List of rivers of the West Siberian Plain. Tectonic structure of the West Siberian Plain

The West Siberian Plain is one of the largest accumulative lowland plains on the globe. It extends from the shores of the Kara Sea to the steppes of Kazakhstan and from the Urals in the west to the Central Siberian Plateau in the east. The plain has the shape of a trapezoid tapering towards the north: the distance from its southern border to the northern reaches almost 2500 km, the width is from 800 to 1900 km, and the area is only slightly less than 3 million km2.

The relief of the West Siberian Plain is one of the most homogeneous in the world. Occupying an area of ​​2.6 million km 2, the West Siberian Plain stretches from west to east, from the Urals to the Yenisei, for 1900 km, north to south, from the Arctic Ocean to the Altai Mountains, for 2400 km. Only in the extreme south do altitudes exceed 200 m; the vast majority of the plain has an altitude of less than 100 m above sea level; Alluvial-lacustrine and accumulative relief predominates (also denudation in the south). Relief features characteristic of Western Siberia, such as vast floodplains and huge swamps, are especially common in the northern part of the plain; The relief north of the latitudinal section of the Ob River was formed under the influence of transgressions of the sea and glaciers.

In the northwest and northeast of the West Siberian Plain, the relief is accumulative glacial, formed by glaciers descending from the mountains of the Northern Urals and the Putorana Plateau. The valleys of large rivers are terraced. On the Yamal and Gydan peninsulas there are aeolian dunes. The relatively elevated and dry areas where the bulk of the population of Western Siberia is concentrated are located south of 55 °C. Sh.

The differentiated subsidence of the West Siberian Plate in the Mesozoic and Cenozoic led to the predominance within its boundaries of processes of accumulation of loose sediments, the thick cover of which levels out the surface irregularities of the Hercynian basement. Therefore, the modern West Siberian Plain has a generally flat surface. However, it cannot be considered as a monotonous lowland, as was recently believed. In general, the territory of Western Siberia has a concave shape. Its lowest sections (50-100 m) are located mainly in the central (Kondinskaya and Sredneobskaya lowlands) and northern (Nizhneobskaya, Nadymskaya and Purskaya lowlands) parts of the country. Along the western, southern and eastern outskirts stretch low (up to 200-250 m) hills: North Sosvinskaya, Turinskaya, Ishimskaya, Priobskoye and Chulym-Yenisei plateaus, Ketsko-Tymskaya, Verkhnetazovskaya, Nizhneeniseiskaya. A clearly defined strip of hills is formed in the inner part of the plain by the Siberian Uvals (average height - 140-150 m), stretching from the west from the Ob to the east to the Yenisei, and the Vasyugan Plain parallel to them.

Some orographic elements of the West Siberian Plain correspond to geological structures: gentle anticlinal uplifts correspond, for example, to the Verkhnetazovskaya and Lyulimvor hills, and the Barabinskaya and Kondinskaya lowlands are confined to syneclises of the base of the plate. However, in Western Siberia, discordant (inversion) morphostructures are also common. These include, for example, the Vasyugan Plain, which formed on the site of a gently sloping syneclise, and the Chulym-Yenisei Plateau, located in the zone of basement deflection.

The West Siberian Plain is one of the largest accumulative lowland plains on the globe. It extends from the shores of the Kara Sea to the steppes of Kazakhstan and from the Urals in the west to the Central Siberian Plateau in the east. The plain has the shape of a trapezoid tapering towards the north: the distance from its southern border to the northern reaches almost 2500 km, width - from 800 to 1900 km, and the area is only slightly less than 3 million. km 2 .

In the Soviet Union there are no longer such vast plains with such weakly rugged terrain and such small fluctuations in relative heights. The comparative uniformity of the relief determines the distinct zoning of the landscapes of Western Siberia - from tundra in the north to steppe in the south. Due to the poor drainage of the territory, hydromorphic complexes play a very prominent role within its boundaries: swamps and swampy forests occupy a total of about 128 million hectares. ha, and in the steppe and forest-steppe zones there are many solonetzes, solods and solonchaks.

The geographical position of the West Siberian Plain determines the transitional nature of its climate between the moderate continental climate of the Russian Plain and the sharply continental climate of Central Siberia. Therefore, the country’s landscapes are distinguished by a number of unique features: the natural zones here are somewhat shifted to the north compared to the Russian Plain, there is no zone of broad-leaved forests, and landscape differences within the zones are less noticeable than on the Russian Plain.

The West Siberian Plain is the most populated and developed (especially in the south) part of Siberia. Within its boundaries are the Tyumen, Kurgan, Omsk, Novosibirsk, Tomsk and North Kazakhstan regions, a significant part of the Altai Territory, Kustanai, Kokchetav and Pavlodar regions, as well as some eastern regions of the Sverdlovsk and Chelyabinsk regions and western regions of the Krasnoyarsk Territory.

The first acquaintance of Russians with Western Siberia probably took place in the 11th century, when the Novgorodians visited the lower reaches of the Ob. The campaign of Ermak (1581-1584) ushered in the brilliant period of the Great Russian geographical discoveries in Siberia and the development of its territory.

However, scientific study of the country’s nature began only in the 18th century, when detachments of first the Great Northern and then academic expeditions were sent here. In the 19th century Russian scientists and engineers are studying the conditions of navigation on the Ob, Yenisei and the Kara Sea, the geological and geographical features of the route of the then designed Siberian railway, salt deposits in the steppe zone. A significant contribution to the knowledge of the Western Siberian taiga and steppes was made by the research of soil-botanical expeditions of the Resettlement Administration, undertaken in 1908-1914. in order to study the conditions of agricultural development of areas allocated for the resettlement of peasants from European Russia.

The study of the nature and natural resources of Western Siberia acquired a completely different scope after the Great October Revolution. In the research that was necessary for the development of productive forces, it was no longer individual specialists or small detachments that took part, but hundreds of large complex expeditions and many scientific institutes created in various cities of Western Siberia. Detailed and comprehensive studies were carried out here by the USSR Academy of Sciences (Kulundinskaya, Barabinskaya, Gydanskaya and other expeditions) and its Siberian branch, the West Siberian Geological Department, geological institutes, expeditions of the Ministry of Agriculture, Hydroproject and other organizations.

As a result of these studies, ideas about the country's topography changed significantly, detailed soil maps of many regions of Western Siberia were compiled, and measures were developed for the rational use of saline soils and the famous Western Siberian chernozems. The forest typological studies of Siberian geobotanists and the study of peat bogs and tundra pastures were of great practical importance. But the work of geologists brought especially significant results. Deep drilling and special geophysical research have shown that in the depths of many regions of Western Siberia there are rich deposits natural gas, large reserves of iron ore, brown coal and many other minerals, which already serve as a solid basis for the development of industry in Western Siberia.

Geological structure and history of development of the territory

Tazovsky Peninsula and Middle Ob in the section Nature of the World.

Many features of the nature of Western Siberia are determined by the nature of its geological structure and history of development. The entire territory of the country is located within the West Siberian epi-Hercynian plate, the foundation of which is composed of dislocated and metamorphosed Paleozoic sediments, similar in nature to similar rocks of the Urals, and in the south of the Kazakh hillocks. The formation of the main folded structures of the basement of Western Siberia, which have a predominantly meridional direction, dates back to the era of the Hercynian orogeny.

The tectonic structure of the West Siberian plate is quite heterogeneous. However, even its large structural elements appear in the modern relief less clearly than the tectonic structures of the Russian Platform. This is explained by the fact that the surface relief of Paleozoic rocks, descended to great depths, is leveled here by a cover of Meso-Cenozoic sediments, the thickness of which exceeds 1000 m, and in individual depressions and syneclises of the Paleozoic basement - 3000-6000 m.

Mesozoic formations of Western Siberia are represented by marine and continental sandy-clayey deposits. Their total capacity in some areas reaches 2500-4000 m. The alternation of marine and continental facies indicates the tectonic mobility of the territory and repeated changes in conditions and sedimentation regime on the West Siberian Plate, which subsided at the beginning of the Mesozoic.

Paleogene deposits are predominantly marine and consist of gray clays, mudstones, glauconitic sandstones, opokas and diatomites. They accumulated at the bottom of the Paleogene sea, which, through the depression of the Turgai Strait, connected the Arctic basin with the seas then located in Central Asia. This sea left Western Siberia in the middle of the Oligocene, and therefore the Upper Paleogene deposits are represented here by sandy-clayey continental facies.

Significant changes in the conditions for the accumulation of sediments occurred in the Neogene. Formations of rocks of Neogene age, outcropping mainly in the southern half of the plain, consist exclusively of continental lacustrine-fluvial deposits. They were formed in the conditions of a poorly dissected plain, first covered with rich subtropical vegetation, and later with broad-leaved deciduous forests of representatives of the Turgai flora (beech, walnut, hornbeam, lapina, etc.). In some places there were areas of savannah where giraffes, mastodons, hipparions, and camels lived at that time.

The events of the Quaternary period had a particularly great influence on the formation of the landscapes of Western Siberia. During this time, the country's territory experienced repeated subsidence and continued to be an area predominantly of accumulation of loose alluvial, lacustrine, and, in the north, marine and glacial sediments. The thickness of the Quaternary cover in the northern and central regions reaches 200-250 m. However, in the south it noticeably decreases (in some places to 5-10 m), and in the modern relief the effects of differentiated neotectonic movements are clearly expressed, as a result of which swell-like uplifts arose, often coinciding with the positive structures of the Mesozoic cover of sedimentary deposits.

Lower Quaternary sediments are represented in the north of the plain by alluvial sands filling buried valleys. The base of alluvium is sometimes located in them at 200-210 m below the modern level of the Kara Sea. Above them in the north usually lie pre-glacial clays and loams with fossil remains of tundra flora, which indicates that a noticeable cooling of Western Siberia had already begun then. However, in the southern regions of the country dark coniferous forests with an admixture of birch and alder predominated.

The Middle Quaternary in the northern half of the plain was an era of marine transgressions and repeated glaciations. The most significant of them was Samarovskoe, the sediments of which form the interfluves of the territory lying between 58-60° and 63-64° N. w. According to currently prevailing views, the cover of the Samara glacier, even in the extreme northern regions of the lowland, was not continuous. The composition of the boulders shows that its food sources were glaciers descending from the Urals to the Ob valley, and in the east - glaciers of the Taimyr mountain ranges and the Central Siberian Plateau. However, even during the period of maximum development of glaciation on the West Siberian Plain, the Ural and Siberian ice sheets did not meet one another, and the rivers of the southern regions, although they encountered a barrier formed by ice, found their way to the north in the interval between them.

The sediments of the Samarova strata, along with typical glacial rocks, also include marine and glaciomarine clays and loams that formed at the bottom of the sea advancing from the north. Therefore, the typical forms of moraine relief are less clearly expressed here than on the Russian Plain. On the lacustrine and fluvioglacial plains adjacent to the southern edge of the glaciers, forest-tundra landscapes then prevailed, and in the extreme south of the country loess-like loams formed, in which pollen of steppe plants (wormwood, kermek) is found. Marine transgression continued in the post-Samarovo period, the sediments of which are represented in the north of Western Siberia by the Messa sands and clays of the Sanchugov Formation. In the northeastern part of the plain, moraines and glacial-marine loams of the younger Taz glaciation are common. The interglacial era, which began after the retreat of the ice sheet, in the north was marked by the spread of the Kazantsev marine transgression, the sediments of which in the lower reaches of the Yenisei and Ob contain the remains of a more heat-loving marine fauna than that currently living in the Kara Sea.

The last, Zyryansky, glaciation was preceded by regression of the boreal sea, caused by uplifts of the northern regions of the West Siberian Plain, the Urals and the Central Siberian Plateau; the amplitude of these uplifts was only a few tens of meters. At the maximum stage of development of the Zyryan glaciation, glaciers descended to the areas of the Yenisei Plain and the eastern foot of the Urals to approximately 66° N. sh., where a number of stadial terminal moraines were left. In the south of Western Siberia at this time, sandy-clayey Quaternary sediments were overwintering, aeolian landforms were forming, and loess-like loams were accumulating.

Some researchers of the northern regions of the country paint a more complex picture of the events of the Quaternary glaciation era in Western Siberia. Thus, according to geologist V.N. Saksa and geomorphologist G.I. Lazukov, glaciation began here in the Lower Quaternary and consisted of four independent eras: Yarskaya, Samarovskaya, Tazovskaya and Zyryanskaya. Geologists S. A. Yakovlev and V. A. Zubakov even count six glaciations, attributing the beginning of the most ancient of them to the Pliocene.

On the other hand, there are supporters of a one-time glaciation of Western Siberia. Geographer A.I. Popov, for example, considers the deposits of the glaciation era of the northern half of the country as a single water-glacial complex consisting of marine and glacial-marine clays, loams and sands containing inclusions of boulder material. In his opinion, there were no extensive ice sheets on the territory of Western Siberia, since typical moraines are found only in the extreme western (at the foot of the Urals) and eastern (near the ledge of the Central Siberian Plateau) regions. During the glaciation era, the middle part of the northern half of the plain was covered with the waters of marine transgression; the boulders contained in its sediments were brought here by icebergs that broke off from the edge of the glaciers that descended from the Central Siberian Plateau. Geologist V.I. Gromov recognizes only one Quaternary glaciation in Western Siberia.

