Great Basin, a remarkable triangular plateau of North America, occupying the western portion of Utah and nearly the whole of Nevada, as well as a section of Oregon and California, and extending at its north-eastern angle into Idaho. It is bounded on the W. by the Sierra Nevada, and on the E. by the Wahsatch Mountains. The base of the triangle, in the N., is some 500 miles from east to west; it extends from N. to S. for nearly 800 miles, and its area is slightly greater than that of France. It is girdled round on every side by high mountains, and traversed throughout by numerous ranges, frequently parallel, yet as often irregularly blending or crossing; the valleys are usually sinks, the chief drainage centre being Great Salt Lake (q.v.), and the Humboldt and Carson sinks, at about the same elevation. It has been pointed out by the United States Geological Survey that the Great Basin's areas of greatest depression are to be found near the borders, while its central portion reaches a much greater elevation. The loftiest range is the East Humboldt, near the middle, which culminates in Mount Bonpland (11,321 feet). Volcanic masses form or conceal the original rocks of many of these ranges. The Great Basin contains many streams and lakes, the latter for the most part salt, whose waters never reach the ocean, but are either taken up by evaporation or sink in the desert sands. The mean annual rainfall ranges in different localities from 4 to 15 inches. The plateau is nearly destitute of trees, and in general only the upper parts of the valleys are clothed with desert shrubs, their lower portions often being occupied either by bodies of water or by a muddy bottom covered with several inches' depth of alkaline salts left by evaporation.
See, besides reports to the United States Geol. Survey, works by I. C. Russell on Lake Lahontan (1883 and 1885) and Southern Oregon (1884); and Hague, The Volcanic Rocks of the Great Basin (1884).