Topic 12. Altai - Sayan mountainous country

Position, orography and hypsometry. The west of the country is occupied by ridges and basins Altai. Alpine Central Altai consists of ridges: Katunsky with the highest point Altai - Sayan country Belukhoy (4506 m), Severo- and Yuzhnochuysky, Kuraisky, Listvyag, Terektinsky, Kholzun. They are separated by intermountain basins - the “steppes” of Abai, Kurai, Uimon, Chui and the Ukok plateau. Southern Altai stretches in a sublatitudinal direction from Sailyugem in the east through the Tavan-Bogdo-Ula mountain node with a height of up to 4082 m, the Southern Altai, Tarbagatai, Sarymsakty ridges to Narymsky in the west. Ridges Eastern Altai(Shapshalsky, Chikhacheva) have a submeridional strike; they are adjacent to the Chulyshman Plateau. All of the above regions can be combined as high-mountain and mid-mountain core Altai.

Mid-mountain and low-mountain-foothill ridges fan out from this core. Within Russia these are numerous ridges North-Eastern Altai(Aigulaksky, Sumultinsky, Chulyshmansky, Korbu, Iolgo, Altyntu, Seminsky, Cherginsky, Anuysky, Bashelaksky, Korgonsky, Abakansky, Biyskaya Griva, Koksuysky, Tigiretsky and others). The Russian part of Altai stands out as Mountain Altai(or Eastern Altai in broadly understood term); tectonically, it is characterized by relatively ancient Early Paleozoic (mainly Salair) folded structures. Ranges are located within Kazakhstan Northwestern or Rudny Altai, corresponding to relatively younger (Epihercynian) folded structures. South East End Altai, located within the PRC and Mongolia, is divided into Mongolian(maximum height 4362 m.) and Gobi Altai(in the northwest – up to 4 km, in the southeast – 500 – 1000 m). The western border of Altai with the Tien Shan and Kazakh small hills is formed by the Zaisan depression and the Irtysh valley, the northern border with the West Siberian Plain is drawn along the “northern face” of Altai - a clearly defined transition from flat to mountainous terrain.

Salair-Kuznetsk region located north of Altai. It includes the Salair Ridge, the Tom-Kolyvan Plain, the Kuznetsk Basin and the Kuznetsk Highlands. The western and northern borders with the West Siberian Plain are very arbitrary. They approximately coincide with the valleys of the Chumysh, Berd, Ob rivers and the southern border of the West Siberian plate. The eastern border of the Kuznetsk Alatau is complicated by the presence of a number of basins separated by ridges. From north to south they successively change: the Arga ridge (the far spur of the Eastern Sayan, bordered on three sides by the Chulym bend, along which a fragment of the administrative border of the Kemerovo region passes), the Nazarovskaya depression, the Solgon ridge - the far ledge of the Eastern Sayan with a maximum height of 875 m, Chulymo - Yenisei Basin, Batenevsky Ridge (spur of the Kuznetsk Alatau), Minusinsk Basin.

Western Sayan stretches from the river basin. Abakan in the southwest to the Udinsky ridge of the Eastern Sayan in the northeast. Its axis is the Sailyg-Khem-Taiga ridges (crowned by Mount Karagosh with a maximum height of 2930 m for the Eastern Sayan), Sayansky, Oysky, Ergaki, Tazarama (Ergak-Targak-Taiga), Kurtushibinsky with heights of 1800-2500 m. They are accompanied by numerous feathers ridges northwestern(Joysky, Dzhebashsky, Borus, Kulumys) and southeastern (Khemchiksky, Mirsky) macroslopes, inferior to the axial zone in height only on the periphery.

Eastern Sayan extends from the Solgon Ridge in the northwest to the Tunka Basin, separating it from the Baikal country, in the southeast. The highest axial ridges are two parallel chains: Udinsky and Kryzhina (Grandiozny peak - 2922 m) and separated from them by the longitudinal valleys of Kazyr and Uda, the Dzhuglymsky ridge and Agulskie Belki with peaks 2-2.5 km high. The valleys of the tributaries of the Kan and Angara separate the feathering ridges of the northeastern macroslope (Biryusinsky, Gutarsky, Tagulsky, Kanskoye and Manskoye Belogorya). In the extreme southeast there are differently oriented ridges (chars): Okinsky, Belsky, Kitoisky, Tunkinsky, Bolshoi Sayan. They highlight the complexly constructed basin of the upper Oka with heights of 1-1.5 km.

Tuva differs in the complexity of orography. To the east of the Shapshalsky ridge stretches a chain of ridges of southern Tuva (Tsagan-Shibetu, Western and Eastern Tannu-Ula, Sengilen). They separate the Ubsunur (its foreign part predominates) and Tuva basins. The latter is separated from the Todzha Basin by the Academician Obruchev Ridge.

Geological development and structure. From a fixist point of view, folding in the Altai-Sayan country began in the Riphean period of the Proterozoic and continued until the end of the Paleozoic era. It first appeared in the northeast, at the southwestern edge of the Siberian Platform, during the Baikal folding era. Sites of Baikalides have been identified in the axial zone of the Eastern Sayan and in Tuva. Folded structures of the Middle Cambrian (Salairids) predominate in more western regions: central Tuva, Eastern Altai, Kuznetsk Alatau and Mountain Shoria. In the Western Sayan, Caledonian folded structures predominate, and in the extreme west of the Altai-Sayan country, Hercynian folding has appeared. Sometimes the so-called early Hercynides are distinguished, where folding occurred in the Devonian period (according to the terminology of Siberian geologists, this is the Telbes phase of folding) - on Salair and in the eastern part of Rudny Altai. Typical or late Hercynides completed their formation in the Carboniferous-Permian, these are the structures of the Tom-Kolyvan folded zone and the Kazakh part of the Rudny Altai. At the same time, the formation of the Kuznetsk marginal trough took place and its degeneration into an intermountain trough.