At the end of the Zyryan glaciation, the northern coastal regions of the West Siberian Plain subsided again. The subsided areas were flooded by the waters of the Kara Sea and covered with marine sediments, composing post-glacial marine terraces, the highest of which rises by 50-60 m above the modern level of the Kara Sea. Then, after regression of the sea, a new incision of rivers began in the southern half of the plain. Due to the small slopes of the channel, lateral erosion prevailed in most river valleys of Western Siberia; the deepening of the valleys proceeded slowly, which is why they usually have a significant width but small depth. In poorly drained interfluve spaces, the reworking of the glacial relief continued: in the north it consisted of leveling the surface under the influence of solifluction processes; in the southern, non-glacial provinces, where more precipitation fell, the processes of deluvial washout played a particularly prominent role in the transformation of the relief.

Paleobotanical materials suggest that after the glaciation there was a period with a slightly drier and warmer climate than now. This is confirmed, in particular, by the finds of stumps and tree trunks in the deposits of the tundra regions of Yamal and the Gydan Peninsula at 300-400 km north of the modern border of tree vegetation and the widespread development in the south of the tundra zone of relict large-hilly peat bogs.

Currently, on the territory of the West Siberian Plain there is a slow shift of the boundaries of geographical zones to the south. Forests in many places encroach on the forest-steppe, forest-steppe elements penetrate into the steppe zone, and tundras slowly displace woody vegetation near the northern limit of sparse forests. True, in the south of the country man interferes with the natural course of this process: by cutting down forests, he not only stops their natural advance on the steppe, but also contributes to the shift of the southern border of forests to the north.

Relief

See photographs of the nature of the West Siberian Plain: the Tazovsky Peninsula and the Middle Ob in the Nature of the World section.

Scheme of the main orographic elements of the West Siberian Plain

The differentiated subsidence of the West Siberian Plate in the Mesozoic and Cenozoic led to the predominance within its boundaries of processes of accumulation of loose sediments, the thick cover of which levels out the surface irregularities of the Hercynian basement. Therefore, the modern West Siberian Plain has a generally flat surface. However, it cannot be considered as a monotonous lowland, as was recently believed. In general, the territory of Western Siberia has a concave shape. Its lowest areas (50-100 m) are located mainly in the central ( Kondinskaya and Sredneobskaya lowlands) and northern ( Nizhneobskaya, Nadym and Pur lowlands) parts of the country. Along the western, southern and eastern outskirts there are low (up to 200-250 m) elevations: Severo-Sosvinskaya, Turinskaya, Ishimskaya, Priobskoye and Chulym-Yenisei plateaus, Ketsko-Tymskaya, Verkhnetazovskaya, Nizhneneiseyskaya. A clearly defined strip of hills forms in the inner part of the plain Sibirskie Uvaly(average height - 140-150 m), stretching from the west from the Ob to the east to the Yenisei, and parallel to them Vasyuganskaya plain.

Some orographic elements of the West Siberian Plain correspond to geological structures: for example, the Verkhnetazovskaya and Lyulimvor, A Barabinskaya and Kondinskaya the lowlands are confined to the syneclises of the slab foundation. However, in Western Siberia, discordant (inversion) morphostructures are also common. These include, for example, the Vasyugan Plain, which formed on the site of a gently sloping syneclise, and the Chulym-Yenisei Plateau, located in the zone of basement deflection.

The West Siberian Plain is usually divided into four large geomorphological regions: 1) marine accumulative plains in the north; 2) glacial and water-glacial plains; 3) periglacial, mainly lacustrine-alluvial plains; 4) southern non-glacial plains (Voskresensky, 1962).

The differences in the relief of these areas are explained by the history of their formation in Quaternary times, the nature and intensity of recent tectonic movements, and zonal differences in modern exogenous processes. In the tundra zone, relief forms are especially widely represented, the formation of which is associated with the harsh climate and widespread permafrost. Thermokarst depressions, bulgunnyakhs, spotted and polygonal tundras are very common, and solifluction processes are developed. Typical of the southern steppe provinces are numerous closed basins of suffusion origin, occupied by salt marshes and lakes; The network of river valleys here is sparse, and erosional landforms in the interfluves are rare.

The main elements of the relief of the West Siberian Plain are wide, flat interfluves and river valleys. Due to the fact that the interfluve spaces account for most of the country's area, they determine the general appearance of the plain's topography. In many places, the slopes of their surfaces are insignificant, the flow of precipitation, especially in the forest-swamp zone, is very difficult and the interfluves are heavily swamped. Large areas are occupied by swamps north of the Siberian Railway line, on the interfluves of the Ob and Irtysh, in the Vasyugan region and the Barabinsk forest-steppe. However, in some places the relief of the interfluves takes on the character of a wavy or hilly plain. Such areas are especially typical of some northern provinces of the plain, which were subject to Quaternary glaciations, which left here piles of stadial and bottom moraines. In the south - in Baraba, on the Ishim and Kulunda plains - the surface is often complicated by numerous low ridges stretching from northeast to southwest.

Another important element The country's topography is river valleys. All of them were formed under conditions of slight surface slopes and slow and calm river flows. Due to differences in the intensity and nature of erosion, the appearance of the river valleys of Western Siberia is very diverse. There are also well-developed deep ones (up to 50-80 m) valleys of large rivers - the Ob, Irtysh and Yenisei - with a steep right bank and a system of low terraces on the left bank. In some places their width is several tens of kilometers, and the Ob valley in the lower reaches reaches even 100-120 km. The valleys of most small rivers are often just deep ditches with poorly defined slopes; During spring floods, water completely fills them and even floods neighboring valley areas.

Climate

See photographs of the nature of the West Siberian Plain: the Tazovsky Peninsula and the Middle Ob in the Nature of the World section.

Western Siberia is a country with a fairly harsh continental climate. Its large extent from north to south determines a clearly expressed climate zonation and significant differences in the climatic conditions of the northern and southern parts of Western Siberia, associated with changes in the quantity solar radiation and the nature of the circulation of air masses, especially the westerly transport flows. The southern provinces of the country, located inland, at a great distance from the oceans, are also characterized by a more continental climate.

During the cold period, two baric systems interact within the country: an area of ​​relatively high atmospheric pressure located over the southern part of the plain, and an area of ​​low pressure, which in the first half of winter stretches in the form of a trough of the Icelandic baric minimum over the Kara Sea and the northern peninsulas. In winter, continental air masses of temperate latitudes predominate, which come from Eastern Siberia or are formed locally as a result of cooling of the air over the plain.

Cyclones often pass through the border zone of areas of high and low pressure. They recur especially often in the first half of winter. Therefore, the weather in the coastal provinces is very unstable; on the coast of Yamal and the Gydan Peninsula there are strong winds, the speed of which reaches 35-40 m/sec. The temperature here is even slightly higher than in neighboring forest-tundra provinces, located between 66 and 69° N. w. However, further south, winter temperatures gradually rise again. In general, winter is characterized by stable low temperatures; there are few thaws here. Minimum temperatures throughout Western Siberia are almost the same. Even near the southern border of the country, in Barnaul, there are frosts down to -50 -52°, i.e. almost the same as in the far north, although the distance between these points is more than 2000 km. Spring is short, dry and relatively cold; April, even in the forest-swamp zone, is not yet quite a spring month.

In the warm season, low pressure sets over the country, and an area of ​​higher pressure forms over the Arctic Ocean. In connection with this summer, weak northern or northeastern winds predominate and the role of westerly air transport noticeably increases. Happens in May rapid rise temperatures, but often, when arctic air masses invade, there are returns of cold weather and frosts. The warmest month is July, the average temperature of which ranges from 3.6° on Bely Island to 21-22° in the Pavlodar region. The absolute maximum temperature is from 21° in the north (Bely Island) to 40° in the extreme southern regions (Rubtsovsk). High summer temperatures in the southern half of Western Siberia are explained by the arrival of heated continental air from the south - from Kazakhstan and Central Asia. Autumn comes late. Even in September the weather is warm during the day, but November, even in the south, is already a real winter month with frosts down to -20 -35°.

Most of the precipitation falls in the summer and is brought by air masses coming from the west, from the Atlantic. From May to October, Western Siberia receives up to 70-80% of the annual precipitation. There are especially many of them in July and August, which is explained by intense activity on the Arctic and polar fronts. The amount of winter precipitation is relatively small and ranges from 5 to 20-30 mm/month. In the south, during some winter months there is sometimes no snow at all. There are significant fluctuations in precipitation in different years. Even in the taiga, where these changes are less than in other zones, precipitation, for example, in Tomsk, falls from 339 mm in a dry year up to 769 mm in wet. Especially large ones are observed in the forest-steppe zone, where, with an average long-term precipitation amount of about 300-350 mm/year in wet years it falls up to 550-600 mm/year, and on dry days - only 170-180 mm/year.

There are also significant zonal differences in evaporation values, which depend on the amount of precipitation, air temperature and the evaporative properties of the underlying surface. The most moisture evaporates in the precipitation-rich southern half of the forest-swamp zone (350-400 mm/year). In the north, in the coastal tundras, where air humidity is relatively high in summer, the amount of evaporation does not exceed 150-200 mm/year. It is approximately the same in the south of the steppe zone (200-250 mm), which is explained by the already low amount of precipitation falling in the steppes. However, evaporation here reaches 650-700 mm Therefore, in some months (especially in May) the amount of evaporated moisture can exceed the amount of precipitation by 2-3 times. The lack of precipitation is compensated in this case by reserves of moisture in the soil accumulated due to autumn rains and melting snow cover.

The extreme southern regions of Western Siberia are characterized by droughts, occurring mainly in May and June. They are observed on average every three to four years during periods with anticyclonic circulation and increased frequency of arctic air intrusions. Dry air coming from the Arctic, when passing over Western Siberia, warms up and is enriched with moisture, but its heating is more intense, so the air moves further and further away from the saturation state. In this regard, evaporation increases, which leads to drought. In some cases, droughts are also caused by the arrival of dry and warm air masses from the south - from Kazakhstan and Central Asia.

In winter, the territory of Western Siberia is covered with snow cover for a long time, the duration of which in the northern regions reaches 240-270 days, and in the south - 160-170 days. Due to the fact that the period of solid precipitation lasts more than six months, and thaws begin no earlier than March, the thickness of the snow cover in the tundra and steppe zones in February is 20-40 cm, in the forest-swamp zone - from 50-60 cm in the west up to 70-100 cm in the eastern Yenisei regions. In treeless - tundra and steppe - provinces, where there are strong winds and snowstorms in winter, the snow is distributed very unevenly, as the winds blow it from elevated relief elements into depressions, where powerful snowdrifts form.

The harsh climate of the northern regions of Western Siberia, where the heat entering the soil is not enough to maintain a positive temperature of the rocks, contributes to soil freezing and widespread permafrost. On the Yamal, Tazovsky and Gydansky peninsulas, permafrost is found everywhere. In these areas of continuous (merged) distribution, the thickness of the frozen layer is very significant (up to 300-600 m), and its temperatures are low (in watershed areas - 4, -9°, in valleys -2, -8°). To the south, within the northern taiga to a latitude of approximately 64°, permafrost occurs in the form of isolated islands interspersed with taliks. Its power decreases, temperatures rise to?0.5 -1°, and the depth of summer thawing also increases, especially in areas composed of mineral rocks.

Water

See photographs of the nature of the West Siberian Plain: the Tazovsky Peninsula and the Middle Ob in the Nature of the World section.

Western Siberia is rich in underground and surface waters; in the north its coast is washed by the waters of the Kara Sea.

The entire territory of the country is located within the large West Siberian artesian basin, in which hydrogeologists distinguish several second-order basins: Tobolsk, Irtysh, Kulunda-Barnaul, Chulym, Ob, etc. Due to the large thickness of the cover of loose sediments, consisting of alternating water-permeable ( sands, sandstones) and water-resistant rocks, artesian basins are characterized by a significant number of aquifers confined to formations of various ages - Jurassic, Cretaceous, Paleogene and Quaternary. The quality of groundwater in these horizons is very different. In most cases, artesian waters of deep horizons are more mineralized than those lying closer to the surface.

In some aquifers of the Ob and Irtysh artesian basins at a depth of 1000-3000 m There are hot salty waters, most often of calcium-sodium chloride composition. Their temperature ranges from 40 to 120°, the daily flow rate of wells reaches 1-1.5 thousand. m 3, and total reserves - 65,000 km 3; such pressurized water can be used for heating cities, greenhouses and greenhouses.

Groundwater in the arid steppe and forest-steppe regions of Western Siberia is of great importance for water supply. In many areas of the Kulunda steppe, deep tube wells were built to extract them. Groundwater from Quaternary deposits is also used; however, in the southern regions, due to climatic conditions, poor surface drainage and slow circulation, they are often highly saline.

