Yakut folk song as a genre of folklore. Styles of Yakut folk song

The West Siberian Plain, which occupies about 3 million. km 2, is one of the greatest plains on the globe: in size it can only be compared with the Amazonian lowland.

The boundaries of the lowland are clearly defined natural boundaries: in the north - the coastline of the Kara Sea, in the south - the Turgai Table Country, the foothills of the Kazakh hills, Altai, Salair and Kuznetsk Alatau, in the west - the eastern foothills of the Urals, in the east - the valley of the river. Yenisei. The orographic boundaries of the lowland coincide with the geological ones, which are considered to be the outcrops of dislocated Paleozoic and older rocks in some places along the edges of the lowland, for example in the south, near the Kazakh hills. In the Turgai trough, which connects the West Siberian Lowland with the plains of Central Asia, the border is drawn along the Kustanai swell, where the pre-Mesozoic foundation lies at a depth of 50-150 m from the surface. The length of the plain from north to south is 2500 km. Maximum width - 1500 km- it reaches in the southern part. In the north of the lowland, the distance between the western and eastern points is about 900-950 km. Almost the entire territory of the lowland is located within the RSFSR - Yamalo-Nenets and Khanty-Mansiysk national districts, in the regions - Kurgan, Sverdlovsk, Tyumen, Omsk, Novosibirsk, Tomsk, Kemerovo; in the regions - Altai and Krasnoyarsk. The southern part belongs to the Kazakh SSR - to the regions of the Tselinny Territory - Kustanai, North Kazakhstan, Kokchetav, Tselinograd, Pavlodar and Semipalatinsk.

Relief and geological structure. The relief of the West Siberian Plain is characterized by complexity and diversity. Over a long distance, fluctuations in heights are insignificant. Maximum marks (250-300 m) concentrated in the western part of the plain - in the pre-Ural region. The southern and eastern parts of the plain are also elevated compared to the central one. In the south, heights reach 200-300 m. In the central part of the plain, absolute elevations on watersheds are about 50-150 m, and in the valleys - less than 50 m; for example, in the river valley Ob, at the mouth of the river. Wah, altitude 35 m, and near the city of Khanty-Mansiysk - 19m.

On the peninsulas the surface rises: absolute elevations on the Gydan Peninsula reach 150-183 m, and on Tazovskam - about 100m.

In general orographic terms, the West Siberian Plain has a concave shape with raised edges and a lowered central part. Along its outskirts there are hills, plateaus and sloping plains, descending towards its central parts. Among them, the largest are: North Sosvinskaya, Tobolsk-Tavdinskaya, Ishimskaya, Ishimskaya-Irtyshskaya and Pavlodarskaya inclined plains, Vasyuganskaya, Priobskoe and Chulym-Yenisei plateaus, Vakh-Ketskaya and Srednetazovskaya uplands, etc.

To the north of the latitudinal current of the Ob, from the Urals to the Yenisei, one hill after another stretches, forming a single orographic axis of the West Siberian Plain - the Siberian Ridges, along which the Ob-Taz and Ob-Pur watersheds pass. All large lowlands are concentrated in the central parts of the plain - Khanty-Mansiysk, Surgut Polesie, Sredneobskaya, Purskaya, Kheta, Ust-Obskaya, Barabinskaya and Kulundinskaya.

The flatness of the territory was created by a long geological history in pre-Quaternary times. The entire West Siberian Plain is located in the area of ​​Paleozoic folding and tectonically represents the West Siberian plate of the Ural-Siberian epi-Hercynian platform. The folded structures that were on the site of the West Siberian Plain, as a result of tectonic movements, sank to different depths either at the end of the Paleozoic, or at the very beginning of the Mesozoic (in the Triassic).

Deep boreholes in various areas of the plain passed through Cenozoic and Mesozoic rocks and reached the surface of the slab foundation at various depths: at the Makushkino railway station (half the distance between Kurgan and Petropavlovsk) - at a depth of 693 m(550 m from sea level), 70 km east of Petropavlovsk - at 920 m(745 m from sea level), and in Turgay - at 325 m. In the area of ​​the eastern slope of the North Sosvinsky arch, the Paleozoic foundation is lowered to a depth of 1700-2200 m, and in the central part of the Khanty-Mansi depression - 3500-3700 m.

The sunken sections of the foundation formed syneclises and troughs. In some of them, the thickness of Mesozoic and Cenozoic loose sediments reaches more than 3000m 3.

In the north of the West Siberian plate, in the interfluve of the lower Ob and Taz rivers, the Ob-Taz syneclise stands out, and in the south, along the course of the middle Irtysh, there is the Irtysh syneclise and in the area of ​​the Kulundinsky lake - the Kulundinsky depression. In the north, slabs in syneclises, according to the latest data,

the foundation goes to a depth of 6000 m, and in some places - by 10,000 m. In anteclises the foundation lies at a depth of 3000-4000 m from the surface.

In terms of geological structure, the foundation of the West Siberian Plate is apparently heterogeneous. It is believed that it consists of folded structures of the Hercynian, Caledonian, Baikal and more ancient ages.

Some large geological structures of the West Siberian plate - syneclises and anteclises - correspond to elevated and lowland areas in the relief of the plain. For example, lowlands-syneclises: the Baraba lowland corresponds to the Omsk depression, the Khanty-Mansi lowland formed on the site of the Khanty-Mansi depression. Examples of anteclise hills are: Lyulinvor and Verkhnetazovskaya. In the marginal parts of the West Siberian Plate, sloping plains correspond to monoclinal morphological structures, in which the general lowering of the topographic surface follows the lowering of the basement into syneclises of the plate. Such morphostructures include the Pavlodar, Tobolsk-Tavdinsk inclined plains, etc.

During the Mesozoic, the entire territory represented a mobile land area, which experienced only epeirogenic fluctuations with a general tendency to subsidence, as a result of which the continental regime was replaced by a marine one. Thick layers of sediment accumulated in sea basins. It is known that in the Upper Jurassic time the sea occupied the entire northern part of the plain. During the Cretaceous period, many areas of the plain turned into dry land. This is evidenced by finds of weathering crust and continental sediments.

The Upper Cretaceous sea gave way to the Tertiary. Sediments of the Paleogene seas smoothed out the pre-Tertiary relief and created the ideal flatness of the West Siberian Plain. The sea reached its maximum development in the Eocene era: at that time it covered almost the entire area of ​​the West Siberian Plain and the connection between the sea basins of the Aral-Caspian Basin and the West Siberian Plain was carried out through the Turgai Strait. Throughout the Paleogene, there was a gradual subsidence of the plate, reaching its greatest depth in the eastern regions. This is evidenced by the increasing thickness and character of Paleogene deposits to the east: in the west, in the Cis-Urals, near the Kazakh hillocks, sands, conglomerates and pebbles predominate. Here they are highly elevated and reach the surface or lie at shallow depths. Their power reaches 40-100 in the west m. To the east and north, sediments descend beneath Neogene and Quaternary sediments. For example, in the Omsk region, Paleogene deposits were discovered by drilling wells at a depth of more than 300 m from the surface, and even deeper they lie north of the station. Tatarskaya. Here they become thinner (clays, flasks). At the confluence of the river Irtysh in the river Ob and further north along the river. Ob Paleogene layers rise again and emerge along river valleys in natural outcrops.

After a long marine regime, the primary accumulative plain uplifted by the beginning of the Neogene, and a continental regime was established on it. Judging by the nature of the occurrence of Paleogene sediments, we can say that the primary accumulative marine plain had a bowl-shaped relief structure: it was all most depressed in the central part. This surface structure at the beginning of the Neogene largely predetermined the modern features of the relief of the West Siberian Plain. During this period, the land was covered with numerous lakes and lush subtropical vegetation. This is evidenced by the wide distribution of exclusively continental deposits, consisting of pebbles, sand, sandy loam, loams and clays of lacustrine and river origin. The best sections of these deposits are known from the Irtysh, Tavda, Tura and Tobol rivers. The sediments contain well-preserved remains of flora (swamp cypress, sequoia, magnolia, linden, walnut) and fauna (giraffes, camels, mastodons), which indicates warmer climatic conditions in the Neogene compared to modern ones.

In the Quaternary period, a cooling of the climate occurred, which led to the development of an ice sheet in the northern half of the plain. The West Siberian Plain experienced three glaciations (Samarovsky, Tazovsky and Zyryansky). Glaciers descended onto the plain from two centers: from the mountains of Novaya Zemlya, the Polar Urals and from the mountains of Byrranga and Putorana. The existence of two glaciation centers in the West Siberian Plain is proven by the distribution of boulders. Glacial boulder deposits cover vast areas of the plain. However, in the western part of the plain - along the lower reaches of the Irtysh and Ob rivers - the boulders consist mainly of Ural rocks (granites, granodiorites), and in the eastern part - along the valleys of the Vakha, Ob, Bolshoi Yugan and Salym rivers; in the interfluves of the Gydan Peninsula, trap fragments predominate, brought from the northeast from the Taimyr center. The ice sheet descended during the Samarovsky glaciation along a leveled surface to the south, to approximately 58° N. w.

The southern edge of the glacier stopped the flow of pre-glacial rivers that directed their waters into the Kara Sea basin. Some of the river water apparently reached the Kara Sea. Lake basins arose at the southern edge of the glacier, and powerful fluvioglacial flows formed, flowing southwest, towards the Turgai Strait.

In the south of the West Siberian Plain, from the foothills of the Urals to the Irtysh, and in some places further to the east (Prichulym plateau), loess-like loams are common; they lie on the surface of interfluve plateaus, overlying their bedrock. It is assumed that the formation of loess-like loams is associated with aeolian or eluvial processes, and perhaps these are deltaic and coastal deposits of ancient seas.

During interglacial periods, the northern part of the West Siberian Lowland was flooded by the waters of the boreal transgression, which penetrated through the valleys of large rivers - the Ob, Taz, Pura, Yenisei, etc. Sea waters entered the furthest south along the river valley. Yenisei - up to 63° N. w. The central part of the Gydan Peninsula was an island in the marine boreal basin.

The Boreal Sea was significantly warmer than the modern one, as evidenced by marine sediments formed by thin sandy loams and loams with the inclusion of heat-loving mollusks. They lie at an altitude of 85-95 m above modern sea level.

The last glaciation in Western Siberia did not have a cover character. Glaciers descending from the Urals, Taimyr and Norilsk Mountains ended not far from their centers. This is indicated by the location of their terminal moraines and the absence of moraine deposits of the last glaciation in the northern part of the West Siberian Plain. For example, sea

The deposits of the boreal transgression in the north of the lowland are nowhere covered by a moraine.

In the distribution of various genetic types of relief over the territory, a consistent change is observed when moving from north to south, which makes it possible to distinguish geomorphological zones.

