Relief of the West Siberian Plain. West Siberian Lowland: characteristics

The vast territory of the Russian Federation is located on 2 continents - Europe and Asia, which border each other along the line of the Ural Mountains. In the west of the Asian part Russian state, between the Ural Mountains and Far East, the expanses of Siberia are located. In accordance with tectonic boundaries and characteristics of geographical zones, it is divided into several natural areas. In a more generalized form, Siberia is divided into 2 parts - Western and Eastern.

The basis of Western Siberia

The fundamental element of this region is the lowland, which is called West Siberian Plain. The geographical feature constitutes approximately 80% of the entire geographical region, which is approximately equal to 3 million km². On the map, its boundaries resemble a trapezoid with a wide base (south) and a narrow apex (north).

Boundaries of the Plain

From the west it is supported by the mountain ranges of the Urals.
On the opposite side it is limited by the Yenisei watershed.
On the southern side – the Kazakhstan small hills of Sary-Arka and the foothills of the Altai Territory.
The north of the lowland is outlined by the winding coast of the Kara Sea and its bays.

Character traits

There are several features that most clearly characterize the West Siberian Plain:

The fluctuation in heights has a very small amplitude (only 200 m) for such a large space.
Natural-climatic zones in the north-south direction are widely covered, tied to latitudes and have distinct transitions, which is due to their large extent and flat topography. This latitudinal zonation is called classical.
The absence of slopes at the surface forms a large number of swamp landscapes in the northern part of the lowland and salt accumulation landscapes in the southern part.
The climate is transitional between moderate continental in the west and sharply continental in the east.

Geological structure

The tectonic plate on which the West Siberian Plain is located bears the same name. The plate belongs to the Hercynian orogeny, characterized by the collapse of sediments into mountain folds - the Hercynides. In accordance with the name of the era of tectogenesis, the plate is also called Hercynian or Epihercynian.

The foundation of the plate was based on Paleozoic sediments, which, as a result of subsequent tectonic movements (folded dislocation), changed the original structure of the formations.

At the end of the Jurassic period, due to destruction and fractures, a huge section of the mountain formation sank below sea level. The result was the formation of a new basin followed by sedimentogenesis (deposition of particles).

In the last Paleogene era, a reverse movement occurred, the plate rose and got rid of the waters of the world's oceans. However, this was not the end of the alternating lowering and raising of the slab - it was repeated again.

Therefore, a powerful, leveling cover of loose substance, both marine and continental deposits of the Mesozoic-Cenozoic, was formed on top of the Hercynides basement. Ice ages added moraine deposits in the northern part.

The average thickness of the sedimentary cover is more than 1 km, and in low areas of the basement the thickness reaches 4 km.

Relief characteristics

Despite the meager elevation difference, the plain still has a varied topography. That is, here you can observe the presence of both lowlands and hills. There are also sloping plains in the range of reliefs. Also present sufficient quantity plateau.

The north and center are represented mainly by low areas, among which the following lowlands can be noted:

Nizhneobskaya, Nadymskaya and Purskaya in the north
Kondinskaya and Sredneobskaya in the center

Elevated areas are located mainly on 3 sides on the periphery, among which are:

North Sosva Upland and Turin Sloping Plain in the west
Ishim steppe, Chulym-Yenisei and Priob plateaus in the south
Ket-Tym Upland in the east

Some terrain changes in Lately occur as a result of human activities - mining and agriculture. As a result of disruption of the natural structure of rocks, as well as chemicalization of the soil with fertilizers, erosion processes are accelerated.

The Russian Federation has one of the largest plains in area located on the surface of the globe. In the north, its border is the Kara Sea. In the south it extends to the space of the Kazakh fine sand. The eastern part is the Central Siberian Plateau. The border in the west becomes ancient. The total area of this flat space is almost 3 million kilometers.

In contact with

Relief features

The territory where the West Siberian Plain is located was formed a long time ago and has successfully survived all tectonic shocks.

