Altai Mountains

The Altai are not one continuous crest. They are a wide, branching system of separate ridges and massifs arranged around high valleys, steppe basins, plateaus, and deeply cut river corridors. The highest and most heavily glaciated terrain lies in the central Altai around the Katun, South Chuya, and Tavan Bogd massifs, while elevations generally diminish toward the outer ranges.

On a regional map, the Altai stand between western Siberia to the north, the Kazakh uplands to the west, the Great Lakes Depression of Mongolia to the east, and the Junggar Basin to the south. This position makes the range both a highland junction and a transition from forested northern slopes to increasingly dry steppe, semidesert, and basin country.

Much of the Altai belongs to the Central Asian Orogenic Belt, an ancient collage of crustal fragments, volcanic arcs, sedimentary rocks, and granitic intrusions assembled mainly during Paleozoic mountain building. Later deformation renewed uplift along inherited faults, helping create the present pattern of raised blocks and subsiding intermontane basins.

Modern relief combines sharp alpine crests with broader uplands and fault-bounded depressions. In the high massifs, former glaciers carved cirques and U-shaped valleys and left moraines along valley floors and mountain fronts. Lower sectors are more rounded or dissected, and steep streams carry rock debris onto fans where valleys open into dry basins.

Present-day glaciers cluster in the highest massifs, including the Belukha area, the Chuya ranges, and Tavan Bogd. They occupy only the coldest upper valleys and cirques, but together with seasonal snow they sustain runoff beyond the short summer melt season. Glacial landforms are more extensive than the modern ice, recording much larger ice fields and valley glaciers in the past.

Drainage divides give the Altai much of their geographic importance. The Katun and Biya unite to form the Ob, which flows north across western Siberia to the Arctic Ocean. The upper Irtysh drains western and southern parts of the mountain system before ultimately joining the Ob. East and south of the main divides, rivers such as the Khovd descend toward enclosed lakes and depressions, where water has no outlet to the sea.

Distance from the oceans gives the Altai a strongly continental climate, with long cold winters, short summers, and large temperature ranges. Elevation cools the high ridges, while slope aspect and valley form create local contrasts in snow cover, evaporation, and exposure to cold-air drainage.

Moisture generally decreases from the northwestern and western Altai toward the southeast. Westerly air brings more precipitation to exposed high slopes, supporting denser forests and larger snow and ice accumulations in the wetter sectors. Leeward valleys and the Mongolian and Chinese margins are drier, where steppe and semidesert basins can lie close to high peaks. The range is therefore a climate boundary as well as a topographic one.

The Altai connect several distinct physical regions. Their northern rivers enter the western Siberian drainage network; their eastern ridges frame the Great Lakes Depression; and their southern ranges overlook the Junggar Basin. The adjoining Sayan Mountains extend the larger upland pattern northeastward, while lower ranges and plateaus connect westward into eastern Kazakhstan.

Within Geography Atlas, the Altai belong with the Mountain Hub as a continental highland system shaped by old crust, renewed relief, glaciation, and divided drainage. They compare especially well with the nearby Tian Shan: both rise beside dry interior basins, but the Altai occupy a more northerly transition between Siberian forest landscapes and the arid interior of Mongolia and northwestern China.