ALTABAN, or ALTASAN, A head-hunting tribe in Nueva Vizcaya province, Luzon. See PHILIPPINES.
ALTAI (51-ti') MOUNTAINS (Tatar, gold en mountains, from alt nn, &tan, golden; Chin. keen-shan. same meaning). A mountain range of Central Asia forming part of the elevated re gion on the borders of Siberia and the Chinese Empire. The name formerly had a much wider significance, and included the entire line of high lands from the Irtysh River to the Okhotsk Sea, which is composed of several structurally inde pendent units; but it is now limited to the much smaller group lying on the borders of Mongolia, Sungaria, and Siberia, and between about 45° and 54° N. latitude. The range has a general northwest and southeast trend, nearly at right angles to that of the larger system. The Altai Mountains begin on the southeast with the Ektag range (Greater Altai), in the region of the Gobi Desert, and for some distance they form the boundary between Mongolia and Sungaria. To ward the northwest, the range increases in breadth by the converging of outlying mountains, and also in height, but after passing the Siberian frontier it gradually loses its massive character and fades out into the steppes. On the slopes of the Ektag are the sources of the Black Irtysh, Kobdo, and tirunp•u rivers. North of this range and across the valley of the Bukharma River are several mountainous groups which constitute the Northern Altai. The latter are arranged along
an axis parallel to that of the Ektag range, and attain an extreme elevation of over 10,000 feet in Mount Byelukha (White Mountain). The Tarbagatai group, further west, may also be in cluded with the Altai range. This group be gins in Sungaria and reaches across the Siberian frontier, where it is continued by the Tschun gistan Mountains into the region of the Khirgis steppes. Geologically, the Altai consist of a central core of sehists and granite broken through by intrusions of igneous rocks, with Paleozoic strata ranging from the Silurian into Carboniferous on the outer edges. As the moun tains were formed by upheaval at an early geo logical period, they have been subjected to long continued denudation and erosion. Their crests, of which only the highest rise above the snow line, are generally well rounded, and their slopes are covered with a rich growth of grass. or with heavy forests of pine, cedar, and birch. Deer, hares, and wolves abound in the lower and bears in the higher portions of the range. The moun tains are but thinly populated, except within the limits of the Russian Altai, where there is a well developed mining industry.