It is strictly limited by officially recognized coordinates of the extreme points:

on the mainland part of the space the extreme eastern point becomes Cape Dezhnev, 169°42′ W. d.;
in the north, Cape Chelyuskin (Russia), 77°43′ N becomes such a point. sh.;
coordinates 60° 00′ N. w. 100° 00′ E. d.

Hills

The altitude above sea level of the space under consideration is characterized by minimal differences.

It is shaped like a shallow dish. Elevation differences vary from 50 (minimum) to more than 100 meters in low areas, the prevailing heights up to 200-250 meters located on the southern, western and eastern outskirts. On the northern outskirts, the landscape rise is about 100-150 meters.

This is due to the location of the plain in the space of the Epihercynian plate, the basis of which is the foundation created by the overlay of Paleozoic sediments. This plate began to form in the Upper Jurassic period, the so-called Upper Jurassic.

During the formation of the surface layer of the planet, the flat terrain sank, turned into a lowland and became a sedimentation basin. The site is located on an area located between the Urals and the Siberian platform.

Average values

This space is one of the largest low-lying areas on the planet, a type of accumulative plain, and has an average height of 200 meters. Low-lying areas are located in the central part of the square, on northern areas, on the borders of the Kara Sea. Almost half space is located at an altitude below 100 meters above sea level. This ancient section of the earth’s space also has its own “elevations,” smoothed out over billions of years since its creation. For example, the North Sosvinskaya Upland (290 meters). The Verkhnetazovskaya Upland rises to 285 meters.

Low places

The surface has a concave shape with minimal heights in the central part. The average minimum height is 100 meters. Counting is carried out according to tradition from sea level.

Fully justifies the name “plain”. The height differences in the colossal space are minimal.

This feature also shapes the continental climate. Frosts in some areas can reach up to -50 degrees Celsius. Such indicators are noted, for example, in Barnaul.

In absolute terms, this territory is also not distinguished by large numbers. The absolute height here is only 290 meters. Parameters were recorded on the North Sosvenskaya Upland. In most of the plain the figure is 100-150 meters.

This geographical object occupies 1/7 of the Russian Federation. The plain extends from the Kara Sea in the north to the Kazakh steppes in the south. In the west it is limited by the Ural Mountains. The size is almost 3 million kilometers.

Characteristic

The general characteristics are based on the process of formation of the plain during the most ancient stages of the development of the planet and the long-term leveling of the surface during the passage of glacial masses. This explains the monotony of the smoothed relief. Due to this, the space is strictly zoned. The north is distinguished by tundra and the south - steppe landscapes. The soil is minimally drained. Most of it is occupied by swampy forests and swamps. Such hydromorphic complexes occupy a lot of space, about 128 million hectares. The south of the plain is characterized by a large number of spaces such as different kinds solods, solonetzes and large-sized solonchaks.

Note! The climate of the plain due to its large area ranges from moderately continental on the Russian Plain to sharply continental. Central Siberia is distinguished by this indicator.

For a long time, people have lived on the West Siberian Plain. Already in the 11th century, Novgorodians came here. Then they reached the lower reaches of the Ob. The period of opening up space for the Russian state is associated with the legendary campaigns of Ermak from 1581 to 1584. It was at this time that many discoveries of lands were made in Siberia. The study of nature was carried out and described in the 18th century during the Great Northern and Academic Expeditions. Development in these areas continued in the following decades. It was related:

with the resettlement of the peasantry from Central Russia in the 19th century;
planning the construction of the Siberian Railway

Detailed soil and geographic Maps of this land. Active development of the territories continued in the years after the change state power in 1917 onwards.

As a result, today it has become inhabited and mastered by people. Here are located such large regions of Russia as Pavlodar, Kustanai, Kokchetav regions, Altai Territory, western regions Krasnoyarsk Territory, eastern territories Sverdlovsk and Chelyabinsk regions.

About 150 years ago, the role of Siberia as a kind of bridge between the European part of Russia and its eastern part. In our time, the role of this territory as an economic bridge, especially with the construction of the Baikal-Amur Mainline, has finally taken shape, using all types of transport for development.

