Lesson topic: "Eastern Siberia: general features of nature." Northeast Siberia
The hydrographic network of the region belongs to the Arctic Ocean basin and is distributed over the private basins of the Kara, Laptev, East Siberian and Chukchi seas.
Eastern Siberia covers a vast part of the Asian continent, located east of the Yenisei and extending to the shores of the Bering Sea, and in meridional direction- from the shores of the Northern Arctic Ocean to the Mongolian People's Republic.
The hydrographic network of the region belongs to the Arctic Ocean basin and is distributed among the private basins of the Kara, Laptev, East Siberian and Chukchi seas. By the nature of the relief, Eastern Siberia belongs to the mountainous regions, with mountains of medium height and extensive plateaus predominating here, while the lowlands occupy only small spaces.
Between the Yenisei and Lena lies the Siberian Plateau, dissected by erosion. Its height is on average 300-500 m above sea level; Only in some places higher elevations stand out among the plateau - the Putorana Ridge (1500 m), the Vilyui Mountains (1074 m) and the Yenisei Ridge (1122 m). The Sayano-Baikal folded country is located in the upper part of the Yenisei basin. This is the most high-mountainous area of the region, with heights up to 3480 m (peak Munku-Sardyk).
To the east of the lower reaches of the Lena River extends the Verkhoyansk-Kolyma Mountain country, characterized by sharp contrasts of lowland and mountain landscapes. Along the right bank of the Lena stretches a powerful arc of the Verkhoyansk ridge with heights of up to 2000 m, then to the east rises the Chersky ridge - a mountain node with a height of 2000-3000 m, the Tas-Khayakhtakh ridge, etc. Along with the mountain ranges, the Verkhoyansk-Kolyma mountain region includes Oymyakon, Nerskoe and Yukaghir plateaus. In the south, the border of the region is formed by the Yablonovy, Stanovoy and Duzhgdzhur ridges, whose heights reach 2500-3000 m. In the east, the Kolyma Range, or Gydan, stretches along the coast of the Sea of Okhotsk.
On the territory of Eastern Siberia there are also lowland plains, among which the Leno-Vilyuiskaya lowland, which is a grandiose synclinal trough, stands out for its size. The extreme north of the region, along the coast of the marginal seas, is occupied by the Subpolar Sea Lowland, the height of which does not exceed 100 m above sea level; lowlands are also located in the lower reaches of Alazeya, Kolyma and Indigirka.
The subpolar lowland is occupied by tundra and forest-tundra. Most of the territory of Eastern Siberia belongs to the taiga zone. The forest landscape is dominated by Daurian larch, which is most adapted to the harsh climate and the presence permafrost; There are significantly fewer pine trees here. The forests of Eastern Siberia are slightly swamped.
The taiga zone in Eastern Siberia is dominant and extends far to the south; areas of steppe and forest-steppe are interspersed with it in the form of spots (Minusinsk Basin, which has a steppe character, the steppes of Transbaikalia).
Geologically, the area is characterized by shallow bedrock crystalline rocks, which often come to the surface here. Ancient igneous rocks - traps - are widespread, especially within the Central Siberian Plateau, forming characteristic vertical outcrops in the form of columnar units (locally called pillars) along river valleys.
The rivers of Eastern Siberia predominantly have the form of mountain streams; flowing through the lowlands, they acquire a flat character.
The climatic conditions of Eastern Siberia are largely determined by its geographical location within the Asian continent. Great influence on climatic conditions The area is affected by the Siberian anticyclone that forms in the center of Asia in winter - an area of high pressure, a powerful spur of which occupies the entire Eastern Siberia. Under conditions of stable anticyclonic weather, winter is characterized by low clouds and a predominance of calm conditions, which entails strong cooling. Clear, harsh, little snow, stable and long winters and rather dry, short and hot summers - these are the main features of the climate of Eastern Siberia. Frosts, for example, in the area of Verkhoyansk and Oymyakon reach -60, -70. These are the lowest air temperatures observed in globe, which is why the area of Verkhoyansk and Oymyakon is called the pole of cold. Average monthly air temperatures in the coldest month - January - range from -25 -40 in the south of the region to -48 in Verkhoyansk. In summer, daily air temperatures sometimes rise to 30-40. Average monthly temperatures of the warmest month - July - in the northern part of the region (in the tundra zone) are about 10, in the south, in the upper reaches of the Yenisei (Minusinsk Basin), up to 20.8. Air temperature transition from 0 to far north observed in mid-June, in autumn - in mid-September, and in southern parts district (Minusinsk Basin) - in the twenties of April and in mid-October. The arid Minusinsk Basin stands out sharply in its climatic conditions; its climate approaches the climate of the steppes of the European part of the USSR.