The surface of the West Siberian Plain is drained by many thousands of rivers, the total length of which exceeds 250 thousand km. km. These rivers carry about 1,200 km 3 waters - 5 times more than the Volga. The density of the river network is not very large and varies in different places depending on the topography and climatic features: in the Tavda basin it reaches 350 km, and in the Barabinsk forest-steppe - only 29 km per 1000 km 2. Some southern regions of the country with a total area of ​​more than 445 thousand. km 2 belong to territories of closed drainage and are distinguished by the abundance of closed lakes.

The main sources of nutrition for most rivers are melted snow waters and summer-autumn rains. In accordance with the nature of the food sources, the runoff is uneven over the seasons: approximately 70-80% of its annual amount occurs in spring and summer. Especially a lot of water flows down during the spring flood, when the level of large rivers rises by 7-12 m(in the lower reaches of the Yenisei even up to 15-18 m). For a long time (in the south - five, and in the north - eight months), Western Siberian rivers are frozen. Therefore, no more than 10% of the annual runoff occurs in the winter months.

The rivers of Western Siberia, including the largest ones - the Ob, Irtysh and Yenisei, are characterized by slight slopes and low flow speeds. For example, the fall of the Ob riverbed in the area from Novosibirsk to the mouth for 3000 km equals only 90 m, and its flow speed does not exceed 0.5 m/sec.

The most important water artery of Western Siberia is the river Ob with its large left tributary the Irtysh. The Ob is one of the greatest rivers on the globe. The area of ​​its basin is almost 3 million hectares. km 2 and the length is 3676 km. The Ob basin is located within several geographical zones; in each of them the nature and density of the river network are different. Thus, in the south, in the forest-steppe zone, the Ob receives relatively few tributaries, but in the taiga zone their number increases noticeably.

Below the confluence of the Irtysh, the Ob turns into a powerful stream up to 3-4 km. Near the mouth, the width of the river in some places reaches 10 km, and depth - up to 40 m. This is one of the most abundant rivers in Siberia; it brings an average of 414 to the Gulf of Ob per year km 3 waters.

The Ob is a typical lowland river. The slopes of its channel are small: the fall in the upper part is usually 8-10 cm, and below the mouth of the Irtysh does not exceed 2-3 cm by 1 km currents. During spring and summer, the flow of the Ob River near Novosibirsk is 78% of the annual rate; near the mouth (near Salekhard), the distribution of flow by season is as follows: winter - 8.4%, spring - 14.6, summer - 56 and autumn - 21%.

Six rivers of the Ob basin (Irtysh, Chulym, Ishim, Tobol, Ket and Konda) have a length of more than 1000 km; the length of even some second-order tributaries sometimes exceeds 500 km.

The largest of the tributaries is Irtysh, whose length is 4248 km. Its origins lie outside the Soviet Union, in the mountains of the Mongolian Altai. For a significant part of its course, the Irtysh crosses the steppes of Northern Kazakhstan and has almost no tributaries up to Omsk. Only in the lower reaches, already within the taiga, several large rivers flow into it: Ishim, Tobol, etc. Throughout the entire length of the Irtysh, the Irtysh is navigable, but in the upper reaches in the summer, during the period of low water levels, navigation is difficult due to numerous rapids.

Along the eastern border of the West Siberian Plain flows Yenisei- the most abundant river Soviet Union. Its length is 4091 km(if we consider the Selenga River as the source, then 5940 km); The basin area is almost 2.6 million. km 2. Just like the Ob, the Yenisei basin is elongated in the meridional direction. All its large right tributaries flow through the territory of the Central Siberian Plateau. Only the shorter and shallower left tributaries of the Yenisei begin from the flat, swampy watersheds of the West Siberian Plain.

The Yenisei originates in the mountains of the Tuva Autonomous Soviet Socialist Republic. In the upper and middle reaches, where the river crosses the bedrock spurs of the Sayan Mountains and the Central Siberian Plateau, there are rapids (Kazachinsky, Osinovsky, etc.) in its bed. After the confluence of the Lower Tunguska, the current becomes calmer and slower, and sandy islands appear in the channel, breaking the river into channels. The Yenisei flows into the wide Yenisei Bay of the Kara Sea; its width near the mouth, located near the Brekhov Islands, reaches 20 km.

The Yenisei is characterized by large fluctuations in costs according to the seasons of the year. The minimum winter flow rate near the mouth is about 2500 m 3 /sec, the maximum during the flood period exceeds 132 thousand. m 3 /sec with an annual average of about 19,800 m 3 /sec. Over the course of a year, the river carries more than 623 km 3 waters. In the lower reaches the depth of the Yenisei is very significant (in places 50 m). This makes it possible for sea vessels to climb up the river by more than 700 km and reach Igarka.

On the West Siberian Plain there are about one million lakes, the total area of ​​which is more than 100 thousand hectares. km 2. Based on the origin of the basins, they are divided into several groups: those occupying the primary unevenness of the flat terrain; thermokarst; moraine-glacial; lakes of river valleys, which in turn are divided into floodplain and oxbow lakes. Peculiar lakes - “fogs” - are found in the Ural part of the plain. They are located in wide valleys, overflow in the spring, sharply reducing their size in the summer, and by autumn many disappear altogether. In the forest-steppe and steppe regions of Western Siberia there are lakes that fill suffusion or tectonic basins.

Soils, vegetation and fauna

See photographs of the nature of the West Siberian Plain: the Tazovsky Peninsula and the Middle Ob in the Nature of the World section.

The flat terrain of Western Siberia contributes to pronounced zonality in the distribution of soils and vegetation cover. Within the country there are gradually replacing one another tundra, forest-tundra, forest-swamp, forest-steppe and steppe zones. Geographical zoning thus resembles in general terms the zoning system of the Russian Plain. However, the zones of the West Siberian Plain also have a number of local specific features that significantly distinguish them from similar zones in Eastern Europe. Typical zonal landscapes are located here in dissected and better drained upland and riverine areas. In poorly drained interfluve spaces, where drainage is difficult and the soils are usually highly moist, swamp landscapes predominate in the northern provinces, and landscapes formed under the influence of saline groundwater in the south. Thus, here, much more than on the Russian Plain, the role in the distribution of soils and plant cover is played by the nature and density of the relief, causing significant differences in the soil moisture regime.

Therefore, there are, as it were, two independent systems of latitudinal zoning in the country: the zoning of drained areas and the zoning of undrained interfluves. These differences are most clearly manifested in the nature of the soils. Thus, in drained areas of the forest-swamp zone, mainly strongly podzolized soils are formed under coniferous taiga and sod-podzolic soils under birch forests, and in neighboring undrained areas - thick podzols, swamp and meadow-swamp soils. The drained spaces of the forest-steppe zone are most often occupied by leached and degraded chernozems or dark gray podzolized soils under birch groves; in undrained areas they are replaced by marshy, saline or meadow-chernozemic soils. In the upland areas of the steppe zone, either ordinary chernozems, characterized by increased fatness, low thickness and tongue-like (heterogeneity) soil horizons, or chestnut soils predominate; in poorly drained areas, spots of malts and solodized solonetzes or solonetzic meadow-steppe soils are common among them.

Fragment of a section of the swampy taiga of Surgut Polesie (according to V. I. Orlov)

There are some other features that distinguish the zones of Western Siberia from the zones of the Russian Plain. In the tundra zone, which extends much further north than on the Russian Plain, large areas are occupied by arctic tundra, which are absent in the mainland regions of the European part of the Union. The woody vegetation of the forest-tundra is represented mainly by Siberian larch, and not spruce, as in the regions lying west of the Urals.

In the forest-swamp zone, 60% of the area of ​​which is occupied by swamps and poorly drained swampy forests 1, pine forests dominate, occupying 24.5% of the forested area, and birch forests (22.6%), mainly secondary. Smaller areas are covered with damp dark coniferous cedar taiga (Pinus sibirica), fir (Abies sibirica) and ate (Picea obovata). Broad-leaved species (with the exception of linden, which is occasionally found in the southern regions) are absent in the forests of Western Siberia, and therefore there is no broad-leaved forest zone here.

1 It is for this reason that the zone is called forest swamp in Western Siberia.

The increase in continental climate causes a relatively sharp transition, compared to the Russian Plain, from forest-swamp landscapes to dry steppe spaces in the southern regions of the West Siberian Plain. Therefore, the width of the forest-steppe zone in Western Siberia is much smaller than on the Russian Plain, and the tree species found in it are mainly birch and aspen.

The West Siberian Plain is entirely part of the transitional Euro-Siberian zoogeographical subregion of the Palearctic. There are 478 species of vertebrates known here, including 80 species of mammals. The country's fauna is young and in its composition differs little from the fauna of the Russian Plain. Only in the eastern half of the country are some eastern, Trans-Yenisei forms found: the Djungarian hamster (Phodopus sungorus), chipmunk (Eutamias sibiricus) etc. In recent years, the fauna of Western Siberia has been enriched by muskrats acclimatized here (Ondatra zibethica), brown hare (Lepus europaeus), American mink (Lutreola vison), teledut squirrel (Sciurus vulgaris exalbidus), and carp were introduced into its reservoirs (Cyprinus carpio) and bream (Abramis brama).

Natural resources

See photographs of the nature of the West Siberian Plain: the Tazovsky Peninsula and the Middle Ob in the Nature of the World section.

The natural resources of Western Siberia have long served as the basis for development various industries farms. There are tens of millions of hectares of good arable land here. Particularly valuable are the lands of the steppe and forested steppe zones with their favorable climate for agriculture and highly fertile chernozems, gray forest and non-solonetzic chestnut soils, which occupy more than 10% of the country's area. Due to the flatness of the relief, land development in the southern part of Western Siberia does not require large capital expenditures. For this reason, they were one of the priority areas for the development of virgin and fallow lands; In recent years, more than 15 million hectares have been involved in crop rotation here. ha new lands, the production of grain and industrial crops (sugar beets, sunflowers, etc.) increased. Lands located to the north, even in the southern taiga zone, are still underutilized and are a good reserve for development in the coming years. However, this will require significantly greater expenditures of labor and funds for drainage, uprooting and clearing of bushes from the land.

Pastures in the forest-swamp, forest-steppe and steppe zones are of high economic value, especially water meadows along the Ob, Irtysh, Yenisei and their large tributaries. The abundance of natural meadows here creates a solid basis for the further development of livestock farming and a significant increase in its productivity. Important For the development of reindeer husbandry, reindeer moss pastures of the tundra and forest-tundra, occupying more than 20 million hectares in Western Siberia, are available. ha; More than half a million domestic reindeer graze on them.

A significant part of the plain is occupied by forests - birch, pine, cedar, fir, spruce and larch. The total forested area in Western Siberia exceeds 80 million. ha; timber reserves are about 10 billion. m 3, and its annual growth is over 10 million. m 3. The most valuable forests are located here, which provide wood for various sectors of the national economy. The forests most widely used at present are along the valleys of the Ob, the lower reaches of the Irtysh and some of their navigable or raftable tributaries. But many forests, including especially valuable tracts of pine, located between the Urals and Ob, are still poorly developed.

Dozens of large rivers of Western Siberia and hundreds of their tributaries serve as important shipping routes connecting the southern regions with the far north. The total length of navigable rivers exceeds 25 thousand. km. The length of the rivers along which timber rafting is approximately the same. The country's deep rivers (Yenisei, Ob, Irtysh, Tom, etc.) have large energy resources; if fully utilized, they could generate more than 200 billion. kWh electricity per year. The first large Novosibirsk hydroelectric power station on the Ob River with a capacity of 400 thousand. kW entered service in 1959; above it a reservoir with an area of ​​1070 km 2. In the future, it is planned to build hydroelectric power stations on the Yenisei (Osinovskaya, Igarskaya), in the upper reaches of the Ob (Kamenskaya, Baturinskaya), and on the Tomskaya (Tomskaya).

The waters of large Western Siberian rivers can also be used for irrigation and water supply of semi-desert and desert regions of Kazakhstan and Central Asia, which are already experiencing a significant lack of water resources. Currently, design organizations are developing the basic provisions and feasibility study for transferring part of the flow of Siberian rivers to the Aral Sea basin. According to preliminary studies, the implementation of the first stage of this project should ensure the annual transfer of 25 km 3 waters from Western Siberia to Central Asia. For this purpose, it is planned to create a large reservoir on the Irtysh, near Tobolsk. From it to the south along the Tobol valley and along the Turgai depression into the Syr Darya basin, the Ob-Caspian canal, more than 1500 long, will go to the reservoirs created there km. It is planned to lift water to the Tobol-Aral watershed by a system of powerful pumping stations.

At the next stages of the project, the volume of annually transferred water can be increased to 60-80 km 3. Since the waters of the Irtysh and Tobol will no longer be enough for this, the second stage of work involves the construction of dams and reservoirs on the upper Ob, and possibly on the Chulym and Yenisei.

Naturally, the withdrawal of tens of cubic kilometers of water from the Ob and Irtysh should affect the regime of these rivers in their middle and lower reaches, as well as changes in the landscapes of the territories adjacent to the projected reservoirs and transfer channels. Forecasting the nature of these changes now occupies a prominent place in the scientific research of Siberian geographers.