Note! The active development of territories is largely due to large volumes of deposits: natural gas, oil, brown coals, iron ores and many others.

The successful development of the territory was facilitated by a large number of large, for the most part shipping, especially such giants as Ob, Irtysh, Yenisei. Nowadays, rivers are convenient transport routes and are used to generate energy to provide high level quality of life of the regional population.

Age indicator

The basis of the smooth and level flat surface east of the Ural Mountains is a plate formed during the Paleozoic period. According to the parameters of the formation of the planet’s surface, this plate is quite young. Over millions of years of formation, the surface of the plate was covered with Mesozoic and Cenozoic sediments.

According to their characteristics, they belong to the type of sea and sand- clay deposits. Layer thickness is up to 1000 meters. In the southern part, deposits in the form of loess reach a thickness of 200 meters, formed due to the presence of lacustrine sediment formation areas in these areas.

WEST SIBERIAN PLAIN, The West Siberian Lowland, one of the largest plains on the globe (third largest after the Amazon and East European plains), in northern Asia, Russia and Kazakhstan. Occupies the entire Western Siberia, stretching from the coast of the Arctic Ocean in the north to the Turgai plateau and the Kazakh small hills in the south, from the Urals in the west to the Central Siberian Plateau in the east. The length from north to south is up to 2500 km, from west to east from 900 km in the north to 2000 km in the south. The area is about 3 million km 2, including 2.6 million km 2 in Russia. The prevailing heights do not exceed 150 m. The lowest parts of the plain (50–100 m) are located mainly in the central (Kondinskaya and Sredneobskaya lowlands) and northern (Lower Obskaya, Nadymskaya and Purskaya lowlands) parts. The highest point of the West Siberian Plain - up to 317 m - is located on the Ob Plateau.

At the base of the West Siberian Plain lies West Siberian Platform. In the east it borders Siberian platform, in the south - with the Paleozoic structures of Central Kazakhstan, the Altai-Sayan region, in the west - with the folded system of the Urals.

Relief

The surface is a low accumulative plain with a fairly uniform topography (more uniform than the relief of the East European Plain), the main elements of which are wide flat interfluves and river valleys; Characterized by various forms of manifestation of permafrost (extended up to 59 ° N latitude), increased swampiness and developed (mainly in the south in loose rocks and soils) ancient and modern salt accumulation. In the north, in the area of distribution of marine accumulative and moraine plains (Nadym and Pur lowlands), the general flatness of the territory is broken by moraine gently ridged and hilly-ridged (North-Sosvinskaya, Lyulimvor, Verkhne-, Srednetazovskaya, etc.) hills with a height of 200–300 m, whose southern border runs around 61–62°N. sh.; they are covered in a horseshoe shape from the south by flat-topped hills, including the Poluyskaya Upland, the Belogorsk Continent, the Tobolsk Continent, the Sibirskie Uvaly (245 m), etc. In the north, exogenous permafrost processes (thermoerosion, soil heaving, solifluction) are widespread, deflation is common on sandy surfaces, in swamps there is peat accumulation. On the Yamal, Tazovsky and Gydansky peninsulas, permafrost is widespread; The thickness of the frozen layer is very significant (up to 300–600 m).

To the south, the area of moraine relief is adjacent to flat lacustrine and lacustrine-alluvial lowlands, the lowest (40–80 m high) and the most swampy of which are the Kondinskaya lowland and the Middle Ob lowland with the Surgut lowland (height 105 m). This territory, not covered by Quaternary glaciation (south of the Ivdel-Ishim-Novosibirsk-Tomsk-Krasnoyarsk line), is a weakly dissected denudation plain, rising to 250 m to the west, to the foot of the Urals. In the area between the Tobol and Irtysh rivers there is a sloping, in some places with ragged ridges, lacustrine-alluvial Ishim Plain(120–220 m) with a thin cover of loess-like loams and loess overlying salt-bearing clays. Adjacent to it are alluvial Baraba Lowland, Vasyugan Plain and Kulunda Plain, where the processes of deflation and modern salt accumulation are developed. In the foothills of Altai there are the Priob Plateau and the Chulym Plain.

