SIBERIAN AREA, an administrative unit of Asiatic Russia, with an area of 4,028,615 square kilometers. The Arctic ocean, from Gyda bay to Khatanga bay forms its northern, and Mon golia and the Kazakstan S.S.R. its southern boundary. To the west lies the Uralsk Area, and to the east the Yakutsk and Buriat Mongol republics. It coincides roughly with the former Yeniseisk, Tomsk and Irkutsk Governments of Imperial Russia. The name Siberia (Sibir) was the Russian name given to the chief settlement, Isker on the Irtysh, of the Tatar Khan Kuchum, and was subse quently extended to include the whole of the Russian dominions in Asia. After the 1917 revolution various republics and areas, each having a good deal of local autonomy were separated off and now the name Siberia is limited to the central region which was not thus split off. Much of it consists of the basin of the Yenisei river (q.v.). Stretching from the Sayan alpine regions in the south (lat. 51° 45' N.) to Cape Chelyuskin in the north 38' N.), it displays much orographical variety. The West Sayan mountains have their southern base on the plateau, and their northern at a much lower level, and reach heights of 1 o,000 feet. Around and north-east of Lake Baikal well-marked ridges fringe the plateau, with steep north-western slopes turned towards the valleys (e.g., the beautiful and fertile valley of the Irkut river between the Tunka Alps and the Sayan). A typical feature of the north-eastern border of the high plateau is a succession of broad valleys, longitudinal in an orographical sense, but not geologically, since they are erosion valleys and not synclinal foldings of rocks. Formerly submerged by Alpine lakes, they are now sheeted by flat alluvial soil, suitable for agriculture, and drained by rivers which afterwards make their way northwards through narrow gorges pierced in the mountain walls; the valleys of the Us, the Upper Oka and Irkut are of this type.
An Alpine region, ioo to iso m. in breadth, fringes the plateau to the north-west, and is called in east Siberia the taiga: it con sists of separate chains of mountains (4,800 to 6,5oo ft.) clothed with dense forest, except on the highest parts, and having narrow marshy valleys, thickly strewn with boulders, e.g., the Altai in the west, the Kuznetskiy Ala-tau, the Us and Oya mountains in West Sayan, the Nizhne-Udinsk taiga, and several chains pierced by the Oka river. North of these alpine regions is the broad belt
of fertile black-earth high plains (1,20o to 1,700 ft.) stretching from Tomsk eastwards, and from Kansk penetrating in a great arc south-eastwards to Irkutsk (see YENISEI RIVER for structure). North of the town of Yeniseisk, and east of the Yenisei river is a broad belt of Alpine tracts of Archaean origin reaching their greatest elevation in the Yeniseisk taiga, between the Angara (Upper Tunguska) and the Middle or Stony Tunguska. North of this region begins the slope towards the Arctic plains, interrupted by the north-west to south-east ranges of the Upper Inbatsk district and the Syverma, beyond which lie the bleak tundra plains.
The Taimyr peninsula is strictly the name of the northward projection from Taimyr bay on the west to Khatanga gulf on the east, but it is often applied to the whole district between the Yenisei gulf and the Khatanga gulf. The northern coast and the islands off it are not yet accurately known : the Russian explorer Vilkitski, in 1913-14, discovered the islands named after him, lying south of the Nordenskjiild archipelago. Recent corrections of the coast of western Siberia resulting from the explorations of Russian navigators indicate that, except for Cape Chelyuskin, the Taimyr peninsula stretches about 4o m. farther north, and that the gulfs of the Ob and Yenisei should be farther to the west than shown on older maps. East of Cape Chelyuskin good harbours are scarce, but the Eclipse in 1914-15 wintered safely in a bay in long. 92° E., and Vilkitski's Taimyr in that winter remained safely frozen in Toll bay in lat. 76° 3o' N., long. Ioo° E. A rolling treeless tundra plain (I oo to 15o ft.) covers Taimyr except for the Byrranga mountains (2,00o to 3,00o ft.) and, though compara tively well drained, is difficult to cross except in winter : erratic blocks are widely distributed. Polar bears and seals are found in summer, and in that season Samoyede reindeer breeders migrate to Taimyr Land with their herds, avoiding the Taimyr gulf region, which is deficient in reindeer "moss." In winter the region is deserted.