TA-HSEH MOUNTAINS

WadeGiles romanization Ta-hseh Shan, Pinyin Daxue Shan, also called Szechwanese Alps, or Sino-tibetan Chain, great mountain range in the west of Szechwan province, China. These enormously high and rugged mountain chains were formed around the eastern flank of the ancient stable block of the Tibetan Plateau; their formation occurred during successive foldings that took place in the final phase of the Jurassic mountain-building process, as well as during the Cretaceous Period, and during the Himalayan earth movements that occurred in the Tertiary Period. Throughout the complex system, metamorphic rocks, schists, quartzites, and metamorphic limestones are the predominant rock formations, with massive intrusions of granite. The ranges form a part of the vast belt of folding that continues southward into the Indochinese Peninsula. The area was further uplifted in Quaternary times. The Ta-hseh Mountains are not a single range, but a series of north-south ridges drained by a series of tributaries of the Yangtze River that flow north to south. The most important of the rivers are the Ya-lung and, farther west, the Chin-sha. The mountains are almost Himalayan in scale, with many peaks rising to more than 20,000 feet (6,000 m). The highest peak of all, Mount Kung-k'a (Minya Konka), rises to 24,790 feet (7,556 m). Much of the highest land is covered with snow, and Mount Kung-k'a has a complex of glaciers. The snow line is between 16,500 and 19,000 feet (5,000 and 5,800 m). The mountains are still thickly forested on the eastern flank, with mixed forests of birch, hemlock, poplar, and aspen below about 8,200 feet (2,500 m). From there to about 13,000 feet (4,000 m) are fir and spruce forests. In the drier northern area, grasslands or mixed forests of pine and oak are common. Above 13,000 feet, the tree cover gives way to Alpine pasture and grassland. The vegetation, however, and the climatic regime vary greatly over comparatively small areas because of the influences of elevation and the terrain. The area has only scattered patches of cultivated land, mostly occurring in the alluvial fans of the wider river valleys. Wheat and corn (maize) can be grown up to about 9,200 feet (2,800 m) in favourable positions; above that elevation, hardy oats, barley, potatoes, and beans are the chief crops. The Chinese population is mostly clustered around the few towns located on the caravan trails that cross the area into the Tibet Autonomous Region. Most of the inhabitants are pastoral Tibetans. There is confusion about the names given to the various ranges. Usually the great range on the Szechwan border between the Ta-tu and Ya-lung rivers is called the Ta-hseh Mountains (meaning great snow mountains), while the range beyond, between the Ya-lung and Chin-sha rivers, is known as the Sha-lu-li Mountains. The southern part of this range, however, which is well over 20,000 feet in altitude and is permanently snow-covered, is also known as the Ta-hseh Mountains or as the Mu-la Mountains.