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Where is the West Siberian Plain located? West Siberian Lowland: characteristics

The material contains information about the relief, which is typical for this territory. The article considers the processes that had a significant impact on the formation of the landscape of the West Siberian Plain. A table is given that allows you to better understand the features of the formation of land cover throughout the existence of a flat area.

Relief of the West Siberian Plain

The plane is expressed by an extremely low accumulative plain with a uniform relief.

The main elements of the relief are wide flat interfluves and river valleys.

Various forms of manifestation of permafrost and high waterlogging are typical here. Also in the southern tip, one can notice both ancient and modern salt accumulations.

Rice. 1. Salt deposits.

In the north, there is a general flatness. The homogeneous structure of the territory is disturbed by gently sloping and hilly-sloping hills with an average height of 200-300 m.

"Living" land

The tectonic structure of the West Siberian Plain is such that it includes a foundation and a cover. The flat plate is in constant motion.

Underground rivers “hide” in the cuff of loose rocks, which carry both fresh and mineral-rich waters. There are hot springs with water temperatures ranging from 10 to 15°C.

Rice. 3. Underground river.

The West Siberian plate began its formation in the Mesozoic era. During this period, the land between the Urals and the Siberian platform "sank", which led to the formation of a sedimentation basin.

Table "Relief of the West Siberian Plain"

*Geographic area*	*Geological specificity*	*Relief*
Yamal, Red Sea coast	Plate of the Paleozoic period. Covered by a sedimentary cover formed by glacial deposits	Laminations of a horizontal order, turning into uplifts
Vasyuganye, Narym	Plate of the Paleozoic period. Covered by a sedimentary cover of river sediments and glacial deposits	Deflections in the central region and elevation in the form of Siberian Ridges
Altai foot	Plate of the Paleozoic period. Covered with sediment	flat elevation
	Caledonian orogeny	Destruction of ancient mountains. The formation of modern as a result of raising the layers

What have we learned?

We found out what determines the specificity of relief formation in the territory of the West Siberian Plain. We received information about the depth of the frozen layer on this land area. We received information about the relief, which is typical for mountainous areas. The historical period of the formation of the West Siberian plate was clarified.

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The West Siberian Plain is one of the largest accumulative lowland plains. the globe. It stretches 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 to 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 sq. km 2 .

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

The geographical position of the West Siberian Plain determines the transitional nature of its climate between the temperate continental Russian Plain and sharply continental climate Central Siberia. Therefore, the landscapes of the country are distinguished by a number of peculiar features: the natural zones here are somewhat shifted to the north compared to the Russian Plain, the zone deciduous forests is absent, and landscape differences within the zones are less noticeable than on the Russian Plain.

The West Siberian Plain is the most inhabited 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 Altai Territory, Kustanai, Kokchetav and Pavlodar regions, as well as some eastern regions of the Sverdlovsk and Chelyabinsk regions and western areas Krasnoyarsk region.

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

However, the scientific study of the nature of the country began only in the 18th century, when detachments of the Great Northern expedition 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 Siberian railway that was being designed at that time, salt deposits in the steppe zone. A significant contribution to the knowledge of the West Siberian taiga and steppes was made by studies of soil-botanical expeditions of the Migration Administration, undertaken in 1908-1914. in order to study the conditions for the agricultural development of plots 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 the productive forces, no longer individual specialists or small detachments took part, but hundreds of large complex expeditions and many scientific institutes created in various cities of Western Siberia. Detailed and versatile studies were carried out here by the USSR Academy of Sciences (Kulunda, Baraba, Gydan and other expeditions) and its Siberian branch, the West Siberian Geological Administration, geological institutes, expeditions of the Ministry of Agriculture, Hydroproject and other organizations.

As a result of these studies, ideas about the country's relief have changed significantly, detailed soil maps of many regions of Western Siberia have been compiled, and measures have been developed for the rational use of saline soils and the famous West Siberian chernozems. big practical value had forest typological studies of Siberian geobotanists, the study of peat bogs and tundra pastures. But especially significant results were brought by the work of geologists. Deep drilling and special geophysical studies have shown that the richest deposits are contained in the bowels of many regions of Western Siberia. natural gas, large reserves of iron ore, brown coal and many other minerals, which already serve as a solid base for the development of industry in Western Siberia.

Geological structure and history of the development of the territory

Taz Peninsula and the Middle Ob in the section Nature of the world.

Many features of the nature of Western Siberia are due to the nature of its geological structure and history of development. The entire territory of the country is located within the West Siberian epihercynian plate, the foundation of which is composed of dislocated and metamorphosed Paleozoic deposits, similar in nature to those of the Urals, and in the south of the Kazakh upland. The formation of the main folded structures of the basement of Western Siberia, which have a predominantly meridional direction, refers to the era of the Hercynian orogeny.

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

The Mesozoic formations of Western Siberia are represented by marine and continental sandy-argillaceous 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 the conditions and regime of sedimentation on the West Siberian Plate that sank at the beginning of the Mesozoic.

Paleogene deposits are predominantly marine and consist of gray clays, mudstones, glauconite 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 that were then located on the territory of Central Asia. This sea left Western Siberia in the middle of the Oligocene, and therefore the Upper Paleogene deposits are already represented here by sandy-clayey continental facies.

Significant changes in the conditions of accumulation of sedimentary deposits occurred in the Neogene. The suites of Neogene rocks, which come to the surface mainly in the southern half of the plain, consist exclusively of continental lacustrine-river deposits. They formed in the conditions of a poorly dissected plain, first covered with rich subtropical vegetation, and later with broad-leaved deciduous forests from representatives of the Turgai flora (beech, walnut, hornbeam, lapina, etc.). In some places there were areas of savannas, where giraffes, mastodons, hipparions, and camels lived at that time.

Especially big influence events had an impact on the formation of landscapes in Western Siberia Quaternary period. During this time, the territory of the country experienced repeated subsidence and was still an area of predominantly accumulation of loose alluvial, lacustrine, and in the north - marine and glacial deposits. 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 up 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 deposits are represented in the north of the plain by alluvial sands filling buried valleys. The sole of alluvium is located in them sometimes at 200-210 m below the current level of the Kara Sea. Above them in the north, pre-glacial clays and loams with fossil remains of the tundra flora usually occur, which indicates a noticeable cooling of Western Siberia that had already begun at that time. However, dark coniferous forests with an admixture of birch and alder prevailed in the southern regions of the country.

The Middle Quaternary time in the northern half of the plain was an epoch of marine transgressions and repeated glaciations. The most significant of them was Samarovskoye, the deposits of which compose the interfluves of the territory lying between 58-60 ° and 63-64 ° N. sh. 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 boulders shows that its sources of food 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 in the West Siberian Plain, the Ural and Siberian ice sheets did not merge with each other, and the rivers of the southern regions, although they met a barrier formed by ice, found their way north in the gap between them.

