Great Basin, Or Fremont's Basin the region lying between the Wahsatch mountains on the east and the Sierra Nevada on the west, embracing Nevada, the W. portion of Utah, and the S. E. part of California. In shape it resembles an ancient shield, the broad end toward the north, and the S. extremity rounded to a point. Its waters have no outlet to the ocean, and it evidently formed at a remote period an inland sea. The greatest depressions are near the borders, especially along the E. and W. sides, while the central portion reaches a much greater elevation, and is broken into a series of detached ridges. Along the line of the Central Pacific railroad the elevations are as follows: at Brigham, on the border of Great Salt lake, 4,220 ft. above the level of the sea; at Pequop, a short distance W. of the Nevada boundary, 0,184 ft.; and at Desert, in the W. part of Nevada, 4,017 ft. The height at the points of greatest depression in the S. E. and S. W. parts has not been accurately determined, but in the neighborhood of Sevier lake it is not more than 4,500 ft. above the sea. The highest ranges in the basin probably attain an elevation of from 7,500 to 8,000 ft.

The Wahsatch range, which, running almost directly N. and S. near the 112th meridian, forms the E. rim, rises abruptly from the narrow plains, seldom sending out foot hills or slopes. The mountain ridges in the interior, separated by valleys of various width, run parallel to each other in a N. and S. direction, determining the course of the minor streams, though the few principal rivers break through them. The elevation which forms the N. rim, separating the basin from the valley of the Columbia, also consists of parallel ridges running N. and S. The principal body of water is Great Salt lake in the N. E. part, the region draining into it being known as the Great Salt Lake basin. Other lakes are Utah and Sevier, in Utah; "Walker's lake, Carson lake, Pyramid lake, and Mud lake, in Nevada; and Mono and Owen's lakes, in California. Bear river empties into Great Salt lake; the Provo or Timpanogas into Utah lake; while the Jordan discharges the waters of Utah lake into Great Salt lake. Sevier, Walker's, Carson, and Owen's lakes receive rivers of the same names; the Truckee empties into Pyramid lake.

Humboldt river rises in the N. E. part of Nevada, and after a course a little S. of W. of about 300 m. disappears in the " Humboldt sink." Reese river flows N. toward the Humboldt, but generally sinks before reaching it. The greater portion of the basin is an arid and sterile waste, covered with alkaline deposits, and producing only a growth of sage brush. Considerable tracts, however, may be rendered productive by irrigation, and larger portions are adapted to grazing. Except upon the mountains in the N. part forests scarcely exist. The climate is dry, rain rarely falling from April to October. The basin is rich in the precious metals, particularly silver.