Regardless of the age of folding, units of a lower rank are distinguished in the listed structures - structural-formational zones, subdivided into horst-anticlinoria (Katunsky, Kurtushibinsky, Abakansky and others) and graben-synclinoria (Uymen-Lebedsky, Anui-Chuysky). Within the former, denudation processes predominated, exposing ancient (Precambrian and Early Paleozoic) strata. Sedimentation processes took place in the grabens-synclinoriums, and strata of relatively young Late Paleozoic or even Meso-Cenozoic sediments accumulated. Structural and formational zones are separated, as a rule, by long-established, extensive and deep (often mantle) zones of deep faults. An example is the Kuznetsk-Altai deep fault, which separates the Kuznetsk Basin and the Kuznetsk Alatau and continues over a significant part of Altai.

There are also mobilist views (developed, in particular, by L.P. Zonenshain), which consider the development of the entire country or its individual parts (for example, Kuznetsk Alatau and Salair) as a result of the convergence of small lithospheric plates drifting over considerable distances, prevailing in the Altai-Sayan country. According to mobilists, the existence of a mechanism of subduction and obduction in the geological past is indicated by a large number of ophiolite plates, representing fragments of the ancient ocean floor, pushed onto the hard edges of blocks of the continental crust. A large number of such plates (allochthons), consisting of ultrabasic rocks of the basaltic layer of the oceanic crust or even mantle rocks, were discovered in Kuznetsk Alatau and Salair.

Features of the tectonic structure are reflected in the orography and morphostructure of the region. Horst anticlinoria usually correspond to axial zones of mountain structures, in which crystalline rocks predominate: ancient metamorphic and intrusive rocks of different ages, predominantly of acidic composition (granites and granitoids). Graben-synclinores correspond to intermountain basins composed of relatively young volcanogenic, carbonate and terrigenous (conglomerates, sandstones, siltstones, mudstones) rocks. An important role was played by secondary (superimposed) orogenic basins of various ages (Episalairian Minusinsk and Rybinsk, small Mesozoic basins within the Kuznetsk trough and others). Seismic focal zones that generate fairly strong earthquakes are associated with deep faults. In this regard, not only the entire territory of the Altai-Sayan country, but also the adjacent areas of the plains are seismic. The highest seismicity (up to 9 points or more) is characteristic of the extreme southern regions (Tuva, southern Altai). In the northern direction, the degree of seismicity naturally decreases and in the extreme northern territories is 5-6 points.

With the completion of the formation of folded structures, the leading role passed to block dislocations and structures. In the Triassic, echoes of the events of the Tunguska syneclise appeared in the Kuznetsk trough, where they led to outpourings of basalts, the introduction of diabase intrusions and the formation of thick strata of tuff conglomerates of the trap formation. In the Jurassic period, differentiated block movements caused the appearance of a highly dissected relief. Due to the destruction of relief protrusions, coarse sediments became widespread everywhere from Kuzbass to Baikal, which served as the source material for the formation of conglomerates and sandstones. At the same time, in numerous lakes that arose in depressions of the relief, significant reserves of organic residues accumulated, which later turned into fossil coals. However, in the Cretaceous and Paleogene periods the intensity of tectonic processes noticeably decreased, the processes of peneplanation of the relief and the formation of various weathering crusts became widespread.

Recent tectonics and morphostructure. As in the predominant part of Russia, the formation of the modern morphostructure of the Altai-Sayan country occurred under the influence of modern tectonics. Differentiated recent uplifts appeared regardless of the age of folded structures. In a number of areas in the region, intense block and arch uplifts were observed, which led to the revival of the high- and mid-mountain topography of Altai, Sayan, the mountains of southern Tuva, Kuznetsk Alatau and Mountain Shoria. Along their periphery, the uplifts were moderate, leading to the renewal of the low-mountain and foothill relief of mountain structures, as well as the high plains of Salair. Finally, weak uplifts, which led to the emergence of the relief of low-lying and elevated plains, divided their surface into many isolated flat or slightly convex watersheds with deeply incised terraced river valleys.

As a result, the morphostructure of block- and arch-folded mountains and highlands, as well as the erosion-denudation plains associated with them, took a dominant position. A subordinate role is played by the accumulative plains and lava plateaus of the Eastern Sayan, Tuva, the melaphyre horseshoe of the Kuznetsk Basin and other regions. Intense block movements along a developed system of tectonic faults engulfed the Todzha Basin at the beginning of the Pleistocene. They were accompanied by active volcanism. Eruptions of basic composition predominated, forming lava flows no less than 80 km long and basaltic (lava) plateaus with a thickness of 70 to 200 m. In the Early Pleistocene, along with lavas, pyroclastics erupted, due to which shield volcanoes (predominant) and ethno-Vesuvian stratovolcanoes Sorug were formed - Chushku-Azu, Shivit, Derby-Taiga and others - a total of 16 volcanoes. Stratovolcanoes reached 1000 m in height and up to 15 km in diameter.