Along with typical glacial rocks, the composition of the sediments of the Samarovo stratum also includes marine and glacial-marine clays and loams formed at the bottom of the sea advancing from the north. Therefore, the typical moraine relief forms are less distinct here than on the Russian Plain. On the lacustrine and fluvioglacial plains adjoining the southern edge of the glaciers, then forest-tundra landscapes prevailed, and in the extreme south of the country loess-like loams were formed, in which pollen of steppe plants (wormwood, kermek) is found. Marine transgression continued in the post-Samarovo time, the deposits of which are represented in the north of Western Siberia by Messov 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 epoch, which began after the retreat of the ice sheet, was marked in the north by the spread of the Kazantsevo marine transgression, whose deposits in the lower reaches of the Yenisei and Ob contained the remains of a more heat-loving marine fauna than currently living in the Kara Sea.

The last, Zyryansk, glaciation was preceded by a regression of the boreal sea, caused by uplifts in 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. During the maximum stage of development of the Zyryansk glaciation, glaciers descended into the regions 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, sandy-argillaceous Quaternary sediments were being blown over at that time, eolian landforms were forming, and loess-like loams were accumulating.

Some researchers of the northern regions of the country draw a more complex picture of the events of the Quaternary glaciation in Western Siberia. Thus, according to the geologist V.N. Saks and geomorphologist G.I. Lazukov, glaciation began here as early as the Lower Quaternary and consisted of four independent epochs: Yarskaya, Samarovo, Taz and Zyryanskaya. Geologists S. A. Yakovlev and V. A. Zubakov even count six glaciations, referring 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. The middle part of the northern half of the plain during the epoch of glaciation was covered by the waters of marine transgression; the boulders enclosed in its deposits are brought here by icebergs that have come off the edge of the glaciers that descended from the Central Siberian Plateau. Only one Quaternary glaciation of Western Siberia is recognized by the geologist V. I. Gromov.

At the end of the Zyryansk glaciation, the northern coastal regions of the West Siberian Plain again sank. The subsided areas were flooded by the waters of the Kara Sea and covered with marine sediments that make up post-glacial marine terraces, the highest of which rises 50-60 m above the modern level of the Kara Sea. Then, after the 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 in most of the river valleys of Western Siberia, lateral erosion prevailed, the deepening of the valleys proceeded slowly, therefore they usually have a considerable width, but a small depth. In poorly drained interfluve spaces, the reworking of the ice age relief continued: in the north, it consisted in leveling the surface under the influence of solifluction processes; in the southern, non-glacial provinces, where more atmospheric 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 somewhat drier and warm 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 to the north of the modern border of woody vegetation and the wide development of the tundra zone of relict large-hilly peatlands in the south.

Currently, there is a slow shift of borders on the territory of the West Siberian Plain. geographical areas to the south. Forests in many places are advancing on the forest-steppe, forest-steppe elements penetrate the steppe zone, and the tundra is slowly replacing woody vegetation near the northern limit of sparse forests. True, in the south of the country, man intervenes in the natural course of this process: cutting down forests, he not only stops their natural advance on the steppe, but also contributes to the displacement of the southern border of forests to the north.

Relief

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

Scheme of the main orographic elements of the West Siberian Plain

Differentiated subsidence of the West Siberian Plate in the Mesozoic and Cenozoic determined the predominance of accumulation processes of loose deposits within it, the thick cover of which levels the unevenness of the surface of the Hercynian basement. Therefore, the modern West Siberian Plain is characterized by a generally flat surface. However, it cannot be considered as a monotonous lowland, as it was considered until recently. In general, the territory of Western Siberia has a concave shape. Its lowest parts (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: Severo-Sosvinskaya, Turin, Ishimskaya, Priobskoe and Chulym-Yenisei plateau, Ketsko-Tymskaya, Verkhnetazovskaya, Lower Yenisei. A distinct strip of hills form in the inner part of the plain Siberian Ridges(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: gently sloping anticlinal uplifts correspond, for example, to the Verkhnetazovsky and lulimvor, but Barabinskaya and Kondinskaya the lowlands are confined to the syneclises of the slab basement. However, discordant (inversion) morphostructures are also not uncommon in Western Siberia. 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 basement trough zone.

Differences in the relief of these areas are explained by the history of their formation in the Quaternary, the nature and intensity of the latest 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 a harsh climate and the widespread distribution of permafrost. Thermokarst basins, bulgunnyakhs, spotted and polygonal tundras are quite common, and solifluction processes are developed. The southern steppe provinces are characterized by numerous closed basins of suffusion origin, occupied by salt marshes and lakes; the network of river valleys here is not dense, 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 a large part of the country's area, they determine the general appearance of the relief of the plain. In many places, the slopes of their surface are insignificant; precipitation, especially in the forest-bog zone, is very difficult and the interfluves are heavily swamped. Large areas are occupied by swamps to the north of the line of the Siberian railway, on the interfluve of the Ob and Irtysh, in the Vasyugan region and the Baraba 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 certain northern provinces of the plain, which were subjected to Quaternary glaciations, which left here a heap 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 the northeast to the southwest.

Another important element of the country's relief is the river valleys. All of them were formed in conditions of small slopes of the surface, slow and calm flow of rivers. 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 (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 places, their width is several tens of kilometers, and the Ob valley in the lower reaches even 100-120 km. The valleys of most small rivers are often only deep ditches with poorly defined slopes; during spring floods, water completely fills them and floods even neighboring valley areas.

Climate

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

Western Siberia is a country with a fairly severe continental climate. Its large length from north to south determines a clearly pronounced climate zoning and significant differences in climatic conditions in the northern and southern parts of Western Siberia, associated with a change in the amount of solar radiation and the nature of the circulation of air masses, especially western transport flows. The southern provinces of the country, located inland, on long distance from the oceans, are characterized, in addition, by a greater continental climate.

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

Cyclones often pass in the border zone of areas of high and low pressure. Especially often they are repeated in the first half of winter. Therefore, the weather in the maritime provinces is very unstable; on the coast of Yamal and the Gydan Peninsula, strong winds are guaranteed, the speed of which reaches 35-40 m/s. The temperature here is even somewhat higher than in the neighboring forest-tundra provinces located between 66 and 69°N. sh. Further south, however, winter temperatures gradually rise again. In general, winter is characterized by stable low temperatures, there are few thaws here. The 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 comparatively cold; April, even in the forest-marsh zone, is not yet quite a spring month.

