a highland in the North American cordillera, in the western United States. It unites territories located between the Sierra Nevada and the Cascade Mountains in the west and the Rocky Mountains in the east and has no runoff into the ocean. The basin covers an area of more than 500,000 sq km. It consists of a multitude of short ranges (elevation up to 3,900 m) and broad interconnected basins. The relief was formed on a Precambrian-Mesozoic fold foundation which was subjected to fault dislocations in the Cenozoic era. These movements were accompanied by volcanic activity. Most of the basins are of tectonic origin; the ranges that separate them are horst blocks. The absence of external runoff and an outlet for the products of destruction of the ranges led to the filling of the basins with a thick layer of rocky and sand-clay deposits, which partially scoured the primary mountain relief. The climate is sharply continental, subtropical for most of the basin, and temperate in the north. Summers are hot and cloudless, and winters are cool, with frequent fog. The average July temperature is 20°–22°C (maximum 56.7° C); in January the average is 0°–2° C (minimum –30° C; to –60° C in the mountains). The average annual precipitation is about 200 mm, in individual basins less than 100 mm, and on the western slopes of the mountains, up to 500 mm. The largest part of the Great Basin is irrigated by short, episodic (primarily winter) waterways which end in basins. The main river is the Humboldt. The largest lakes include the Great Salt Lake, Pyramid Lake, Sevier Lake, and Utah Lake. Most of the lakes remain on the site of larger bodies of water that existed in the Pleistocene epoch—Lake Bonneville and others. Artesian wells, located most frequently at the outer edges of the basins, are an important source for irrigation. The most widely distributed soils are brown sierozems, solonchak, and saline (in the basins), and mountain chestnut (in the mountains). Most of the territory is semi-desert; in the north (north of 37° N lat.) there are grass-sagebrush and goosefoot, and in the south, creosote with patches of cactus and agave. The more moist mountain slopes are covered with stunted pine and juniper forests. The most widely distributed animals include reptiles, especially rattlesnakes, poisonous lizards, and horned toads. There is agriculture in the irrigated areas.
G. M. IGNAT’EV