There is little precipitation. In the predominant part of the region, their number does not exceed 200-400 mm per year. The Leno-Vilyui Lowland is extremely poor in precipitation (200 mm). Even less precipitation falls in the north, in the Subpolar Sea Lowland, where the annual amount does not exceed 100 mm. For example, in the area of the river delta. Lena rains only about 90 mm per year. Approximately the same amount of precipitation falls on the islands of the Arctic zone (New Siberian Islands, Wrangel Island). Precipitation is more abundant in the Sayan Mountains, where the annual amount reaches 600-700 mm, and in some places even 1200 mm.
Most of the precipitation (70-80%) falls in the summer in the form of rain, which is usually continuous. In the cold part of the soda there is little precipitation - no more than 50 mm.
The snow cover is thin; Only in the Yenisei basin and within the Central Siberian Plateau does relatively much snow fall. The least amount of snow falls in the Yana and Indigirka basins.
In the harsh climate of Eastern Siberia, with its long periods of little snow and cold winter, a characteristic feature of the region is the widespread distribution of permafrost. The thickness of the permafrost layer in the northern and central regions reaches 200-500 m or more. In the southern parts of the region (Transbaikalia, the upper Yenisei basin), the thickness of permafrost decreases, and more or less significant areas devoid of permafrost (taliks) appear.
The presence of permafrost creates complex hydrogeological conditions. Groundwater supplies in most of Eastern Siberia are very poor; groundwater is represented predominantly by perched water, which does not participate in river feeding. Outcrops of sub-permafrost water are relatively rare and are confined to areas of young faults in the earth's crust and karst areas (upper reaches of the Aldan).
In a number of places (Leno-Vilyuiskaya lowland, lowlands of the mouth areas of the Kolyma and Indigirka rivers, etc.) they are found at a shallow depth from the surface buried ice, occupying significant areas; their thickness sometimes reaches 5-10 m or more.
The harsh climate and permafrost determine the uniqueness of the water regime in Eastern Siberia. Given the complete impermeability of frozen soils and low losses due to filtration and evaporation, the surface runoff here is relatively high, despite the small amount atmospheric precipitation. Permafrost is the cause of poor groundwater supply to rivers and the widespread occurrence of freezing phenomena, as well as the formation of ice dams. In permafrost conditions, erosion processes also develop in a unique way. Soils bound by permafrost are difficult to erode, and therefore deep erosion develops poorly. Lateral erosion predominates, leading to widening of valleys.
Research carried out in recent years has shown that modern glaciation is widespread in Eastern Siberia. It is found in the most elevated parts of the Verkhoyansk and Chersky ridges - in the upper reaches of the Yana and Indigirka basins. The glaciation area reaches 600-700 km2, which is approximately equal to the area of modern Altai glaciation. The size of the glaciers is small. The largest glacier of the Sauntar group (on the watershed of Indigirka and Okhota) has a length of up to 10 km.
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Eastern Siberia as a geographical region
Note 1
Various sources propose different physical-geographical zoning schemes. But the features of the relief make it possible to combine these schemes into a single system. This is especially true for Siberia. Western Siberia is a well-defined region within the West Siberian Plain.
The Yenisei Valley serves as a natural border between the regions. The entire territory of the Middle and North-Eastern Siberia, lying east of the Yenisei, are united under the name “Eastern Siberia”. This region stretches from the Ob-Yenisei interfluve in the west to the mountain ranges of the Pacific watershed in the east. In the north, Eastern Siberia opens up to the coast of the Arctic Ocean. The south of the region borders Mongolia and China.
