Nan Shan(redirected from Nan Mountains)
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a mountain system in Central Asia, in China. It encloses the Tsaidam Basin from the northeast and forms the southwestern border of the Ala Shan Desert. The system is 800 km long and 320 km wide. It consists of several ranges extending primarily from northwest to southeast and is divided by longitudinal valleys. The major ranges are Ch’i-lien Shan (Richt-hofen), T’ao-lai Shan, Sule-nan Shan (Suess) with the system’s highest peak (6,346 m), Ulan Daban (Humboldt), Daken Daban (Ritter), and Koko Nor. Whereas the northern ranges tower 4,500 m above Ala Shan, the relative elevation of the southern ranges is about 1,500 m. The southern spurs often deviate from the system’s basic trend and form a series of short ridges.
Geologically, the Nan Shan is divided into three different zones: the Early Paleozoic northern ranges, formed by folded strata of sandstone, slate, and basic effusive rock; the Precambrian crystalline axis of the inner ranges, consisting chiefly of metamorphic rock; and the southern ranges, composed of sediments of the Late Paleozoic and Triassic. Where there is limestone, karst has developed. The Nan Shan ranges have about 1,000 glaciers, mainly on the northern slopes. Most of the glaciers are 1 or 2 km long. Glatiation occurs mainly in the western part of the Nan Shan, and the snowline drops from 5,200 to 4,200 m from west to east. Most of the Nan Shan belongs to the region of interior runoff in Central Asia, and the southeastern regions are part of the Huang Ho basin. The rivers, of which the largest are the Sulo, the Jo Shui, and the Buhin Gol, are deep in spring and summer.
The western part of Nan Shan is predominantly a desert region. Here deserts and steppes occur up to 3,000 m, above which are found meadows and mountain tundra. Above 4,000 m is a nival zone. The eastern part of Nan Shan is influenced by monsoons from the Pacific Ocean, and the eastern slopes tend to have a well-developed loess cover. Steppe and forest-steppe landscapes predominate. Spruce forests grow in places up to 3,000 m (in the lower regions they are mixed with birch and aspen). At higher elevations there are dwarf forests, high-grass subalpine and alpine meadows, and mountain tundra. Altitudinal zonation is more pronounced on the northern slopes than on the southern slopes. The Nan Shan was studied in the late 19th century by the renowned Russian explorers N. M. Przheval’skii, V. I. Robo-rovskii, G. N. Potanin, G. E. GrummGrzhimailo, and V. A. Obruchev.
REFERENCESObruchev, V. A. Tsentral’naia Aziia, Severnyi Kitai i Nan ’shan’, vols. 1–2. St. Petersburg, 1900–01.
Roborovskii, V. I. Puteshestvie ν Vostochnyi Tian’-Shan’ i Nan’-Shan’. Moscow, 1949.
V. M. SINITSY