PHYSICAL FEATURES. Tibet presents two dis tinct physical divisions: (1) A region of lakes in the north, and (2) a region of rivers in the south and east. The first, occupying the greater portion of the Nvestern half of the country, is known as the Chang Tang or 'Northern Plain.' It is an arid treeless and shrubless solitude, with rounded hills and broad fiat valleys between them, and a number of sharply defined mountain ridges ruing several thousand feet above the plain. It has an average elevation of from 14,000 to 16,000 feet, falls away gradually to the east and south, and is dotted with lakes— mostly salt, some of them of considerable size. The more or less parallel mountain ridges, to gether with their separate valleys, He buried beneath a vast accumulation of mountain dAris, giving the surface the aspect of a plateau of uplift, or of one of tectonic construction. The streams terminate in salt lakes, which give unmistakable evidence of gradual desiccation. Large stretches toward the Kuen-lun are uninhabitable, and are abandoned to the wild beasts. In the southern zone, between the parallels of 32° and 33° north, a lofty range reaches as far east as 90° 25'—the Nin-chin Tang-la, the highest peak of which has an alti tude of 24,153 feet, the Goring-la pass having an elevation of 19,587 feet. From 33° 50' north toward the linen-Inn there are ranges of extinct volcanoes with altitudes of 20,000 feet. One of the best known lakes of this region is the Pa ngong-tso, 13,930 feet above sea-level, partly in Ladakh (about latitude 34° north and longitude 79° east).
This inhospitable region is bordered on the east and south by the region of rivers, which is also a region of snow and ice-covered moun tains and deep ravines. Its eastern section
covers the whole eastern half of the country, stretching from about 90° east to China. It is almost entirely occupied by a succession of more or less wooded but lofty and steep mountains, with a general north to south trend, cut into deep narrow gorges, in which flow the rapid streams of melted snow which unite to form the upper courses of the great rivers which are known in their lower courses as the Hoang-ho, the Yang-tse-kiang, the Mekong, and the Sal win (qq.v.). The southern section of this river region lies to the south of the Chang-tang and extends from the Kin-chin Tang-la north of Lhasa, the capital, to the great South Chain, and is overlooked by Mount Everest, the highest peak of the Himalaya. Its mountains have a southeast and east trend, with many lateral intersecting ranges and spurs, which give direction to its numerous streams. In it are found the sources of three important rivers—the Indus and the Sutlej (qq.v), which rise in the Gang-ni or Kailas Mountains in the west and flow through India. and the Brahma putra, which, under the name of Yaru-Tsangpo, rises farther east in the Mariam-la Mountains. The principal lakes of this region are the Sacred Manasarowar, near the sources of the Indus and the Sutlej, and 'Scorpion Lake,' the Yamdok or Palti, south of Lhasa, with a cir cuit of 45 miles. Here are found the bulk of the population, the seat of the government, and the great centres of culture and refinement.