The region includes the territories of the Krasnoyarsk and Transbaikal territories, the Chita region, Buryatia, Tuva and Yakutia. The region is striking in its size. Its territory can accommodate several large European states. The total area of the region is more than $7 million km²$.
Relief and geological structure of Eastern Siberia
The tectonic structure of Eastern Siberia is based on the ancient Siberian platform, sections of the emerging Mesozoic platform of North-East Siberia, folded areas of various eras of mountain building. Complicated story The formation of the territory led to a wide variety of relief. In general, the area is very elevated, which is why it is called “High Siberia.” Mountains and plateaus occupy three quarters of the region's total area. Average heights exceed $500$ m.
In the Cenozoic, the formation of the Central Siberian Plateau on the basis of the Siberian platform was completed. In Taimyr, the relief has rejuvenated and the Byrranga Mountains have been revived. The following mountain systems also include rejuvenated relief forms:
- Verkhoyansk ridge;
- Chersky ridge;
- Koryak Highlands.
Intermountain troughs contain lowlands such as the Vilyuiskaya and North Siberian. The Yana-Indigirka and Kolyma lowlands represent the lowered edge of Eurasia. Some geologists identify the young Kolyma Plate at their base. The relief is dotted with faults in the earth's crust and traces of magmatic outpourings. As the magma poured out and solidified, it formed lava plateaus.
Among the relief features, it should be noted that mountain ranges block access to Pacific air masses, and plains open to the northern coast.
Soil and climatic conditions of Eastern Siberia
The territory of Eastern Siberia is located in the Arctic, subarctic and temperate regions climatic zones. Due to its geographical location and topography, a sharply continental climate has been established here. Winter is very long, with little snow and cold. It is in Eastern Siberia (in the area of Verkhoyansk and Oymyakon) that the cold pole of the northern hemisphere is located. The minimum temperature recorded was $-71°C.
Summer is characterized by low clouds and fairly high temperatures (up to $ +30°$C). Humidity comes from the Arctic and Pacific Oceans air masses, establishing an arctic front. Snowfields and glaciers can form in the mountains. Much of the region is permafrost.
The region's soils are varied. From north to south they change from poor soils arctic deserts to the chernozems of intermountain basins. Permafrost soils predominate.
Features of wildlife in Eastern Siberia
In the north of the region and in the mountains, tundra and forest-tundra are common. But in most of the territory of Eastern Siberia there is light-coniferous taiga. The main forest-forming species is larch. In the northern and mountainous regions, dwarf cedar is common. In the southern regions they grow pine forests(Siberian cedar).
Note 2
Characteristic feature The fauna of Eastern Siberia is the abundance of fur-bearing animals. Their fur was a traditional source of trade for the local population. The most valuable fur animals are:
- squirrel;
- sable;
- ermine;
- marten;
- speakers;
- otter.
Reindeer are bred on the plains of the north, and sika, red and red deer are bred in the southern regions.
North-Eastern Siberia is located east of the Lena valleys and the lower reaches of the Aldan, from the Verkhoyansk Range to the shores of the Bering Sea and is washed by the seas of the Arctic and Pacific oceans in the north and south. It is located in the eastern and western hemispheres. On the Chukotka Peninsula is the easternmost point of Russia and all of Eurasia - Cape Dezhnev.
The geographical location in the subpolar and subpolar latitudes near cold seas and the dissected relief with a semi-circular orographic barrier from the south, west and east and slope to the north predetermined the harsh natural conditions countries with bright, unusually contrasting physical and geographical processes, typical only for this territory.