For geological structure and mineral resources, see Art. West Siberian Platform ,

Climate

The West Siberian Plain is dominated by a harsh, continental climate. The significant extent of the territory from north to south determines the well-defined latitudinal zonation of the climate and noticeable differences in the climatic conditions of the northern and southern parts of the plain. The nature of the climate is significantly influenced by the Arctic Ocean, as well as the flat terrain, which facilitates the unhindered exchange of air masses between north and south. Winter in polar latitudes is severe and lasts up to 8 months (the polar night lasts almost 3 months); The average January temperature is from –23 to –30 °C. In the central part of the plain, winter lasts almost 7 months; The average temperature in January is from –20 to –22 °C. In the southern part of the plain, where the influence of the Asian anticyclone increases, at the same average monthly temperatures, winter is shorter - 5–6 months. The minimum air temperature is –56 °C. The duration of snow cover in the northern regions reaches 240–270 days, and in the southern regions – 160–170 days. The thickness of the snow cover in the tundra and steppe zones is 20–40 cm, in the forest zone – from 50–60 cm in the west to 70–100 cm in the east. In summer, the westerly transport of Atlantic air masses predominates with invasions of cold Arctic air in the north, and dry warm air masses from Kazakhstan and Central Asia in the south. In the north of the plain, summer, which begins under polar day conditions, is short, cool and humid; in the central part it is moderately warm and humid, in the south it is arid and dry with hot winds and dust storms. The average July temperature increases from 5 °C in the Far North to 21–22 °C in the south. The duration of the growing season in the south is 175–180 days. Atmospheric precipitation falls mainly in summer (from May to October - up to 80% of precipitation). The most precipitation - up to 600 mm per year - falls in the forest zone; the wettest ones are the Kondinskaya and Sredneobskaya lowlands. To the north and south, in the tundra and steppe zones, the annual precipitation gradually decreases to 250 mm.

Surface water

More than 2,000 rivers flowing through the West Siberian Plain belong to the Arctic Ocean basin. Their total flow is about 1200 km 3 of water per year; up to 80% of the annual runoff occurs in spring and summer. The largest rivers - the Ob, Yenisei, Irtysh, Taz and their tributaries - flow in well-developed deep (up to 50–80 m) valleys with a steep right bank and a system of low terraces on the left bank. The rivers are fed by mixed water (snow and rain), the spring flood is extended, and the low water period is long in summer, autumn and winter. All rivers are characterized by slight slopes and low flow speeds. Ice cover on rivers lasts up to 8 months in the north, and up to 5 months in the south. Large rivers are navigable, are important rafting and transport routes and, in addition, have large reserves of hydropower resources.

There are about 1 million lakes on the West Siberian Plain, total area of which there are more than 100 thousand km 2. The largest lakes are Chany, Ubinskoye, Kulundinskoye, etc. Lakes of thermokarst and moraine-glacial origin are common in the north. In the suffusion depressions there are many small lakes (less than 1 km2): in the interfluve of the Tobol and Irtysh - more than 1500, in the Barabinskaya Lowland - 2500, among them many are fresh, salty and bitter-salty; There are self-sedating lakes. The West Siberian Plain is distinguished by a record number of swamps per unit area (the area of the wetland is about 800 thousand km 2).

Types of landscapes

The uniformity of the relief of the vast West Siberian Plain determines a clearly defined latitudinal zonation of landscapes, although in comparison with the East European Plain natural areas here they are shifted to the north; landscape differences within the zones are less noticeable than on the East European Plain, and the zone deciduous forests absent. Due to the poor drainage of the territory, hydromorphic complexes play a prominent role: swamps and swampy forests occupy about 128 million hectares here, and in the steppe and forest-steppe zones there are many solonetzes, solods and solonchaks.