Until quite recently, many geologists, based on the idea of ​​the uniformity of the thick strata of loose sediments composing the plain and the seeming simplicity of its tectonic structure, very cautiously assessed the possibility of discovering any valuable minerals in its depths. However, geological and geophysical research carried out in recent decades, accompanied by the drilling of deep wells, showed the fallacy of previous ideas about the country's poverty in mineral resources and made it possible to imagine in a completely new way the prospects for the use of its mineral resources.

As a result of these studies, more than 120 oil fields have already been discovered in the Mesozoic (mainly Jurassic and Lower Cretaceous) deposits of the central regions of Western Siberia. The main oil-bearing areas are located in the Middle Ob region - in Nizhnevartovsk (including the Samotlor field, where oil can be produced up to 100-120 million tons). t/year), Surgut (Ust-Balyk, West Surgut, etc.) and South-Balyk (Mamontovskoe, Pravdinskoe, etc.) regions. In addition, there are deposits in the Shaim region, in the Ural part of the plain.

In recent years, the largest natural gas fields have also been discovered in the north of Western Siberia - in the lower reaches of the Ob, Taz and Yamal. The potential reserves of some of them (Urengoy, Medvezhye, Zapolyarny) amount to several trillion cubic meters; Gas production at each can reach 75-100 billion. m 3 per year. In general, the forecast gas reserves in the depths of Western Siberia are estimated at 40-50 trillion. m 3, including categories A+B+C 1 - more than 10 trillion. m 3 .

Oil and gas fields of Western Siberia

The discovery of both oil and gas fields is of great importance for the development of the economy of Western Siberia and neighboring economic regions. The Tyumen and Tomsk regions are turning into important areas of the oil production, oil refining and chemical industries. Already in 1975, more than 145 million were mined here. T oil and tens of billions of cubic meters of gas. To deliver oil to areas of consumption and processing, the Ust-Balyk - Omsk oil pipelines (965 km), Shaim - Tyumen (436 km), Samotlor - Ust-Balyk - Kurgan - Ufa - Almetyevsk, through which oil gained access to the European part of the USSR - to the places of its greatest consumption. For the same purpose, the Tyumen-Surgut railway and gas pipelines were built, through which natural gas from Western Siberian fields goes to the Urals, as well as to the central and northwestern regions of the European part of the Soviet Union. In the last five-year period, the construction of the giant Siberia-Moscow supergas pipeline was completed (its length is more than 3000 km), through which gas from the Medvezhye field is supplied to Moscow. In the future, gas from Western Siberia will go through pipelines to Western European countries.

Brown coal deposits also became known, confined to the Mesozoic and Neogene deposits of the marginal regions of the plain (North Sosvinsky, Yenisei-Chulym and Ob-Irtysh basins). Western Siberia also has colossal peat reserves. In its peatlands, the total area of ​​which exceeds 36.5 million. ha, concluded a little less than 90 billion. T air-dry peat. This is almost 60% of all peat resources of the USSR.

Geological research led to the discovery of the deposit and other minerals. In the southeast, in the Upper Cretaceous and Paleogene sandstones of the vicinity of Kolpashev and Bakchar, large deposits of oolitic iron ores were discovered. They lie relatively shallow (150-400 m), the iron content in them is up to 36-45%, and the predicted geological reserves of the West Siberian iron ore basin are estimated at 300-350 billion. T, including in the Bakcharskoye field alone - 40 billion. T. Hundreds of millions of tons of table salt and Glauber's salt, as well as tens of millions of tons of soda, are concentrated in numerous salt lakes in the south of Western Siberia. In addition, Western Siberia has enormous reserves of raw materials for the production of building materials (sand, clay, marls); Along its western and southern outskirts there are deposits of limestone, granite, and diabase.

Western Siberia is one of the most important economic and geographical regions of the USSR. About 14 million people live on its territory (the average population density is 5 people per 1 km 2) (1976). In cities and workers' settlements there are machine-building, oil refining and chemical plants, forestry, light and food industries. Various branches of agriculture are of great importance in the economy of Western Siberia. About 20% of the USSR's commercial grain, a significant amount of various industrial crops, and a lot of oil, meat and wool are produced here.

The decisions of the 25th Congress of the CPSU planned further gigantic growth of the economy of Western Siberia and a significant increase in its importance in the economy of our country. In the coming years, it is planned to create new energy bases within its borders based on the use of cheap coal deposits and hydropower resources of the Yenisei and Ob, to develop the oil and gas industry, and to create new centers of mechanical engineering and chemistry.

The main directions of development of the national economy plan to continue the formation of the West Siberian territorial-production complex, to transform Western Siberia into the main base of the USSR for oil and gas production. In 1980, 300-310 million will be mined here. T oil and up to 125-155 billion. m 3 natural gas (about 30% of gas production in our country).

It is planned to continue the construction of the Tomsk petrochemical complex, put into operation the first stage of the Achinsk oil refinery, expand the construction of the Tobolsk petrochemical complex, build oil gas processing plants, a system of powerful pipelines for transporting oil and gas from the northwestern regions of Western Siberia to the European part of the USSR and to oil refineries in the eastern regions of the country, as well as the Surgut-Nizhnevartovsk railway and begin construction of the Surgut-Urengoy railway. The tasks of the five-year plan provide for accelerating the exploration of oil, natural gas and condensate fields in the Middle Ob region and in the north of the Tyumen region. Wood harvesting and the production of grain and livestock products will also increase significantly. In the southern regions of the country, it is planned to carry out a number of large reclamation measures - to irrigate and water large tracts of land in Kulunda and the Irtysh region, to begin construction of the second stage of the Alei system and the Charysh group water supply system, and to build drainage systems in Baraba.

,

1. Geographical location.

2. Geological structure and relief.

3. Climate.

4. Inland waters.

5. Soil-vegetation cover and fauna.

6. Natural areas.

Geographical position

The border of the West Siberian Plain is clearly expressed in relief. Its border in the West is the Ural Mountains, in the East the Yenisei Ridge and the Central Siberian Plateau. In the north, the plain is washed by the waters of the Kara Sea, the southern edge of the plain enters the territory of Kazakhstan, and the southeastern edge borders on Altai. The area of ​​the plain is about 3 million km2. the length from north to south is almost 2500 km, from west to east 1500-1900 km. The southern part of the plain is the most developed by man, its nature has been changed to some extent. The northern and central parts of the plain began to be developed in the last 30-50 years in connection with the development of oil and gas.

Geological structure and relief

The geological structure of the plain is determined by its position on the Paleozoic West Siberian plate. The foundation of the slab is a huge depression with steep sides. It consists of the Baikal, Caledonian and Hercynian blocks, broken by deep faults. In the north, the foundation lies to a depth of 8-12 km. (Yamalo-Taz syneclise), in the middle part the depth is 3-4 km. (Middle Ob anteclise), to the south the depth decreases. The plate cover is represented by Mesozoic and Cenozoic sediments of continental and marine origin.

The territory of the West Siberian Plate has repeatedly undergone transgressions. The glaciation of Western Siberia was repeated several times: Demyansk, Samarovsk, Tazovsk, Zyryansk and Sartan. Glaciers moved from 2 centers: from the Polar Urals and the Putorana plateau. Unlike the Russian Plain, where meltwater flowed to the south, in Western Siberia, which has a general slope to the north, these waters accumulated at the edge of the glacier, forming periglacial reservoirs. In areas free of ice, deep soil freezing occurred.

The modern relief of the plain is due to geological structure and the influence of exogenous processes. The main orographic elements correspond to the tectonic structures of the plate, although the accumulation of Meso-Cenozoic strata compensated for the irregularities of the basement. The absolute heights of the plain are 100-150 meters, with hills and lowlands alternating within the plain. The general slope of the plain is to the north. Almost the entire northern half of the plain is less than 100 meters high. The marginal parts of the plain are elevated to 200-300 meters. These are the North Sosvinskaya, Verkhnetazovskaya, Lower Yisei uplands, the Priobskoye plateau, the Ishimskaya and Kulundinskaya plains. The strip of Siberian Uvals is clearly expressed in the middle part of the plain, stretching from the Urals to the Yenisei near 63˚N, their average height is 100-150 meters. The lowest areas (50-100 m) are located in the northern parts of Western Siberia. These are the Lower Ob, Nadym, Pur, Taz, Kondinsk, and Middle Ob lowlands. Western Siberia is characterized by: marine accumulative plains (on the Yamal and Gydan peninsulas), glacial and aquaglacial plains with moraine hills, ridges, etc. (central part of Western Siberia), alluvial-lacustrine plains (valleys of large rivers), denudation plains (southern part of Western Siberia).

Climate

The climate of Western Siberia is continental, arctic and subarctic in the north and temperate in the rest of the territory. It is more severe than on the Russian Plain, but softer than in Eastern Siberia. Continentality increases to the southeast of the plain. Radiation balance from 15 to 40 kcal/cm2 per year. At the same time, compared to the Russian Plain, Western Siberia receives slightly more solar radiation due to the lower frequency of cyclones. The western transport remains, but the influence of the Atlantic is noticeably weakened here. The flatness of the territory promotes deep meridian air exchange. In winter, the climate is formed under the influence of the spur of the Asian High, which stretches across the south of the plain and troughs of low pressure over the northern peninsulas. This contributes to the transport of cold continental air from the Asian High to the plain. Winds predominate from the south. In general, January isotherms are submeridian in nature, from -18˚-20˚С in the west to almost -30˚С in the Yenisei valley. The absolute minimum in Western Siberia is -55˚С. Snowstorms are common in winter. During the cold season, 20-30% of precipitation falls. Snow cover sets in in the north in September, in the south in November and lasts from 9 months in the north to 5 months in the south. The thickness of the snow cover in the forest zone is 50-60 cm, in the tundra and steppe 40-30 cm. In summer over Western Siberia, the pressure gradually decreases to the southeast. Winds prevail in a northerly direction. At the same time, the role of Western transfer is increasing. July isotherms take latitudinal directions. In the north of Yamal the average July temperature is +4˚С, near the Arctic Circle +14˚С, in the south of the plain +22˚С. Absolute maximum +45˚С (extreme south). The warm period accounts for 70-80% of precipitation, especially in July-August. Droughts are possible in the south. The greatest amount of precipitation per year (550-600 mm) falls in the middle reaches of the Ob from the Urals to the Yenisei. To the north and south the amount of precipitation decreases to 350 mm. The climate of Western Siberia largely contributes to the maintenance of permafrost. The northern and central parts of Siberia (more than 80% of its area) have a moisture coefficient greater than 1 (excessive moisture). Such conditions lead to the development of swamping in the area. In the south the coefficient is less than 1 (insufficient moisture).

Inland waters

Western Siberia is characterized by a huge accumulation of inland waters. Several thousand rivers flow on the plain, most of which belong to the Ob basin and, accordingly, the Kara Sea. Few rivers (Taz, Pur, Nadym, etc.) flow directly into the Kara Sea. In the south of the plain there are areas of internal (closed) drainage. All rivers of Western Siberia are characterized by low slopes, with a predominance of lateral erosion. The rivers are fed mixed, with a predominance of snow, in addition there is rain and swamp-soil. Flood occurs from April in the south to June in the north. The maximum water rise reaches 12 meters on the Ob, and 18 meters on the Yenisei. A prolonged flood is typical, despite the “friendly” spring. The rise is fast, and the fall of the water is very slow. Freeze-up lasts up to 5 months in the south and up to 8 months in the north. Ice jams are typical. The largest rivers are the Ob and Yenisei. The length of the Ob from the source of the Irtysh is 5410 km, and the basin area is 3 million km2. If we count the Ob from the confluence of the Biya and Katun rivers, then its length is 3650 km. In terms of water content, the Ob is second only to the Yenisei and Lena. The Ob flows into the Ob Bay (estuary). The largest tributary is the Irtysh, and its tributaries are the Ishim, Tobol, and Konda. The Ob also has tributaries - Chulym, Ket, Vasyugan, etc. The Yenisei is the most abundant river in Russia, its length is 4092 km, the basin area is 2.5 million km2. Only a small left-bank part of the basin lies on the territory of Western Siberia. There are about 1 million lakes on the plain. The lake content varies from 1% in the south to 3% in the north. In the Surgut lowland it reaches 20%. In the south the lakes are brackish. The largest lake is Chany. It is drainless and salty. The maximum depth is 10 m. Swamps occupy about 30% of the territory of Western Siberia. In some places in the forest zone the swampiness reaches 80% (forest-swamp zone). The development of swamps is facilitated by: flat terrain, poor drainage, excessive moisture, prolonged floods and permafrost. The swamps are rich in peat. According to hydrogeological conditions, the plain is a West Siberian artesian basin.

