The Snake River or Lewis fork of the Columbia takes its rise in a small lake which is separated by the main range of the Rocky Mountains from the large lakes of the Yellowstone, that being less than twenty miles distant from it. The Yellowstone, the Madison, Jefferson and Gallatin, forming the head waters of the Missouri, and the Snake, the largest tributary fork of the Columbia, all rise within or near the limits of the territory recently dedicated by the Government to the purpose of a National Park. As contrasted with the large rivers of regions other than the one it traverses, the Snake River would be a very remarkable stream, but there, where everything in nature is wonderful, it is simply one of the marked features in its physical geography. From its source to its junction with the Clarke fork of the Columbia, a distance of nine hundred miles, it flows through a region which, at some remote period, has been the scene of greater volcanic action than any other portion of North America. Unlike other streams, which are formed by rivulets and springs, this river is scarcely less formidable in its appearance at its commencement than at its termination. It leaps into rapids from the moment of its exit, and its waters, blackened by the basaltic bed through which it flows, roar and fret, and lash the sides of the gloomy cañon which it enters, presenting a scene of tumult and fury, that extends far beyond the limits of vision. This initiatory character it maintains, alternated with occasional reaches of quiet large expansions, and narrow contractions, fearful and tremendous cataracts, to its debouchure into the Columbia. Its channel and its course, alike sinuous, have obtained for it its name. Navigation is impeded by reason of fearful rapids, every few miles of the first five hundred after leaving the lake. The shores for most of the distance are barren rock, always precipitous, often inaccessible from the river, and frequently engorged by lofty mountains and rocky cañons which shut its inky surface from the light of day. The scenery, though on the most tremendous scale, is savage, unattractive, and frightful. Its waters lash the base of the three Tetons, so celebrated as the great landmarks of this portion of the continent. As they approach the Columbia they break into frequent cataracts, the largest of which, the great Shoshone Fall, with a perpendicular descent of two hundred and fifty feet, presents many points of singular interest.