IN warm time year, a lower pressure is established over the country, and an area of higher pressure is formed over the Arctic Ocean. In connection with this summer, weak northerly or northeasterly winds predominate, and the role of western air transport noticeably increases. In May, there is a rapid increase in temperatures, but often, with the intrusions of arctic air masses, there are returns of cold weather and frosts. The warmest month is July, the average temperature of which is 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 inflow of heated continental air here 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 up 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 intensive activity on the Arctic and polar fronts. The amount of winter precipitation is relatively low and ranges from 5 to 20-30 mm/month. In the south, in some winter months, snow sometimes does not fall at all. Significant fluctuations in the amount of precipitation in different years are characteristic. 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 into wet. Especially large differences are observed in the forest-steppe zone, where, with an average long-term precipitation of about 300-350 mm/year in wet years drops up to 550-600 mm/year, and in dry - 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. Moisture evaporates most of all in the rainy-rich southern half of the forest-bog zone (350-400 mm/year). In the north, in the coastal tundra, where the 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 already explained by the 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 evaporating moisture can exceed the amount of precipitation by 2-3 times. In this case, the lack of atmospheric precipitation is compensated by the 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, which occur 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. The dry air coming from the Arctic, when passing over Western Siberia, is warmed up and enriched with moisture, but its heating is more intense, so the air is more and more removed from the state of saturation. In this regard, evaporation increases, which leads to drought. In some cases, the cause of droughts is also the inflow 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 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 precipitation in solid form lasts more than half a year, 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 swampy 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 strong winds and snowstorms occur in winter, 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 the freezing of soils and the widespread permafrost. On the Yamal, Tazovsky and Gydansky peninsulas, permafrost is found everywhere. In these areas of its continuous (confluent) distribution, the thickness of the frozen layer is very significant (up to 300-600 m), and its temperatures are low (on the watershed spaces - 4, -9 °, in the valleys -2, -8 °). Further south, within the limits of the northern taiga up to a latitude of about 64°, permafrost occurs already 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 photos of the nature of the West Siberian Plain: the Taz 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 basins of the second order: Tobolsk, Irtysh, Kulunda-Barnaul, Chulym, Ob, etc. Due to the large thickness of the cover of loose deposits, consisting of alternating permeable ( sands, sandstones) and water-resistant rocks, artesian basins are characterized by a significant number of aquifers associated with formations of various ages - Jurassic, Cretaceous, Paleogene and Quaternary. Quality groundwater these horizons are 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 chloride calcium-sodium composition. Their temperature is from 40 to 120°C, the daily flow rate of wells reaches 1-1.5 thousand tons per day. m 3, and total stocks - 65,000 km 3; such pressure water can be used for heating cities, greenhouses and greenhouses.

Groundwater in arid steppe and forest-steppe regions of Western Siberia has great importance for water supply. In many areas of the Kulunda steppe, deep tubular wells were built to extract them. Quaternary groundwater is also used; however, in the southern regions, due to climatic conditions, poor drainage of the surface 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 out into the Kara Sea annually about 1200 km 3 water - 5 times more than the Volga. The density of the river network is not very large and varies in different places depending on the relief and climatic features: in the Tavda basin it reaches 350 km, and in the Baraba forest-steppe - only 29 km per 1000 km 2. Some southern regions of the country with a total area of more than 445,000 sq. km 2 belong to the territories of closed flow and are distinguished by an abundance of endorheic lakes.

The main sources of food for most rivers are melted snow water and summer-autumn rains. In accordance with the nature of food sources, the runoff is seasonally uneven: 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) the West Siberian rivers are ice-bound. Therefore, the winter months account for no more than 10% of the annual runoff.

The rivers of Western Siberia, including the largest ones - the Ob, Irtysh and Yenisei, are characterized by slight slopes and low flow rates. So, for example, the fall of the Ob channel in the section from Novosibirsk to the mouth over 3000 km equals only 90 m, and its flow rate does not exceed 0.5 m/s.

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 in the world. 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. So, in the south, in the forest-steppe zone, the Ob receives relatively few tributaries, but in the taiga zone their number noticeably increases.

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 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 km 3 water.

The Ob is a typical flat 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 for 1 km currents. During spring and summer, the runoff of the Ob near Novosibirsk is 78% per annum; Near the mouth (near Salekhard), the seasonal distribution of runoff 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 - 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 turning, the Irtysh crosses the steppes of Northern Kazakhstan and has almost no tributaries right up to Omsk. Only in the lower reaches, already within the taiga, several large rivers flow into it: Ishim, Tobol, etc. The entire length of the Irtysh is navigable, but in the upper reaches in summer, during a period of low water level, navigation is difficult due to numerous rifts.

Along the eastern border of the West Siberian Plain flows Yenisei- the most abundant river in the Soviet Union. Her length is 4091 km(if we consider the Selenga River as the source, then 5940 km); the basin area is almost 2.6 million sq. km 2. Like the Ob, the Yenisei basin is elongated in the meridional direction. All its major right tributaries flow through the territory of the Central Siberian Plateau. From the flat swampy watersheds of the West Siberian Plain, only the shorter and less watery left tributaries of the Yenisei begin.

The Yenisei originates in the mountains of the Tuva ASSR. In the upper and middle reaches, where the river crosses the spurs of the Sayan Mountains and the Central Siberian Plateau, composed of bedrock, there are rapids in its channel (Kazachinsky, Osinovsky, etc.). 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 expenditure by season. Its minimum winter consumption near the mouth is about 2500 m 3 /sec, the maximum during the flood period exceeds 132 thousand km. m 3 /sec with an annual average of about 19,800 m 3 /sec. During the year, the river brings to its mouth more than 623 km 3 water. In the lower reaches, the depth of the Yenisei is very significant (in places 50 m). This makes it possible for sea vessels to rise up the river by more than 700 km and reach Igarka.

There are about one million lakes on the West Siberian Plain, the total area of which is more than 100 thousand hectares. km 2. According to the origin of the basins, they are divided into several groups: occupying the primary irregularities of the flat relief; 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, flood 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 wildlife

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

The plain relief of Western Siberia contributes to a pronounced zonality in the distribution of soils and vegetation. Within the country there are tundra, forest-tundra, forest-bog, forest-steppe and steppe zones gradually replacing one another. Geographical zoning resembles, therefore, in in general terms zoning system of the Russian Plain. However, the zones of the West Siberian Plain also have a number of local specific features which noticeably distinguish them from similar zones in Eastern Europe. Typical zonal landscapes are located here on dissected and better drained upland and riverine areas. In poorly drained interfluve spaces, the runoff from which is difficult, and the soils are usually highly moistened, marsh landscapes prevail in the northern provinces, and landscapes formed under the influence of saline groundwater in the south. Thus, the nature and density of relief dissection play a much greater role here than on the Russian Plain in the distribution of soils and vegetation cover, causing significant differences in the regime of soil moisture.