Land cover and fauna

The soils are located as follows from north to south: tundra-gley, podzolic, sod-podzolic, chernozem and chestnut. At the same time, large areas are occupied by semi-hydromorphic soils due to swampiness. Therefore, most soils, unlike their analogues on the Russian Plain, have signs of gleyization. In the south there are solonetzes and solods. The vegetation of Western Siberia is to some extent similar to the vegetation of the Russian Plain, but there are differences that are associated with the wide distribution of swamps, the severity of the climate and the characteristics of the flora. Along with spruce and pine forests, fir, cedar and larch forests are widespread. The forest-tundra is dominated by larch, and not spruce, as on the Russian Plain. Small-leaved forests here are not only secondary, but also primary. Mixed forests here are represented by pine and birch. Large areas in Western Siberia are occupied by floodplain vegetation (more than 4% of the plain), as well as swamp vegetation. The fauna has many similarities with the Russian Plain. In western Siberia there are about 500 species of vertebrates, of which 80 species are mammals, 350 species of birds, 7 species of amphibians and about 60 species of fish. There is a certain zonality in the distribution of animals, but forest animals penetrate far to the north and south along the ribbon forests along the rivers, and inhabitants of polar reservoirs are found on the lakes of the steppe zone.

Natural areas

Natural zones on the plain extend latitudinally. Zoning is clearly expressed. Zones and subzones change gradually from north to south: tundra, forest-tundra, forests (forest-swamps), forest-steppe, steppe. Unlike the Russian Plain, there is no zone of mixed and deciduous forests, zones of semi-deserts and deserts. The tundra extends from the coast of the Kara Sea and almost to the Arctic Circle. The length from north to south is 500-600 km. Polar day and night last here for almost three months. Winter is from October to mid-May. Average temperatures range from -20˚C in the west to -30˚C in the east. Winds and snowstorms are typical. Snow cover lasts for about 9 months. Summer lasts not much more than one month. The average temperature in August is +5˚C, +10˚C (but sometimes the air can warm up to +25˚C). Precipitation per year is 200-300 mm, but most of it falls in the warm period. Permafrost is widespread everywhere, so the tundra is characterized by solifluction processes, thermokarst, polygons, peat mounds, etc. There are many swamps and lakes. The soils are tundra-gley. The flora is not rich, only about 300 species of higher plants. Vegetation is especially sparse on the sea coast, where arctic lichen tundras from cladonia and others are developed. To the south, mosses begin to predominate and flowering plants appear - cotton grass, partridge grass, arctic bluegrass, and a number of sedges, etc. In the south of the zone, the tundra becomes shrubby, where along with mosses and dwarf birches, willows, and alders grow with lichens; in some places on the southern slopes and river valleys - buttercups, wisps, crowberry, arctic poppy, etc. Animals include reindeer, wolves, arctic foxes, lemmings, voles, ptarmigan, snowy owls; many marsh and waterfowl (waders, ducks, geese, etc.).

The forest-tundra stretches in a relatively narrow strip (50-200 km), expanding from the Urals to the Yenisei. It lies along the Arctic Circle and descends further south than on the Russian Plain. The climate is subarctic and more continental than in the tundra. And although winter here is somewhat shorter, it is more severe. The average temperature in January is -25-30˚C, the absolute minimum is up to -60˚C. Summers are warmer and longer than in the tundra. The average July temperature is +12˚C+14˚C. Permafrost is widespread. Therefore, the frozen topography again predominates, and erosion processes are limited. The zone is crossed by many rivers. The soils are gley-podzolic and permafrost-taiga. The tundra vegetation here is supplemented by sparse larch forests (their height is 6-8 meters). Dwarf birch is widespread, there are many swamps, and there are floodplain meadows in the river valleys. The fauna is richer than in the tundra; along with representatives of the tundra fauna, there are also inhabitants of the taiga.

Forests (taiga) occupy the largest area of ​​Western Siberia. The length of this zone from north to south is 1100-1200 km, almost from the Arctic Circle to 56°N. on South. There is an almost equal proportion of forests on podzolic soils of the taiga and peat-bog soils of sphagnum bogs. Therefore, the taiga of Western Siberia is often called the forest-swamp zone. The climate is temperate continental. Continentality increases from west to east. The average January temperature ranges from -18˚C in the southwest to -28˚C in the northeast. In winter, anticyclonic weather prevails. Cyclones often pass through the north of the taiga zone. The thickness of the snow cover is 60-100 cm. Summer is relatively long, the growing season is from 3 months. in the north up to 5 months. on South. The average July temperature ranges from +14˚C in the north to +19˚C in the south. More than half of all precipitation falls in summer. The moisture coefficient is everywhere greater than 1. Permafrost is widespread in the north of the zone. Lots of swamps and rivers. The swamps are of various types, but ridge-hollow peatlands predominate, there are ridge-lake peats and swamps. Swamps are confined to the lowest places with stagnant moisture. On the hills, ridges of interfluves, on the terraces of river valleys, coniferous forests of spruce, fir, and cedar grow. In some places there are pine, larch, birch, and aspen. To the south of the taiga, 50-200 km wide, stretches a strip of small-leaved forests of birch and, to a lesser extent, aspen, on soddy-podzolic soils. The fauna is represented by Siberian species, but there are also “Europeans” (marten, European mink, otter). The most typical are brown bear, wolverine, lynx, sable, chipmunk, squirrel, fox, wolf, water rat, elk, many birds whose life is associated with coniferous forests (nutcracker, bee-eater, kuksha, wood grouse, woodpeckers, owls, etc.) , but there are few songbirds (hence the name “deaf taiga”).

The forest-steppe stretches in a narrow strip (150-300 km) from the Urals to the Salair Ridge and Altai. The climate is temperate continental, with harsh winters with little snow and hot, dry summers. The average temperature in January is -17˚C-20˚C, and in July +18˚C+20˚C, (maximum +41˚C). Snow cover is 30-40 cm, annual precipitation is 400-450 mm. The moisture coefficient is less than 1. Suffusion processes are characteristic; there are lakes, some of which are saline. The forest-steppe is a combination of aspen-birch coppices on gray forest soils and areas of meadow steppes on chernozems. The forest cover of the zone ranges from 25% in the north to 5% in the south. The steppes are mostly plowed. The fauna is represented by forest and steppe species. In the steppes and floodplain meadows, rodents predominate - gophers, hamsters, ground hare, voles, and there is a brown hare. In the groves there are foxes, wolves, weasels, ermine, polecats, white hare, roe deer, black grouse, partridges, and in the ponds there are a lot of fish.

The steppe zone occupies the extreme south of Western Siberia. Unlike the steppes of the Russian Plain, there are more lakes here and the climate is more continental (little rainfall, cold winters). The average temperature in January is -17˚C-19˚C, and in July +20˚C+22˚C. Annual precipitation is 350-400 mm, with 75% of precipitation falling in summer. The humidification coefficient ranges from 0.7 in the north to 0.5 in the south of the zone. In summer there are droughts and dry winds, which lead to dust storms. The rivers are transit, small rivers dry up in summer. There are many lakes, mostly of suffusion origin, almost all salty. The soils are chernozem, in the south dark chestnut. There are salt marshes. The plowed state of the steppes reaches 90%. In the remaining areas of the steppes, various feather grasses, fescue, thyme, zopnik, wormwood, iris, steppe onion, tulip, etc. grow. In saline areas, saltwort, licorice, sweet clover, wormwood, chiya, etc. grow. In wetter places there are caragana shrubs , spirea, rose hips, honeysuckle, etc., along the river valleys to the south there are pine forests. In the floodplains of rivers there are swampy meadows. The fauna is represented by various rodents (ground squirrel, hamster, marmots, voles, pikas, etc.), among predators are the steppe ferret, corsac fox, wolf, weasel, among birds - the steppe eagle, buzzard, kestrel, larks; on the lakes there are waterfowl. In Western Siberia, 4 nature reserves have been created: Malaya Sosva, Yugansky, Verkhne-Tazovsky, Gydansky.

Features of the geographical location of Western Siberia

Note 1

To the east of the Ural Mountains lie vast expanses of the Asian part of Russia. This territory has long been called Siberia. But due to the diversity of the tectonic structure, this territory was divided into several separate regions. One of them is Western Siberia.

The basis of Western Siberia is the West Siberian Plain. It is bounded in the west by the Ural Mountains, and in the east by the Yenisei River. In the north, the plain is washed by the waters of the Arctic Ocean. The southern borders approach the Kazakh small hills and the Turgai plateau. The total area of ​​the plain is about $3$ million km²$.

The characteristic features of the West Siberian Plain are the following:

• slight fluctuations in altitude over such a vast area;
• the extension from north to south and the almost flat topography determined a clear change in natural zones with latitude (classical latitudinal zoning);
• formation largest areas swamps in the taiga and landscapes of salt accumulation in the steppe zone;
• A transitional climate is formed from the temperate continental Russian Plain to the sharply continental Central Siberia.

History of the formation of the plain

The West Siberian Lowland lies on the Upper Paleozoic plate. Sometimes this tectonic structure is also called epihercynian. The crystalline slab foundation contains metamorphosed rocks. The foundation sinks towards the center of the slab. The total thickness of the sedimentary cover exceeds $4$ km (in some areas – up to $6-7$ km).

As already mentioned, the foundation of the plate was formed as a result of the Hercynian orogeny. Next, peneplanation (leveling of the relief through erosion processes) of the ancient mountainous country occurred. In the Paleozoic and Mesozoic, troughs formed in the center, and the foundation was flooded by the sea. Therefore, it is covered with a significant thickness of Mesozoic sediments.

Later, during the Caledonian folding era, the southeastern part of the plain rose from the bottom of the sea. In the Triassic and Jurassic, the processes of relief denudation and the formation of sedimentary rocks prevailed. Sedimentation continued into the Cenozoic. During the Ice Age, the north of the plain was under a thick glacier. After its melting, a significant area of ​​Western Siberia was covered with moraine deposits.

Characteristics of the relief of Western Siberia

As already noted, geological history determined the formation of flat relief on the territory of the West Siberian Plain. But a more detailed study of the physical and geographical features of the region showed that the orography of the territory is complex and diverse.

The major relief elements on the plain are:

• lowlands;
• sloping plains;
• hills;
• plateau.

In general, the West Siberian Plain has the shape of an amphitheater, open to the Arctic Ocean. Plateau and upland areas predominate in the western, southern and eastern periphery. In the central regions and in the north, lowlands predominate. The lowlands are represented by:

• Kandinskaya;
• Nizhneobskaya;
• Nadymskaya;
• Purskoy.

Among the plateaus, the Priobskoye Plateau stands out. And the hills are represented by:

• Severo-Sosvinskaya;
• Turinskaya;
• Ishimskaya;
• Chulymo-Yeniseiskaya and others.

The relief includes zones of glacial-marine and permafrost-solifluction processes (tundra and northern taiga), fluvioglacial forms of glaciolacustrine plains (up to the middle taiga) and a zone of semiarid structural-denudation plateaus with erosion processes.

Note 2

Currently, human economic activity plays an important relief-forming role. The development of Western Siberia is accompanied by the development of mineral resources. This causes changes in the structure of rock layers and changes the course of physical and geographical processes. Erosion processes are intensifying. In the south, during the development of agriculture, large amounts of minerals are introduced into the soil. Chemical erosion develops. It is necessary to carefully approach the issues of developing the nature of Siberia.

The West Siberian Lowland is a single physical-geographical region consisting of two flat bowl-shaped depressions, between which lie latitudinally elongated elevations (up to 175-200 m), united orographically into the Siberian ridges.

The lowland is delineated by natural boundaries on almost all sides. In the west it is clearly delimited by the eastern slopes of the Ural Mountains, in the north by the Kara Sea, in the east by the valley of the Yenisei River and the cliffs of the Central Siberian Plateau. Only in the south is the natural boundary less pronounced. Gradually rising, the plain here passes into the adjacent hills of the Turgai plateau and the Kazakh hillocks.

The West Siberian Lowland occupies about 2.25 million km 2 and has a length from north to south of 2500 km, and from east to west (in the southern widest part) 1500 km. The exceptionally flat relief of this territory is explained by the leveling of the complex folded foundation of the West Siberian Platform with a thick cover of Meso-Cenozoic sediments. During the Holocene, the territory experienced repeated subsidence and was an area of ​​accumulation of loose alluvial, lacustrine, and in the north - glacial and marine sediments, the thickness of which in the northern and central regions reaches 200-250 m. However, in the south the thickness of Quaternary sediments drops to 5-10 m and the modern relief clearly shows signs of the impact of neotectonic movements.

The peculiarity of the paleogeographical situation lies in the strong watering of the territory inherited from the Holocene and the presence at present of a huge number of residual reservoirs.

Large modern landforms of Western Siberia are morphostructures created by recent movements of the earth's crust. Positive morphostructures: hills, plateaus, ridges - have a more dissected topography and better drainage. Negative morphostructures are dominant for the relief of the territory - plains covered with a thickness of loose layered sediments, often gleyed to great depths. These properties impair the water permeability of the strata and inhibit groundwater flow.

The flatness of the territory determined the special nature of the hydrographic network: low water flow rates and significant tortuosity of the riverbeds. The rivers of Western Siberia have a mixed supply - snow, rain, ground, with a predominance of the first. All rivers are characterized by long spring floods, often turning into summer ones, which is explained by different times of river opening in various parts watersheds. Flood waters, spreading for many kilometers, are important factor extremely high watershed watersheds, and rivers practically do not play their drainage role during this period.

Thus, the combination of physical and geographical factors that favorably influence the swamp formation process determined the intensity of the formation and accumulation of huge reserves of peat and the widespread distribution of peat deposits throughout the West Siberian Plain.