1. The zone of the Prikar marine stepped accumulative plains occupies the entire coastal strip of the Kara Sea, extending deep into the interior of the mainland along the Ob, Taz and Yenisei bays. The plain was composed of marine clays and sands during the boreal transgression; it rises to a height of 80 m. Toward the coastline, the heights decrease, forming several marine terraces.

2. The zone of the Ob-Yenisei accumulative hilly and flat-undulating water-glacial plains is located between 70 and 57° N. t., from the Urals to the Yenisei. On the Gydansky and Yamal peninsulas it occupies internal areas, extending north of 70° N. sh., and in the Cis-Ural region it descends south of 60° N. sh., in the river basin Tavdy. In the central regions, up to the southern border of the Samarov glaciation, this territory was covered with glaciers. It is composed of boulder clays, boulder sands, and loams.

Prevailing altitudes above sea level - 100-200 m. The surface of the plain is flat-undulating, with moraine hills 30-40 m high. m, with ridges and shallow lake depressions, rugged topography and ancient drainage hollows. Large areas are occupied by outwash lowlands. There are especially many lakes found among the vast interfluve swamps of the Ob-Tazov Plain.

3. The zone of periglacial water-accumulative plains is located south of the boundary of maximum glaciation and extends from the river. Tavda, south of the latitudinal segment of the Irtysh valley, to the river. Yenisei.

4. The zone of non-glacial flat and wavy-gully erosion-accumulative plains includes the Priishimskaya Plain, located in the river basin. Ishim, Baraba and Kulunda steppes. The main landforms were created by powerful water flows, which formed wide hollows of ancient flow of the south-west direction, filled with alluvial deposits. Watershed periglacial areas have a rugged topography. Manes height 5-10 m are elongated mainly in the same direction as the ancient drainage basins. They are expressed especially clearly in the Kulundinskaya and Barabinskaya steppes.

5. The zone of piedmont denudation plains is adjacent to the mountain structures of the Urals, Salair Ridge and Kuznetsk Alatau. The foothill plains are the most elevated areas of the West Siberian Plain; they are composed of sediments of Mesozoic and Tertiary ages and are overlain by Quaternary loess-like eluvial-deluvial loams. The surfaces of the plains are dissected by wide erosional valleys. The watershed areas are flat, with closed basins and depressions, some of which contain lakes.

Thus, on the territory of the West Siberian Plain, geomorphological zoning is clearly visible, which is determined by the history of the development of the entire territory, especially during the Ice Age. Geomorphological zoning is predetermined by the activity of glaciers, Quaternary tectonic movements, and boreal transgression.

When comparing the geomorphological zones of the West Siberian and Russian plains, it is revealed general pattern, namely: both here and here

Narrow strips of sea plains, an area of ​​glacial demolition (located in the northwest and northeast), zones of glacial accumulation, stripes of woodlands and non-glacial zones clearly emerge. But on the Russian Plain the non-glacial zone ends with marine plains, and on the West Siberian Plain it ends with a zone of foothill plains.

The valleys of the Ob and Irtysh rivers, reaching a width of 80-120 km, pass through all the indicated geomorphological zones. Valleys cut through Quaternary and Tertiary sediments to a depth of 60-80 m. The floodplains of these rivers are 20-40 wide km have numerous meandering channels, oxbow lakes, and coastal ramparts. Terraces rise above the floodplains. Everywhere in the valleys there are two terraces of accumulative-erosive type with a height of 10-15 and about 40 m. In the foothills the valleys narrow, the number of terraces increases to six, their height increases to 120 m. The valleys have an asymmetrical structure. On steep slopes there are ravines and landslides.

Minerals are concentrated in the primary and quaternary sediments of the plain. In Jurassic deposits there are coal deposits that have been studied in the southwestern part of the plain and in the Turgai Plain. Brown coal deposits were discovered in the Middle Ob basin. The Middle Ob basin includes the Tomskoye, Prichulymskoye, Narymskoye and Tymskoye fields. Phosphorites and bauxites, discovered in the northern part of the Turgai trough, are concentrated in the Cretaceous deposits of the plain. Iron ore deposits, represented by oolitic iron ores, were recently discovered among the Cretaceous deposits in the south of the West Siberian Plain and in the northwestern part of the Turgai trough. In recent years, on the territory of the West Siberian Plain, deep drilling has revealed iron ore deposits on the left bank of the Ob, from the city of Kolpashevo to the village. Narym, and, in addition, in the basins of the Vasyugan, Keti and Tym rivers. Iron ores contain iron - from 30 to 45%. Iron ore deposits were discovered in the Kulundinskaya steppe (area of ​​Lake Kuchu k, Kulunda station, Klyuchi), they contain up to 22% iron. IN Tyumen region large gas fields are known (Berezovskoye and Punginskoye). At the end of 1959, from a borehole laid on the bank of the river. Konda (near the village of Shaim), the first industrial oil in Western Siberia was obtained. In March 1961, a well clogged in the center of the West Siberian Lowland, in the middle reaches of the river. Ob, near the village of Megion. Industrial oil is concentrated in Lower Cretaceous sediments. Oil and gas fields are confined to Jurassic and Cretaceous rocks. Paleogene deposits of the southern part of the lowland and the Turgai trough have deposits of oolitic iron ores, lignites and bauxites. Building materials are widespread throughout the territory - sands and clays of marine and continental origin (Mesozoic and Quaternary), and peat bogs. Peat reserves are huge. The total volume of explored peatlands is more than 400 million. m 2 air-dry peat. The average thickness of peat layers is 2.5-3 m. In some ancient drainage depressions (Tym-Paiduginskaya and others), the thickness of peat layers reaches 5 - 6 m, In the lakes of the southern part there are large reserves of salts (table salt, mirabilite, soda).

Climate. The climate of the West Siberian Plain is formed as a result of the interaction of a number of factors, namely:

1) geographical location. The main part of the surface is located in temperate latitudes, and the peninsulas are located beyond the Arctic Circle.

The entire plain is thousands of kilometers away from the Pacific and Atlantic oceans. The large extent of the territory from north to south predetermines different amounts of total radiation, which significantly affects the distribution of air and ground temperatures. Total radiation increases when moving from north to south from 60 to 110 kcal/cm 2 per year and is distributed almost zonally. It reaches its greatest value at all latitudes in July (in Salekhard - 15.8 kcal/cm 2, in Pavlodar -16.7 kcal/cm 2). In addition, the position of the territory in temperate latitudes determines the flow

air masses from the Atlantic Ocean under the influence of west-east transport. The considerable distance of the West Siberian Plain from the Atlantic and Pacific oceans creates conditions above its surface for the formation of a continental climate;

2) pressure distribution. Areas of high (Asian anticyclone and Voeikov axis) and low pressure (over the Kara Sea and Central Asia) determine the strength of the wind, its direction and movement;

3) the topography of the swampy and concave plain, open to the Arctic Ocean, does not prevent the invasion of cold Arctic air masses. They freely penetrate to Kazakhstan, changing as they move. The flatness of the territory allows continental tropical air to penetrate far to the north. Thus, meridional air circulation occurs. Do the Ural Mountains have a significant influence on the amount and distribution of precipitation in the plain, since a significant part of it falls on the western slopes of the Urals? and western air masses arrive on the West Siberian Plain drier;

4) the properties of the underlying surface - large forest cover, swampiness and a significant number of lakes - have a significant impact on the distribution of a number of meteorological elements.

In winter, the entire area gets very cold. To the east of the West Siberian Plain, a stable region of the Asian High is formed. Its spur is the Voeikov axis, which extends across the southern part of the plain from November to March. A trough of low pressure of the Icelandic low stretches over the Kara Sea: the pressure decreases from south to north - towards the Kara Sea. Therefore, southern, southwestern and southeastern winds predominate.

Winter is characterized by persistent negative temperatures. Absolute minimums reach from -45 to -54°. January isotherms in the northern part of the plain have a meridional direction, but south of the Arctic Circle (approximately 63-65 Q With. sh.) - southeastern.

In the south there is an isotherm of -15°, and in the northeast -30°. West Side the plains are warmer than the eastern one by 10°. This is explained by the fact that the western parts of the territory are under the influence of western air masses, while in the east the territory is cooled under the influence of the Asian anticyclone.

Snow cover in the north appears in the first ten days of October and lasts on the peninsulas for approximately 240-260 days. At the end of November, almost the entire territory is covered with snow. In the south, snow lasts up to 160 days and usually disappears at the end of April, and in the north - at the end of June (20/VI).

In summer, over all of Asia, as well as over the territory of the West Siberian Plain, the pressure is reduced, so Arctic air freely penetrates its territory. When moving south, it warms up and is additionally moistened due to local evaporation. But the air warms up faster than it is humidified, which causes a decrease in its relative humidity. Warmer western air masses arriving on the West Siberian Plain are transformed along the way more than the Arctic ones. Intensive transformation of both Arctic and Atlantic air masses leads to the fact that the lowland area is filled with dry continental temperate air with a high temperature. Cyclonic activity develops most intensively in the northern part of the plain, due to increasing temperature differences between cold Arctic and warm continental air, i.e. on the Arctic front line. In the middle and southern parts of the plain, cyclonic activity is weakened, but cyclones still penetrate here from the European territory of the USSR.

Average July isotherms run almost in the latitudinal direction. In the far north, across the island. Bely, the isotherm is +5°, to the south of the Arctic Circle there is an isotherm of +15°, through the steppe regions it stretches with a deviation to the southeast - to Altai - the isotherm is +20, +22°. The absolute maximum in the north reaches +27°, and in the south +41°. Thus, when moving from north to south, changes in summer temperatures are more significant compared to winter ones. The growing season, due to temperature conditions, also changes when moving from north to south: in the north it reaches 100 days, and in the south - 175 days.

Precipitation is distributed unevenly across the territory and seasons. Highest rainfall - from 400 to 500 mm- falls in the middle zone of the plain. To the north and south the amount of precipitation decreases noticeably (up to 257 mm - on Dikson Island and 207 mm- in Semipalatinsk). The greatest amount of precipitation falls throughout the plain from May to October. But the maximum precipitation gradually moves from south to north: in June it is in the steppe, in July in the taiga, in August in the tundra. Showers occur during the passage of a cold front and during thermal convection.

In the middle and southern zones of the plain, thunderstorms occur from May to August. For example, in the Barabinskaya and Kulundinskaya steppes, during the warm period, from 15 to 20 days with thunderstorms are observed. In Tobolsk, Tomsk, and Tselinograd, up to 7-8 days with thunderstorms were recorded in July. During thunderstorms, squalls, heavy downpours, and hail are common.

The West Siberian Plain is crossed by three climatic zones: arctic, subarctic and temperate.