Therefore, there are, as it were, two independent systems of latitudinal zonality in the country: the zonality of drained areas and the zonality of undrained interfluves. These differences are most clearly manifested in the nature of the soils. So, in the drained areas of the forest-bog zone, mainly strongly podzolized soils are formed under the coniferous taiga and soddy-podzolic soils under the birch forests, and in neighboring undrained places - thick podzols, marsh and meadow-bog soils. drained spaces forest-steppe zone mostly occupied by leached and degraded chernozems or dark gray podzolized soils under birch groves; in undrained areas, they are replaced by marsh, saline or meadow-chernozem soils. In the upland areas of the steppe zone, either ordinary chernozems, which are characterized by increased obesity, low thickness, and linguality (heterogeneity) of soil horizons, or chestnut soils predominate; in poorly drained areas, they usually include spots of solods and solodized solonetzes or solonetsous meadow-steppe soils.

Fragment of a section of swampy taiga in Surgut Polissya (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 continental regions of the European part of the Union. The woody vegetation of the forest-tundra is represented mainly by Siberian larch, and not by spruce, as in the regions lying west of the Urals.

In the forest-bog zone, 60% of the area of which is occupied by swamps and poorly drained swampy forests 1, pine forests occupy 24.5% of the forested area, and birch forests (22.6%), mainly secondary ones, predominate. 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, occasionally found in the southern regions) are absent in the forests of Western Siberia, and therefore there is no zone of broad-leaved forests here.

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

An increase in the continentality of the climate causes a relatively sharp transition, compared to the Russian Plain, from forest-bog 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 less than on the Russian Plain, and of the tree species it contains mainly birch and aspen.

The West Siberian Plain is wholly part of the transitional Eurosiberian zoogeographic subregion of the Palearctic. 478 species of vertebrates are known here, of which 80 species are mammals. The fauna of the country 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 Dzungarian hamster (Phodopus sungorus), chipmunk (Eutamias sibiricus) etc. In last years the fauna of Western Siberia was enriched by muskrats acclimatized here (Ondatra zibethica), hare-hare (Lepus europaeus), American mink (Lutreola vison), teleutka squirrel (Sciurus vulgaris exalbidus), and carp were introduced into its reservoirs (Cyprinus carpio) and bream (Abramis brama).

Natural resources

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

The natural wealth of Western Siberia has long served as the basis for the development of various sectors of the economy. There are tens of millions of hectares of good arable land here. Particularly valuable are the lands of the steppe and forest steppe zones with their favorable conditions for Agriculture climate and highly fertile chernozems, gray forest and non-saline chestnut soils, which occupy more than 10% of the country's area. Due to the flatness of the relief, the development of the lands of 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. ha new lands, the production of grain and industrial crops (sugar beet, sunflower, etc.) increased. The lands located to the north, even in the southern taiga zone, are still underused and are a good reserve for development in the coming years. However, this will require much greater expenditures of labor and funds for draining, uprooting and clearing land from shrubs.

The pastures of the forest-bog, forest-steppe and steppe zones are of high economic value, especially the flood meadows along the Ob, Irtysh, Yenisei and their valleys. major tributaries. The abundance of natural meadows here creates a solid base for further development animal husbandry and a significant increase in its productivity. Importance For the development of reindeer breeding, moss pastures of the tundra and forest-tundra occupy more than 20 million hectares in Western Siberia. ha; more than half a million domestic deer 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 hectares. ha; timber reserves of about 10 billion m 3, and its annual growth is over 10 million tons. m 3 . The most valuable forests are located here, which provide wood for various industries. National economy. The forests along the valleys of the Ob, the lower reaches of the Irtysh and some of their navigable or raftable tributaries are currently most widely used. But many forests, including especially valuable massifs of condo pine, located between the Urals and the 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 25,000 km. km. Approximately the same is the length of the rivers along which timber is rafted. Full-flowing rivers countries (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 400,000 kWh. kW entered service in 1959; above it, a reservoir with an area of 1070 km 2. In the future, it is planned to build a hydroelectric power station on the Yenisei (Osinovskaya, Igarskaya), in the upper reaches of the Ob (Kamenskaya, Baturinskaya), on the Tom (Tomskaya).

The waters of the large West Siberian rivers can also be used for irrigation and watering of the semi-desert and desert regions of Kazakhstan and Central Asia, which are already experiencing a significant shortage of water resources. Currently, design organizations are developing the main provisions and a feasibility study for the transfer of 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 provide an annual transfer of 25 km 3 waters from Western Siberia to Central Asia. To this end, on the Irtysh, near Tobolsk, it is planned to create a large reservoir. From it, to the south along the Tobol valley and along the Turgai depression into the Syrdarya basin, the Ob-Caspian canal, more than 1500 meters long, will go to the reservoirs created there. km. The rise of water to the Tobol-Aral watershed is supposed to be carried out by a system of powerful pumping stations.

At the next stages of the project, the volume of water transferred annually can be increased to 60-80 km 3 . Since the waters of the Irtysh and Tobol will no longer be enough for this, the work of the second stage 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.

Quite recently, many geologists, based on the idea of the uniformity of the thick strata of loose deposits that make up the plain and the apparent simplicity of its tectonic structure, very carefully assessed the possibility of discovering any valuable minerals in its depths. However, held in recent decades geological and geophysical surveys accompanied by drilling deep wells, showed the fallacy of previous ideas about the poverty of the country in minerals and made it possible to imagine the prospects for the use of its mineral resources in a completely new way.

As a result of these studies, in the strata of the Mesozoic (mainly Jurassic and Lower Cretaceous) deposits central regions More than 120 oil fields have already been discovered in Western Siberia. The main oil-bearing areas are located in the Middle Ob region - in Nizhnevartovsk (including the Samotlor field, which can produce oil up to 100-120 million tons). t/year), Surgut (Ust-Balykskoe, Zapadno-Surgutskoe, etc.) and Yuzhno-Balyksky (Mamontovskoe, Pravdinskoe, etc.) districts. In addition, there are deposits in the Shaim region, in the Ural part of the plain.

In recent years, in the north of Western Siberia - in the lower reaches of the Ob, Taz and Yamal - the largest deposits of natural gas have also been discovered. 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 cubic meters. m 3 per year. In general, the predicted 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 oil-producing, oil-refining and chemical industry. Already in 1975, more than 145 million tons of oil were mined here. T oil and tens of billions of cubic meters of gas. Oil pipelines Ust-Balyk - Omsk (965 km), Shaim - Tyumen (436 km), Samotlor - Ust-Balyk - Kurgan - Ufa - Almetyevsk, through which oil got out to European part 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 West Siberian deposits 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 plan, the construction of the giant supergas pipeline Siberia - Moscow (its length is more than 3,000 km) was completed. km), through which gas from the Medvezhye field is supplied to Moscow. In the future, gas from Western Siberia will go through pipelines to the countries of Western Europe.