Minerals. Folded structures of various ages are rich in endogenous deposits. Given the global trend towards the depletion of Early Paleozoic structures in metals, the Altai-Sayan country, on the contrary, is rich in iron deposits, sometimes with titanium impurities. They are concentrated in Mountain Shoria and Kuznetsk Alatau. Geologists emphasize their connection with a vast magma chamber enriched in iron that existed in the Cambrian. Currently, the presence of a so-called iron belt has been revealed, stretching from the Ampalyk deposit in the north of Kuznetsk Alatau to titanomagnetite occurrences in the Mrassu basins and magnetite ore deposits in Khakassia. Genetically, sulfides of copper, zinc, lead, silver, antimony, and arsenic are closely related to magnetites, but when using Gornoshorsky ores, all these impurities are simply lost. There are deposits of polymetals on Salair, but the main role is played by deposits of the Kazakh part of Rudny Altai. Mercury is confined to the deep fault zones of the Altai Mountains (Aktash) and Salair. Tuva is rich in endogenous deposits (cobalt, asbestos, talc, chromium, nickel, etc.). In the Kuznetsk Alatau, the Kiya-Shaltyrskoye deposit of nepheline syenites is distinguished. In all mountain structures there are numerous outcrops of decorative and semi-precious stones (marble, jasper, hornfels, etc.).

Among the exogenous deposits, the Paleozoic and Jurassic coals of Kuzbass, as well as Tuva and Khakassia, are especially prominent; bauxites of Eastern Sayan and Salair; a variety of building materials and gold deposits in many areas.

Impact of Pleistocene events on modern nature. Morphosculpture. A noticeable cooling and increased climate aridity, which manifested itself in the Neogene, reached a maximum in the Pleistocene. The mountainous regions were covered by ground glaciation, and permafrost was widespread on the plains. The heat-loving flora and fauna mostly died, only in rare shelters (refugia) individual representatives of pre-glacial vegetation were preserved. The most famous refugium is the Kuzedeevsky “linden island”, in which, in addition to the Siberian linden, about 35 relicts of pre-Pleistocene vegetation are known. Tundra-steppes with the dominance of tough cereals and “mammoth fauna” of cold-hardy animals with long hair, capable of digesting rough food, spread across the plains. To this day, the forms of glacial-exaration and glacial-accumulative relief, as well as the corresponding moraine deposits, have been preserved. Relics of cryogenic relief are more difficult to identify, but they were widespread. Fluvioglacial forms alternated with glacial forms. In non-glacial lowland areas located in periglacial zones, under conditions of significant aridity of climate, there was an accumulation of fine dusty material carried from the surface of glaciers by water flows or, rarely, by wind. Over thousands of years, strata of loess-like or cover loams of deluvial or aeolian origin were formed from it.

Several warming eras were observed, when glaciers were greatly reduced, and an interglacial - the complete disappearance of glaciers. The climate simultaneously became humid, black soil steppes, forests and even swamps became widespread. They were inhabited by forest and steppe animals, in particular, small steppe inhabitants, especially rodents. The bones of small animals are quickly leached completely; only rodent teeth protected by enamel are preserved in the loess. Evidence of the existence in the past of repeated relatively warm pluvial epochs is the horizons of buried chernozem soils, clearly visible in the strata of loams within the city of Novokuznetsk and in its environs.

Modern landforms are varied. The most common fluvial relief is represented by valley-watershed forms. There are a number of karst areas within the Kuznetsk Highlands, Salair, Altai, and Western Sayan.

Climate. The Altai-Sayan country is located closer to the center of the Eurasian continent than the lowland countries of Siberia. Nevertheless, researchers (B.P. Alisov, S.P. Suslov, etc.) note decrease the degree of continentality of its climate in comparison with the plains. The reasons for this paradox lie in a decrease in the degree of continentality under the influence of mountainous terrain. Winter in the mountains is warmer under the influence of temperature inversions, summer with normal troposphere stratification is cooler, which causes a decrease in the annual temperature amplitude - the main indicator of continentality. Under the influence of mountainous terrain, the amount of precipitation increases (with the exception of special cases) (this is also an important indicator of continentality). The increase in precipitation under the influence of orography (on slopes of western exposure) and the influence of altitude (the higher, the more) is due to a sharp intensification of cyclones moving along western trajectories, mainly due to the aggravation of temperature contrasts (usually due to a decrease in the temperatures of cold sectors). Of course, this increase is facilitated by convective and orographic precipitation, but it occurs relatively rarely and only in the warm part of the year. Finally, the contrast between the summer maximum and the winter minimum is moderated, that is, the continental precipitation regime appears not as sharply as on the plains (also an indicator of the degree of continental climate).

A characteristic feature of the climate of the Altai-Sayan country, like any mountainous territory, is diversity of climates, due to differences in altitude, slope exposure, local circulation conditions, etc. It follows from the diversity of distribution of individual climatic indicators: temperature, precipitation, humidity, degree of continentality, etc. Finally, there are strictly individual, unique features of the climate of the mountains of Southern Siberia. For example, in accordance with the geographical latitude, Altai, Sayan and Tuva lie in zones of insufficient moisture (steppe, semi-desert), therefore, steppe or semi-desert appear on vast plateaus and intermountain basins (noting this feature, the Altai basins were given the name “steppes”).