On the Yamal, Tazovsky and Gydansky peninsulas, in conditions of continuous permafrost, landscapes of the Arctic and subarctic tundra with moss, lichen and shrub (dwarf birch, willow, alder) vegetation were formed on gley soils, peat gley soils, peat podburs and turf soils. Polygonal grass-hypnum bogs are widespread. The share of indigenous landscapes is extremely small. To the south, tundra landscapes and swamps (mostly flat-hilly) are combined with larch and spruce-larch woodlands on podzolic-gley and peat-podzolic-gley soils, forming a narrow zone of forest-tundra, transitional to the forest (forest-swamp) zone of the temperate zone, represented by the subzones northern, middle and southern taiga. What is common to all subzones is swampiness: over 50% of the northern taiga, about 70% - middle, about 50% - southern. The northern taiga is characterized by flat- and large-hilly raised bogs, the middle one - ridge-hollow and ridge-lake bogs, the southern one - hollow-ridge, pine-shrub-sphagnum, transitional sedge-sphagnum and lowland tree-sedge. The largest swamp massif - Vasyugan Plain. Forest complexes of different subzones are unique, formed on slopes with varying degrees of drainage.

Northern taiga forests on permafrost are represented by sparse, low-growing, heavily swampy, pine, pine-spruce and spruce-fir forests on gley-podzolic and podzolic-gley soils. Indigenous landscapes of the northern taiga occupy 11% of the plain's area. Indigenous landscapes in the middle taiga occupy 6% of the area of the West Siberian Plain, in the southern - 4%. What is common to the forest landscapes of the middle and southern taiga is the wide distribution of lichen and dwarf-sphagnum pine forests on sandy and sandy loam ferruginous and illuvial-humus podzols. On loam soils in the middle taiga, along with extensive swamps, there are spruce-cedar forests with larch and birch forests on podzolic, podzolic-gley, peat-podzolic-gley and gley peat-podzols.

In the subzone of the southern taiga on loams - spruce-fir and fir-cedar (including urmans - dense dark coniferous forests with a predominance of fir), small grass forests and birch forests with aspen on sod-podzolic and sod-podzolic-gley (including with a second humus horizon) and peat-podzolic-gley soils.

The subtaiga zone is represented by parkland pine, birch and birch-aspen forests on gray, gray gley and soddy-podzolic soils (including with a second humus horizon) in combination with steppe meadows on cryptogleyed chernozems, sometimes solonetzic. Indigenous forest and meadow landscapes have practically not been preserved. Swampy forests turn into lowland sedge-hypnum (with ryams) and sedge-reed bogs (about 40% of the zone's territory). For forest-steppe landscapes of sloping plains with loess-like and loess covers on salt-bearing tertiary clays, birch and aspen-birch groves on gray soils and malts in combination with forb-grass steppe meadows on leached and cryptogleyed chernozems are typical, to the south - with meadow steppes on ordinary chernozems, places mi solonetzic and solonchakous. There are pine forests on the sands. Up to 20% of the zone is occupied by eutrophic reed-sedge bogs. In the steppe zone, indigenous landscapes have not been preserved; in the past, these were forb-feather grass steppe meadows on ordinary and southern chernozems, sometimes saline, and in the drier southern regions - fescue-feather grass steppes on chestnut and cryptogley soils, gley solonetzes and solonchaks.

Environmental problems and protected natural areas

In oil production areas, due to pipeline breaks, water and soil are polluted with oil and petroleum products. In forestry areas there are overcuttings, waterlogging, the spread of silkworms, and fires. In agricultural landscapes there is an acute problem of lack of fresh water, secondary salinization of soils, destruction of soil structure and loss of soil fertility during plowing, drought and dust storms. In the north, there is degradation of reindeer pastures, in particular due to overgrazing, which leads to a sharp reduction in their biodiversity. No less important is the problem of preserving hunting grounds and places natural habitat fauna.