Brown coal deposits have also become known, confined to the Mesozoic and Neogene deposits of the marginal regions of the plain (North-Sosva, 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 hectares. 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 have been 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 tons. T, including in one Bakcharskoye field - 40 billion cubic meters. T. Numerous salt lakes in the south of Western Siberia contain hundreds of millions of tons of common and Glauber's salt, as well as tens of millions of tons of soda. In addition, Western Siberia has huge reserves of raw materials for the production of building materials (sand, clay, marls); on its western and southern outskirts there are deposits of limestones, granites, diabases.

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 refineries and chemical plants, enterprises of the timber, light and food industries. Various branches of agriculture are of great importance in the economy of Western Siberia. It produces about 20% of the commercial grain of the USSR, a significant amount of various industrial crops, a lot of butter, meat and wool.

The decisions of the 25th Congress of the CPSU outlined further gigantic growth in 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, develop the oil and gas industry, and 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 turn Western Siberia into the USSR's main oil and gas production base. In 1980, 300-310 million tons will be produced 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 plants for processing petroleum gas, 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 refineries eastern regions countries, as well as the Surgut-Nizhnevartovsk railway and begin construction of the Surgut-Urengoi railway. The tasks of the five-year plan provide for accelerating the exploration of oil, natural gas and condensate fields in the Middle Ob and in the north of the Tyumen region. The harvesting of timber, the production of grain and livestock products will also increase substantially. In the southern regions of the country, it is planned to carry out a number of major land reclamation measures - to irrigate and water large areas of land in the Kulunda and Irtysh regions, to begin construction of the second stage of the Aley system and the Charysh group water pipeline, and to build drainage systems in Baraba.

The West Siberian Plain is one of the largest accumulative low-lying plains in the world. It stretches 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 narrowing to 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 km 2.

The relief of the West Siberian Plain is one of the most uniform in the world. Occupying an area of 2.6 million km², 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 Altai mountains, - at 2400 km. Only in the extreme south do heights exceed 200 m; the vast majority of the plain has a height of less than 100 m above sea level; alluvial-lacustrine and accumulative relief prevails (in the south also denudation). Such relief features characteristic of Western Siberia as vast floodplains and huge swamps are especially common in the northern part of the plain; the relief to the 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. Valleys of large rivers are terraced. There are eolian dunes on the Yamal and Gydan peninsulas. Relatively elevated and dry territories, where the main part of the population of Western Siberia is concentrated, are located south of 55 °C.

Differentiated subsidence of the West Siberian Plate in the Mesozoic and Cenozoic determined the predominance of accumulation processes of loose deposits within it, the thick cover of which levels the unevenness of the surface of the Hercynian basement. Therefore, the modern West Siberian Plain is characterized by a generally flat surface. However, it cannot be considered as a monotonous lowland, as it was considered until recently. 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 (Nizhnoeobskaya, Nadymskaya and Purskaya lowlands) parts of the country. Low (up to 200-250 m) elevations stretch along the western, southern and eastern outskirts: the North Sosvinskaya, Turinskaya, Ishimskaya, Priobskoye and Chulym-Yenisei plateaus, the Ketsko-Tymskaya, Verkhnetazovskaya, Nizhneeniseiskaya. A distinctly pronounced strip of uplands is formed in the inner part of the plain by the Siberian Uvaly (average height - 140-150 m), extending 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 Lulimvor uplands, and the Baraba and Kondinsky lowlands are confined to syneclises of the plate basement. However, discordant (inversion) morphostructures are also not uncommon in Western Siberia. 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 basement trough zone.

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) near-glacial, mainly lacustrine-alluvial, plains; 4) southern non-glacial plains (Voskresensky, 1962).
Differences in the relief of these areas are explained by the history of their formation in the Quaternary, the nature and intensity of the latest 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 a harsh climate and the widespread distribution of permafrost. Thermokarst basins, bulgunnyakhs, spotted and polygonal tundras are quite common, and solifluction processes are developed. The southern steppe provinces are characterized by numerous closed basins of suffusion origin, occupied by salt marshes and lakes; the network of river valleys here is not dense, and erosional landforms in the interfluves are rare.

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 certain northern provinces of the plain, which were subjected to Quaternary glaciations, which left here a heap 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 the northeast to the southwest.

Western Siberia. Photo: Bernt Rostad

Currently, in 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 advance on the forest-steppe, forest-steppe elements penetrate into the steppe zone, and the tundra is slowly replacing woody vegetation near the northern limit of sparse forests. True, in the south of the country, man intervenes in the natural course of this process: cutting down forests, he not only stops their natural advance on the steppe, but also contributes to the displacement of the southern border of forests to the north.

West Siberian Plain.

This is a flat-low country with an area of 3 million km 2, one of the largest accumulative plains in the world. Its borders: the Kara Sea - the Turgai Plateau, the Urals - the Yenisei (trapezoid). The length from north to south is 4,500 km, from west to east 950 km in the north, up to 1,600 in the south.

Characteristics:

one). A slight fluctuation in heights (there are no such vast territories in the CIS).

2). The large length from north to south led to a constant increase in solar radiation from north to south, which led to a clear latitudinal differentiation of landscapes (from arctic deserts to dry steppes). Country of classical latitudinal zonality.

3). In the humid and cool climate of poorly drained plains, the largest areas of swamps (waterlogging) were formed against the background of the taiga. In the south - steppe landscapes with salt accumulation.

4). The geographical position determines the transitional nature of the climate (from temperate continental in the Russian Plain to sharply continental in Central Siberia).

Territory development.

The development of the plain by the Russians began after the campaign of Yermak (1581-1584). Scientific study began in the 18th century (Great Northern and academic expeditions). The navigation conditions of the Ob, Yenisei, Kara Sea are being studied. Intensive development of the forest-steppe in the south and the steppe zones of Western Siberia began in the 80s of the last century, in connection with the resettlement of peasants from densely populated provinces (A.P. Chekhov p.5). Soil-botanical expeditions are sent here. However, until 1917 Western Siberia remained little developed and almost unexplored.

Only in Soviet times (virgin lands) did large industrial enterprises begin to be created, at first associated with virgin lands, fisheries, and forestry.

The discovery of a number of deposits of iron ore, oil, gas, and others contributed to the development of industry.

The study of Western Siberia is carried out by many scientific institutions: the Academy of Sciences of Russia, the Siberian Branch of the Russian Academy of Sciences, the West Siberian Geological Administration, the Ministry of Agriculture, Hydroproject.

The history of the formation of the territory.

one). At the base of the West Siberian Lowland lies the epihercynian plate. The foundation of the slab is of Paleozoic age.