Rivers and lakes. The rivers of the West Siberian Plain belong to the basins of the Ob, Taz, Pura and Yenisei. The Ob basin covers an area of ​​about 3 million km. km 2 and is one of the largest river basins in the USSR.

Large rivers - Ob, Irtysh, Ishim, Tobol - flow through several geographical zones, which determines the diversity of morphological and hydrological features of individual sections of rivers and their valleys. All rivers of the West Siberian Plain are typically lowland. They have small slopes: the average slope of the river. Obi - 0.000042, rub. Irtysh from Omsk to the mouth - 0.000022.

The rivers flowing into the Ob and Irtysh have flow rates of 0.1-0.3 in the summer within the taiga region m/sec, and in spring flood - 1.0 m/sec. All rivers flow in loose, mainly Quaternary sediments, have a large tortuosity of the channel, wide valleys with well-defined floodplains and terraces.

The largest rivers - the Ob, Irtysh, Tobol - and many of their tributaries begin in the mountains. Therefore, they bring a large amount of clastic material to the West Siberian Plain and their hydrological regime partly depends on the melting of snow and ice in the mountains. The main flow of the lowland rivers is directed to the north-northwest. This is related to the peculiarities of the ice regime: on all rivers, freeze-up begins in the lower reaches and

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gradually moves upstream. In the north, ice cover lasts 219 days, and in the south - 162 days. Spring ice drift begins in the upper parts of the basins and gradually moves to the mouths of rivers, as a result of which powerful ice jams form on large rivers and the water level in the rivers rises sharply. This creates strong floods and leads to vigorous development of lateral erosion in the valleys.

In the south, rivers open in April - May, in the north - from mid-May to mid-June. The duration of spring ice drift is usually up to 25 days, but can reach up to 40 days. This is explained by the following reasons: in areas located in the lower reaches of rivers, spring comes later; The ice on the rivers in the lower reaches reaches great thickness, and therefore a large amount of heat is spent on its melting.

Rivers freeze from north to south in a much shorter period of time, about 10-15 days. The average duration of the navigation period in the upper reaches is 180-190 days (at Novosibirsk - 185 days, in the lower reaches - 155 days).

West Siberian rivers are predominantly fed by snow, but also by rain and groundwater. All rivers have spring floods, and they can last for quite a long time. The spring flood gradually turns into a summer flood, which depends on rain and ground nutrition.

River Ob. The Ob begins near the city of Biysk from the confluence of the Biya and Katun rivers. The length of the Ob, counting from the confluence of these rivers, is 3680 km, and if we take the source of the river as the beginning of the Ob. Katun, then its length will be 4345 km. The length of the Ob-Irtysh system from the sources of the Irtysh to the Kara Sea (including the Ob Bay) - 6370 km. According to the water content of the river. The Ob ranks third among the rivers of the USSR, losing the first two places to the Yenisei and Lena. Its average annual water consumption is 12,500 m 3 /sec.

The largest tributaries of the river. The Ob receives from the left (the Irtysh river with the Ishim and Tobol rivers), the right tributaries are much shorter, so the configuration of the river basin has an asymmetrical shape: the right bank part of the basin makes up 33% of the catchment area, and the left bank - 67%.

According to the hydrographic and hydrological conditions and morphology of the river valley. The Ob is divided into three parts: Upper Ob - from the confluence of the Biya and Katun rivers to the mouth of the river. Tom, Middle Ob - from the mouth of the river. Tom to the mouth of the river. Irtysh and Lower Ob - from the mouth of the river. Irtysh to the Ob Bay. The Upper Ob flows in the hilly foothills of the Altai steppe. The main tributaries of the Upper Ob are: on the right - the river. Chumysh and R. Inya, flowing through the Kuznetsk basin, on the left are the rivers Charysh and Alei, flowing from Altai.

The Middle Ob flows through swampy taiga plains, crossing the Vasyugan-swampy plains. This area is characterized by excessive moisture, slight surface slopes and a dense network of slow-flowing rivers. In the middle reaches of the river. The Ob receives many tributaries on both sides. The Lower Ob flows in a wide valley through the northern taiga and forest-tundra.

Irtysh River - largest tributary of the river Obi. Its length is 4422 km, pool area - 1,595,680 km 2. The sources of the Irtysh are located at the edge of the glaciers of the elephant mountains of the Mongolian Altai.

The largest tributaries of the Irtysh on the right are the rivers Bukhtarma, Om, Tara, Demyanka, and on the left - Ishim, Tobol, Konda. The Irtysh flows through the steppe, forest-steppe and taiga zones. It receives large tributaries in the taiga zone, and the most turbulent ones - from the Altai mountains; in the steppe - from

Semipalatinsk to Omsk, i.e. at a distance of over 1000 km, The Irtysh has almost no tributaries.

The narrowest section of the river valley. Irtysh - from the mouth of Bukhtarma to the city of Ust-Kamenogorsk. Here the river flows through a mountain gorge. Near the city of Semipalatinsk r. The Irtysh overlooks the West Siberian Plain and is already a typically flat river with a wide valley - up to 10-20 km width, and at the mouth - up to 30-35 km. The river bed is divided into branches by numerous sandy islands; The channel slopes are insignificant, the banks are composed of sandy-clayey deposits. All along the river. The highest bank of the Irtysh is the right one.

Lakes. There are many lakes on the West Siberian Plain. They are found in all natural zones of the plain and are common both in river valleys and on watersheds. The large number of lakes is due to the flatness and poor drainage of the territory; the activity of the cover glacier and its melt waters; permafrost-sinkhole phenomena; river activities; suffusion processes occurring in loose sediments of the southern part of the lowland; destruction of peat bogs.

Based on the origin of the basins, the lakes of the West Siberian Plain are divided into the following types: 1) lacustrine basins, which inherited the overdeepened areas of the ancient runoff depressions. Their formation is associated with the activity of water flows in the marginal zones of ancient glaciations and in the areas of flow of dammed waters of the Ob and Yenisei rivers during cover glaciations. Lakes of this type are located in ancient drainage depressions. They have a predominantly elongated or oval shape and insignificant (0.4-0.8 m) depth: however sometimes they reach a depth of 25 m; 2) lake basins of inter-ridge depressions of outwash plains, most common in the south in the forest-steppe and steppe; 3) oxbow lakes of modern and ancient river valleys. The formation of such lakes is associated with sharp changes in river channels in accumulative sediments. Their shapes and sizes are very diverse; 4) lake basins caused by thermokarst. They are common in the north of the plain in permafrost conditions and are found on all elements of the relief. Their sizes vary, but no more than 2-3 km in diameter, depth - up to 10-15 m; 5) moraine lake basins formed in depressions of moraine deposits, especially in the marginal parts of ice sheets. An example of such lakes is the northern group of lakes on the Yenisei-Tazovsky interfluve within the Siberian Uvaly. In the south of the forest zone, ancient moraine lakes are already in a transitional stage; 6) sor lakes formed in the depressions of the mouths of tributaries in the lower reaches of the Ob and Irtysh rivers. During spills and floods in the spring, depressions are filled with water, forming huge reservoirs with an area of ​​​​several hundred square kilometers and a depth of 1-3 m, and in riverbeds - 5-10 m. In the summer, they gradually discharge water into the beds of the main river, and in the middle of summer, and sometimes towards the end of it, flat areas covered with silt remain in place of the reservoirs. Sora lakes are favorite feeding grounds for many species of fish, as they heat up quickly and are rich in food; 7) secondary lakes, the basins of which are formed due to the destruction of peatlands. They are common in swampy forests on flat watersheds and river terraces. Their sizes reach from several square meters to several square kilometers at a depth of 1.5-2 m. There are no fish in them; 8) suffosion lake basins, common in the southern regions of the lowland. In loose sediments, from which dust particles are washed out under the influence of groundwater, soil subsidence occurs. Depressions, funnels, and saucers form on the surface. The emergence of basins of many salty and bitter-salty lakes is apparently associated with suffusion processes.

Groundwater. According to hydrogeological conditions, the West Siberian Plain represents a huge artesian basin, which is called the West Siberian. Groundwater in Western Siberia is characterized by various conditions of occurrence, chemistry and regime. They lie at different depths in the bedrock pre-Mesozoic, Meso-Cenozoic and Quaternary sediments. Aquifers are sands - marine and continental (alluvial and outwash), sandstones, loams, sandy loams, opoka, dense fractured rocks of the folded foundation.

The main areas of modern feeding of the artesian basin are located in the southeast and south (Chulyshman, Irtysh and Tobolsk basins). The movement of water occurs from the southeast and south to the north.

Foundation groundwater is concentrated in rock cracks. They are distributed in its peripheral part to approximately a depth of 200-300 m and at this depth they flow into the loose strata of the Mesozoic-Cenozoic. This is confirmed by the almost complete absence of water in deep wells in the central part of the basin.

In Quaternary deposits, water is mostly free-flowing, with the exception of those areas where it is concentrated in intermoraine fluvioglacial deposits and among the loamy strata of the Ob Plateau.

In the Irtysh and Tobolsk artesian basins, the waters of Quaternary sediments are fresh, salty and brine in composition. In the rest of the West Siberian basin, the waters of Quaternary sediments are fresh hydrocarbonate with a mineralization rarely exceeding 0.5g/l.

The rivers and lakes of the West Siberian Plain are widely used in the national economy. In lowland wetlands, rivers are the most important means of communication. The Ob River and its large tributaries - Irtysh, Tobol, Vasyugan, Parabel, Ket, Chulym, Tom, Charysh and others - are used for regular navigation. The total length of shipping routes within the West Siberian Plain is more than 20,000 km. The Ob River connects the Northern Sea Route with the railways of Siberia and Central Asia. The significant branching of the river systems of the West Siberian Plain makes it possible to use the tributaries of the Ob and Irtysh to transport goods from west to east and back over long distances. The most significant disadvantage of the Ob basin as a transport route is its isolation from neighboring river basins, despite the fact that the upper reaches of many tributaries of the river. The Ob approaches close to neighboring river basins; for example, the right tributaries of the Ob - the Ket and Vakh rivers - come close to the left tributaries of the river. Yenisei; left tributaries of the river Ob and tributaries of the river. Tobola comes close to the river basin. Ural and to the river basin Kama.

The rivers of the West Siberian Plain have enormous energy resources: the Ob annually discharges 394 billion. m 3 waters into the Kara Sea. This corresponds to approximately the amount of water from 14 rivers such as the Don. On the Ob, above the city of Novosibirsk, the Novosibirsk hydroelectric power station was built. On the river A cascade of energy nodes was built in the Irtysh River. Rocky narrow valley of the river. Irtysh from the mouth of the river. The bays to the city of Ust-Kamenogorsk are most favorable for the construction of hydroelectric power stations. The Ust-Kamenogorsk hydroelectric power station and the Bukhtarma hydroelectric power station were built.

