NAN MOUNTAINS

Chinese (Wade-Giles and Pinyin) Nan Shan, a vast complex of mountain ranges in the northwestern region of China. The ranges lie between the Tsaidam Basin to the southwest and the plateau of northwestern Kansu province to the north. The Nan Mountains consist of ranges with a predominantly northwest-to-southeast axis, forming a complex of folded blocks separated by synclinal troughs. The ranges are for the most part about 13,00016,500 feet (4,0005,000 m) in elevation; individual peaks, however, often exceed 20,000 feet (6,000 m) and the highest peak reaches 20,820 feet (6,346 m). The ranges are higher and more complex in the west, to the south of Tun-huang and Y-men (both in Kansu), where, in spite of the aridity of the climate, many peaks are covered with snow and glaciers. The eastern section of the mountains is somewhat lower, and only a few high peaks have a permanent snow cover. Among the ranges are a number of large intermontane depressions and fault basins. The largest of these is the depression in which lies Koko Lake (Koko Nor). The northernmost range, fronting the Kansu Corridor, is the Ch'i-lien Mountains. The ranges to the south are the T'o-lai Mountains and the Ta-t'ung Mountains. The Ta-t'ung ranges form the northern side of the two major lake depressions, Ha-la Lake in the northwest and Koko Lake to the southeast, both being areas of internal drainage. South of these depressions are the South Koko Lake Mountains and the A-te-erh-kan Mountains (Adirgan Ula), again enclosing further basins with lakes and saline swamps. The western part of these mountains is extremely arid. Vegetation is everywhere sparse, and great areas of the Nan Mountains are completely barren. Elsewhere the cover largely consists of hardy desert-type plants, of sparse grassland on higher ground, and of a sort of mountain tundra (treeless plain) above 12,500 feet (3,800 m). The eastern sections of the mountains are much wetter, and the vegetation cover is more diverse and richer. On the wetter slopes there are spruce forests, and alpine meadows are found up to the snow line. The dry intermontane basins, however, have semidesert or steppe (grassland) vegetation. East of Koko Lake, a widespread, largely coniferous forest cover occurs between 8,000 and 10,000 feet (2,400 and 3,000 m), mostly consisting of spruce, pine, and birch. Above this elevation are alpine shrubs and subalpine meadows similar to those of the borderlands of Szechwan province. Generally speaking, the environment of the western parts of the range is typical of Central Asia, while that of the eastern sections is more typically Chinese. The Nan Mountains area is very sparsely populated, and vast areas are virtually uninhabited. Most of the inhabitants are seminomadic Tibetan or western Mongol (Khoshut, or Tu-Mongor) herdsmen. Chinese (Wade-Giles and Pinyin) Nan Ling, series of mountain ranges in southern China that forms the divide and watershed between Hunan and Kiangsi provinces (sheng) and the Yangtze River basin to the north and Kwangtung province and the Chuang autonomous ch' (region) of Kwangsi and the Hsi River valley to the south. The ranges also form a sharp divide in climate, for they shelter southern China from the cold, continental north winds. Traditionally the mountains were referred to simply as the Ling (Ranges), while the area to the south was known as Ling-wai (Beyond the Ranges) or Ling-nan (South of the Ranges). Until the 12th century AD or even later, the far south was still an exotic, semicolonized area, and the Nan Mountains were a major cultural boundary. As a human boundary it played almost as important a role as the Tsinling Mountains in the north (which run west to east from Kansu to Shensi provinces), though it is a comparatively small-scale mountain range. Structurally the Nan Mountains are complex, the landforms resulting from two distinct periods of foldingthe first in the later part of the Mesozoic Era, which produced massive folding with a westeast axis, and the second representing a later stage that superimposed the southwest-to-northeast folding characteristic of southeastern China. The latter forms predominate in the eastern section of the Nan Mountains. The entire system is some 870 miles (1,400 km) long and consists of a wide mountain belt rather than a single sharply defined range. The central section, on the borders of southern Hunan and Kiangsi, is the broadest and most complex in structure, with many subordinate chains that are often at right angles to the main axis. The elevation of the ranges is comparatively low and is seldom more than 3,300 feet (1,000 m). The geology of the area, like its topography, is extremely complex. The main axis of the ranges is formed of granites and very ancient sedimentary rocks that were heavily metamorphosed. The flanks are formed of red sandstone dating from the Cretaceous Period and the Tertiary Period. The whole range has been much-eroded by a complex drainage system, and its extensive limestone areas have developed a typical karst topography. The Nan Mountains have for long been an important source of mineral wealth. A major source of silver in medieval times, the mountains now yield tin, copper, wolfram, zinc, antimony, tungsten, and iron. In addition, there are small deposits of coal to the north of Shao-kuan (in Kwangtung) in the central range. Little of the area is cultivated apart from valley bottoms, and much of it suffers badly from soil erosion. Three major passes cross the range: the Kuei-lin, followed by the Ling Canal, which affords an easy passage from southern Hunan to Kuei-lin and eastern Kwangsi, the chief route in early times; the Che-ling, northwest of Shao-kuan, which connects Hunan with central Kwangtung and is followed by the Canton to Wu-han railway; and the Mei-ling (Ta-y), northeast of Shao-kuan, which led into southern Kiangsi and was the major northsouth route until the end of the 19th century.