2). The basement rocks are highly dislocated and metamorphosed. The surface of the foundation within the slab plunges towards the center and north, so the thickness of the cover increases from the periphery to the center of the slab, reaching here 4-4.5 km (center), and 6-7 km in the north.

There is a pattern of change and composition of rocks in the same direction.

3). The upper tier (sheath) is formed by Meso-Cenozoic deposits.

In the history of the development of the West Siberian Plain, 3 stages can be distinguished:

1. Formation of peneplanation of an ancient folded country (Late Paleozoic - Jurassic).

2. Formation of the inner depression and the formation of the main tectonic structures (Jurassic - Eocene).

3. Formation of morphostructural elements of modern relief (Oligocene - Pleistocene).

In the early Paleozoic geosynclinal area. As a result of the Caledonian folding, the southeastern part of the West Siberian platform was also formed and emerged from under the sea level. In the Hercynian folding - most of the territory - the center and north.

In the Triassic and Early Jurassic, the platform occupied a high position and was an area of intense denudation. The rise of the rigid platform was accompanied by its cracking and alteration of the lavas. In the Jurassic, the contours of a vast internal depression are laid down, a thick stratum of sedimentary rocks accumulates, which covers all the irregularities of the Triassic relief.

Climatic conditions favored the growth of lush vegetation and the formation of peat bogs (material for coal).

1 transgression:

In the Early Jurassic, the transgression of the West Siberian Sea begins, which was due to the intense subsidence of the northern regions. The subsidence of the basement continues into the Middle Jurassic.

In the Late Jurassic, the transgression of the sea continues to the south, almost the entire territory is flooded, with the exception of the North Sosvinskaya Upland and the extreme south and southeast. In the Early Cretaceous, within the West Siberian Plate, the formation of a vast lowered Inner Region (all this during the Jurassic and Cretaceous) ends in basic terms.

11 transgression:

In the Cretaceous, a reduction in the area of the sea begins, which leaves the southern part. A lacustrine-alluvial regime is established over a large area. By the end of the Late Cretaceous, an even more extensive transgression is observed, which covers the entire territory of Western Siberia. The sea reaches the borders of the modern Urals in the west, and in the south it connects through the Turgai trough with the Turan Sea.

111 transgression:

Paleogene - tectonic movements are activated in the eastern border areas of the plains, the land area is expanding significantly. The sea is preserved only in the central and western parts.

In the middle of the Paleogene, there was again an extensive transgression of the sea, penetrating far to the south and connecting with the Turan Sea.

The end of the Paleogene is characterized by a powerful new stage of activation of tectonic movements. There comes a regression of the sea, which gradually leaves the territory of the West Siberian lowland.

The main features of the modern relief of the West Siberian Plain were formed at the turn of the Paleogene and Neogene. It was at this time that a river network began to form on the low-lying accumulative plain that emerged from under the sea level. The surface of the plain in general terms corresponded to the geostructural plan: the lowered areas coincided with tectonic depressions, and river valleys were located in them. The center of the plain already had a saucer-shaped structure, many rivers were directed towards the center (the general flow to the north).

Neotectonic movements were sharply manifested in the southeast near Altai, in the west near the Urals, and in the east near the Yenisei Ridge.

The heat-loving tropical vegetation in the Neogene consisted of swamp cypress, sequoia, magnolia, hornbeam, beech, oak, linden, and walnut.

The fauna is numerous, but poor in species: giraffe, mastodon, camel, hipparion, predators.

Neogene. In the Pliocene, a change in climatic conditions occurs (cooling, increased continentality).

The dominating position in the north is occupied by dark coniferous (spruce, cedar, fir, pine, larch), to the south broad-leaved and steppe grasses. At this time, forest-steppe and steppe landscape zones were formed, which occupy their current position.

At the end of the Pliocene and in the early Pleistocene, glaciation appeared (1 Eopleistocene glaciation - Demyansk and 3 Pleistcene). The epoch of this glaciation coincides with the transgression of the polar sea, which penetrated to the south and formed vast bays. The transgression continued into the interglacial (Tobolsk) epoch and reached its maximum during the epoch of the maximum Samarovsk glaciation. The sea covered the entire territory north of the Siberian Ridges. This is a zone of marine glaciation; cover ice and icebergs were widespread. The sea in the west and east approached the glaciers of the Urals and Putorana.

Synchronicity of glaciations and transgressions.

Siberian Uvaly - continental glaciation. They formed, as it were, a dam, to the south of which a huge dammed reservoir arose. The flow from it went through the Turgai Strait. In the late Pleistocene, a short-term regression is distinguished, which was replaced by a new 2nd transgression, after its maximum, the Zyryanovsk glaciation began (lower reaches of the Ob). In this ice age, the continentality of the climate intensifies, permafrost is formed in the north of the plain.

The last was the mountain-valley Taz glaciation (Sartan).

Climate warming in the Holocene. At this time, the plain experienced a general uplift, the sea level dropped, river valleys deepened, and terraces formed.

Quaternary history is characterized by:

Synchronicity of glaciations and transgressions.

The north and south differed in the sign of the latest tectonic movements. Pleistocene - the north sags, the south rises (glacier). Later, the north rises more intensively than the south.

The glacier has influenced organic world. The cooling of the climate in the Quaternary was accompanied by an increase in its continentality. Natural zones changed not only their boundaries, but also the composition: soils, vegetation and wildlife. In the Pleistocene, the pre-Quaternary fauna and flora disappeared, and new cold-resistant species (boreal flora) appeared to replace them. In the south, forest-steppe and steppe landscapes. Broad-leaved flora has completely disappeared.

Relief.

Differentiated subsidence of the West Siberian Plate determined the predominance of the processes of accumulation of loose deposits, which leveled the unevenness of the surface of the Hercynian basement, therefore the modern West Siberian Plain is characterized by the predominance of a flat relief. However, as a result of research in recent years, it has become obvious that its orographic surface is quite complex and diverse.

Here are large relief elements - plateaus, uplands, sloping plains and lowlands.

The surface of the plain has the general form of an amphitheater, open to the north. Plateaus, uplands, sloping plains prevail along the western, southern and eastern peripheries, while lowlands are concentrated in the central and northern parts.

In the center and in the north - Kandinsky, Sredneobskaya, Nizhneobskaya, Nadymskaya, Purskaya - lowlands. West, south, east - North Sosvinskaya, Turinskaya, Ishimskaya, Priobskoye (plateau), Chulym-Yenisei, Ketsko-Tymskaya, Verkhnetazkhovskaya, Nizhneeniseiskaya - uplands.

On the plain, the zoning of the modern relief is clearly manifested (3 geomorphological zones):

The zone of glacier-marine and permafrost-solifluction processes, covering Far North to the Siberian Ridges (tundra, forest-tundra, northern taiga). The relief is formed by glacial, glacial-marine, hydroglacial accumulation, permafrost. Modern conditions relief formation - cold climate, excessive moisture, continuous distribution of permafrost.