Ichthyofauna of the river Obi is varied. In certain sections of the river, various fish are of commercial importance. In the upper reaches, before the river flows into it. Chulym, there are commercial fish: sturgeon - sturgeon, sterlet; from salmon - nelma, cheese, muksun. Along the tributaries they catch Siberian roach (of the cyprinids), crucian carp, pike, perch, and burbot. In the middle reaches of the river. The Ob River, where morbidity is highly developed in winter, fish that require oxygen, leave. Fishes that live in rivers permanently are of commercial importance - roach (chebak), dace, ide, crucian carp, pike, perch. In the summer, on the way to spawning or feeding, sturgeon, nelma, cheese, and muksun come here. In the lower reaches of the river - up to the Gulf of Ob - there are: sturgeon, nelma, cheese, pyzhyan, muksun, etc.

In the southern part of the West Siberian Plain there are many mineral lakes with large amounts of salt, soda, mirabilite and other chemical products.

Lakes are the most important source of water supply in many arid regions of the West Siberian Plain. But sharp fluctuations in the level of lakes, especially those with weak ground nutrition, affect their mineralization: in the fall, the volume of water in lakes usually decreases sharply, the water becomes bitterly salty and, therefore, cannot be used for drinking. To reduce evaporation and maintain a sufficient volume of water in lakes, they resort to diking lake basins, afforestation, snow retention in catchment areas,

increasing drainage areas under favorable topographic conditions by connecting several isolated drainage basins.

Many lakes, especially Chany, Sartlan, Ubinskoye and others, are of fishing importance. The lakes are home to: perch, Siberian roach, pike, crucian carp, Balkhash carp and bream. A large number of waterfowl find refuge in the reed and sedge thickets of lakes from spring to autumn.

Large numbers of geese and ducks are caught annually on the Baraby lakes. In 1935, a muskrat was released into the lakes of western Baraba. It acclimatized and spread widely.

Geographical zones. On the vast West Siberian Plain, the latitudinal zonation of all components of nature that were formed in post-glacial times, namely climate, soils, vegetation, water, and fauna, is extremely clearly manifested. Their combination, interconnection and interdependence create latitudinal geographical zones: tundra and forest-tundra, taiga, forest-steppe and steppe.

The natural zones of the West Siberian Plain are unequal in area (see Table 26).

The table shows that the dominant position is occupied by the forest zone, and the smallest area is occupied by forest-tundra.

Natural zones of the West Siberian Plain are part of geographical zones extending across the entire territory Soviet Union from west to east, and retain their common features. But thanks to the local Western Siberian natural conditions (flatness, widely developed clay-sandy deposits with horizontal occurrence, a climate with transitional features between the temperate continental Russian Plain and continental Siberia, severe swampiness, the special history of the development of the territory in pre-glacial and glacial times, etc.) zones of the West Siberian Lowland have their own characteristics. For example, the subzone of mixed forests of the Russian Plain extends east only to the Urals. The oak forest-steppe of the Russian Plain does not cross the Urals. West Siberian is characterized by aspen-birch forest-steppe.

Tundra and forest-tundra. From the shores of the Kara Sea and almost to the Arctic Circle, between the eastern slope of the Urals and the lower reaches of the river. Yenisei, tundra and forest-tundra extend. They occupy all the northern peninsulas (Yamal, Tazovsky and Gydansky) and a narrow strip of the mainland part of the plain.

The southern border of the tundra near the Ob and Taz bays runs at approximately 67° N. sh.; R. It crosses the Yenisei north of the town of Dudinka. The forest-tundra stretches in a narrow strip: in the area of ​​the Ob Bay, its southern border goes south of the Arctic Circle, and to the east of the Ob Bay, along the Arctic Circle; beyond the river valley The Taz border runs north of the Arctic Circle.

The main rocks that make up the peninsulas and the adjacent islands - Bely, Sibiryakova, Oleniy and others - are Quaternary - glacial and marine. They lie on an uneven surface of pre-Quaternary relief and consist of clay and sand with rare boulders. The thickness of these deposits in depressions of the ancient relief reaches 70-80 m, and sometimes more.

Along the coast stretches a primary marine plain with a width of 20-100 km. It is a series of sea terraces with different heights. There is an increase in the heights of the terraces to the south, which is apparently caused by Quaternary uplifts. The surface of the terraces is flat, with scattered saucer-shaped lakes 3-4 deep m. On the surface of the sea terraces there are dunes 7-8 high m, blowing basins. The formation of aeolian forms is favored by: 1) the presence of loose sea sands not fixed by vegetation; 2) poor sand moisture in spring and summer; 3) strong wind activity.

The interior parts of the peninsulas have a hilly-moraine surface with numerous small lakes.

The formation of the modern relief of the peninsulas is greatly influenced by permafrost. The thickness of the active layer in many areas reaches only 0.5-0.3 m. Therefore, erosion activity, especially deep-seated, is weakened. Erosion activity is prevented by continuous drizzling rains and numerous lakes, which regulate runoff throughout the warm season. Therefore, floods do not occur on rivers. However, erosion activity is currently one of the main factors transforming the original relief of the moraine-hilly and marine plain: wide river valleys, many meanders, young ravines along the ledges of terraces, valleys and lake basins. Slope changes occur as a result of colluvial erosion, solifluction and landslides.

In areas where permafrost develops, thermokarst phenomena are common, resulting in the formation of sinkholes, sinkholes, saucers, and lakes. The emergence of thermokarst forms continues to occur today; This is evidenced by trunks and stumps immersed in lakes, flooded trees and shrubs, and cracks in the ground. Spotted tundras form on smooth, flat watersheds or on slightly inclined slopes. Spots devoid of vegetation reach a diameter from 1-2 to 30-50 m.

The harsh climate of the tundra is due to its northern position, the influence of the cold Kara Sea and the entire Arctic basin, as well as vigorous cyclonic activity and cooling in winter of the neighboring territory - the region of the Asian anticyclone.

Winter in the Western Siberian tundra is more severe than in Europe, but less frosty than east of the river. Yenisei. Average January temperatures are -20-30°. Winter weather types prevail from mid-October to early May. Average monthly wind speed in the tundra -7-9 m/sec, maximum - 40 m/sec, which at low temperatures, sometimes reaching -52°, creates greater harshness of the weather. Snow cover lasts for about 9 months (from half of October to half of June). Under the influence of strong winds, the snow is blown and therefore its thickness is uneven. The weather depends on the frequent passage of cyclones and on the intrusions of Arctic air masses from the Kara Sea and polar continental ones from Central Siberia.

In summer, arctic air invades the entire territory, but the process of its transformation is still poorly expressed. Summer in the tundra is cool, with frosts and snowfalls. The average July temperature is about +4, +10°; maximum +20, +22° (Tombey), to the south it reaches +26, +30° (New Port); the temperature in summer drops to -3, -6°. In the forest-tundra the average July temperatures are +12, +14°. The sum of temperatures above 10° on the southern border of the tundra is 700-750°.

Annual precipitation - from 230 mm in the northern part up to 300 mm in southern part. Maximum precipitation falls in the summer, mainly in the form of long-term drizzling rains; showers with thunderstorms are rare. Due to the lack of heat, frequent precipitation, weak evaporation and the presence of permafrost in places, the soil is very swampy and the relative humidity is very high. Evaporation on the coast - 150 mm, and on the southern border of the forest-tundra there are about 250 mm. The tundra and forest-tundra zone is characterized by an excessively humid climate.

Groundwater is shallow, which contributes to swamping of the area and poor development of soil aeration. For most of the year, groundwater is frozen.

Soil formation occurs in Quaternary parent rocks - clay-sandy deposits of glacial and marine origin. Soils are formed under conditions of low air and soil temperatures, low precipitation, insignificant drainage of the territory and lack of oxygen. All these conditions lead to the development of gley-bog type soils. However, the combination of local natural components creates diversity in the formation of soil cover. The most common are tundra gley and peat-bog soils, which form under conditions of high moisture. On sands where there is no permafrost or where it lies at great depths, there is no swamping and weakly podzolic soils develop. In the forest-tundra, the process of formation of podzolic soils is more pronounced: they form not only on sands, but also on loams. Therefore, the main types of forest-tundra soils are gley-podzolic.

When moving from north to south within the tundra, changes in climate, soil formation and vegetation cover are observed.

B. N. Gorodkov identified the following subzones of the tundra: 1) arctic tundra; 2) typical tundra; 3) southern tundra; 4) forest-tundra.

The Arctic tundra occupies the northern parts of the Yamal and Gydan peninsulas. The Arctic tundra is dominated by spotted tundra. Its vegetation is very sparse and settles only in hollows and cracks surrounding bare patches of soil. The vegetation cover is completely free of sphagnum mosses and shrubs. The latter occasionally enter from the south along river valleys. The species composition is poor; the most typical species are: foxtail( Alopecurus alpinus), sedge ( Carex rigida), moss ( Polytrichum strictum), sorrel ( Oxyria digyna), meadowweed ( Deschampsia arctica).

Typical tundra occupies the middle and southern parts of the Yamal and Gydansky peninsulas and the northern part of the Tazovsky. The southern border of the tundra lies north of the Arctic Circle. The vegetation of a typical tundra is varied. Mosses, lichens, herbs and shrubs are widespread: they are found not only along river valleys, but also on watersheds.

The vegetation of a typical tundra forms three tiers: the upper one is shrubby, consisting of birch( Betuladad), wild rosemary ( Ledumpalustre), bush willow( Salix glauca, S. pulchra), blueberries ( Vaccinium uliginosum); medium - herbaceous - sedge(Sa rex rigida), dropsy ( Empetrum nigrum), cranberries ( Oxycoccos microcarpa O. palustris), partridge grass (Dryas octopetala), bluegrass (Roa arctica), cotton grass ( Eriophorum vaginatum). Sedges predominate among other plants; lower tier- lspeynikovo-moss. It consists of lichens: alectoria( Alectoria), cetraria ( Cetraria), reindeer moss ( Cladonia rangiferina), mosses - hypnum and sphagnum( Sphagnum lenense).

Typical tundra varies in individual areas: moss tundra forms on moist clay soils. Lichen tundra develops in elevated loamy and sandy areas. In areas of strong wind activity there are small areas of patchy clay tundra. In spring and summer, moss tundras provide good grazing land for deer, which eat cotton grass, shrub foliage, and various grasses. In the ravines, on the slopes of southern exposure, tundra meadows consisting of forbs develop. The meadows are used as summer pastures for deer.