Winter flows under the control of the central part of the Siberian High, anticyclonic weather prevails, during which a particularly variegated temperature distribution is observed. The lowest average January and minimum temperatures are set in intermountain basins, but they also vary greatly: January temperatures from -16...-18 degrees in the foothills of Altai, Kuznetsk Alatau and Minuses to -34 degrees in the Tuva basin, minimums from -40 to –62 degrees (in the Kemerovo region and within –55...-56 degrees). In the low mountains, January temperatures are noticeably higher (in low mountain Temirtau –14, and in the Ust-Kabyrza basin –22 degrees). An increase in temperatures is caused by the occurrence of cyclones, less often by the passage of hair dryers; in such cases, temperatures are relatively equalized over large areas. Only cyclonic precipitation is present, and it is caused by both Atlantic cyclones of the Arctic front and Mediterranean cyclones of the polar front. In most areas, the snow cover is thick (minimum 40 cm), especially on the slopes of western exposure in the mid- and highlands (100-200 cm). On the eastern macroslopes and in basins it decreases to 10-15 cm. In such cases, the soil freezes to a depth of 150-200 cm. The annual minimum precipitation occurs in February-March. Stable snow cover is established in the mountains in October, on the plains in November. Its destruction occurs on the plains in April, in the mountains a month later.

In summer Low atmospheric pressure sets in, especially over the Tuva and other basins. Therefore, Atlantic cyclones (there are no Mediterranean cyclones in summer) freely penetrate the region, bringing increased amounts of moisture. Summer precipitation in Altai accounts for 35–50% of the annual amount. To the east and south their share increases to 55-65% (Tuva), which is one of the indicators of increasing continentality in these directions. In the presence of a summer maximum absolute quantity summer precipitation in the basins is insufficient (75 mm in the Chui steppe, in the Salair region - 185-200 mm). Along with cyclonic precipitation, convective precipitation plays a certain role, spreading over limited areas and having a showery, but short-term nature. Rain prevails, but snowfalls are common in June and August; temporary snow cover may be established in the highlands at the end of August.

In the foothills and basins, average July temperatures are 18...20 degrees, and at an altitude of more than 1800 m they drop to 8 degrees. With the dominance of the western transport, a northern component often arises, leading to a decrease in temperature, frosts and even noticeable frosts (in the Tuva Basin, even in July up to -6...-7 degrees). The absolute maximums are 35-39 (in the Kemerovo region 38 everywhere) degrees and even in the highlands about 30 degrees. Most often they are associated with heat advection from Kazakhstan, the Turanian Plain, China and Mongolia.

In the western parts of the region the climate is continental. For example, in the Kuznetsk Basin, continentality indices are everywhere less than 70%. The increase in continentality in the eastern and southern regions leads to the emergence of a sharply continental climate. In the Kemerovo region, the degree of continentality increases noticeably in small orographic basins (Mrassko-Kabyrzinskaya, Ortonskaya, Tomsko-Mrasskaya) of Mountain Shoria (due to the increased severity of winters), and the climate can also be called sharply continental. But in low and middle mountains, due to relatively mild winters with an average January temperature of about -14...-15 degrees, the degree of continentality is noticeably reduced.

Inland waters. Rivers belong to the basins of the Ob and Yenisei, flowing into the Kara Sea. Only the sources of small rivers of the Ubsunur basin carry water into the internal drainage basin of this basin. Its watershed with the Yenisei basin runs along the ridges of southern Tuva, and with the Ob basin, along the Chikhachev and Kurai ridges, the spurs of the Chulyshman Highlands and the Tsagan-Shibetu ridge. The watershed of the two great rivers consists of the Shapshalsky, Abakansky ridges and the watershed zone of the Kuznetsk Alatau.

Most rivers have mixed feeding, that is, none of the sources provides half of the annual flow. At the same time, in the eastern regions, rain nutrition predominates (which is due to the significant summer maximum precipitation due to the high degree of continental climate), in the northern and western regions - snow, and in the regions of Central Altai with modern glaciation - glacial. In the east of the region (east of the Eastern Sayan and Tuva) a regime similar to the Far Eastern one appears, in the predominant part - the Altai type. The standard of this type is Tom in the Novokuznetsk region.

Lakes. A unique “twin” lake of Baikal is Lake Teletskoye with a tectonic basin processed by a glacier. A large lake with a basin of tectonic origin is located on western border Altai – Markakol. There are numerous lakes in the Todzha Basin - Noyon-Khol, Kadysh-Khol, Darlig-Khol and others (“khol” means lake). Among them, narrow, deep (100-195 m) lake basins prevail, which arose when trough valleys were dammed by moraines. Shallow lakes of the outwash plain are less common. On peneplain surfaces there are many sewage lakes dammed by moraine dams. A large number of small karn lakes are located in the highlands.

The groundwater. The region alternates between hydrogeological mountain fold regions (Altai, Kuznetsk Highlands, Sayan Mountains, mountains of Southern Tuva, etc.) and hydrogeological basins of large basins. The hydrogeological basin of the Kuznetsk Basin has been well studied. Its feeding areas are located in Salair and the Kuznetsk Highlands. From them, water migrates into the deep layers of the axial part of the basin. An asymmetry is observed: in the near-Salair part of the basin, the groundwater is noticeably saline and has a variegated composition, while in the near-Alatau part its composition is homogeneous and there is no salinity. With increasing depth, the degree of water mineralization increases noticeably. In the Yerunakov area, a well was drilled to a depth of 200 m. Interstratal waters with a salinity of 3.2 to 55 g/l came from it. After 6 years of continuous flowing, water with double the chloride content came from the well due to the influx of water from deep horizons. Near Novokuznetsk, salty (35 g/l) groundwater was discovered at depths of about 2.5 km.

