressions intervene between the Andes arid the Rocky Mountains on the Isthmus of Panama and on that of (ANDES.] This mountain system, which is noticed generally under /smelliest, voL i. col 284, may be divided into three parts—the Southern, Coutral, and Northern Reeky Mountains. The Southern extenda from 19° to 40° N. lat. ; the Central from 40° to 49° N. let,; and the Northern from 49° to 70° N. let. The whole length is about 5000 miles.
The Southern Mountains, about 22° N. lat., divide into several ranges, which are described under MEXICO. The most easterly belong to Texas. That part of the Southern Mountains which extends from to 42° N. lat., has a breadth of from 50 to 100 miles. The mountains rise abruptly from the plains to the east of them, towering into peaks of great height, which are visible at the distauce of more than 100 miles east of their base. They consist of ridges, knobs, and peaks variously disposed, among which there are many wide and fertile valleys. The more elevated parts of the mountains are covered. with perpetual snow, which gives them a luminous, and at a great distance even a brilliant appearance, whence they have derived the name of the Shining Mountains ;' and some of the loftiest summits are moro than 11,000 feet above the sea-leveL This part of the range is described under New Maxrco. Here occurs, near 36° N. let, the most frequented
pass over the Southern Rocky Mountains, being that of the great overland route from Missouri to Santa F6 in New Mexico and the country westward. Some distance south of this, near the boundary of Mexico and the United States, is another much-frequented pass, that of the Paso del Norte.
The Central portion of the Rocky Mountains, extending from 40° to 49° N. let, appears to consist in its southern part of two, but farther north of three or four, distinct ranges. These rauges are loftier and more difficult of transit than any other part of the system. The only really practicable pass is that known as the Great South Pass, near 42° N. lat., over which flows the great stream of emigration to Utah and California. The mountains of tho central range are how ever of very unequal elevation ; they present rather the appearance of extensive groups than regular ranges, and are here and there overtopped by high peaks, among which 'some rise more than 13,000 feet above the level of the sea. Fremont's Peak, north of the Great South Pass, is 13,570 feet high. [NORTII-WEST TERRITORY: WASHINGTON TERRI Tour.] The higher parts of the ranges consist of granite, and are bleak and bare, being nearly destitute of vegetation, but many of the inferior ridges are scantily clothed with scrub pines, oaks, cedar, and furze. In some places these mountains have traces of volcanic action. On the eastern side of this region originate the numerous rivers by whose confluence the Missouri is formed, besides its first great con fluents the Yellow Stone River, which receives the waters of the Big horn River, and the Nebraska or Platte River. The great velocity with'which the Missouri flows through all its course, and the numerous falls on its upper branches, together with the severity of the climate, favour the supposition that tho base of this hilly region is at least 5000 feet above the sea-level. On the western side of this part of the Rocky Mountain system originate most of the upper tributaries of the Oregon or Columbia River.