Riverine thickets of willow bushes are moving north along river valleys. Compared to other plant groups, shrubs develop in conditions of less swampiness, thicker snow cover and faster and deeper thawing of the active soil layer.

In the south of the typical tundra, shrubs begin to dominate the vegetation cover. They form dense thickets of birch and willow up to 1.5-3 m not only along river valleys, but also on watersheds, among moss and lichen tundras. The widespread development of shrub groups in the more southern parts of the tundra is explained by weakened wind activity in winter, thicker snow cover and more precipitation.

The tundra is gradually replaced by forest-tundra. In the northern part of the forest-tundra, small areas of open forest and crooked forest appear, which increase to the south and turn into the taiga. In the forest-tundra, trees grow at some distance from each other; Between them are areas of shrub, moss, lichen, and sometimes spotted tundra. The most favorable areas for woody vegetation are sandy areas, protected from the wind and well heated. The forests consist of larch and spruce. Dwarf birch and scrub alder are common under the forest canopy. The ground cover consists of sphagnum mosses, forming peat bogs with a lumpy surface. In dry sandy places, where there is a fairly thick snow cover, the soil is covered with lichens, mainly reindeer moss. The main types of soils are gleyic-podzolic.

The slopes of river valleys and terraces in summer are covered with lush, variegated meadows consisting of buttercups, fireweeds, valerian and berries. The meadows are an excellent pasture for deer in summer and autumn, and a habitat for many animals and birds.

For the tundra of the West Siberian Plain, the most typical animal species is the domestic reindeer. He gets his food all year round: moss, or reindeer moss, berries, mushrooms, leaves and grass. Large reindeer herding state and collective farms have been created in the tundra, provided with pastures and veterinary and zootechnical stations. The enemies of reindeer herds are wolves that live in the forest-tundra and tundra.

The arctic fox, or polar fox, lives in the tundra and forest-tundra. It feeds on a variety of foods, but the main food is lemmings, or lemmings. In the spring it destroys bird nests, eating eggs and young chicks.

Lemming is a small tundra rodent. It feeds on the bark of willows and dwarf birches, and the foliage of plants. It itself serves as food for many mammals and bird predators. In the tundra of Western Siberia, two types of lemmings are found: Ob and ungulate.

Along the river valleys of the forest-tundra, in forests and thickets of bushes, forest animals are found: squirrel, mountain hare, fox, wolverine, which penetrate far to the north - into the tundra.

There are especially many waterfowl in the tundra, of which the most typical for its landscape are geese, ducks, swans, and loons. All year round The white partridge lives in the tundra. The white owl is a diurnal bird in the tundra.

In winter, the tundra is poor in birds: few of them remain to live in harsh climatic conditions. To the south, geese, ducks, swans, and the red-breasted goose fly away, nesting only in the tundra and forest-tundra, from the river. Ob to the river Yenisei. The peregrine falcon is also a migratory bird and feeds on waterfowl. Migratory birds spend no more than 2-4.5 months a year in the north.

For about 9 months the tundra is covered with snow. The thickness of the snow cover in some places reaches 90-100 cm. Arctic fox, white partridge, and lemming burrow into the loose, fine snow. Compacted snow facilitates easy movement of tundra animals: for example, the arctic fox walks freely on the crust. In the partridge, the claws lengthen and by autumn the fingers are covered with a thick cover of dense flexible feathers, forming a wide elastic surface. Because of this, the increased supporting surface of the paw allows it to run through the snow without sinking deeply. In loose, deep snow, the white partridge plunges into it up to its abdomen and can only with great difficulty wander around the bushes. Areas with little snow are most favorable for deer, as they can easily reach moss from under the snow.

The most important economic problem in the development of the tundra is the development of vegetable growing. To do this, it is necessary to improve the soil by draining it, improving aeration, lowering the level of permafrost, protecting soils from freezing by accumulating snow in the fields, and adding manure to the soil. Frost-resistant crops can grow in the tundra.

Forest zone. Most of the area of ​​the West Siberian Plain is covered with forests - taiga. The southern border of the forest zone approximately coincides with the parallel of 56° N. w.

The relief of the taiga zone was created by the accumulative activity of continental glaciation, glacial melt and surface waters. The southern boundaries of the distribution of ice sheets passed within the forest zone. Therefore, to the north of them, the dominant type of relief is accumulative glacial plains, modified by the activity of melted glacial waters of the retreating maximum glacier and partially melted glacial waters of the last glaciations.

The area of ​​the glacial plains is about 1/4 of the area of ​​the entire West Siberian Plain. The surface is composed of Quaternary deposits - glacial, fluvio-glacial, alluvial, lacustrine. Their power sometimes reaches more than 100m.

The forest zone is part of the West Siberian continental climatic region. Continental temperate air dominates over the entire territory all year round.

Winter weather is predominantly anticyclonic and is associated with the Asian Anticyclone, but passing cyclones create unstable weather. Winters are long, with strong winds, frequent snowstorms and rare thaws. Average January temperature: -15° in the southwest and -26° in the east and northeast. Frosts reach -60° in some areas. With the arrival of a cyclone, temperatures can change dramatically. Snow cover lasts for about 150 days in the south of the zone and 200 days in the northeast. The height of the snow cover by the end of February reaches 20-30 cm in the south and 80 cm in the north-east. Snow cover lasts from mid-October to mid-May.

In summer, air flows into the forest zone of the West Siberian Plain from the north. On the way to the south it transforms and therefore in the northern regions it is still quite humid, while in the southern regions it warms up and moves further and further from the saturation point. Summer throughout the territory is relatively short, but warm. Average July temperatures are +17.8° (Tobolsk), +20.4° (Tselinograd) and +19° (Novosibirsk).

Amount of precipitation - 400-500 mm, maximum - in summer. Over the entire territory at the same latitudes in the European part of the Soviet Union, more precipitation falls than in Western Siberia.

Long winters with low temperatures in the northern part of the plain contribute to the existence of permafrost; the southern border runs from west to east within approximately 61-62° N. w. Under the riverbeds, the top of the frozen soil is much lower than on the watersheds, and under the Ob and Yenisei rivers it is not found at all.

Groundwater is fresh and lies close to the surface (at a depth of 3-5 to 12-15 m). Extensive sphagnum bogs have developed along the watersheds. The rivers have slight slopes and flow slowly in wide, strongly meandering channels. This is associated with the weak mineralization of river waters (50-150 mg/l) and poor aeration of stagnant waters. Deadlocks form in rivers. The essence of the death phenomena comes down to the following: groundwater and swamp water containing a small amount of oxygen and a lot of organic substances enter the Ob and its tributaries. With the formation of ice on rivers, the supply of oxygen from the air stops, but swamp water continues to flow into the rivers and absorb oxygen. This leads to oxygen deficiency and causes massive fish deaths. The overseas zone occupies an area of ​​about 1,060,000 in the basin of the Ob and Irtysh rivers. km 2. To the north, the overseas zone advances to the lower reaches of the river. Ob and even extends to the Gulf of Ob.

Soils. Soil formation occurs in conditions of flat, heavily swampy terrain, covered with taiga vegetation. The parent rocks are diverse: glacial, fluvioglacial, lacustrine and eluvial-deluvial consist of sandy, sandy-clayey and boulder-free sediments, as well as loess-like loams. The forest zone of the plain is characterized by podzolic, podzolic-swamp and peat-swamp soils.

Vegetation. Within the forest zone, moving from north to south, the following subzones are distinguished.

1. Subzone of pre-tundra larch woodland. This subzone stretches in a narrow strip from the Urals to the river. Yenisei, expanding in the east.

The strip of woodland consists of Siberian larch( Larix sibirica) with a touch of spruce ( Picea obovata) and cedar ( Pinus sibirica), especially in the southern part of the subzone, but spruce is more common in the west than in the east. Forests are sparse, treeless areas are occupied by small swamps and tundra formations.

2. The northern taiga subzone is characterized by an open forest stand and a wide distribution of flat-hilly sphagnum bogs. The forests consist of larch with some spruce, birch, and cedar. In the northern part of the subzone, in some places they are clean, without impurities. Larch forests are spread over the sands, and to the south, pine forests settle on the sands along river valleys and watersheds. The ground cover of forests is formed by lichens and mosses. Typical shrubs and herbs include: bearberry, crowberry, lingonberry, sedge (Carex globularis ) , horsetails ( Equisetum sylvaticum, E. pratense); the undergrowth consists of birchberry, wild rosemary and blueberry. These forests occupy large areas closer to the Yenisei and Ob rivers. The middle part of the northern taiga is dominated by swamps.

3. Subzone of the middle taiga. Dark coniferous forests are formed by spruce and cedar with an admixture of larch and fir( Abies sibirica). Larch is found throughout the zone, but in small areas. Birch is more widespread than in the northern taiga, which often grows together with aspen, forming birch-aspen forests. The dark coniferous taiga is characterized by great density and gloominess. Dark coniferous forests are distributed unevenly within the subzone. The most significant massifs are concentrated in the middle and eastern parts. To the west of the Ob and Irtysh rivers, pine forests with sphagnum bogs predominate. Forests of spruce and cedar are found mainly in river valleys. They have varied grass cover and dense thickets of Siberian pigweed shrubs (Cornus tatarica ) , bird cherry, viburnum, honeysuckle ( Lonicera altaica).

4. Southern taiga. For the southern taiga, the dominant species is fir; birch and aspen forests are widespread. In the west, in the southern taiga forests, linden is found( Tilia sibirica) with herbal companion - whine( Aegopodium podagraria). The middle and southern taiga is classified as urman-marshy taiga.

5. The subzone of deciduous forests is formed mainly by downy birch( Betula pubescens) and warty (IN. verrucosa) and aspen ( Populus tremula), alternating with grass and sphagnum bogs, meadows and pine forests. Spruce and fir enter the deciduous forest subzone. Birch and aspen forests are confined to soddy-podzolic soils, leached chernozems and malts.

Pine forests grow on the sands; They occupy the largest area in the river basin. Tobola.

The subzone of deciduous forests gradually turns into forest-steppe. In the west (west of the Ishima River) the forest-steppe is more forested than in the east. This is apparently due to the high salinity of the soils in its central and eastern parts.

The fauna of the Western Siberian taiga has many species in common with the European taiga. Everywhere in the taiga they live: brown bear, lynx, wolverine, squirrel, ermine. Birds include capercaillie and black grouse. The distribution of many animal species is limited to the Ob and Yenisei valleys. For example, the roller and the European hedgehog do not penetrate further east than the river. Obi; The birds that do not cross the Yenisei are the great snipe and the corncrake.

