Relief form of Western Siberia. Relief of the West Siberian Plain


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 the Altai Mountains, for 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 Uvals (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 the syneclises of the basement of the plate. 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.

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, the runoff of 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.

Western Siberia. Photo: Bernt Rostad

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.

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.



1. Geographic location.

2. Geological structure and relief.

3. Climate.

4. Internal waters.

5. Soil and vegetation cover and fauna.

6. Natural areas.

Geographical position

The boundary of the West Siberian Plain is clearly expressed in the relief. Its boundaries in the West are 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 southeast 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 mastered by man, its nature has been changed to some extent. The northern and central part 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-Tazovskaya syneclise), in the middle part the depth is 3-4 km. (Sredneobskaya anteclise), to the south, the depth of occurrence decreases. The cover of the plate is represented by Mesozoic and Cenozoic deposits of continental and marine origin.

The territory of the West Siberian plate has repeatedly been subjected to transgressions. The glaciation of Western Siberia was repeated many times: Demyanskoe, Samarovskoe, Tazovskoe, Zyryanskoe and Sartanskoe. Glaciers moved from 2 centers: from the Polar Urals and the Putorana plateau. In contrast to 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 near-glacial reservoirs. In areas free of ice, there was a deep freezing of the soil.

The modern relief of the plain is due to the 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 has leveled the unevenness of the basement. The absolute heights of the plain are 100-150 meters, while within the plains alternating highlands and lowlands. The general slope of the plain is towards the north. Almost the entire northern half of the plain is less than 100 meters high. The marginal parts of the plain are raised up to 200-300 meters. These are the North Sosvinskaya, Verkhnetazovskaya, Lower Yenisei uplands, the Ob plateau, the Ishim and Kulunda plains. The Siberian Ridges are distinctly expressed in the middle part of the plain, extending 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 Nizhneobskaya, Nadymskaya, Purskaya, Tazovskaya, Kondinskaya, Sredneobskaya lowlands. Western Siberia is characterized by: marine accumulative plains (on the Yamal and Gydan Peninsulas), glacial and water-glacial 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 towards the southeast of the plain. The radiation balance is from 15 to 40 kcal/cm2 per year. At the same time, in comparison with the Russian Plain, Western Siberia receives somewhat more solar radiation, due to the lower frequency of cyclones. The western transfer persists, but the influence of the Atlantic is noticeably weakened here. The flatness of the territory promotes deep meridional air exchange. In winter, the climate is formed under the influence of the spur of the Asian High, which stretches along the south of the plain and depression of low pressure over the northern peninsulas. This contributes to the removal of cold continental air from the Asian High to the plain. Winds are dominated by southerly directions. In general, January isotherms are submeridian, from -18˚-20˚С in the west to almost -30˚С in the Yenisei valley. The absolute minimum of Western Siberia is -55˚С. Snowstorms are typical in winter. During the cold period, 20-30% of precipitation falls. Snow cover is established 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 enhanced. 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 largest 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 contributes in many respects 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 of the territory. 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) runoff. All rivers of Western Siberia are characterized by small slopes, with a predominance of lateral erosion. The food of the rivers is mixed, with a predominance of snow, in addition, there is rain and swamp-soil. High water runs from April in the south to June in the north. The rise of water reaches a maximum of 12 meters on the Ob, and 18 meters on the Yenisei. A protracted flood is characteristic, despite the “friendly” spring. The rise is fast, but the fall is very slow. Freeze 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 consider 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 the Lena. The Ob flows into the Ob Bay (estuary). The largest tributary is the Irtysh, and its tributaries are the Ishim, Tobol, 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 dry 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, swampiness reaches 80% (forested swamp zone). The development of swamps is facilitated by: flat relief, poor drainage, excessive moisture, prolonged floods and permafrost. The swamps are rich in peat. According to hydrogeological conditions, the plain is the West Siberian artesian basin.