Modern glaciation concentrated in Altai (according to M.V. Tronov, 629 sq. km), the Sayan-Tuva Highlands (according to M.G. Grossvald, 13 sq. km) and Kuznetsk Alatau (embryonic forms of glaciers) . Most of the glaciers are located in Central and Southern Altai and on the Chikhachev Ridge. A smaller number of them are found on the Kholzun, Kuraisky, Sailyugem, Sarymsakty, Shapshalsky ridges. The largest glacial center of Mount Belukha is located in the Katunsky Range, and on its northern slope the area of ​​glaciers is 170 sq. km, while on the southern slope they occupy 62 sq. km.

Z onality can be traced fragmentarily, within the basins, due to which the latitudinal zonality gives way to island zoning. In the flat version there are “islands” of meadow steppes (forest-steppes), steppes and semi-deserts. Island forest-steppe take place in the Kuznetsk, Chulym-Yenisei, Minusinsk basins and in Tuva. The Kuznetsk forest-steppe is located along the relatively well-moistened outskirts of the basin, enclosing the arid steppe core in a semicircle. The main background consists of meadow steppes and steppe meadows on leached and podzolized chernozems, now almost completely plowed. Among them are scattered birch stakes on podzolized gray forest soils. The steppe core of the Kuznetsk basin is located in the Salair region, it is also completely replaced by agricultural land. In the past, under the most favorable moisture conditions, they grew here forb-grass steppes, in less moisturized areas – feather grass-grass steppes on chernozem soils. On the slopes of Salair they are replaced by rocky steppe, and in Pre-Salair they are replaced by halophytic vegetation on saline soils. Semi-desert areas occur in Tuva.

Altitudinal zone. In many areas of the northern and western parts of the Altai-Sayan country, a steppe-forest-steppe type of altitudinal zone is observed. In the eastern and southern regions with an increased degree of continentality and aridity of climate, it is replaced by the southern taiga type of altitudinal zone. In both cases, the mountain-taiga belt predominates in the structure of altitudinal zonation. In the steppe-forest-steppe type, this belt is dominated by aspen-fir ​​(black taiga), and in the taiga type, light coniferous (Siberian larch) forests dominate. In the lower part of the mountain taiga belt, only along the slopes of eastern exposure in the foothills (from 250-300 m a.l.), the belt spreads in the form of separate forests birch-light coniferous forests. They are typical for the northeastern foothills of Salair, where Scots pine clearly predominates, but in the northern direction the role of Siberian larch increases; northeastern foothills of the Kuznetsk Highlands (dominated by larch) and Eastern Altai. Along with conifers, there are significant admixtures of birch, and birch forests are not uncommon. In the absence (“loss”) of this belt in the foothills and low mountains, a belt is allocated fir-aspen forests (black taiga) with the dominance of Siberian fir, which is replaced in clearings, forest clearings, edges and fires by aspen, and less often by birch. There is also an admixture of Siberian cedar, Scots pine and larch. Under conditions of significant steepness of slopes, a special variety of pseudopodzolic mountain taiga soils develops. The black taiga occupies the largest areas in the Kuznetsk Highlands, Salair, in the foothills of the Kuznetsk Basin, in the northeastern part of the Altai Mountains, in the Sayan Mountains and in the east of Tuva.

The admixture of cedar increases with altitude, and at altitudes of 800-2000 m (lower boundary of the belt) - 1100-2500 m the dark coniferous taiga belt spreads with a significant role of cedar(from minor admixture to fir to the emergence of pure cedar forests). The nature of soil formation changes with altitude, leading to the dominance of brown pseudopodzolic mountain taiga soils. The heights of the belt increase from the foothills of the Kuznetsk Basin to the Western Sayan and Eastern Altai.

Within the Rudny Altai, the southern part of the Altai Mountains, Tuva, the inner parts of the Sayan Mountains, the northeastern slope of the Kuznetsk Alatau, the lower part of the mountain taiga belt is dominated by Siberian larch. On the slopes of northern exposure the soil is covered with lichen, and on the southern slopes there is grass cover. With altitude, the role of cedar admixture increases, and then cedar forests. The altitudinal zonation is perfectly visible when crossing the Seminsky Pass

Near the upper border of the forest, cedar trees take on a depressed appearance: the trees become stunted, twisted, and in open areas, under the influence of frequent and strong winds, their crown takes on a flag-like shape. Dwarf thickets of coniferous species, most often dwarf cedar, appear. Dominance passes to Podgoltsy(or subalpine) belt. Its development occurs on steep slopes dotted with angular granite blocks (kurums), often well camouflaged by vegetation. Along with dwarf trees, tall subalpine shrubs (birch, willow) and tall grass subalpine meadows on subalpine soils are common here. Moss-lichen tundras with an admixture of shrubs and a large number of mushrooms develop on the shady slopes. The fauna is specific: white partridges, bats, pikas - haymakers, mustelids, occasionally musk deer and reindeer.

Loach (alpine) The belt is occupied by mountain tundras and alpine meadows. Their distribution is controlled by power snow cover: at high power the soils are free from permafrost, which contributes to the appearance of short-grass alpine meadows on alpine soils. The absence or low thickness of snow cover ensures the development of permafrost and the emergence of mountain tundras various types: moss-lichen, shrub, sedge, herbaceous on mountain tundra soils. Above the alpine belt, rocky wastelands, rocky cliffs, snowfields and glaciers are developed.