Numerous reserves, national and natural parks have been created to study and protect typical and rare natural landscapes. Among the largest reserves: in the tundra - Gydansky Reserve, in the northern taiga - Verkhnetazovsky Reserve, in the middle taiga - Yugansky Reserve and Malaya Sosva, etc. In the sub-taiga it was created national park Pripyshminskie Bors. Natural parks have also been organized: in the tundra - Oleniy Ruchi, in the north. taiga - Numto, Siberian Uvaly, in the middle taiga - Kondinsky lakes, in the forest-steppe - Bird Harbor.

The first acquaintance of Russians with Western Siberia probably took place back in the 11th century, when the Novgorodians visited the lower reaches of the Ob River. With the campaign of Ermak (1582–85), the period of discoveries in Siberia and the development of its territory began.

West Siberian Plain(West Siberian Lowland) is one of the largest accumulative lowland plains on the globe. It extends from the shores of the Kara Sea to the steppes of Kazakhstan and from the Urals in the west to the Central Siberian Plateau in the east. The plain has the shape of a trapezoid tapering towards the north: the distance from its southern border to the northern reaches almost 2500 km, the width is from 800 to 1900 km, and the area is only slightly less than 3 million km 2. It occupies the entire western part of Siberia from the Ural Mountains in the west to the Central Siberian Plateau in the east, and includes regions of Russia and Kazakhstan. Geographical position The West Siberian Plain determines the transitional nature of its climate between the moderate continental Russian Plain and the sharply continental climate of Central Siberia. Therefore, the country’s landscapes are distinguished by a number of peculiar features: the natural zones here are somewhat shifted to the north compared to the Russian Plain, there is no zone of broad-leaved forests, and landscape differences within the zones are less noticeable than on the Russian Plain.

Geological structure and history of development

The West Siberian Plain is located within the epi-Hercynian West Siberian plate, the foundation of which is composed of intensely dislocated and metamorphosed Paleozoic sediments, similar in nature to similar rocks of the Urals, and in the south of the Kazakh hills. The formation of the main folded structures of the basement of Western Siberia, which have a predominantly meridional direction, dates back to the era of the Hercynian orogeny. They are everywhere covered with a cover of loose marine and continental Meso-Cenozoic rocks (clays, sandstones, marls and the like) with a total thickness of over 1000 m (in the depressions of the foundation up to 3000-4000 m). The youngest, anthropogenic deposits in the south are alluvial and lacustrine, often covered with loess and loess-like loams; in the north - glacial, marine and ice-sea (thickness in some places up to 4070 m).

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

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

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

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

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

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

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

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

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

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

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

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

Sources

Gvozdetsky N.A., Mikhailov N.I. Physical geography of the USSR. Ed. 3rd. M., "Thought", 1978.

Literature

West Siberian Lowland. Essay on Nature, M., 1963; Western Siberia, M., 1963.
Davydova M.I., Rakovskaya E.M., Tushinsky G.K. Physical geography of the USSR. T. 1. M., Education, 1989.

The West Siberian Plain is of the accumulative type and is one of the largest low-lying plains on the planet. Geographically, it belongs to the West Siberian plate. On its territory there are regions of the Russian Federation and the northern part of Kazakhstan. The tectonic structure of the West Siberian Plain is ambiguous and diverse.

Russia is located on the territory of Eurasia, the largest continent on the planet, which includes two parts of the world - Europe and Asia. Separates the cardinal directions tectonic structure Ural mountains. The map makes it possible to clearly see the geological structure of the country. Tectonic zoning divides the territory of Russia into geological elements such as platforms and folded areas. The geological structure is directly related to the surface topography. Tectonic structures and landforms depend on the region they belong to.

Within Russia there are several geological regions. The tectonic structures of Russia are represented by platforms, folded belts and mountain systems. On the territory of the country, almost all areas have undergone folding processes.

The main platforms within the country are East European, Siberian, West Siberian, Pechora and Scythian. They, in turn, are divided into plateaus, lowlands and plains.

Relief of Western Siberia

The territory of Western Siberia is sinking stepwise from south to north. The relief of the territory is represented by a wide variety of forms and is complex in origin. One of important criteria relief is the difference in absolute elevations. On the West Siberian Plain, the difference in absolute elevations is tens of meters.