Land cover and fauna

Soils are arranged as follows from north to south: tundra-gley, podzolic, sod-podzolic, chernozem and chestnut. At the same time, large areas due to waterlogging are occupied by semi-hydromorphic soils. Therefore, most soils, in contrast to their analogues on the Russian Plain, have signs of gleying. Solonetzes and solods are found in the south. 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 peculiarities of the flora. Along with spruce and pine forests, fir, cedar and larch forests are widespread. In the forest-tundra, larch dominates, and not spruce, as on the Russian Plain. Small-leaved forests here are not only secondary, but also indigenous. Mixed forests here are represented by pine-birch. Large areas in Western Siberia are occupied by floodplain vegetation (more than 4% of the plain area), as well as swamp vegetation. The animal world has many similarities with the Russian Plain. In Western Siberia, there are about 500 species of vertebrates, including 80 species of mammals, 350 species of birds, 7 species of amphibians and about 60 species of fish. A certain zonality is observed in the distribution of animals, but along the ribbon forests along the rivers, forest animals penetrate far to the north and south, and inhabitants of polar water bodies are found on the lakes of the steppe zone.

natural areas

Natural areas on the plain extend latitudinally. Zoning is pronounced. Zones and subzones change gradually from north to south: tundra, forest-tundra, forests (forest-bogs), forest-steppe, steppe. Unlike the Russian Plain, there is no zone of mixed and broad-leaved forests, a zone of semi-deserts and deserts. The tundra stretches from the coast of the Kara Sea and almost to the Arctic Circle. The length from north to south is 500-600 km. The polar day and night last here for almost three months. Winter from October to mid-May. The average temperature is from -20˚C in the west to -30˚C in the east. Characterized by winds and blizzards. The snow cover lies for about 9 months. Summer lasts not much more than one month. The average August temperature 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 is in the warm period. Permafrost is ubiquitous, so the tundra is characterized by solifluction processes, thermokarst, polygons, peat mounds, etc. Lots of swamps and lakes. The soils are tundra-gley. The flora is not rich, only about 300 species of higher plants. Vegetation is especially poor on the coast of the sea, where lichen arctic tundra from cladonia, etc. and lichens grow dwarf birch, willow, alder; in some places on the southern slopes and river valleys - buttercups, flames, crowberry, polar poppy, etc. Reindeer, wolves, arctic foxes, lemmings, voles, white partridges, snowy owls live in summer; many marsh and waterfowl (waders, sandpipers, 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 the 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 everywhere. Therefore, again, the permafrost relief prevails, and erosion processes are limited. The zone is crossed by many rivers. The soils are gley-podzolic and permafrost-taiga. To the tundra vegetation here are added sparse forests of larch (their height is 6-8 meters). Dwarf birch is widespread, there are many swamps, and floodplain meadows in 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. Here, there is an almost equal ratio of forests on the podzolic soils of the taiga and peat-bog soils of sphagnum bogs. Therefore, the taiga of Western Siberia is often called the forest-bog zone. The climate is temperate continental. Continentality increases from west to east. The average January temperature varies 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. The summer is relatively long, the growing season is from 3 months. in the north up to 5 months. on South. The average July temperature is 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 greater than 1 everywhere. Permafrost is widespread in the north of the zone. Lots of swamps and rivers. Bogs of various types, but ridge-hollow peat bogs predominate, there are ridge-lake and swamp bogs. The 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, 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 forest (nutcracker, smurf, kuksha, capercaillie, 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 severe 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 30-40 cm, annual precipitation 400-450 mm. The moisture coefficient is less than 1. Suffosion processes are typical, there are lakes, some of which are saline. The forest-steppe is a combination of aspen-birch copses on gray forest soils and areas of meadow steppes on chernozems. The forest cover of the zone is from 25% in the north to 5% in the south. The steppes are mostly plowed up. The fauna is represented by forest and steppe species. In the steppes and floodplain meadows, rodents predominate - ground squirrels, hamsters, earth hare, voles, there is a hare. Foxes, wolves, weasels, ermines, polecats, white hare, roe deer, black grouses, partridges are found in the groves, in reservoirs 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, the climate is more continental (little precipitation, cold winters). The average temperature in January is -17˚C-19˚C, and in July +20˚C+22˚C. The annual rainfall is 350-400 mm, with 75% of precipitation falling in summer. Moisture coefficient from 0.7 in the north to 0.5 in the south of the zone. In summer, there are droughts and hot winds, which leads to dust storms. The rivers are transit, small rivers dry up in summer. There are many lakes, mostly of suffusion origin, almost all of them are salty. The soils are chernozem, dark chestnut in the south. There are salt marshes. The plowing of the steppes reaches 90%. Various feather grasses, fescue, thyme, sagebrush, wormwood, iris, steppe onions, tulips, etc. grow in the surviving areas of the steppes. Saltwort, licorice, sweet clover, wormwood, chiy, etc. grow in saline areas. In more humid places there are shrubs from caragana , spirea, wild rose, honeysuckle, etc., along the river valleys, pine forests come to the south. In the floodplains of the rivers there are swampy meadows. The fauna is represented by various rodents (ground squirrel, hamster, marmots, voles, pikas, etc.), predators include steppe polecat, corsac, wolf, weasel, birds - steppe eagle, buzzard, kestrel, larks; on the lakes - waterfowl. Four reserves have been created in Western Siberia: Malaya Sosva, Yugansky, Verkhne-Tazovsky, Gydansky.