The riverine taiga and secondary aspen-birch forests are rich in animals. Typical inhabitants of these forests are elk, mountain hare, ermine, and weasel. Previously, beavers were found in large numbers in Western Siberia, but at present they are preserved only along the left tributaries of the Ob. A beaver reserve was organized here along the Konda and Malaya Sosva rivers. Muskrat (musk rat) is successfully bred in reservoirs. American mink have been released in many places in the Western Siberian taiga.

Birds nest in the taiga. Cedar forests - favorite place nutcrackers; The Siberian crossbill is more common in larch forests; the three-toed woodpecker taps in spruce forests. There are few songbirds in the taiga, so they often say: the taiga is silent. The most diverse bird kingdom is found in birch-aspen burnt areas and on river banks; Here you can find waxwings, finch, long-tailed bullfinch, and ruby-throated nightingale. On reservoirs - geese, ducks, waders; A white partridge wanders through the moss swamps far to the south, almost to the forest-steppe. Some birds fly to the West Siberian taiga from the southeast. Many of them winter in China, Indochina, and the Sunda Islands. The long-tailed bullfinch, ruby-throated nightingale, etc. fly there for the winter.

Of commercial importance are: squirrel, fox, ermine, and weasel. Birds include hazel grouse, black grouse, capercaillie and white partridge.

Forest-steppe and steppe The West Siberian Plain was formed in special physical and geographical conditions, namely: on a flat, poorly drained topography, on saline parent rocks, at a considerable distance from the oceans, in a more continental climate. Therefore, their appearance is sharply different from the forest-steppe and steppe of the Russian Plain.

The West Siberian forest-steppe stretches in a narrow strip from the Urals to the foothills of the Salair Ridge and Altai.

This is the southern part of the marine Tertiary plain, covered with loose Quaternary sediments, ancient alluvial and fluvioglacial

sands, colluvial loess-like loams, loess and modern lacustrine and alluvial sands and clays.

Bedrock - tertiary clays, sands, loams - are exposed by river valleys and appear in natural outcrops in the bedrock banks or at the base of terraces in the western, southern and southeastern parts of the steppe zone, where tertiary rocks are uplifted and form plateaus or inclined plains.

The modern relief of the forest-steppe and steppe was greatly influenced by ancient streams, which formed wide runoff depressions crossing the Priobskoe plateau, the Kulunda, Barabinskaya lowlands and other territories. The ancient hollows are directed from northeast to southwest. The bottoms of the hollows are flat, composed of loose sediments. The interfluves between the runoff depressions are elongated in the same direction as the depressions and are called “manes.” Modern rivers flow through the hollows, which flow either into the Ob and Irtysh or into lakes, or are lost in the steppe. All these landforms are clearly visible from an airplane, especially in early spring, when they still have patches of snow and the watershed areas are already free of snow. One of the features of the steppe and forest-steppe zones of Western Siberia should be considered the abundance of lake basins. They are common on flat watersheds and river valleys. The largest of them are the lakes of the Barabinsk steppe, where the largest shallow lake is located. Chany and Ubinskoye Lake. Of the lakes of the Kulunda steppe, the largest is Kulunda. The lakes of the Ishim steppe are mostly small. The largest lakes include Seletytengiz. There are many small lakes on the Ishim-Irtysh inclined plain and the Ishim Upland.

Thousands of lakes occupy depressions in ancient hollows; they represent the remains of former river channels. The shores of such lakes are low, often swampy or overgrown with pine forests. The lakes are fed by melt and rainwater formed as a result of surface runoff. For many reservoirs, especially large ones, ground nutrition is also essential.

Lakes periodically change their level, and therefore their outline and their water supply: they either dry out or fill up again with water 1 . Changes in lake levels are associated with fluctuations in climatic conditions: with the ratio of precipitation and evaporation. Human activity also has some influence on changes in lake levels: building dams, laying ditches, burning birch stakes, and mowing reed thickets along the banks. For example, in the Barabinskaya, Kulundinskaya and Ishimskaya steppes, after fires, new lakes with a depth of up to 1.5-2 m. After mowing down the coastal thickets of reeds and reeds, some of the fresh lakes in the Kulunda steppe turned into salt lakes, since snowdrifts stopped accumulating on them in winter, which led to a sharp reduction in one of the most important sources of their nutrition.

Over the past 250 years (since XVII to the middle XXc.) seven complete cycles of fluctuations in the levels of steppe lakes have been established, usually lasting from 20 to 47 years. Based on the analysis of precipitation and temperature conditions, cycles of high and low precipitation activity, warm and cold periods were identified.

Thus, the dependence of lake level fluctuations on fluctuations in precipitation and air temperature is outlined.

It is assumed that fluctuations in the levels of individual lakes are associated with neotectonic movements. Fluctuations in the levels of lakes in the Chany group have been repeatedly recorded.

The steppe and forest-steppe are dominated by lakes containing brackish water (Chany, Ubinskoye, etc.). Lakes are divided according to their chemical composition into three types: hydrocarbonate (soda), chloride (actually salty) and sulfate (bitterly salty). In terms of reserves of salt, soda and mirabilite, the lakes of Western Siberia occupy one of the first places in the USSR. The Kulunda lakes are especially rich in salts.

The climate of the forest-steppe and steppe of the West Siberian Plain differs from the climate of the forest-steppe and steppe of the Russian Plain by being more continental, manifested in an increase in the annual amplitude of air temperature and a decrease in the amount of precipitation and the number of days with precipitation.

Winter is long and cold: the average January temperature in the forest-steppe drops to -17, -20°, sometimes frosts reach -50°; in the steppes the average January temperatures are -15, -16°, frosts also reach -45, -50°

Winter sees the least amount of precipitation. The first half of winter is characterized by snowfalls and strong winds, the speed of which in the open steppes reaches 15 m/sec. The second half of winter is dry, with weakened wind activity. The snow cover is small (40-30 cm) power and is distributed unevenly over the surface of the forest-steppe and steppe.

In spring, insolation and air temperature increase rapidly. The snow cover melts in April. Snow melts very quickly, in the steppe - sometimes in one week.

The average air temperature in the steppe reaches + 15° in May, and the highest - up to +35°. However, in the first half of May there are severe frosts and snow storms. After the snow melts, the temperature rises very quickly: already in the first ten days of May the average daily temperature exceeds +10°.

In the formation of spring dry weather great importance have dry winds, which are most frequent in May. During dry winds the temperature

air reaches +30°, relative humidity below 15%. Dry winds are formed during southern winds that arise on the western edge of the Siberian anticyclones.

Summer in the forest-steppe and steppe is hot and dry with frequent winds and dry weather types. In the forest-steppe the average temperature is about +19°, in the steppe it rises to 22-24°. Relative humidity reaches 45-55% in the steppe, and 65-70% in the forest-steppe.

Droughts and hot winds occur more often in the first half of summer. During summer dry winds, the air temperature can rise to +35, +40°, and the relative humidity reaches about 20%. Droughts and hot winds are caused by the penetration and intense heating of Arctic air masses and the invasion of hot and dry air from Central Asia. Every year, especially in dry years, dust storms occur in the steppes from April to October. Their greatest number occurs in May and early June. More than half of the annual precipitation falls in summer.

The first half of autumn is often warm. In September the air temperature can reach +30°; however, there are also frosts. A rapid drop in temperature is observed from October to November. In October, precipitation increases. Moisture accumulates in the soil in autumn, since evaporation is insignificant at this time. In the northern part of the steppe, snow cover appears at the end of October. Stable frosts set in from November.

The history of the formation of the forest-steppe and steppe of the West Siberian Plain in the Tertiary and Quaternary periods differed sharply from the history of the formation of the steppe and forest-steppe of the Russian Plain. Therefore, the modern appearance of the forest-steppe and steppe of Western Siberia has its own characteristics, which are most clearly manifested in the relief, soils and vegetation. The modern continental climate contributes to the development of drier steppes of the West Siberian Plain compared to the East European Plain and enhances their differences.

The forest-steppe and steppe of the West Siberian Plain are dominated by primary flat, poorly drained plains, covered with extensive swamps, numerous fresh and salt lakes, saucers, wide hollows and ridges.

The gully-gully network is less developed than on the Russian Plain. However, the manifestation of gully activity is observed in all natural zones of the West Siberian Plain, and especially on sloping plains and plateaus adjacent to the Urals and Altai, and along the valleys of the Ob and Irtysh rivers. In the steppes, nivation gullies are widely developed, the formation of which is caused by the accumulation of snow under the influence of strong winds near various natural barriers, especially in gullies and ravines. Soil-forming processes occur in a geologically young, poorly drained area with saline soil, in conditions of insufficient moisture. The zonal soils of the forest-steppe of Western Siberia are meadow-chernozem, leached and podzolized chernozems.

Salt marshes, solonetzes and solods are widespread; their formation is associated with shallow groundwater, soil salinity and increased evaporation. They are confined to depressions. Due to the increase in humidity, the process of soil leaching increased, which led to the destruction of solonetzes and the appearance of malts.

In the steppe zone, southern and ordinary chernozems are developed, which gradually turn into dark chestnut soils with a humus horizon thickness of up to 50 m and with a humus content of 3-4%. Dark chestnut soils have weak signs of solonetsity, an insignificant boiling depth and a large amount of gypsum at a depth of 1m.

The forest-steppe of the West Siberian Plain is called birch forest-steppe. In the northern part of the forest-steppe, the forest cover of the territory is about 45-60%. Isolated forests of birch are called birch tufts. The tufts consist of downy birch with an admixture of aspen, warty birch and willow in the undergrowth. The grass cover in the groves is formed by steppe and forest species. Of the forests, stoneweed is typical( Rubus saxatilis), purchased ( Polygonatum officinale) ; from bushes - currants ( Ribes nigrum). Pine is the most common coniferous species in the forest-steppe. Pine forests occupy sandy and sandy loam areas and extend along the floodplain terraces of valleys south to the steppe zone. Under the pine canopy, taiga plant groups move to the south - the pine's companions: sphagnum bogs, on which grow: wintergreen, lingonberries, blueberries, cranberries, sundews, cotton grass, sedges and orchids. In the most elevated, dry places, white moss forests with a ground cover of reindeer lichen (moss moss) are developed. The soil cover of pine forests is very diverse and consists of podzols, dark-colored solodized peaty soils and solonchaks. But at the same time, steppe species (fescue and steppe timothy) are common in the grass cover of southern pine forests.

Steppe areas have a dense herbaceous cover, consisting of typical meadow rhizomatous grasses: reed grass, meadow grass, steppe timothy. The most common legumes are clover and peas, and the asteraceae are meadowsweet.( Filipendula hexapetala), Solonchak forms appear on salt marshes.