A peculiar manifestation of altitudinal zonation is observed in the intermountain basins of the Altai-Sayan country located at different altitude levels. Their bottoms, in conditions of a sharp deficit of moisture and a significant increase in the degree of continentality of their climate, are usually treeless - mountain-steppe landscapes dominate there. There are two types of mountain steppes.

1. Steppes of low- and mid-mountain basins and plateaus with a very short period of flowering and development associated with spring moisture reserves and unfavorable temperature conditions. The typical steppe vegetation (feather grass, tonkonogo, alfalfa, sainfoin, buttercup, lumbago, adonis, anemone) growing on southern chernozems is mixed with subalpine representatives (edelweiss, astragalus).

2. Steppes of mid- and high-mountain basins lying above 1500 m (Chuya steppe, Ukok plateau and others). Low-growing and creeping forms of pebble feather grass, caragana, halophytes and alpine representatives predominate. In more arid conditions (Tuva), on chestnut soils, often rocky and gravelly, dry steppes and semi-deserts appear with the predominance of cold wormwood, dwarf caragana, and xerophytic grasses. Within the Kemerovo region, in the southern part of Mountain Shoria, in small basins in the basins of the Kondoma, Mrassu and upper Tom rivers (Kabyrzinsko-Mrasskaya, Verkhnekondomskaya, Ortonsko-Mrasskaya) there are areas of mountain-steppe landscapes. In conditions of an increased degree of continental climate (Ivanov continentality index 71-75% instead of 55-65% in most of the highlands), low precipitation (850-870 mm versus 900-1175 mm on the highlands), low snow cover (75 cm, highlands - over 100 cm), soil freezing (their surface temperature is up to –24 degrees (usually –17 degrees)) and the development of chievo-volosnetsy, anthracite and small sedge steppe meadows and steppes on mountain meadow soils with signs of salinity.

Physico-geographical zoning. Identification of the highest rank unit – physical-geographical country is carried out taking into account the following criteria. A. Geomorphological criterion: in terms of the dominance of mountainous terrain, it is clearly contrasted with the large plains of neighboring countries. B. Geotectonic criterion: a mountain-folded region of different ages against the background of platform (plate) structures of plain Siberia. B. Macroclimatic criterion - the “variegated” climate of a mountainous country with a reduced degree of continentality in comparison with the comparative uniformity of the climate of lowland countries. D. The presence of altitudinal zonality of soil and vegetation cover instead of the dominance of latitudinal zonality of neighboring plains.

Two stand out physical and geographical areas. The selection criterion is the type of altitudinal zonation. Within the regions, physico-geographical provinces and districts(units of the third and fourth ranks). The internal zoning scheme of the Altai-Sayan country takes on the following form.

A. Kuznetsk-Altai region. It is dominated by the steppe-forest-steppe type of altitudinal zone. There are two provinces: a. Altaiskaya, b. Salairo-Kuznetskaya. The latter is divided into regions (Tom-Kolyvan Plain; Kuznetsk Basin; Salair; Kuznetsk Alatau; Mountain Shoria). Genetic differences in physical and geographical areas are predetermined by the specifics (total amplitude and speed) of the latest tectonic uplifts. This led to differences in terrain, climate, hydrology, soil-vegetable cover, fauna, and ultimately - to the emergence of natural complexes that differ from each other (physical-geographical regions or landscapes).

B. Sayano-Tuva region with the dominance of the (southern) taiga type of altitudinal zone and the identification of provinces: a. Sayanskaya, b. Tuva.

A natural change in processes and phenomena with altitude in the mountains. It is caused by changes in density, pressure, temperature, moisture and dust content of air. Atmospheric pressure decreases in the troposphere by 133 n/m2 (1 mmHg for every 11-15 m of altitude); at 5.5 km it is approximately half as low as at sea level. Half of all water vapor is concentrated below 1.5-2 km, and the dust content in the air quickly decreases upward. For these reasons, the intensity of solar radiation in the mountains increases with altitude, and the return of long-wave radiation from the surface of mountain slopes into the atmosphere and the influx of counter radiation from the atmosphere decrease. Under the conditions of absorption and release of radiation and vertical exchange of air created in the atmosphere, the air temperature, as a rule, decreases within the troposphere by an average of 5-6 ° C for each kilometer of altitude. The conditions for condensation of water vapor are such that the number of clouds, concentrated mainly in the lower kilometers of the troposphere, increases to a certain height. This leads to the existence of the belt maximum precipitation and to their decrease at higher levels.

The set of altitudinal belts of a macroslope (slope) of a mountainous country or a specific slope of a separate ridge is usually called a set or spectrum of belts. In each spectrum, the basic landscape is the foothills of the mountains, close to the conditions of the horizontal natural zone in which the given mountainous country is located. The combination of numerous factors influencing the structure of the high-altitude spectrum causes a complex differentiation of the types of altitude spectra. Even within one zone, the spectra of V. p. are often heterogeneous; for example, they become richer as the height of the mountains increases.

Altitudinal zonation in Altai.

A complex geological history, sharply demarcated relief, contrasting climatic conditions and diverse soils predetermined the formation in Altai of a unique set and mosaic of vegetation cover.

The main patterns in the distribution of vegetation are associated with altitudinal zones, the identification of which is due to changes in climatic indicators with altitude. Currently, among the works published by researchers on altitudinal zonation (zoning), there is no unity in the identification of zones.