Geological structure of Western Siberia

The basis of the West Siberian Plain is a young plate of the same name. The plate in the east borders on the Siberian platform, from the south Paleozoic structures of Central Kazakhstan, Altai, the Salair-Sayan region approach it, and in the west the border goes with the folded system of the Urals. It is difficult to determine the northern border, because it is covered by the waters of the Kara Sea. The basis of the West Siberian Plate is the Paleozoic basement, with an average depth of $7$ km. In the mountainous regions of the southeastern part, ancient Precambrian and Paleozoic rocks come to the surface, and within the West Siberian Plain they are hidden by a thick cover of sedimentary rocks.

The West Siberian plate began its formation in the Mesozoic era, in the Upper Jurassic period. At this time, the area between the Urals and the Siberian platform sank, resulting in a huge sedimentation basin. Marine transgressions captured the West Siberian plate more than once in the course of its development. In the Lower Oligocene, the plate was freed from the sea and turned into a huge lacustrine-alluvial plain. A new uplift of the northern part of the plate occurs in the late Oligocene and Neogene, and in the Quaternary period of the Cenozoic era, the plate sinks again. The development of the plate occurs in a way that resembles the process of oceanization and the development of swamps.

The foundation of the slab is divided into two parts:

  1. External instrument belt. It is represented by slopes of mountain-folded framing descending towards the central part of the depression. The foundation is located at a depth of $2.5$ km. In the southwest of the Kustanai saddle, it approaches the surface by only $300$-$400$ m.
  2. Inner area. It is divided into two stages: the southern stage is the Sredneobskaya mega-anteclise with a basement depth of up to $4$ km and the northern stage is the Yamalo-Taz mega-syneclise lowered to a depth of up to $12$ km.

Between the sedimentary cover and the basement of the plate lies a transitional complex, the age of which is Triassic-Lower Jurassic. The basement underwent extension and, as a result, an intracontinental rift zone with a system of graben-like depressions was formed. The basins were the place of accumulation of sedimentary-volcanic and sedimentary coal-bearing continental sequences up to $5$ km thick. The transitional complex also contains igneous rocks represented by basaltic lavas and tuffs.

The development of the intracontinental rift zone within Western Siberia did not lead to the formation of a new ocean. Almost continuous formation of the cover under conditions of plate subsidence took place in the Mesozoic and Cenozoic eras. It is composed of sandy-siltstone coastal-continental deposits and marine clayey and sandy-clayey strata. Their thickness reaches $4$ km in the southern part and $7$-$8$ km in the northern part. Numerous local structures are expressed in the sedimentary cover. These are mainly reservoirs of oil and gas.

The general orographic features of Western Siberia were already formed by the end of the Neogene. The sea level was $200$-$250m lower than the modern one, and a significant part of the bottom of the Kara Sea was land. At the end of the Neogene, a general cooling of the climate and the development of the Quaternary glaciation began.

Relief of Western Siberia

The development of modern relief in Western Siberia was greatly influenced by the geological development of the territory, tectonic structure, and exogenous relief-forming processes. The irregularities of the foundation were leveled as a result of the accumulation of a thick layer of loose deposits. The periphery of the plain has a small amplitude of uplifts, reaching $100$-$150$ m. The central and northern parts of the plain are characterized by subsidence of $100$-$150$ m. Nevertheless, a number of lowlands and uplands can be distinguished. The plain is open to the north, to the Kara Sea, and has the form of a stepped amphitheatre.

There are three altitudinal levels on the territory of the West Siberian Plain:

  1. The first level has a height of less than $100$ m and occupies half of the territory;
  2. The second level is at an altitude of $100$-$150$ m;
  3. The third level is located in the range of $150$-$200$ m with small sections from $250$-$300$ m.