When moving south, the grass cover of the steppes thins, the species composition changes - steppe species begin to predominate, and meadow and forest species are noticeably reduced. Among the cereals, turf xerophytes predominate: fescue( Festuca sulcata) and thin-legged ( Koeleria gracilis), feather grasses appear( Stipa rubens, St. capillata). Of the forbs, the most typical are alfalfa( Medicago falcata) and sainfoin ( Onobrychis arenaria). Salt marsh plants are beginning to be found more often: licorice, solyanka, large plantain, astragalus. There are fewer birch trees, and the area's forest cover is only 20-45%.

In the Western Siberian forest-steppe, as already noted, wetlands called borrow areas are widespread. The lands are covered with marsh vegetation: sedge, reeds, reeds, cattails. They occupy low interfluve spaces and are the final stage of overgrowing reservoirs. Loans are especially abundant in the Barabinsk steppe. In addition, moss-sphagnum swamps overgrown with rare, oppressed pine are common in the Western Siberian forest-steppe. They are called ryams. Pine forests, fields and ryams in the modern dry climate should be considered intrazonal plant groups that possibly formed during the Ice Age.

The steppes occupy the extreme south of the West Siberian Plain. Within the steppe zone of Western Siberia, two subzones are distinguished: the northern - feather-grass-forb chernozem steppe and the southern - feather-grass-fescue chestnut steppe. The composition of the northern steppes is dominated by xerophytic narrow-leaved grasses: reddish feather grass( Stipa rubens), hairy sheep, fescue, thin-legged sheep, desert sheep ( Auenastrum desertorum), timothy grass Forbs are less abundant than in the forest-steppe steppes and consist of yellow alfalfa, bedstraw, speedwell, sleep grass, cinquefoil, and wormwood.

In terms of species composition and aspect, the Western Siberian steppes differ from the colorful European steppes of this subzone. In the Siberian steppes there are no sage, black crow, rouge, or clovers.( Trifolium montanum T. alpestre), but xerophytic forbs predominate.

The southern steppes of the West Siberian Plain are dominated by turf grasses: fescue, tonkonogo and feather grass. Abundant rhizomatous steppe sedge( Carex sypina). Among the herbs, xerophytic species predominate, for example: wormwood ( Artemisia glauca, Alatifolia), onion ( Allium lineare) , Adonis ( Adonis wolgensis), gerbils ( Arenaria graminifolia); many Siberian forms that do not extend into the European steppe: iris ( Iris scariosa), goniolimon ( Goniolimon speciogum) and etc.

The grass cover is sparse, and the turf cover of the steppes reaches 60-40%. Along the shores of lakes, on salt licks, solonetzic species, such as sea wormwood, grow. In depressions with close groundwater and along the shores of salt lakes, salt marshes with typical halophytic vegetation predominate: saltwort, saltmarsh barley, licorice.

In the steppes, along river valleys, hollows of ancient drainage, and logs, there are thickets of willow and birch; along the sands there are patches of pine forests (green moss, lingonberry and white moss with a large number of steppe species). So, for example, in the river valley. Irtysh on the sandy right-bank terrace, vast pine forests stretch from the city of Semipalatinsk to the city of Pavlodar.

The floodplains of large rivers are covered with meadow vegetation, which forms a thick, lush grass stand of wheatgrass, steppe alfalfa, and water-grass; Closer to the water, marsh associations of reeds and sedges dominate. Wet floodplain meadows are an example of a sharp contrast with the dry feather grass-fescue steppes, which quickly burn out in the summer.

The northern and southern steppes are used as pastures and hayfields. Most of their territory is plowed.

The most significant natural difficulties for Agriculture the steppe zone of the West Siberian Plain is the dryness of its climate and the penetration of hot winds.

Forest plantations and belt pine forests help to increase the yield of grain crops, since air and soil humidity around them increases, and the amount of precipitation increases compared to the treeless steppe. In ribbon forests and forest belts, in addition to the main species, pine, pedunculate oak, small-leaved linden, Amur larch, Amur velvet are planted, and in the undergrowth - Amur acacia and Maak bird cherry.

The fauna of the forest-steppe is more diverse than the fauna of the steppe, since the latter is characterized by the uniformity of ecological conditions over vast areas. The forest-steppe fauna includes forest and steppe species. Along the groves and ribbon pine forests, northern (taiga) elements penetrate to the south even into the feather grass-fescue steppes, and along the meadow-steppe areas, the steppe elements enter the northern part of the forest-steppe; for example, in the Kulundinsky pine forests, along with steppe species - garden bunting, field pipit, woolly jerboa - taiga species of animals live: squirrel, flying squirrel, capercaillie.

Animals living in the tundra are found in the forest-steppe and steppe. They are relics ice age. The white partridge is found even in the steppes of Kazakhstan up to 50.5° N. sh., its nesting sites are known on the lake. Chans. Nowhere does it penetrate as far to the south as in the Western Siberian steppes. The laughing gull, typical of the tundra zone of Taimyr, is found on lakes in the forest-steppe and steppe.

The fauna of the forest-steppe and steppe has many similarities in the composition of the fauna and its origin with the fauna of the European steppe and forest-steppe, but the geographical features of the West Siberian Plain predetermined its difference from neighboring territories.

Of the mammals in the forest-steppe and steppe, there are many rodents: voles, steppe pied, ground hare - the largest of the jerboas ( Allactaga gaculus); Djungarian hamster and red-cheeked ground squirrel are often found ( Citellus erythrogenus). The steppe is characterized by the small or gray ground squirrel and marmot (baibak).

The following predators live in the steppe and forest-steppe: wolf, fox, steppe ferret. A small fox - a corsac - comes into the steppe from the south. Typical taiga species are found in the forests of the forest-steppe: weasel, weasel, and ermine.

IN XIV- XIXcenturies in the steppes of the West Siberian Plain there were animals that are currently distributed only in the forest zone. For example, in the valleys of the Tobol, Ishim and Irtysh rivers, south of Petropavlovsk and lake. Chany, there was a beaver, and near the city of Kustanai and between the cities of Petropavlovsk and Tselinograd there was a bear.

Among the birds of the forest-steppe there are many European forms (common bunting, oriole, chaffinch). In the steppe areas, common and Siberian larks are numerous, and little bustards and bustards are occasionally found. In the southern steppes there are more of them: larks - four species (the small or gray lark penetrates from the desert into the steppe). Demoiselle crane and steppe eagle are also found. Grouse, gray and white partridges serve as winter fishery items.

The insect fauna is abundant, consisting of small locust fillies, which sometimes damage crops, and “gnats” - mosquitoes, midges, horseflies.

There are four physical-geographical regions on the West Siberian Plain. Their occurrence is due to the history of the development of the territory in the Quaternary period and modern geographical zoning. Physiographic regions are located in the following order when moving from north to south: 1. Marine and moraine plains of the tundra and forest-tundra zones. 2. Morainic and outwash plains of the forest zone. 3. Alluvial-lacustrine and alluvial plains of forest and forest-steppe zones. 4. The area of ​​lacustrine-alluvial and erosion plains with a cover of loess-like rocks of the forest-steppe and steppe zones. Each of these areas has internal morphological, climatic and soil-plant differences, and is therefore divided into physical-geographical regions.

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

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

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

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

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

West Siberian Lowland the third largest plain on our planet after the Amazon and Russian. Its area is about 2.6 million square kilometers. The length of the West Siberian Lowland from north to south (from the coast to the mountains of Southern Siberia and) is about 2.5 thousand kilometers, and from west to east (from to) - 1.9 thousand kilometers. The West Siberian Lowland is quite clearly limited in the north by the coastline of the sea, in the south by the hills of Kazakhstan and mountains, in the west by the eastern foothills of the Urals, and in the east by the valley of the Yenisei River.

The surface of the West Siberian Lowland is flat with a fairly insignificant difference in elevation. Small elevations are characteristic mainly of the western, southern and eastern outskirts. There their height can reach about 250-300 meters. The northern and central regions are characterized by lowlands with an altitude of 50-150 meters above sea level.

Along the entire surface of the plain there are flat areas of interfluves, as a result of which they are significantly swamped. In the northern part there are sometimes small hills and sandy ridges. Quite impressive areas on the territory of the West Siberian Lowland are occupied by ancient basins, the so-called woodlands. here they are mainly expressed by rather shallow hollows. Only some of the largest rivers flow in deep (up to 80 meters) valleys.

Yenisei River

The glacier also influenced the nature of the relief of Western Siberia. The northern part of the plain was mainly exposed to it. At the same time, water accumulated in the center of the lowland, as a result of which a fairly flat plain was formed. In the southern part there are slightly elevated sloping plains with many shallow basins.

More than 2,000 rivers flow through the West Siberian Lowland. Their total length is about 250 thousand kilometers. The largest are. Not only are they navigable, but they are also used to generate energy. They feed mainly from melt water and rain (in the summer-autumn period). There are also a large number of lakes here. In the southern regions they are filled with salt water. The West Siberian Lowland holds the world record for the number of swamps per unit area (the area of ​​the wetland is about 800 thousand square kilometers). The reasons for this phenomenon are the following factors: excess moisture, flat topography, and the ability of peat, which is available here in large quantities, to retain a significant amount of water.

Due to the large extent of the West Siberian Lowland from north to south and the uniformity of the relief, there are many natural zones within its borders. In all zones, lakes and swamps occupy fairly large areas. are absent here, and the area is rather insignificant.

The zone occupies a large area, which is explained by the northern position of the West Siberian Plain. To the south is the forest-tundra zone. As mentioned above, the forests in this area are mainly coniferous. The forest-swamp zone occupies about 60% of the territory of the West Siberian Lowland. The strip of coniferous forests is followed by a narrow zone of small-leaved (mainly birch) forests. The forest-steppe zone is formed under flat-flat terrain. The groundwater lying here at shallow depths is the cause of a large number of swamps. In the extreme southern part of the West Siberian Lowland is located, which is mostly plowed.

The flat southern regions of Western Siberia are rich in ridges - sandy ridges 3-10 meters high (sometimes up to 30 meters), covered with pine forest, and kolki - birch and aspen groves that are scattered among the steppes.

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 boundaries: Kara Sea - Turgai Plateau, Ural - 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:

1). Slight fluctuation in altitude (there are no such vast areas in the CIS).

2). The large extent 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). A country of classical latitudinal zoning.

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

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

Development of the territory.

The Russian development of the plain began after Ermak’s campaign (1581-1584). Scientific study began in the 18th century (Great Northern and academic expeditions). The conditions of navigation of the Ob, Yenisei, and Kara Seas are being studied. Intensive development of the forest-steppe in the south and 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 and botanical expeditions are sent here. However, until 1917 Western Siberia remained poorly developed and almost unexplored.

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

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

Many scientific institutes are studying Western Siberia: the Russian Academy of Sciences, the Siberian Branch of the Russian Academy of Sciences, the West Siberian Geological Department, the Ministry of Agriculture, Hydroproject.