Vegetation cover of peat deposits West Siberian Lowland has not been studied in sufficient detail. The tree layer of forested peatlands here is much richer in species composition due to species characteristic of the taiga forests of Siberia, such as cedar, fir, and larch. Usually they, together with birch, spruce, and pine, form the forest stand of swamps in various combinations and quantities. Almost pure stands of birch on peat bogs are quite common and, under appropriate conditions, are found in all peat-bog areas of the West Siberian Lowland. Pure thickets of willow are noted on the lowland peat bogs of the floodplains.

In the shrub layer of the vegetation cover of Western Siberian swamps, such a representative of the Siberian flora as Salix sibirica is found, but the European species Calluna vulgaris is not reflected in it. Representatives of the Siberian flora were also noted in the herbaceous layer: Carex wiluica, Cacalia hastata, Ligularia sibirica. Carex globularis, found in the European part of the Union as part of the vegetation of swampy spruce forests, has expanded its habitat in Western Siberia and is found in large numbers on typical high-moor peat bogs. Sph. rubellum and Sph. cuspi datum - typical inhabitants of high peat bogs in the northwestern region of the European part of the Union - are rarely found in the moss cover of peat bogs of the West Siberian Lowland. But in much greater quantities and in more southern latitudes, Sph are distributed here in the moss cover of swamps. lindbergii and Sph. congstroemii, which are typical for peat bogs in the Arkhangelsk region and are rare in peat bogs in the middle zone. Sometimes, in the ridge-lake areas of the Vasyugan watershed peatlands, Cladonia and Cetraria form continuous patches, and up to 12 species of Cladonia are found in this regenerative complex.

Of the plant phytocenoses of the West Siberian Lowland, it is necessary to note the grass-sedge plant, which covers significant areas in the edge areas of the fields (in conditions of some soil salinity). It includes reed grass (Scolochloa festucacea), reed grass (Calamagrostis neglecta), Carex omskiana, C. appropinquata and C. orthostachys. Peat bogs are characterized by birch (up to 15-20 m in height) and conifers: spruce, cedar, pine, larch; in the undergrowth, along with willows (Salix sibirica, S. pentandra), black currant, rowan, bird cherry; in the shrub layer - bog myrtle, lingonberry, blueberry, cloudberry. The grass stand is rich in species and develops luxuriantly; it is dominated by C. caespitosa, other sedges include C. globularis, C. disperma, and taiga plants (Equisetum silvaticum, Casalia hastata, Pyrola rolundifolia) also grow in the forbs along with marsh plants. Elements of taiga flora are also observed in the moss cover: on hummocks Sph. warnstorfii - Pleuroziumschreberi and Hylocomium splendens, in inter-tussock depressions - Thuidium recognitum, Helodium blandowii, on the slopes of hummocks - Climacium dendroides. In the depressions between hummocks in Sogras one can often observe efflorescence of iron.

Most often, sogras cover the edge areas of low-lying marshy swamps of terraces above the floodplain along the channels of the Ob, Irtysh, Chulym, Keti, and Tym rivers. From the outside they gradually turn into swampy forests, towards the center of the peat bog - into a forest complex phytocenosis.

In the West Siberian Plain, borrowings predominate in the Ishim peat-bog region between the Ishim and Tobol rivers in their middle reaches. Here they adjoin the lakes or surround them in a continuous ring. Huge areas are sometimes occupied by land in lowlands that are no longer connected with lakes, but bear the features of former channels between lakes.

Zaimishchno-ryam peatlands are often found in the eastern part of the South Barabinsk peat-bog region, where they are confined to lakes or flat depressions in which surface water stagnates for a long time. Among the fields there are scattered raised convex peat bogs, which occupy a small area compared to the fields. These are the well-known “ryams”. During the growing season, a variable water-mineral regime is created in the fields: in the spring and in the first half of summer they are flooded with fresh deluvial melt water, and often with river hollow water; in the second half of the growing season, the fields dry out over a large peripheral area, and here favorable conditions arise for the capillary rise of saline soil-groundwater to the surface and efflorescence of salts (Ca, Cl and SO 3) is usually observed on the surface.

The borrowing area can be divided into: zone of constant moisture relative to fresh waters(the central part of the borrowings, the shores of lakes and river channels) and a zone of variable moisture, where both the degree of water content and the degree of mineralization of the feeding waters are variable (peripheral parts of the borrowings).

The central parts of the fields are covered with reed phytocenosis, in which the main background plants are reed, reed (Scolochloa festucacea), reed grass, sedge (C. caespitosa and C. wiluica). The phytocenosis includes Carex omskiana, C. buxbaumii, watchwort, and bedstraw (Galium uliginosum) as admixtures. Among the components of the reed phytocenosis, reed, reed grass, Carex caespitosa and C. buxbaumii are salt-tolerant plants.

In the zone of borrowings where constant moisture begins to give way to variable moisture, under conditions of some salinization of the substrate, a gradual thinning of reed thickets and the introduction of sedges (C. diandra, C. pseudocyperus), cattail and reed grass are observed. The sedge-reed phytocenosis is characterized by isolated scattered bushes of birch (B. pubescens) and willow (S. cinerea).

Along the periphery of the fields in the zone of variable moisture, reed grass (Scolochloa, festucacea), which in the conditions of Baraba is an indicator of mixed chloride-sulfate salinity, displaces reed grass from the plant cover, and here a grass-sedge phytocenosis arises mainly from reed grass, Carex omskiana, C. appropinquata and C. orthostachys with a small participation of the same reed grass.

The formation and development of ryams (oligotrophic pine-shrub-sphagnum islands) occurs in isolation from saline soils in both horizontal and vertical directions. Insulation in the horizontal direction is a deposit of loans; insulation in the vertical direction is a layer of reed peat with an average degree of decomposition of 22-23%, underlying the upper ryam deposit. The thickness of the reed peat is 0.5-1.5 m, the thickness of the upper deposit is 0.5-1 m. The upper deposit is composed of weakly decomposed fuscum peat with a degree of decomposition of 5-20%. The stump content of the sphagnum deposit is low and falls from the upper layers to the lower ones.

The surface of the ryam is sharply convex with asymmetrical slopes. Under the tree layer of pine, a shrub layer and a moss cover of Sph are developed. fuscum with impurities Sph. angustifolium and Sph. magellanicum.

The largest ryams up to 1000-1500 hectares (Bolshoy Ubinsky and Nuskovsky) are found in the northern and middle parts of the forest-steppe zone. Usually the area of ​​ryams is 100-400 hectares, sometimes 4-5 hectares (small ryams of the Chulym region).

Peat deposits in Western Siberia are extremely diverse in terms of the conditions of formation and development, qualitative and quantitative indicators of the deposit, vegetation cover, distribution patterns and other factors, the changes of which can be traced to a fairly clear pattern, closely related to natural latitudinal zoning. According to this principle, 15 peat-bog areas have been identified in Western Siberia.

The far north of the West Siberian Lowland occupies area of ​​arctic mineral sedge bogs. It geographically corresponds to the West Siberian subzone of the Arctic tundra. The total swampiness of this territory is almost 50%, which is a consequence of the waterproof frozen layer located close to the surface, the excess of precipitation over evaporation and the flatness of the country. The thickness of the peat layer does not exceed several centimeters. Peatlands with deep deposits should be classified as relics of the Holocene climatic optimum. Polygonal and flat moss-sedge bogs are common here.

The wide distribution of eutrophic moss-sedge bogs with a flat surface (up to 20-25% of the total area) is noteworthy. Carex stans or Eriophorum angustifolium dominate here, with a moss carpet of Calliergon sarmentosum and Drepanocladus revolvens.

In river valleys among sedge bogs there are mounds covered with Sph. warnstorfii, Sph. lenense, Dicranum elongatum and lichens. Flowering plants include abundant thickets of Betula nana and Rubus chamaemorus.

Along the shores of the bays and the Kara Sea there are coastal swamps, which are flooded with sea water during strong winds. These are largely brackish marshes with grasses (Dupontia fisonera), sedges (Carex rariflora, etc.) and Stellaria humifusa.

Mossy tundras are especially characterized by the abundance of Eriophorum angustifolium on the moss cover of Aulacomnium turgidium, Camptothecium trichoides, Aulacomnium proliferum, Dicranum elongatum, and Ptilium ciliare. Sometimes the swampy tundra is dominated by sedges (Carex stans, Carex rotundata) with a similar composition of the moss cover and the participation of sphagnum mosses.

Located further south area of ​​flat-hilly bogs. This zone geographically corresponds to the tundra. The swampiness of the zone is high (about 50%).

Flat-hilly peatlands represent a mosaic complex of hillocks and hollows. The height of the mounds ranges from 30 to 50 cm, rarely reaching 70 cm. The area of ​​the mounds is up to several tens, less often hundreds of square meters. The shape of the mounds is lobed, round, oval, elongated or ridge-like; the tops of the mounds are occupied by lichens, mainly Cladonia milis and Cladonia rangiferina. Cetraria nivalis, C. cucullata, Cladonia amanrocraea are less common. The slopes of the hillocks are covered with green mosses. Aulacomnium turgidium, Polytrichum strictum, Dicranum elongatum are abundant. Among the flowering plants, the strongly oppressed Ledum palustre and Rubus chamaemorus grow in clusters. Between them are fragments of dicrane-lichen associations. The hollows are heavily watered with a continuous carpet of sphagnum mosses from Sph. lindbergii, Sph. balticum, Sph. subsecundum, Sph. Jensenii. Drepanocladus vernicosus is less common in hollows, Drepanocladus fluitans is common, Carex rotundata is common, Carex chordorrhiza is less common, Cephalozia fluitans sometimes grows. Along with swamps, wetlands are widespread, which are swampy shrub tundras with Betula papa and willows, sometimes with Ledum palustre, swampy moss tundras with Betula papa and Ledum palustre, hummocky tundras with Eriophorum vaginatum.

Area of ​​hummocky bogs occupies the northern part of the forest zone and the southern forest-tundra. The swampiness of the area is high. The mounds are found singly, but more often they are located in groups or ridges 1-2 km long, up to 200 m wide. Single mounds have a height of 2-2.5 m, soil mounds 3-5 m, ridge mounds reach a height of 8-10 m. Diameter the bases of the mounds are 30-80 m, the slopes are steep (10-20°). Inter-hill depressions are elongated, occupied by cotton grass-sphagnum and sedge-sphagnum oligotrophic or eutrophic hollows, sometimes with small lakes in the center. The surface of the largest mounds is broken by cracks up to 0.2-0.3 m deep. At the base of the mounds, sphagnum mosses grow and a layer of shrubs, mainly Betula papa, is developed. Higher up the slope, lichens predominate. They are also typical for flat peaks, often subject to wind erosion.

The hummocky peatlands are topped with peat up to 0.6 m thick, under which lies a highly ice-saturated mineral core consisting of ice and loamy, silty-loamy, less often sandy loam material. The mineral core, in addition to ice-cement and its individual crystals, contains numerous ice layers, the thickness of which reaches several tens of centimeters and usually increases downwards, the number of layers also decreases downwards.

North Ob peat-bog region It is a poorly drained lacustrine-alluvial plain composed of medium- and fine-grained sands with clearly defined horizontal layering.

The area is characterized by extremely high swampiness. Peat deposits occupy more than 80% of the territory; form complex systems, covering flat interfluves and high river terraces. Dominated by raised convex, heavily watered sphagnum peatlands with ridge-lake complexes on the flat tops and ridge-lake-hollow complexes on their slopes.

Areas with well-drained areas of peat bogs are insignificant and are confined to the territory with the highest surface elevations. Fuscum and pine-sphagnum phytocenoses with a large number of different lichens are widespread here.

Lowland peat deposits are located mainly on the first terraces above the floodplain of large rivers.

Deposits of high peat bogs are shallow, on average about 2 m. poorly decomposed fuscum, complex, and hollow types of structure predominate.

Kondinskaya peat-bog region It is a vast alluvial and lacustrine-alluvial plain composed of layered sandy and clayey deposits. For the left bank of the river. Konda and the right bank of its lower reaches are characterized by the presence of rugged topography. The region is characterized by extremely high water content. A significant part of the Kondinsk region is confined to an area of ​​intense tectonic subsidence and is therefore characterized by the predominance of accumulation processes and the dominance of poorly drained swamps. Only the western part of the region, where denudation processes predominate, is characterized by low swampiness. The river beds are weakly incised. In the spring, the hollow waters of these rivers overflow widely and do not enter the banks for a long time. Therefore, river valleys are swamped over a large area; Near-terrace swamps are heavily flooded during high water. For the river basin Konda is characterized by the predominance of upland ridge-lake, ridge-lake-hollow and ridge-hollow peat deposits.

Lowland, sedge, reed, reed, birch-reed peat bogs are confined to river beds.

Transitional sedge-sphagnum, woody-sphagnum and sphagnum bogs are found on low terraces and in places where they join into bog systems. There are also complexes formed along the lines of surface intra-fallow flow of swamp waters.