The flat terrain and slight elevation changes are due to the small amplitude of plate movement. On the periphery of the plain, the maximum amplitude of uplifts reaches 100-150 meters. In the central and northern parts, the amplitude of the subsidence is 100-150 meters. The tectonic structure of the Central Siberian Plateau and the West Siberian Plain in the late Cenozoic was relatively calm.

Geographical structure of the West Siberian Plain

IN geographically in the north the plain borders the Kara Sea, in the south the border runs through the north of Kazakhstan and covers a small part of it, in the west it is controlled by the Ural Mountains, in the east by the Central Siberian Plateau. From north to south, the length of the plain is about 2500 km, the length from west to east varies from 800 to 1900 km. The area of the plain is about 3 million km 2.

The relief of the plain is monotonous, almost flat, and occasionally the height of the relief reaches 100 meters above sea level. In its western, southern and northern parts, the height can reach up to 300 meters. The subsidence of the territory occurs from south to north. In general, the tectonic structure of the West Siberian Plain is reflected in the terrain.

The main rivers flow through the plain - the Yenisei, Ob, Irtysh, and there are lakes and swamps. The climate is continental.

Geological structure of the West Siberian Plain

The location of the West Siberian Plain is confined to the epihercynian plate of the same name. The basement rocks are highly dislocated and date back to the Paleozoic period. They are covered with a layer of marine and continental Mesozoic-Cenozoic sediments (sandstones, clays, etc.) more than 1000 meters thick. In the depressions of the foundation this thickness reaches up to 3000-4000 meters. In the southern part of the plain, the youngest - alluvial-lacustrine deposits are observed, in the northern part there are more mature - glacial-marine deposits.

The tectonic structure of the West Siberian Plain includes a foundation and a cover.

The foundation of the slab has the appearance of a depression with steep sides on the east and northeast and gentle sides on the south and west. The foundation blocks belong to the pre-Paleozoic, Baikal, Caledonian and Hercynian times. The foundation is dissected by deep faults of different ages. The largest faults of submeridional strike are the East Trans-Ural and Omsk-Pur. The map of tectonic structures shows that the surface of the plate foundation has an Outer Edge Belt and an Inner Region. The entire surface of the foundation is complicated by a system of rises and depressions.

The cover is interlayered with coastal-continental and marine sediments with a thickness of 3000-4000 meters in the south and 7000-8000 meters in the north.

Central Siberian Plateau

The Central Siberian Plateau is located in the north of Eurasia. It is located between the West Siberian Plain in the west, the Central Yakut Plain in the east, the North Siberian Lowland in the north, the Baikal region, Transbaikalia and the Eastern Sayan Mountains in the south.

The tectonic structure of the Central Siberian Plateau is confined to the Siberian Platform. The composition of its sedimentary rocks corresponds to the Paleozoic and Mesozoic periods. Characteristic rocks for it are sheet intrusions, which consist of traps and basalt covers.

The relief of the plateau consists of wide plateaus and ridges, at the same time there are valleys with steep slopes. The average height of the difference in the relief is 500-700 meters, but there are parts of the plateau where the absolute mark rises above 1000 meters, such areas include the Angara-Lena Plateau. To one of the most high areas The territory includes the Putorana plateau, its height is 1701 meters above sea level.

Sredinny ridge

The main watershed ridge of Kamchatka is a mountain range consisting of systems of peaks and passes. The ridge extends from north to south and its length is 1200 km. A large number of passes are concentrated in its northern part, central part represents large distances between the peaks, in the south there is a strong dissection of the massif, and the asymmetry of the slopes characterizes the Sredinny Range. The tectonic structure is reflected in the relief. It consists of volcanoes, lava plateaus, mountain ranges, and glacier-covered peaks.

The ridge is complicated by lower-order structures, the most striking of which are the Malkinsky, Kozyrevsky, and Bystrinsky ridges.