Forms: marine, glacier-marine and moraine plains (permafrost forms - bulgunyakhas, heaving mounds, thermokarst depressions, lakes).

Zone of fluvioglacial forms of lacustrine-glacial plains and modern erosional-accumulative processes. The zone extends to the middle taiga. Solifluction manifests itself locally. The surface is highly flat. Relief types formed by water-glacial and alluvial accumulation prevail (outland plains). Permafrost has an insular distribution. There are islands of moraine plains (Agansky Uval) and morpho-structural formations (Beleyursky, Tobolsk mainland).

In the north, a flat-hilly flat relief prevails with well-defined edges (near the Urals and the Middle Siberian plateau), ancient glacial forms (moraines, ridges, hills, eskers, kams, basins).

To the south, the surface of the West Siberian Plain is distinguished by exceptional monotony of relief (when they talk about the West Siberian Plain as a giant accumulative plain, they mean this part) - the middle reaches of the Ob, the lower reaches of the Irtysh, the Baraba, Kulundi lowlands. The centers of these lowlands are occupied by lakes (chany, Kulunda).

3. Zone of semi-arid structural-denudation plateaus and plains with suffusion-karst, erosion and deflation processes within forest-steppes and steppes.

Suffosion-karst processes have created numerous drainless depressions, closed basins, and steppe saucers. The most specific feature of the eastern part of the zone is the crest-hollow relief, presumably of fluvioglacial origin. (Hollows - chains of lakes, manes - hills are well oriented in space).

the main elements of the relief of the West Siberian Plain are wide flat interfluves and river valleys. Interfluve spaces occupy most of the country's area, so they determine the appearance of the plain relief. The interfluves are heavily swamped (there is a lot of precipitation, and the runoff is difficult). This is the interfluve of the Ob and Irtysh, Vasyugan, Baraba forest-steppe. About 70% of the area of Western Siberia is waterlogged to some extent.

River valleys - have slight slopes, the flow of rivers is slow, calm. The river valleys are wide, well developed, with a steep right bank and a system of terraces on the left bank. Lateral erosion.

Natural resources.

arable land (million hectares) - 10% of the country's area (forest steppe, steppe does not require investment).

Pastures - forest-bog, forest-steppe and steppe zones, water meadows along the valleys of the Ob, Irtysh, Yenisei. 20 million hectares - moss pastures.

forests - birch, pine, cedar, fir, spruce, larch - 80 million hectares, timber reserve - 10 billion m 3.

The presence of navigable rivers connecting the southern regions with the northern ones. The total length is 25 thousand km. They have a large supply of energy resources (when fully used, they could provide 200 billion kWh of electricity per year).

Oil (Jurassic and Lower Cretaceous) 200 fields. Middle Ob (Nizhnevartovsk, Surgut, Ust-Balyk, Urals). 60% of all oil production.

Gas - the lower reaches of the Ob, Taz, Yamal and Gydan - several tens of trillion m 3. 55% of all gas production.

Brown coals (North Sosva, Chulym-Yenisei and Ob-Irtysh basins).

Peat - 60% of all peat resources.

Oolitic iron ores - southeast (iron content 45%, reserves 300-350 billion tons).

Table salt - south, Glauber's salt, soda.

Raw materials for building materials (sand, clay, marls).

There are two great plains in Eurasia. The one in the east stretches from the mountains of southern Siberia to eternal ice Kara Sea, from the Yenisei to the Urals. The boundless and incredible riches of nature - this is it, the West Siberian Plain.

Borders and area

Western Siberia is an incredibly vast territory. From the Arctic Ocean it stretches for 2.5 thousand kilometers to the steppes of Kazakhstan, from the Urals to the Yenisei it extends for 1.5 thousand kilometers. Almost 80% of all Siberia is located on a plain, consisting of two flat depressions in the form of bowls and full of wetlands. These depressions are separated from each other by the Siberian Ridges, raised up to 175-200 meters. In the southeast, the height of the West Siberian Plain gradually rises, the foothills of Salair, Gornaya Shoria, Altai and Kuznetsk Alatau appear. The area of this great plain is more than 2.4 million square kilometers.

Geological development

The western part of the Siberian Plain was formed back in the Precambrian. Gradually evolving during the Paleozoic, folded structures formed along the edges of the platform. Docking with other parts of the mainland, they formed a single area. However, such a "patchwork" origin gives reason to interpret the nature of the plate in two ways. Quite often, given the facts, it is called heterogeneous, but at the same time, bearing in mind that most of the plain was formed in the Paleozoic, it is considered epipaleozoic. And then, bearing in mind the main role of the Hercynian folding, the plate is called epi-Hercynian.

Simultaneously with the formation of the foundation, starting from the Paleozoic and ending with the Early Jurassic, a cover of the future plain was created. The formation of the cover was completely completed by the Meso-Cenozoic. This not only blocked the border zones of folded structures, but also, thus, significantly increased the area of the plate.

Geographic zoning

The West Siberian Plain includes five zones: tundra, forest-tundra, steppe, forest-steppe and forest. In addition, it includes mountainous and low-mountainous regions. Probably, in no other place is it possible to trace such a correct manifestation of zonal natural phenomena, like here.

Tundra occupies the north of the Tyumen region, which occupied Yamal and the Gydan Peninsula. Its area is 160 thousand square kilometers. The tundra is completely covered with moss and lichen, interspersed with hypnum-grass, lichen-sphagnum and large-hummocky marsh landscape.

forest tundra runs from the tundra to the south in an almost flat strip of 100-150 kilometers. As a kind of transitional area from the tundra to the taiga, it looks like a mosaic of swamps, shrubs and light forests. Crooked larches grow in the north of the zone, located in river valleys.

forest zone occupies a strip of about a thousand kilometers. The north and middle of Tyumen, the Tomsk region, the north of the Novosibirsk and Omsk regions fit into this strip. The forest is divided into northern, southern and middle taiga and birch-aspen forests. Most of it is wood with dark needles - Siberian fir, spruce and cedar.

forest-steppe located near deciduous forests. The main representatives of the zone are meadows, swamps, salt marshes and small areas of forests. The forest-steppe is rich in birch and aspen.

Steppe covered the south of the Omsk region, the west of Altai and the southwest Novosibirsk region. The zone is represented by ribbon pine forests.

The rather significant height of the West Siberian Plain in the highlands makes it possible to develop altitudinal zonality. The main place here is given to forests. In addition, there is black taiga, which is characteristic of the mountains of Siberia. In the middle of this taiga there is a "linden island" - a forest area of 150 square kilometers. Most scientists consider this site as a tertiary vegetation.