The edges of the plain have a higher level and are represented by the North Sosvinskaya, Verkhnetazovsky, Lower Yenisei uplands, the Ob plateau, the Turinskaya, Ishimskaya, Kulundinskaya, Ketsko-Tymskaya plains. The northern and central parts of the plain are represented by areas below $100$ m. These are the lowest parts of the plain. Less than $50$ m in height are the Nizhneobskaya, Nadymskaya, Purskaya, Tazovskaya, Kondinskaya lowlands. In the inner parts of the plain there is a strip of distinctly pronounced uplands - Verkhnetazovskaya, Numto ridge, Belogorsky mainland, Lyulimvor.

From the orographic point of view, the elevation of the plain along the edges and the lowering of the plate surface towards the center are clearly visible. The interior regions of the plain, where thick Mesozoic deposits occur, are already losing the clarity of expression in the relief of large basement structures. The number of inversion structures is growing. The Vasyugan Plain, for example, is nothing but an anteclise located within the syneclise. Within the inner zone, under the conditions of recent subsidence, the formation of accumulative and reservoir-accumulative plains took place. They are composed of Neogene-Quaternary loose deposits.

The types of morphosculptures created by exogenous relief-forming processes are located on the plain in the direction from north to south. Off the coast of the Kara Sea there are sea plains. They were formed in the postglacial period after the retreat of the sea. Moraine and water-glacial plains are located to the south. Here they are adjoined by glacial, lacustrine-alluvial plains.

Minerals of Western Siberia

The main wealth of the West Siberian Plain is hydrocarbons - oil and gas. Experts estimate the area of ​​promising oil and gas fields at $1.7 million sq. km. Such large deposits as Samotlor, Megionskoe, located in the region of Nizhnevartovsk, are connected with the middle Priobye. Large deposits in the Surgut region are Ust-Balykskoye, Fedorovskoye, etc.

Natural gas in the Subpolar region - the field Medvezhye, Urengoy, in the Arctic - Yamburgskoye, Ivankovskoye, etc. There is oil and gas in the Urals, and new promising fields have been discovered on the Yamal Peninsula. In general, more than $300$ of oil and gas fields have been discovered on the plain.

In addition to hydrocarbons, large deposits are known in Western Siberia hard coal, the main reserves of which are located within the Kuzbass. Kuznetsk coal reserves are estimated at $600 billion tons. Almost $30$% of these coals are coking. The large thickness of coal seams and close location to the surface allow their development not only by mine, but also by open pit. Brown Kansk-Achinsk coals occur to the northeast of the Kuznetsk basin. In the largest Itatskoye field, the thickness of the seams reaches $80$ meters, and the depth of occurrence is from $10$ to $220$ meters. The cheapest coal in Russia is mined here. Anthracite coals are concentrated in the Gorlovsky basin, located in the south of the Novosibirsk region. Brown coals of the Tyumen region have not yet been put into operation.

Of the fuel resources in the depths of the West Siberian Plain is $50$% of the total Russian reserves peat.

Stands out for its reserves and ore base. Significant resources of iron ore are concentrated in the Narymskoye, Kolpashevskoye, Yuzhno-Kolpashevskoye deposits. Brown ironstones lie here. Mountain Shoria is characterized by deposits of magnesium ores - these are Tashtagol, Sheregesh. In Altai - Inskoye, Beloretskoye deposits. There are deposits of manganese ores, nephelines in the Kemerovo region. Place of Birth mercury in Altai.

The lakes of the Kulunda steppe contain reserves soda and salt.

Limestones in the Novosibirsk and Kemerovo regions.

Altai has significant reserves building materials.

In addition to minerals, Western Siberia is rich in forest resources. Timber stocks make up $11$% of Russian stocks.

Remark 1

The issues of protection and rational use of natural resources are relevant for Western Siberia as well. The thoughtless use of resources can ruin the environment and lead to negative consequences.

The West Siberian Plain (it will not be difficult to find it on the world map) is one of the largest in Eurasia. It stretches for 2500 km from the harsh shores of the Arctic Ocean to the semi-desert territories of Kazakhstan and for 1500 km from the Ural Mountains to the mighty Yenisei. The whole area consists of two bowl-shaped flat depressions and many wetlands. Between these depressions stretch the Siberian Ridges, which rise to 180-200 meters.

The West Siberian Plain is a rather interesting and fascinating moment that deserves detailed consideration. This natural object is located almost at the same distance between the Atlantic and the center of continentality of the mainland. About 2.5 million sq. km covers the area of ​​​​this huge plain. This distance is very impressive.