The gradual tectonic subsidence of the surface affects the extremely high water content of the territory, which contributes to the intensive development of regressive phenomena in the swamps, the destruction of the sphagnum turf of ridges, hollows, an increase in the area of ​​hollows due to the degradation of ridges, etc.

Among the swamps there are a huge number of lakes. Some of them are completely peaty, but most have retained an open surface of water among peaty banks.

In the river basin Kondy, the main type of peat deposit is raised, in which a complex type of structure predominates, which is due to the dominance of ridge-hollow complexes. Fuscum, Scheuchzeria-sphagnum and Magellanicum deposits are somewhat less common.

Transitional types of deposits make up peat bogs mainly on the second terrace of the river. Konda and its tributaries, and are also found along the edges of high-moor peat deposits, around mineral islands, or are confined to mesotrophic grass and moss swamps. The most common type of deposit is transitional swamp.

Low-lying deposits are found in river floodplains, forming narrow strips confined to overgrown rivers of high-moor swamps.

Analysis of spore-pollen diagrams dates the Kondin peatlands to the early Holocene. Peat bogs are of ancient Holocene age, the depth of which exceeds 6 m.

Middle Ob peat-bog region It is a lacustrine-alluvial and alluvial plain, composed on the surface mainly of cover deposits, underlying either lacustrine layered clays, or light loams, siltstone and sandy strata.

The territory is characterized by the development of progressive and predominant accumulation processes, which determines the predominant distribution of poorly drained swamps and constantly swampy forests. Only in the north of the region, where denudation processes predominate, are relatively drainable swamps found.

The region is characterized by the dominance of raised sphagnum bogs with ridge-lake-hollow and ridge-hollow complexes. The edges of swamps located at lower hypsometric levels (within the first floodplain terraces and floodplains of small lakes) are usually eutrophic or mesotrophic. The deposit of their central parts is represented by fuscum and complex types of structure and has a depth of 4-6 m.

Large peatlands on first-order watersheds are divided into three categories. On flat, level plateaus of watersheds, peatlands have a strongly convex surface with steep slopes and flat central part. The difference in the levels of the center and edges is 4-6 m. The central main part of such peat bogs is represented by a fuscum deposit or a complex raised peat and bears lake-denudation or ridge-lake vegetation complexes on the surface, and ridge-hollow vegetation on the slopes.

On one-sidedly elevated watersheds with a gently concave asymmetrical surface, raised peat bogs give a drop in surface elevations from an elevated slope to a lower one.

The thickness of the peat layer also decreases in the same direction. The deepest part of such peatlands is usually represented by a fuscum type of structure with a ridge-lacustrine complex of vegetation on the surface. In the direction to the opposite slope of the watershed, the fallow becomes a complex upland with a ridge-hollow complex in the vegetation cover. The shallow peripheral area with a transitional swamp deposit bears the vegetation of sphagnum swamps on the surface.

On symmetrical watersheds with a flat plateau, sometimes raised peat bogs with a complex surface line are observed: two evenly raised caps are separated by a trough up to 2-3 m deep. Such peat bogs are composed mainly of raised fuscum or complex peats. On the gangs, the vegetation cover is represented by a ridge-lake complex, in the trough area - by sphagnum swamps, often giving rise to rivers. A. Ya. Bronzov explains the formation of such massifs by the mergers of two (sometimes several) peat bogs with separate pockets of swamping. In some cases, the formation of a deflection could occur during the breakthrough and outpouring of internal waters and partly the most liquefied and plastic peats from the peat bog, followed by subsidence of the peat deposit.

On second-order watersheds, peatlands occupy interfluves that have undergone significant dissection. The depth of the erosion incision here reaches 20-30 m. This is the nature of the watersheds between large rivers flowing approximately parallel to each other in their middle reaches.

In upland conditions, large peat deposits of the raised type with a predominance of fuscum deposits and with ridge-lake and ridge-hollow vegetation complexes on the surface are located on the watersheds of occurrence.

Basically, the Middle Ob region, as well as the Vasyugan region located to the south, are territories of almost continuous swamps. Swamps here completely cover watersheds of the first and second orders, terraces and river floodplains. Peatlands predominate, the total area of ​​which is about 90%.

Tym-Vakh peat-bog region occupies the Tym-Vakh interfluve and is composed of lacustrine-alluvial deposits. Geographically, it is confined to the Middle Vakh Plain and is characterized by high swampiness, which drops sharply in the northeastern part, where surface elevations reach 140 m.

Poorly drained raised sphagnum bogs with ridge-hollow-lake and ridge-hollow complexes dominate the watersheds and fourth terraces. They are also found on low terraces and are confined to the hollows of ancient drainage, where accumulation processes dominate. The deposit is characterized by great homogeneity and is composed of complex raised, Scheuchzerian and fuscum peat.

The deposit of transitional swamps is represented by transitional swamps and forest-swamp types of structure. Lowland peatlands are rare and are confined mainly to floodplains and low terraces. The deposit of lowland bogs is composed of sedge peat.

Ket-Tym peat-bog region occupies the area between the Keti and Tym rivers and extends east to the Yenisei. The watershed of the Ob and Yenisei has a clearly defined slope here with an increase in surface elevations to the east. The interfluve region is composed of lacustrine-alluvial and deluvial deposits and is dissected by a highly developed hydrographic network into big number small interfluves.

Due to the fact that the region is located within the contour of positive structures, the dominance of denudation processes determines the spread of well-drained swamps here. Regressive phenomena are less pronounced, there is a tendency for ridges to transgress, or ridges and hollows are in a state of dynamic equilibrium. The surface of the interfluve plateau has a clearly defined grivny relief. In some places, the dissected relief is leveled by a peat deposit 2-6 m deep - fuscum - or a complex type of structure on ridges, and in depressions - a transitional swamp or mixed swamp deposit with a lower horizon of low-lying sedge peat 1.5 m thick. Some ridges are ridges, towering above the peat deposit, filling the depressions between the ridges by 2-10 m. The width of the ridges is up to 5 km. They are composed of sandy sediments and are usually overgrown with taiga forest of pine, fir, cedar, and birch. The peatlands of the inter-ridge depressions are represented by transitional swamp and mixed swamp types of structure. On the upper part of the slope of the watershed towards the floodplain in the lower reaches of the Keti and Tym rivers there are often small round peat bogs of suffosion depressions (from 10 to 100 ha, rarely more) with transitional and upland deposits, less often with lowland deposits.

The slopes of the watersheds are eroded, weakly dissected or almost undivided by terrace ledges, cloak-like covered with peat deposits, forming large peat bogs that stretch for long distances along the course of both rivers. Closer to the bottom of the watershed, these peatlands are composed of lowland deposits, higher up the slope - transitional, and in the upper sections of the slope - highland. On them, often in the upper part of the slope, rather large lakes with sapropel deposits at the base are scattered among the upper deposits.

In the upper reaches of the Keti and Tym rivers, the narrow terraces of both river valleys are covered with peat. Narrow peatlands stretched along rivers are often composed of transitional deposits. Raised, poorly watered pine-shrub-sphagnum bogs are confined here to the watershed plain. The ridge-hollow complex is developed in the central parts of the largest peat bogs.

Lowland and transitional swamps are widespread on the first and partially on the second terraces of the river. Obi. Especially a lot of mesotrophic and eutrophic sedge, sedge-sphagnum, sedge-hypnum, tree-sedge bogs are found on the right bank terraces of the river. Ob, between the Ketyu and Tym rivers. The average thickness of raised bogs is 3-5 m, lowland 2-4 m. Raised bogs are composed of fuscum, complex and Scheuchzerian-sphagnum types of structure. The deposit of mesotrophic swamps is represented by transitional swamp and forest-swamp types of structure. The deposit of lowland bogs is composed of sedge peat.

In the modern vegetation cover of bogs with a transitional deposit, one can observe an admixture of oligotrophic species, indicating the transition of peat formation to the oligotrophic type stage.

A special feature of the Ket-Tym region is the significant distribution of transitional and lowland peatlands compared to other peat-bog areas of the forest zone, where exclusively raised bogs are dominant.

Tavdinskaya peat-bog region It is a flat, sometimes gently undulating plain, composed of lacustrine-alluvial and alluvial sandy-loamy deposits.

Geographically, its central part is confined to the southern half of the Khanty-Mansi Lowland, where accumulation processes predominate and the greatest swampiness occurs. Its northwestern edge extends into the Tavdo-Kondinskaya Upland, and its southern edge into the Tobol-Ishim Plain. The swampiness of the area is high. A significant area is occupied by poorly drained lowland peat deposits, the deposits of which are composed mainly of sedge and sedge-hypnum types of structure with a small participation of deposits of the forest-bog and forest subtypes. The thickness of the deposits is small (2-4 m), peat deposits 5 m deep are occasionally found. On flat watersheds, small peat bogs with deposits 6-7 m thick are common, often folded almost to the mineral soil with fuscum peat of a low degree of decomposition. There are many lakes on the surface of peat deposits, which at one time served as centers for the formation of most peat deposits in the region.

Vasyugan peat-bog region is a vast, slightly elevated plain experiencing tectonic uplift. It is composed of alluvial and subaerial sandy-loamy deposits. In the north and east of the region, lacustrine-alluvial deposits are common; in the south, subaerial loess-like loams extend into its boundaries. The location of the area to the contours of positive structures determines the distribution of relatively drained swamps. Poorly drained swamps occupy the Demyan-Irtysh interfluve and depressions of the Ob-Irtysh watershed, where accumulation processes are developed.

In general, the region is characterized by high swampiness (up to 70%), especially its western part, where swampiness in some places reaches 80%.

Raised sphagnum bogs with ridge-hollow-lake and ridge-hollow complexes are confined to the flat tops of watersheds. The slopes are less swampy. From the periphery, watershed raised sphagnum bogs are bordered by transitional sphagnum, grass-sphagnum areas of bogs. The deposit of raised bogs is composed of fuscum, complex, hollow and Scheuchzerian types of peat. The stratigraphy of lowland and transitional bogs is dominated by sedge and woody-grass peat species.

In the middle part of the watersheds, low-lying slope deposits occur in very flat depressions. They are moistened by groundwater such as perched water from higher areas of watersheds. At the base of the peatlands lie deoxidized silty calcareous loams, which enrich the deposit with a significant amount of mineral salts. The nature of the vegetation cover indicates that the hard-water regime currently exists. The peat deposit is represented by sedge-hypnum and hypnum types of structure. The thickness of the deposit is from 1.5 to 4.5 m.

Their areas are small, and they alternate with areas of sedge and swamp type of structure with a deposit depth of 1 to 3.5 m. The edges of lowland deposits of the swamp subtype are represented by lowland forest (pine, birch) and forest swamp, wood-sedge, wood-sphagnum, swamp forest types of structure with deposit thickness from 1 to 2.8 m.

The upland areas in the form of islands lie among the lowland deposits. Their peat layer is represented predominantly by the fuscum type of structure and reaches a thickness of 6 m. The world's largest watershed heterogeneous peat deposit, Vasyuganskoye, with an area of ​​over 5 million hectares, is located in the region. Lowland peatlands do not form at all in the region large areas and in addition to the slopes of watersheds, they occupy mainly elongated areas in river valleys.

On low terraces, heavily swamped, lowland sedge-hypnum bogs predominate; lowland and transitional woody-sphagnum, woody-herbaceous bogs develop in the near-terrace part. Floodplains are swamped mainly in the upper reaches of rivers, where lowland sedge, sedge-willow, tree-sedge and forest swamps are formed. In their vegetation cover under the canopy of birch, Carex caespitosa and C. wiluica form high hummocks; in the inter-tussock depressions there is a large amount of forbs.

Deposits of the transitional type are located either at the contact of upland deposits with swampy forests, or at the contact of upland and lowland areas. In both cases, these are most often heavily watered deposits with a thin peat layer (1.5-2 m) and a vegetation cover of herbaceous plants(Carex lasiocarpa, C. rostrata, Scheuchzeria palustris) and from hydrophilic sphagnum mosses (Sph. obtusum, Sph. majus, Sph. fallax, Sph. jensenii), forming a smooth, semi-submerged carpet.

The thickness of the peat layer in floodplain peat bogs does not exceed 1.5-2 m. Their deposits of sedge, Scheuchzeria, wood-sedge or birch peat were in conditions of variable moisture with the participation of river waters, so its ash content is relatively increased.

The Vasyugan region is characterized by intensive peat accumulation. The average thickness of peat deposits is 4-5 m. Their age dates back to the early Holocene. The areas of swamps up to 8 m deep are of ancient Holocene age.

Ket-Chulym peat-bog region characterized by less peat compared to Ket-Tymskaya, which is explained in the geomorphological features of the region. The watershed Ket-Chulym plateau has a significantly greater degree of erosional dissection under the influence of the main water arteries. The rivers here cut deeply into the surface of the watersheds and have well-formed but narrow alluvial terraces. This caused a decrease in groundwater. Therefore, the total peat content in the Ket-Chulym region is reduced to 10%.