In works on altitudinal zonation by G.N. Ogureeva (1980), there are six identified zones: steppe, forest-steppe, forest, subalpine, alpine-tundra, nival.

I.Yu. Koropachinsky (1975), also distinguishes for the entire Altai Sayan region: steppe, forest-steppe, forest, subalpine, alpine, nival.

A.V. Kuminova (1960), gives complex system zonation of vegetation for Western, Northern, Central and South-Eastern Altai.

According to V.V. Rudsky, it is advisable to adhere to the following scheme of altitudinal zones: steppe, forest-steppe, forest, high-mountain, nival.

Let's give brief description vertical belts.

1. Steppe belt.

It has a very limited distribution in Northern Altai within the Altai Territory, and is also represented by the island steppes of the Central and desert steppes of the Southern Altai. Here, plant formations of the semi-desert type are found in fragments, which do not form an independent vegetation belt.

Their existence is explained by a lack of moisture, as well as drying winds - hair dryers, the maximum of which is observed in winter and autumn.

2. Forest-steppe belt.

It is also a small belt bordering the steppe regions and associated with the increasing ruggedness of the terrain and the appearance of forest phytocenoses along the northern slopes of the ridges. In addition to larch, the forest element of the forest-steppe complex consists of birch and pine, and steppe vegetation is represented by formations of meadow steppes. In the vegetation cover, steppe herbaceous and forest formations occupy equal areas. Their differentiation is associated with exposure differences in lighting and moisture conditions.

Thus, on the southern slopes, steppe communities develop, consisting of xeropetrophilous species of herbaceous plants and some shrubs, among which meadowsweet can be distinguished. At the same heights, but on the slopes of northern exposure, forest formations with the participation of birch, aspen, pine, and larch are common.

3. Forest belt.

It has two sub-belts: taiga and light-coniferous forests.

Light coniferous with a predominance of larch, occupies significant areas in the basin of the middle Katun, on the Terektinsky and Kuraisky ridges. In virgin larch forests, a sparse shrub undergrowth and a rich and varied herbaceous cover develop. The subtaiga subbelt includes primarily park larch forests located along river valleys, foothill trails and on gentle slopes. They were once widespread in Altai, but due to economic development they underwent a significant reduction, especially around settlements and along river valleys.

Pine forests are distributed mainly along river valleys (Katun, Chulyshman). Here you can identify areas of park pine forests with well-developed grass stand, in which cereals predominate.

The taiga subbelt occupies the largest area. Within its boundaries, the black taiga, which is widespread in the western foothills of Altai and in the North-Eastern Altai (Lake Teletskoye basin), is of significant interest.

In the tree layer, along with fir, Siberian pine (cedar) can also dominate.

The herbaceous layer consists of large-grass and tall-grass species.

The taiga forests themselves are very diverse in Altai.

The leading position is occupied by the polydominant dark coniferous taiga, where the main cenose-forming species are three species: Siberian fir, common spruce and Siberian pine (cedar). Along with polydominance, the leading role may belong to one of the three above-mentioned species. Then associations of fir dark-coniferous taiga are formed, confined mainly to the middle part of the mountain slopes, cedar taiga, gravitating mainly to the upper parts of the forest belt, and spruce taiga, occupying river valleys. Unlike the black taiga, the dark coniferous taiga is characterized by good development ground cover, consisting of mosses and lichens, the presence of a shrub and subshrub layer and weak development of the herbaceous layer. The upper boundary of the taiga subbelt lies within the altitude range from 1600-1800 to 1700-2465m ( upper limit forests). It is characterized by cedar-larch and cedar forests with an admixture of fir and developed shrub and grass-shrub layers.

4. Alpine belt.

In a simplified form, the high-mountain belt can be divided into two sub-belts: subalpine and alpine-tundra.*

The subalpine sub-belt is represented by subalpine meadows and thickets of shrubs (erniks), alternating with cedar and larch woodlands.

The Alpine-tundra subbelt is characterized by a complex of South Siberian alpine-type formations, distributed at absolute altitudes of 2000-3500m. it is most typically represented on the ridges of Western and Central Altai; as you move south and east, the area of ​​alpine meadows decreases.

A.V. Kuminova (1960) distinguishes four formations of alpine meadows: large-grass, small-grass, grass-sedge and cobresia.

Largest areas the subbelt is occupied by tundra, represented by meadow, moss-lichen, shrub and rocky formations.

5. Nival belt.

More homogeneous throughout its entire length due to the almost complete absence of vegetation and the presence of modern and traces of ancient glaciation.

It is mainly located at altitudes above 3000m.

A special intrazonal plant formation is formed by swamps, widespread everywhere and at different altitudes, but mainly on flat watershed spaces (for example, the Tyugurk swamps on the Terektinsky ridge), flat depressions in the relief of plateaus (Chulyshmanskoe, Ukok), and in the bottoms of trough valleys. Large tracts of swamps were formed as a result of overgrowth and siltation of high-mountain lakes.

V.P. Sedelnikov (1988), in his work throughout the Altai-Sayan mountain region, distinguishes three types of altitudinal zones in the highlands.

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Altitudinal zonality in the mountains.

Altitudinal zonality or altitudinal zonation is a consistent change of natural zones and landscapes with increasing altitude above sea level.

Altitudinal zone or altitudinal zone- a strip more or less uniform in natural conditions. May be intermittent.

Altitudinal zonation (zonation). Characteristic.