Climatic conditions

The geographical position of the West Siberian Plain on the mainland causes interesting climatic conditions. Therefore, the weather in most of the plain has a temperate continental character. From the north, large arctic masses enter this territory, which bring with them severe cold in winter, and in summer the thermometer shows from + 5 ° С to + 20 ° С. In January, on the southern and northern sides, the temperature regime can range from -15 °С to -30 °С. The lowest indicator in winter was recorded in the north-east of Siberia - down to -45 °С.

Humidity on the plain also spreads gradually from south to north. With the beginning of summer, most of it falls on the steppe zone. In the middle of summer, in July, the heat takes possession of the entire south of the plain, and the humid front moves to the north, thunderstorms and downpours sweep over the taiga. At the end of August, the rains reach the tundra zone.

water streams

Describing the geographical position of the West Siberian Plain, it is necessary to talk about the water system. A huge number of rivers flow through this territory, as well as numerous lakes and swamps. The largest and most full-flowing river is the Ob with a tributary of the Irtysh. It is not only the largest in the region, but also one of the greatest in the world. In terms of its area and length, the Ob dominates among the rivers of Russia. The water streams Pur, Nadym, Tobol and Taz, suitable for navigation, also flow here.

Plain in terms of the number of swamps is the world record holder. Such a vast territory cannot be found on the globe. Marshes occupy an area of ​​800 thousand square meters. km. There are several reasons for their formation: excessive moisture, a flat surface of the plain, a large amount of peat, and low air temperature.

Minerals

This region is rich in minerals. This is largely influenced by the geographical position of the West Siberian Plain. Oil and gas deposits are concentrated here in huge quantities. On its vast swampy areas there is a large supply of peat - approximately 60% of the total amount in Russia. There are iron ore deposits. Siberia is also rich in its hot waters, which contain salts of carbonates, chlorides, bromine and iodine.

Animal and plant worlds

The climate of the plain is such that the flora here is quite poor compared to neighboring regions. This is especially noticeable in the taiga and tundra zone. The reason for such a poverty of plants is perennial glaciation, which does not allow plants to spread.

The fauna of the plain is also not very rich, despite the vast extent of the territories. The geographical position of the West Siberian Plain is such that it is almost impossible to meet interesting individuals here. There are no unique animals living only in this territory. All species that live here are common with the rest of the regions, both neighboring ones, and the entire mainland of Eurasia.

Features of the geographical position of Western Siberia

Remark 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 seas of the Arctic Ocean. The southern borders approach the Kazakh uplands and the Turgai plateau. The total area of ​​the plain is about $3$ million km$²$.

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

  • insignificant fluctuation of heights in such a vast territory;
  • the length from north to south and an almost flat relief led to a clear change in natural zones with latitude (classical latitudinal zonality);
  • formation of the largest swamp areas in the taiga and salt accumulation landscapes in the steppe zone;
  • a transitional climate is formed from the temperate continental of the Russian Plain to the sharply continental of Central Siberia.

The 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 basement of the slab contains metamorphosed rocks. The foundation sinks towards the center of the slab. The total thickness of the sedimentary cover exceeds $4$ km (up to $6-7$ km in some areas).

As already mentioned, the foundation of the slab was formed as a result of the Hercynian orogeny. Further there was a peneplenization (leveling of a relief by means of erosive processes) of the ancient mountainous country. In the Paleozoic and Mesozoic, troughs form in the center, and the foundation was flooded by the sea. Therefore, it is covered with a significant thickness of Mesozoic deposits.

Later, during the era of the Caledonian folding, 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 a sedimentary rock mass predominated. Sedimentation continued into the Cenozoic. During the Ice Age, the north of the plain was under the thickness of the 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, the geological history determined the formation of a 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.

Large relief elements on the territory of the plain are:

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

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

  • Kandinsky;
  • Nizhneobskaya;
  • Nadymskaya;
  • Purskoy.

Among the plateau, the Ob plateau stands out. And the elevations are presented:

  • Severo-Sosvinskaya;
  • Turin;
  • Ishimskaya;
  • Chulym-Yenisei and others.

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

Remark 2

Currently, human economic activity plays an important relief-forming role. The development of Western Siberia is accompanied by the development of minerals. 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, a large amount of minerals is introduced into the soil. Chemical erosion develops. It is necessary to take a balanced approach to the development of the nature of Siberia.

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