Geology and orography

In places where the West Siberian Plain is located, the West Siberian Plate is considered the basis. This plate is based on the Paleozoic basement, which is currently located at a depth of about 7 kilometers. The most ancient rocks they come to the surface only in mountainous areas and are hidden in other places by sedimentary rocks. The West Siberian Plain is a rather young submerging platform. The magnitude and rate of subsidence of different sections vary greatly, and therefore the thickness of the cover of loose deposits is also very diverse.

The nature, quantity and size of icing in antiquity is still not really clear. Nevertheless, it is generally accepted that to the north of 60 degrees the entire part of the plain was occupied by glaciers. It is the small number of glaciers that explains the fact that their melting did not leave large moraine accumulations.

Natural resources

Since the plate cover is formed by sedimentary rocks, a large number of fossils cannot be expected here. There are only exogenous deposits - the so-called sedimentary fossils. Among them you can see oil in the south of the plain, gas in the north, coal, peat, iron ore, evaporites.

Climate

West Siberian Plain, geographical position which provides it with such an opportunity, has very interesting climatic characteristics. The fact is that the plain is located almost at the same distance from both the Atlantic and the center of Eurasian continentality. Most of the plain has a temperate continental climate. Due to its northern openness, Western Siberia receives a large amount of arctic masses, bringing cold in winter and not allowing summer to fully manifest itself. Thus, the January temperature from south to north ranges from -15 to -30 degrees, while in July - from +5 to +20. The largest temperature difference - 45 degrees - is observed in the north-east of Siberia.

Reasons for the severity of the climate

Such a rather harsh climate has formed for several reasons.

The West Siberian Plain is located for the most part in temperate latitudes, which leads to a rather small amount of solar radiation that enters the territory.

Considerable remoteness from the Pacific and Atlantic oceans made it possible to develop a continental climate.

The flat topography of the West Siberian Plain allows a large amount of Arctic air to go further south than in other regions, while allowing warm flows from Central Asia and Kazakhstan to fall deep to the north.

Mountains that fenced off the plain from the west from the air currents of the Atlantic and from the southeast from Central Asia.

Relief

The West Siberian Plain has long been considered an "exemplary" lowland plain. The reason for this is the fact that on almost the entire surface its absolute height is below 200 meters. Above this there are only small areas. For a long time on the maps, the entire plain was painted in a uniform color, not taking into account these small rises in height. However, upon closer examination, it became clear that the orography is not so simple. Plains with a height of more than 100 meters are very clearly distinguished.

Biodiversity

The West Siberian Plain is in such climatic conditions that contribute to the formation of too little diversity for such significant territories. The poor choice of higher plants is especially noticeable. On average, the flora in this region is poorer by almost 1.5 times compared to neighboring regions. This difference is especially noticeable in the taiga and tundra zones. The nature of Western Siberia is the most diverse for the region.

The reason for such a limited flora is the same glaciation, which turned out to be devastating for the region. In addition, mountain rephigia, which could feed the migration flow, are at a sufficient distance.

Animal world

Despite the considerable length of the West Siberian Plain, the fauna here also cannot boast of diversity. The only exception can be considered only Western Siberia, on the territory of which a fairly large number of different animals live. For example, more than 80 species of mammals from four main orders have been identified in this area. Of this set, 13 species are common with Eastern Siberia, 16 - with the European part of Russia, 51 - common to the entire territory of Eurasia. There are no unique animals that would live only where the West Siberian Plain is located.

Inland waters

Rivers The West Siberian Plain mainly belong to the Kara Sea basin. All of them are mostly fed by melting snow, thus referring to the West Siberian type of intra-annual runoff. High water in this type is more extended in time, but at the same time, the water discharge in this period is practically indistinguishable from the rest of the time. The reason for this is the natural regulation of runoff. Accordingly, the runoff in the summer is replenished with the waters of floodplains and marshes, in which flood water was “saved”. In winter, only the ground method of water saturation remains, which almost catastrophically reduces the oxygen content in the water. For this reason, the fish that live in the rivers are forced to accumulate in the whirlpools, which is why they are almost constantly in a state of drowsiness.

The groundwater The region is part of the West Siberian hydrogeological basin. The characteristics of these waters fully correspond to the zonal distribution. Given the direction of the West Siberian Plain, it becomes clear that most of these waters are almost on the surface, while remaining very cold. However, when moving south, it becomes clear that the depth of the waters, their temperature, and saturation with minerals also increase. The water in the south is saturated with calcium, sulfate, chlorides. In the very south, there are so many of these compounds in the water that its taste becomes salty and bitter.

swamps with the existing low-lying relief, they are one of the dominant components of the water masses of the plain. Their area and the degree of swampiness are very large. Some researchers believe that the swamps of the region are aggressive, not only remaining in their original form, but also gradually growing, capturing more and more new territories. This process is currently irreversible.

Administrative division

The West Siberian Plain, whose geographical location suggests a rather diverse administrative use, placed on itself many areas and edges. So, these are Tomsk, Novosibirsk, Tyumen, Omsk, Kemerovo regions. Partially, this also includes the Sverdlovsk, Kurgan and Chelyabinsk regions. In addition, parts of the Krasnoyarsk and Altai Territories are located on the plain. The largest city is Novosibirsk, it has about 1.5 million inhabitants. The city is located on the Ob River.

Economic use

On the territory of Western Siberia, the most developed industries are the mining and timber industries. Today, this territory supplies more than 70% of all oil and natural gas produced in our country. Coal - more than 30% of the all-Russian production. And about 20% of the wood harvested by our country.

In Western Siberia today there is a huge oil and gas production complex. In the thickness of sedimentary rocks are the largest deposits of natural gas and oil. The area of land rich in these minerals is more than two million square kilometers. Until the 1960s, the landscapes of Siberia were almost untouched by industry, but at present they are dotted with pipelines, power lines, drilling sites, roads, spoiled by oil spills, killed by burning, blackened by soaked forests that arose as a result of the use of outdated technologies in transportation and production. fossils.

Do not forget that this region, like no other, is rich in rivers, swamps and lakes. This increases the rate of spread of chemical pollution that enters the Ob from small sources. Further, the river takes them out to sea, bringing death and destroying entire ecosystems, even those far removed from the mining complex.

In addition, the Kuznetsk plains mountainous area rich in coal deposits. Mining in this region is about 40% of all coal reserves in our country. The largest coal mining centers are Prokopyevsk and Leninsk-Kuznetsky.

Thus, the West Siberian Plain is not only a refuge for many species of plants and animals, but also plays huge role in the economic and industrial life of our country. Without huge reserves of natural resources, which are the source of production of products necessary for human life, people would simply not be able to live in such a harsh and not very livable climate.