The relief of the watershed Ket-Chulym plateau is characterized by small saucer-shaped depressions of suffusion origin. They predetermine here basically

location and type of peat bogs. The most widespread in the peat bogs of suffosion depressions is the transitional swamp deposit with a total thickness of the peat layer from 1 to 4.5 m. Less common in them are upland deposits, mainly fuscum, complex and Scheuchzerian-sphagnum with a depth of up to 3-6 m. Flat suffosion depressions 1-2 m deep are occupied by cotton grass-sphagnum or magellanicum deposits. Lowland deposits in suffosion depressions are rare and are represented by forest, tree-sedge, multi-layer forest-fen and sedge types of structure. They fill the deepest basins, in which the thickness of the peat suite reaches 4-5 m.

In the Ket-Chulym region, a certain pattern is noted in the distribution of near-terrace peat deposits. In the middle part of the river. Ulu-Yul peatlands are small in size and located on sharply defined terraces. Downstream of the river, the terrace ledges are smoothed out, the surfaces of the terraces expand, and the area of ​​peat deposits increases. The latter acquire an elongated shape and are stretched parallel to the river. Near the mouth of the river. The Ulu-Yul terraces are even less pronounced and peat deposits merge with each other, covering the surface of several terraces.

On terraces and in the near-terrace parts of river valleys, peat bogs are smaller in area (in comparison with the peat bogs of the Ket-Tym region) and, without merging into large-scale massifs, on the terraces they form chains of isolated deep-lying peat deposits extended parallel to the river, often of lowland type with forest, wood-sedge or sedge deposit.

Tura-Ishim peat-bog region It is a lacustrine-alluvial plain composed of sandy-loamy deposits and is characterized by the predominance of denudation processes. The area is heavily swamped. Lowland swamps dominate: sedge, sedge-hypnum, birch-sedge. Raised pine-sphagnum bogs occupy small areas. The most waterlogged central parts of the interfluve are occupied by raised ridge-hollow bogs.

In general, this is an area of ​​high swampiness of weakly dissected gently flat wide river valleys with large lowland sedge-hypnum bogs at the bottoms of terraces and along their slopes and with medium-sized raised and transitional peat bogs on watersheds. The total swampiness of the region is up to 40%.

An example of a peat deposit of the first terraces above the floodplain is “Tarmanskoye”, located in the valley of the river. Tours. It stretches along the river for up to 80 km and adjoins the ledge of the main bank. Its deposit is almost entirely composed of sedge-hypnum and sedge peats, confirming the existence of ground nutrition.

The deposit includes within its boundaries a significant number of primary lakes of a rounded-elongated shape with an emerging orientation along the terrace. At the base of the lakes there are highly mineralized sapropels, which indicates forest-steppe conditions during the formation of the lakes. In the lower horizons of the deposit or on the edges of the deposit, high ash content of peats is observed as a result of clogging of the deposit with colluvial drifts.

North Baraba peat-bog region watershed sedge-hypnum bogs in the north borders on the Vasyugan peat-bog region, in the south on the South Barabinskaya region and is a gently undulating, weakly dissected plain. The region is composed of loess-like loams. There is little peat. It is dominated by small low-lying peatlands, such as borrowed areas, with an area of ​​10 to 100 hectares. The eastern margin, confined to the positive contours of the structures, is characterized by the development of relatively well-drained swamps. More than half of the peat area is lowland peat (54%) and approximately 27% is upland; The percentage of transitional peatlands here is relatively large (19%).

In the central part of the region there are many lakes, depressions and peat deposits. In the western part of the region, on the slopes of the Tara-Tartas interfluve, the main area of ​​sedge-hypnum bogs is concentrated. Hypnosis swamps develop in low-lying elements of the relief, mainly in places where hard-water groundwater flows emerge, along the slopes of watersheds or in the near-terrace parts of river valleys. Therefore, a slightly increased ash content (up to 8-12%) is characteristic of hypnotic peats and peat deposits. The ash content of some near-terrace hypnotic peat bogs averages 6-7%. The same percentages are used to measure the ash content of the sedge-hypnum peat bogs of the Tara-Tartas interfluve.

Towards the east, sedge-hypnum peat bogs give way to their leading position in the lowland type to forest-bog and forest deposits. The latter are located here along the edges of peat deposits, in the central areas of which, as well as in areas with a more elevated bottom topography, there are islands of upland deposits. Moreover, the fuscum fallow is usually peripheral in relation to the complex upland one, which is located in the center, carrying a ridge-lake complex of vegetation on the surface.

Despite the increased carbonate content of the underlying rocks, the relatively low occurrence of groundwater, recharge from atmospheric precipitation, as well as partial uplift of the territory create favorable conditions for the gradual transition of lowland swamps to the oligotrophic stage of development. In the river valleys directly adjacent to the river ridges, the richest in floristic composition are the woody and herbaceous swamps (sogr). In that part of the valley where anoxic groundwater flows and colluvial water does not penetrate, sedge-hypnum bogs are formed. In addition to typical mosses, there are sedge and sedge-grass bogs, and in the east there are reed bogs, characteristic of the grass bog zone.

In the riverine parts of watersheds, along the banks of the upper reaches of rivers, and in the depressions of terraces, transitional forest swamps are widespread. Watershed lowland sedge-hypnum and hypnum bogs usually have a simple structure and are composed of sedge-hypnum and sedge peat species. The presence of ryams (upland sphagnum islands) is a characteristic feature of the sedge-hypnum bogs of the North Barabinsk region. Hypnosis deposits are more typical for swamps on low terraces, where soluble calcium salts predominate in the water-mineral nutrition. In terms of high levels of decomposition and ash content, the deposit of bogs on watershed plains differs from the deposit of peat bogs on low terraces, which have a more complex stratigraphy. Here you can find grass-hypnum, cotton grass-sedge, reed-sedge, reed-sedge, sedge-sphagnum types of peat.

The bottom layers of the deposit are usually composed of reed or sedge-reed types of structure. Peat species of the woody group play a significant role in the structure of deposits of lowland near-terrace and floodplain-near-terrace bogs. Transitional forest swamps are widespread. They form in the interfluves, in the terraces above the floodplain and in the near-terrace parts. The deposits of these swamps are represented by transitional forest and forest-swamp types of structure.

In the ryams, the upper horizons of the deposit (up to 2-4 m) are represented by fuscum peat with separate layers of Magellanicum, Angustifolium, cotton grass-sphagnum, pine-cotton grass and pine-shrub types of peat. The bottom layers of the deposit are usually represented by peat of transitional and lowland types. The average depth of peat deposits on watersheds is 2-3 m; on low terraces the peat thickness increases to 5 m compared to the Vasyugan region. The beginning of the peat formation process dates back to the early Holocene.

Tobol-Ishim peat-bog region located west of the river. Irtysh and crosses the interfluve of Ishim and Tobol in the middle reaches. The surface of the territory is quite dissected and well drained. The swampiness of the region does not exceed 3%. It is dominated by small lowland swamps such as borrows with an area of ​​10 to 100 hectares. The location of the positive contours of the structures determines the development of predominantly well-drained peat deposits here.

The ridged nature of the relief, a poorly developed hydrographic network, a waterproof horizon located close to the surface, and slow runoff of surface waters led to the formation in the interridge spaces of a huge number of lakes, usually round or oval with shallow depths, a flat bottom and strong overgrowth. Lakes are often adjacent to or surrounded by small, shallow-lying sedge-reed bogs. During the period of snowmelt, the fields are filled with meltwater, turning into temporary shallow reservoirs, often interconnected, and then the flow through such a chain of lakes connected by the fields has the character of a river. There are very few isolated lakes. In terms of chemical composition, the waters of the lakes, sometimes located in close proximity to one another, are distinguished by significant diversity. Salty, bitter and fresh lakes lie almost nearby.

Relatively larger fields, characteristic of the northern part of the region, surround lakes with fresh and brackish water. The thickness of the deposits of these fields is up to 1-1.5 m. It is composed of highly mineralized sedge, sedge-reed and reed peats with an average ash content of 20-30%. Their vegetation cover is dominated by reed, reed-sedge and sedge (C. caespitosa, C. omskiana) phytocenoses.

Smaller areas of borrowings are common in the southern part of the region around salt lakes. They are very shallow, composed of reed peat with a high degree of decomposition and high ash content. The reed association, and less often the sedge association, predominate in their vegetation cover.

In the sandy spaces of the Tobol region and in the northern part of the region on the right bank of Ishim, lowland peat bogs (sedge and sedge-hypnum) have separate areas (such as ryams) with high-lying deposits composed of fuscum peat of low degree of decomposition, with a convex surface and secondary vegetation cover of pine trees. shrub phytocenosis that developed as a result of repeated fires.

In small basins of suffoses of ionic origin, shallow “split” peatlands of lowland type are found. They developed in solonetz microrelief depressions - “saucers”. Salinization and the subsequent process of swamping lead to the appearance of areas of swampy meadows with Carex intermedia, which are exclusively characteristic of this territory, which are subsequently covered with thickets of shrubs, mainly Salix sibirica, and a birch stand.

There are also treeless “spike” swamps with sedge hummocks on the surface, surrounded on the periphery by tall-trunked birch. They formed in deeper and more moist depressions with diverse wetland vegetation, greatly varying in composition in some cases: with hummocks of Carex omskiana, sometimes with Salix sibirica in the shrub layer. Such peat bogs are never covered over the entire area with birch; the deposits in them are tree-sedge.

South Baraba peat-bog region large borrow-ryam peatlands are composed of alluvial-lacustrine and loess-like deposits. Its soil cover is dominated by peat-bog soils, solonetzes and solonchaks (up to 60%); Chernozems occupy a smaller area, podzolic soils and etc.

Soil salinization processes (including peat soils) are widespread in the region. Their mineralization naturally increases from north to south. The general calm relief of the region is complicated by low ridges elongated in the southwestern direction in combination with interridge depressions. The hydrographic network is quite dense. Both lakes and river beds are abundantly overgrown with aquatic and wetland vegetation and imperceptibly merge with wetlands. Very often the depressions between the ridges are completely swamped. Characteristic of the Baraba topography are suffusion depressions on various surface elements and a large number of lakes, different in size, origin and chemical composition of water.

The area's swampiness is approximately 33%. Lowland reed-sedge peatlands predominate here, constituting up to 85% of the total wetland area. The remaining 15% is distributed between the upper ryam deposits and the transition deposits of their peripheral areas.

Zaimishchno-ryam peatlands are most widespread in the eastern half of the region, their areas here reach several thousand hectares, and the area of ​​ryams - high, rising up to 8-10 m above the level of the ryam - up to a thousand hectares. Towards the west, the areas of borrowings decrease, ryams are less common, and their height decreases.

The emergence of high-lying ryam deposits among lowland deposits is associated with the feeding of ryam areas with fresh and slightly saline lake or surface stagnant waters. The lakes are still preserved as open reservoirs adjacent to the ryams; sometimes traces of them remain at the base of the ryam deposit in the form of a thin layer of sapropel.

The degree of decomposition of borrowed peats, as a rule, exceeds the species indicator (30-50%), the average ash content is 20%. The deposit of borrowings is composed of highly mineralized peats of the swamp group: reed, reed-sedge and grass (with a predominance of remains of light grass and reed grass in the fiber). The total thickness of the borrowing deposits reaches 1.5 m. In the vegetation cover, in the direction from the center to the periphery, reed, sedge-reed and sedge (or grass-sedge) phytocenoses are successively replaced. The latter borders on saline meadow vegetation. Areas fed by lake waters did not experience variability in moisture and salt conditions. Protected from the influence of saline groundwater by the surrounding low-lying deposits, they were overgrown with alloys of Sph. teres, the reservoirs passed into the peat bog stage; gradually, as the deposits grew, they came out of the influence of lake waters and continued to develop as atmospherically fed peat bogs. Dominance in these areas of Sph. fuscum maintains a regime of high humidity and low temperature in the deposit. Sph. fuscum created its own substrate and microclimate even in forest-steppe conditions and over thousands of years deposited powerful deposits of high-moor peat.

The modern vegetation cover of the ryams is secondary and arose under human influence. The degree of decomposition of the fuscum deposit is always reduced, which is facilitated, in addition to increased humidity and low temperature, apparently by its increased acidity, which inhibits microbiological processes. At the contact of the ryams and the dams themselves, there is usually a belt of transitional deposits with mesotrophic plant cover.

In addition to large ryam peat bogs, the South Barabinsk region is characterized by numerous small peat bogs in saucer-shaped depressions and depressions of suffusion origin along the interfluves and ridges.

Transitional and lowland forest swamps usually form a narrow belt around ryams or are confined to depressions of the mesorelief. In the latter case, forest swamps are genetically related to birch trees. Spike swamps dominated by Carex intermedia are typical of the southern part of the region. Birch-reed swamps here are confined to flat, highly mineralized lowlands and represent one of the initial phases of swamping. The total area of ​​the ryams is insignificant. They are found mainly in the northern half of the region.

According to the radiocarbon method, the absolute age of the ryam with a thickness of 3.1 m dates back to the Middle Holocene, and the borrows with a depth of 1.35 m - to the Late Holocene. The processes of swamping are facilitated by the gradual tectonic uplift of the area, which causes the disintegration of rivers and lakes into separate bodies of water.

East of the river The Yenisei within the Asian part of the Union is divided into seven large natural geographical areas.