The highest point belongs to and is 3621 meters. Some volcanoes, such as Khuvkhoytun, Alnai, Shishel, Ostraya Sopka, exceed 2500 meters.

Ural Mountains

The Ural Mountains are a mountain system that is located between the East European and West Siberian plains. Its length is more than 2000 km, its width varies from 40 to 150 km.

The tectonic structure of the Ural Mountains belongs to the ancient folded system. In the Paleozoic there was a geosyncline here and the sea splashed. Beginning with the Paleozoic, the formation of mountain system Ural. The main formation of folds occurred during the Hercynian period.

Intensive folding occurred on the eastern slope of the Urals, which was accompanied by deep faults and intrusions, the dimensions of which reached about 120 km in length and 60 km in width. The folds here are compressed, overturned, and complicated by thrusts.

On the western slope, folding occurred less intensively. The folds here are simple, without thrusts. There are no intrusions.

Pressure from the east was created by a tectonic structure - the Russian Platform, the foundation of which prevented the formation of folding. Gradually, folded mountains appeared in place of the Ural geosyncline.

In tectonic terms, the entire Urals is a complex complex of anticlinoriums and synclinoriums, separated by deep faults.

The relief of the Urals is asymmetrical from east to west. The eastern slope slopes steeply towards the West Siberian Plain. The gentle western slope smoothly transitions into the East European Plain. The asymmetry was caused by the activity of the tectonic structure of the West Siberian Plain.

Baltic shield

It belongs to the north-west of the East European Platform, is the largest protrusion of its foundation and is elevated above sea level. In the northwest, the border passes with the folded structures of Caledonia-Scandinavia. In the south and southeast, shield rocks are submerged under the cover of sedimentary rocks of the East European Plate.

Geographically, the shield is tied to the southeastern part of the Scandinavian Peninsula, to the Kola Peninsula and Karelia.

The structure of the shield involves three segments, different in age - South Scandinavian (western), Central and Kola-Karelian (eastern). The South Scandinavian sector is tied to the south of Sweden and Norway. The Murmansk block stands out in its composition.

The central sector is located in Finland and Sweden. It includes the Central Kola block and is located in the central part of the Kola Peninsula.

The Kola-Karelian sector is located in Russia. It belongs to the most ancient formation structures. In the structure of the Kola-Karelian sector, several tectonic elements are distinguished: Murmansk, Central Kola, White Sea, Karelian, they are separated from each other by deep faults.

Kola Peninsula

Tectonically tied to the northeastern part of the Baltic crystalline shield, composed of rocks of ancient origin - granites and gneisses.

The relief of the peninsula has adopted the features of a crystalline shield and reflects traces of faults and cracks. The appearance of the peninsula was influenced by glaciers, which smoothed the tops of the mountains.

Based on the nature of the relief, the peninsula is divided into western and eastern parts. The relief of the eastern part is not as complex as the western one. The mountains of the Kola Peninsula are shaped like pillars - at the tops of the mountains there are flat plateaus with steep slopes, and at the bottom there are lowlands. The plateaus are cut by deep valleys and gorges. In the western part there are the Lovozero tundra and the Khibiny Mountains, the tectonic structure of the latter belongs to the mountain ranges.

Khibiny

Geographically, the Khibiny belongs to the central part of the Kola Peninsula and is a large mountain range. The geological age of the massif exceeds 350 million years. Mountain Khibiny is a tectonic structure, which is an intrusive body (frozen magma) complex in structure and composition. From a geological point of view, an intrusion is not an erupted volcano. The massif continues to rise even now, the change per year is 1-2 cm. More than 500 types of minerals are found in the intrusive massif.

Not a single glacier has been discovered in the Khibiny Mountains, but traces of ancient ice are found. The peaks of the massif are plateau-shaped, the slopes are steep with a large number of snowfields, avalanches are active, there are many mountain lakes. The Khibiny are relatively low mountains. The highest elevation above sea level belongs to Mount Yudychvumchorr and corresponds to 1200.6 m.