Central Yakut Lowland

(also Central Yakut Plain and Viliui Lowland), a low-lying plain in the Yakut ASSR. The Central Yakut Lowland lies along the middle and, partially, the lower course of the Lena River and along the lower courses of the Viliui and Aldan rivers. In the south it adjoins the Lena Plateau; its northern and western boundaries run along the drainage divide of the Lena and Olenek rivers and along the headwaters of the Viliui. In the southwest, the lowland is continued by the vast low-lying area in the central part of the Central Siberian Plateau.

The lowland is a flat, extremely swampy plain with numerous thermokarst lakes; it is dissected by a network of river valleys. In the terraced plains, elevations range from 60 to 200 m; the high part of the plain has elevations of up to 300–400 m.

The Central Yakut Lowland is part of the eastern, most highly downwarped section of the Viliui syneclise, The relief was formed by fluvial processes whose intensity was determined by slow oscillatory movements of small amplitude. The predominance of easily eroded deposits resulted in gently sloping land-forms. Permanently frozen rocks are ubiquitous, and alasy (thermokarst depressions) and pingos are commonly encountered. Eolian landforms (tukulany) are found in the northwest, especially near the Lena.

The region has a severe, markedly continental climate. The mean January temperature is –45°C, and the mean July temperature is 17°C. Annual precipitation reaches 300 mm, with up to 70–80 percent falling during the warm period. The rivers generally have high water in the spring and freshets, caused by heavy rains, in the summer. The small rivers freeze to the bottom during the winter. Pale-yellow taiga soils and meadow-chernozem soils have developed; on the low-lying river terraces are widely distributed patches of solonchaks and columnar solonetzes.

Most of the plain is covered by larch taiga with tracts of birch forest and meadow steppes.