1. General Divisions of the Cordillera System.

FOR purposes of description this great region may be divided into the following parts, which differ from one another sufficiently to make it a natural subdivision.

1st. The Rocky Mountains, which embrace the mountain region of Montana, Idaho, Wyoming, Colorado, and New Mexico, with so much of the eastern range as exists in the British Possessions.

2d. The plateau regions drained by the Colorado River and its tributaries.

3d. The Great Basin, with its complex system of ranges.

4th. The Pacific Coast Ranges, including the Sierra Nevada, Cascade, and Coast Ranges of the Pacific States, and the extension of the Cascade Range through British Columbia and Alaska.

Orographically, the Rocky Mountains are divided

into two parts by a break in the system in Southern Wyoming, where, from the southern end of the Wind River Range to the northern end of the Park Ranges, the system is represented only by elevated plateaus. The characteristic of the system is that of parallel chains, trending somewhat west of north. In Northern Montana the Missouri Range faces the plains from the boundary southward to the 46th parallel, and carries the continental water-parting. East of it the monotony of the plains is broken only by a few groups of hills, which, from their isolated position in a flat country, have been, in some cases, honoured beyond their deserts by being called mountains. Among them are the "Little Rocky,"

the "Bear's Paw," etc.

West of the Missouri Range rises Clark's Fork of the Columbia, which pursues a devious course among the many mountain spurs which obstruct its passage, and is finally driven far to the north-west to escape from the mountain maze by which it is surrounded. It finally finds a passage through the second great range of the system, the Bitter Root or Coeur d'Alène, in the southern part of British Columbia. This range trends south-eastward, parallel to the Missouri Range, and at the end of the latter is connected with it by a low broad saddle, known as the Deer Lodge Pass. South of this point the continental water-parting is carried by the Bitter Root Range to its end in latitude 44°. The depression between these two ranges is filled with short ranges trending parallel to them, and contains several fine large valleys, valuable for agriculture and cattle-raising.

The Missouri and Bitter Root Ranges reach altitudes in the peaks of upwards of 9000 feet, and probably the average height of the ranges is in the neighbourhood of 8000 feet. They are crossed at a number of passes at elevations ranging from 5500 to 6500 feet.

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Geog Estab

West of the Bitter Root are several detached ranges, some of considerable extent, as the Salmon River Mountains, which consist of a succession of two or three ranges parallel to the Bitter Root.

In latitude 45° 56', longitude 111° 34', the Missouri River divides into three large streams, known respectively as the Jefferson, Madison, and Gallatin Rivers. These branches head far to the southward, meeting there the head-waters of the Snake, or Lewis' Fork of the Columbia. In the same locality heads the Yellowstone, a large branch of the Missouri, in a great lake, at an elevation of 7738 feet above sea-level.

3. The Yellowstone National Park.

The country about the heads of the Madison, Yellowstone, and Snake Rivers, in the north-western part of Wyoming, seems to have been set aside by the Great Maker for the exhibition of the action of volcanic forces. In time past, but geologically very recent, this region has been repeatedly covered by floods of lava; great ranges of mountains have been built by catastrophic action; and to-day we find these forces still actively at work, as evidenced by the innumerable hot springs and geysers which are found all over the surface. Before the geysers of the Yellowstone National Park, all others of the world-even the celebrated ones of Iceland-sink into insignificance.

Until a very recent period this country was a terra incognita, save from the vague tales of Indians and white hunters and trappers, and these wonders were scarcely suspected. Deterred by the difficulties of approach, many exploring parties have passed by this region. It was not until 1864 that any authentic account of any part of this country was obtained. In that year a prospecting