History of the formation of the territory.

1). At the base of the West Siberian Lowland lies the Epihercynian plate. The foundation of the slab is Paleozoic in age.

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

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

3). The upper tier (cover) 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 peneplainization of an ancient folded country (Late Paleozoic - Jurassic).

2. Formation of the internal 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 region. As a result of the Caledonian folding, the southeastern part of the West Siberian Platform was formed and emerged from under 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 change of lavas. In the Jurassic, the contours of a vast internal depression are laid down, subsidence occurs, and a thick layer 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 began, which was caused by 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 the vast downgraded Inner Region ended in its main features (all this during the Jurassic and Cretaceous).

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 was observed, which covered 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 Turanian Sea.

111 transgression:

Paleogene - tectonic movements intensify in the eastern coastal areas of the plains, the land area expands significantly. The sea remains 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 Turanian Sea.

The end of the Paleogene is characterized by a powerful new stage of intensification of tectonic movements. There is 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 boundary of the Paleogene and Neogene. It was at this time that a river network began to form on the low-lying accumulative plain that rose above sea level. The surface of the plain generally corresponded to the geostructural plan: low areas coincided with tectonic depressions and contained river valleys. The center of the plain already had a saucer-shaped structure, many rivers were directed towards the center (the general flow is to the north).

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

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 dominant position in the north is occupied by dark conifers (spruce, cedar, fir, pine, larch), and to the south by 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 Pleistocene glaciations). The era of this glaciation coincides with the transgression of the polar sea, which penetrated to the south and formed vast bays. The transgression continued during the interglacial (Tobolsk) era and reached its maximum during the maximum Samarov glaciation. The sea covered the entire territory north of the Siberian Uvaly. This is a zone of marine glaciation; sheet 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 a kind of dam, to the south of which a huge dammed reservoir arose. The flow from it went through the Turgai Strait. In the late Pleistocene, there was a short-term regression, which was replaced by a new 2nd transgression; after its maximum, the Zyryanovsky glaciation began (lower Ob). During this glacial era, the continental climate intensifies, and permafrost forms 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 rise, sea level dropped, river valleys deepened, and terraces formed.

Quaternary history is characterized by:

Synchronicity of glaciations and transgressions.

North and south were distinguished by the latest tectonic movements. Pleistocene - the north sags, the south rises (glacier). Later, the north rises more intensely than the south.

The glacier had an impact on the 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 their composition: soils, vegetation and wildlife. In the Pleistocene, the pre-Quaternary fauna and flora disappeared, and new cold-resistant species (boreal flora) appeared in their place. In the south there are forest-steppe and steppe landscapes. The broad-leaved flora has completely disappeared.

Relief.

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

Large relief elements are represented here - plateaus, hills, sloping plains and lowlands.

The surface of the plain has the general shape of an amphitheater, open to the north. The western, southern and eastern peripheries are dominated by plateaus, hills, and sloping plains, while lowlands are concentrated in the central and northern parts.

In the center and in the north there are the Kandinskaya, Sredneobskaya, Nizhneobskaya, Nadymskaya, Purskaya lowlands. West, south, east - North Sosvinskaya, Turinskaya, Ishimskaya, Priobskoye (plateau), Chulymo-Yeniseiskaya, Ketsk-Tymskaya, Verkhnetazkhovskaya, Nizhneeniseiskaya - uplands.

The zonality of the modern relief is clearly visible on the plain (3 geomorphological zones):

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

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

Zone of fluvioglacial forms of lacustrine-glacial plains and modern erosion-accumulation processes. The zone extends to the middle taiga. Solifluction manifests itself locally. Characterized by greater surface evenness. The predominant types of relief formed by water-glacial and alluvial accumulation (outwash plains). Permafrost has an island distribution. There are islands of moraine plains (Agansky Uval) and morpho-structural formations (Beleyursky, Tobolsk continent).

In the north, flat, hilly, flat terrain predominates with ancient glacial forms (moraines, ridges, hills, eskers, kamas, basins) well defined along the edges (near the Urals and the Middle Siberian Plateau).

To the south, the surface of the West Siberian Plain is characterized 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 Barabinskaya, Kulundi lowlands. The centers of these lowlands are occupied by lakes (chany, Kulundinskoye).

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

Suffusion-karst processes created numerous drainless depressions, closed basins, and steppe saucers. The most specific feature of the eastern part of the zone is the ridge-hollow relief, presumably of fluvioglacial origin. (Dells - chains of lakes, ridges - 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 area of ​​the country, therefore it is they who determine the appearance of the relief of the plain. The interfluves are heavily swamped (there is a lot of precipitation, and drainage is difficult). This is the interfluve of the Ob and Irtysh, Vasyugan, Barabinskaya forest-steppe. About 70% of the area of ​​Western Siberia is swamped to one degree or another.

River valleys have slight slopes, the river flow is slow and 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 capital investment).

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

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

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

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

Gas – the lower reaches of the Ob, Taz, Yamal and Gydan several tens of trillions of cubic meters. 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).

WEST SIBERIAN PLAIN (West Siberian Lowland), one of the largest plains on the globe. Located in the northern part of Asia, in Russia and Kazakhstan. The area is over 3 million km2, including 2.6 million km2 in Russia. The length from west to east is from 900 km (in the north) to 2000 (in the south), from north to south up to 2500 km. In the north it is washed by the Arctic Ocean; in the west it borders with the Urals, in the south - with the Turgai plateau and the Kazakh small hills, in the southeast - with the mountains of Southern Siberia, in the east - along the valley of the Yenisei River with the Central Siberian Plateau.

Relief. It is a low accumulative plain with a rather uniform topography, various forms of permafrost (extended up to 59° north latitude), increased swampiness and ancient and modern salt accumulation developed in the south in loose rocks and soils. The predominant heights are about 150 m. In the north, in the area of ​​distribution of marine accumulative and moraine plains, 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, the southern border of which runs around 61-62° north latitude; they are covered in a horseshoe shape from the south by the flat-topped heights of the Belogorsk Continent, Sibirskie Uvaly, etc. In the northern part, exogenous permafrost processes (thermoerosion, soil heaving, solifluction) are widespread, deflation occurs on sandy surfaces, and peat accumulation occurs in swamps. There are numerous ravines on the plains of the Yamal and Gydansky peninsulas and on the moraine hills. To the south, the region of moraine relief is adjacent to flat lacustrine-alluvial lowlands, the lowest (height 40-80 m) and swampy of which are Kondinskaya and Sredneobskaya. The area not covered by Quaternary glaciation (south of the line Ivdel - Ishim - Novosibirsk - Tomsk - Krasnoyarsk) is a weakly dissected denudation plain, rising (up to 250 m) towards the Urals. In the interfluve of the Tobol and Irtysh there is an inclined, in 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. It is adjacent to the alluvial Baraba Lowland and the Kulunda Plain, where processes of deflation and modern salt accumulation develop. In the foothills of Altai there are ridge-hilly Priobskoe plateau (height up to 317 m - highest point West Siberian Plain) and Chulym Plain. For information on the geological structure and mineral resources, see the article West Siberian Platform, with which the West Siberian Plain is geostructurally connected.

Climate. Continental climate prevails. Winter in polar latitudes is severe and lasts up to 8 months (the polar night lasts almost 3 months), average January temperatures range from -23 to -30 °C; in the central part, winter lasts up to 7 months, average January temperatures range from -20 to -22 °C; in the south, where the influence of the Asian anticyclone increases, at the same temperatures winter is shorter (up to 5-6 months). Minimum air temperature -56 °C. In summer, the westerly transport of Atlantic air masses predominates with invasions of cold air from the Arctic in the north, and dry warm air masses from Kazakhstan and Central Asia in the south. In the north, summer is short, cool and humid with polar days, 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. The wettest (400-550 mm per year) are the Kondinskaya and Middle Ob lowlands. To the north and south, annual precipitation gradually decreases to 250 mm.

Surface waters. On the West Siberian Plain there are more than 2000 rivers belonging 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 are the Ob, Yenisei, Irtysh, Taz and their tributaries. 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. Ice cover on rivers lasts up to 8 months in the north, and up to 5 in the south. Large rivers are navigable, are important rafting and transport routes, and, in addition, have large reserves of hydropower resources. The total area of ​​the lakes is more than 100 thousand km2. The largest lakes are located in the south - Chany, Ubinskoye, Kulundinskoye. In the north there are lakes of thermokarst and moraine-glacial origin. In the suffusion depressions there are many small lakes (less than 1 km2): in the Tobol-Irtysh interfluve - more than 1500, in the Barabinskaya Lowland - 2500, including fresh, salty and bitter-salty; There are self-sedating lakes.

Types of landscapes. The uniformity of the relief of the vast West Siberian Plain determines a clearly defined latitudinal zonation of the landscapes, although compared to the East European Plain, the natural zones here are shifted to the north. On the Yamal, Tazovsky and Gydansky peninsulas, under conditions of continuous permafrost, landscapes of arctic and subarctic tundra were formed with moss, lichen and shrub (dwarf birch, willow, alder) cover on gley soils, peat gley soils, peat podburs and turf soils. Polygonal mineral 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 is the Vasyugan Plain. Forest complexes of different subzones are unique, formed on slopes with varying degrees of drainage. Northern taiga forest complexes on permafrost are represented by sparse and low-growing pine, pine-spruce and spruce-fir forests on gley-podzolic and podzolic-gley soils. Indigenous landscapes of the northern taiga occupy 11% of the area of ​​the West Siberian Plain. Common to the forest landscapes of the middle and southern taiga is the wide distribution of lichen and shrub-sphagnum pine forests on sandy and sandy loamy ferruginous and illuvial-humus podzols. On loamy soils in the middle taiga 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 there are spruce-fir small-grass forests and birch forests with aspen on sod-podzolic and sod-podzolic-gley soils (including with a second humus horizon) and peat-podzolic-gley soils. Indigenous landscapes in the middle taiga occupy 6% of the area of ​​the West Siberian Plain, in the southern - 4%. 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 cover 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 natural habitats of 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 - the Gydansky Reserve, in the northern taiga - the Verkhnetazovsky Reserve, in the middle taiga - the Yugansky Reserve, etc. national park- Priishimskiye Bory. Natural parks have also been organized: in the tundra - Oleniy Ruchi, in the northern taiga - Numto, Sibirskie Uvaly, in the middle taiga - Kondinsky Lakes, in the forest-steppe - Bird Harbor.

Lit.: Trofimov V. T. Patterns of spatial variability of engineering-geological conditions of the West Siberian Plate. M., 1977; Gvozdetsky N. A., Mikhailov N. I. Physical geography of the USSR: Asian part. 4th ed. M., 1987; Soil cover and land resources Russian Federation. M., 2001.