Altitudinal zonation (altitudinal zonation) is caused by climate change in the mountains with increasing altitude.

As you climb the mountains:

The air temperature decreases by an average of 6 degrees Celsius for every kilometer,

Air pressure decreases

Solar radiation is becoming more and more intense,

The amount of precipitation changes.

Vegetation.

The vegetation of the subalpine altitudinal zone is represented by subalpine meadows, consisting mainly of cereal and forb tall grasses, and small areas of park forests and crooked woods. The vegetation of subalpine meadows is very rich; during haymaking in some regions of the globe it produces up to 30 c/ha of hay.

Mountain meadow altitudinal belt

The term is used to combine the alpine and subalpine belts.

General characteristics.

The wettest altitude zone. Mountain forest altitude zone represented mainly by forest landscapes. It reaches its greatest development in tropical and equatorial latitudes, but is also found in the arid regions of the planet. In the latter case, the forest does not grow as a continuous mass, but alternates with the steppe, forming a forest-steppe natural zone.

Boundaries of the mountain-forest altitudinal zone.

Below it borders on the desert-steppe belt, on top – on the subalpine or mountain-tundra belt.

Vegetation.

Very rich. The types of vegetation that form mountain forests depend on latitude, continental climate and other factors.

General characteristics.

The desert-steppe altitudinal zone is characteristic of desert, semi-desert and steppe natural zones of the tropics, subtropics and temperate climate zone. Partly represented in the zone of savannas and woodlands of subequatorial belts.

In temperate and subtropical zones, the development of mountain steppes occurs with 350-500 mm of precipitation per year, mountain semi-deserts - with 250-350 mm, mountain deserts - with precipitation amounts of less than 250 mm per year. In tropical or subequatorial climates, these values ​​will be 100-200 mm larger.

The phenomenon of altitudinal zonation

The presence of mountains is one of the main reasons for the violation of the law of geographic zonation and the formation of azonal natural complexes. With an increase in absolute altitude, average daily and, accordingly, average annual temperatures decrease, and indicators atmospheric pressure. Climatic indicators influence soil formation. The combination of these factors influences the development of natural complexes. Differences also form depending on the direction of the slope (insolation).

Definition 1

The change in natural complexes with height is called altitudinal zone .

On the territory of Russia there are Ural Mountains, North Caucasus, mountain structures of Southern Siberia .

## Altitudinal zone of the Ural Mountains

Ural Mountains stretched into submeridional direction of almost $2000 $ km and serve as a conditional border between Europe and Asia. The highest point of the Urals - Mount Narodnaya ($1894 m). The average heights of the Ural Mountains do not exceed $1000$ m. Therefore, the Urals belongs to low mountains

Due to the peculiarities of the geographical location, the natural complexes of the western and eastern slopes differ from each other. Due to the westerly transfer of air masses, the western slopes of the mountains are wetter and warmer, and the eastern slopes are drier and colder. In general, the natural zones of the Urals correspond to the latitudinal ones, but are somewhat “shifted” to the south. The territory of the Ural Mountains is crossed by natural zones temperate zone from tundra to semi-deserts.

Altitudinal zone of the North Caucasus

Greater Caucasian The ridge stretches from northwest to southeast, rising to a height of $5000$ m in large folds. The highest points of the Main Caucasian Range are Elbrus ($5642 m) and Kazbek ($5033 m).

Note 1

Elbrus is the highest point in Russia.

The Caucasus as a mountainous structure is located on the border of temperate and subtropical climatic zones and serves as a barrier to cold northern air. In the southwestern part of the mountains, precipitation falls from $2,600 to $4,000 mm per year. Formed here humid subtropics . And on the southeastern slopes formed dry subtropics .

The mountain tops are covered perennial snow and glaciers . Below, up to an altitude of $2000$ m, there is a belt alpine and subalpine meadows . Even lower, to a height of $1300$ m, they grow spruce-fir forests, changing to the bottom oak forests . At the foot there are thickets evergreen shrubs and vines , and in dry places - thorny bushes (shiblik) .

Altitudinal zonation of the mountains of Southern Siberia

The mountain belt of Southern Siberia stretches from Altai in the west to the mountain systems of Transbaikalia in the east of the country. Altai is the highest mountains of this system ( Mount Belukha ($4506$ m) – the most high point Siberia). On the slopes of Altai up to a height of $500$ m in the north and $1500$ m in the south, steppes . Above the steppes on the damp western slopes of Altai there are spruce-fir forests . On the territory of the Eastern and Western Sayans, the Baikal Mountains and the mountains of Transbaikalia, light coniferous pine-larch forests on mountain taiga permafrost soils. The mountain tops are covered shrub thickets of dwarf cedar . Above the forests in Altai are subalpine and alpine meadows , and in the dry conditions of the Sayans, on the Baikal and Aldan highlands, parts of the mountains are covered mountain tundra with dwarf birch . Complexes are formed on the southern slopes dry Mongolian steppes .

Since there are no higher mountain systems on the territory of Russia, the areas of altitudinal zonation do not play a very important role. big role in nature. And the mountain steppes are experiencing significant changes due to economic activity person. Most of them are plowed, and the rest of the territory is used as hayfields and mountain pastures. Timber development is carried out on forest slopes.

Note 2

The mountain structures of North-Eastern Siberia are of insignificant height. In addition, they are located in the tundra zone. Therefore, the altitudinal zonation in the northeast of Russia is not clearly expressed.