North-Eastern Siberia is a country of young and ancient structures, expressed by mountain systems, ridges, highlands, plateaus, coastal and intermountain plains. The relief combines ancient glacial forms and modern mountain glaciers, deep terraced valleys with numerous thermokarst lakes. The subarctic climate prevails, almost continuous permafrost, fossil ice and giant ice dams are developed. Here, many rivers freeze to the bottom in winter, and in some valleys, on the contrary, sub-permafrost emerges warm waters and are fed by non-freezing watercourses all winter. Rare larch taiga and dwarf pine thickets are widespread. Large areas occupy flat and mountain tundras. There are areas of steppe vegetation up to the north of the Chukotka Peninsula. All these are specific features of the nature of the Northeast as an independent physical and geographical country.
Geological structure
North-Eastern Siberia belongs to the area of Mesozoic folding. The direction of Mesozoic structures was significantly influenced by ancient massifs - Paleozoic and pre-Paleozoic - located within the Northeast and in neighboring territories. The intensity and direction of tectonic processes in Mesozoic times depended on their stability, tectonic activity and configuration. In the west, the Northeast borders the Siberian Precambrian platform, the eastern edge of which had a decisive influence on the direction and intensity of folds in the Verkhoyansk anticlinal zone. The structures of Mesozoic folding were formed in the Early Cretaceous as a result of the collision of the ancient Siberian continent with the microcontinents of Chukotka and Omolon.
In the Northeast, rocks of different ages are found, but Mesozoic and Cenozoic ones are especially widespread. The protrusions of the pre-Riphean basement are composed of gneisses, granite gneisses, crystalline schists and marbled limestones and are overlain by Paleozoic and Mesozoic sediments. They are located in the northeastern and southeastern parts of the Chukotka Peninsula (Chukchi Massif), in the upper reaches of the Omolon River (Omolon Massif), on the Taigonos Peninsula (Taigonos Massif) and in the Okhota River basin (Okhotsk Massif). The Kolyma massif is located in the central part of the North-East. It lies at the base of the Alazeya and Yukagir plateaus, the Kolyma and Abyi lowlands. Its pre-Riphean foundation is overlain by marine and continental sediments of the Paleozoic and Mesozoic. Along the edges of the Kolyma massif there are outcrops of Mesozoic granitoids.
Between the ancient massifs and the Siberian platform there are geostructures of Mesozoic folding. Mesozoic folded areas and ancient massifs are bordered on the south and east by the Okhotsk-Chukotka volcanogenic belt. Its length is about 2500 km, width - 250-300 km. All rocks within its boundaries are intruded and overlain by volcanogenic dislocated formations of the Lower and Upper Cretaceous, the thickness of which reaches several thousand meters. Cenozoic effusive rocks are poorly developed and distributed mainly off the coast of the Sea of Okhotsk. The emergence of the Okhotsk-Chukchi belt is apparently associated with the subsidence and fragmentation of the marginal part of the Mesozoic land in connection with the movements of the continental Eurasian, North American and Pacific oceanic lithospheric plates.
Mesozoic-Cenozoic magmatism covered vast areas of North-East Siberia. The metallogeny of this region is associated with it - numerous deposits of tin, tungsten, gold, molybdenum and other metals.
After the completion of folding, the uplifted territory of the Northeast was subject to erosion. IN Upper Mesozoic and the Paleogene, apparently, there was a hot climate here. This is confirmed by the composition of plant remains (deciduous and evergreen forms) of the Upper Mesozoic and Paleogene deposits, the carbon content of these deposits and the presence of a laterite-type weathering crust.
In the Neogene, under conditions of tectonic quiescence, the formation of planation surfaces occurs. The subsequent tectonic uplifts led to the dismemberment of the planation surfaces, their movement to different heights, and sometimes deformation. The regional mountain structures and the Chersky highlands rose most intensively, and some coasts sank below sea level. Traces of marine transgressions are known at the mouths of rivers in the eastern part of the Chukotka Peninsula. At this time, the northern shallow part of the Sea of Okhotsk sank, the land of Beringia, and the New Siberian Islands separated from the mainland.
Volcanic eruptions occurred along the faults. The volcanoes are confined to a strip of tectonic faults extending from the Momo-Selennyakh depression to the Kolyma valley. The depression arose as a rift zone at the site of the moving apart Eurasian Plate and the Chukotka - Alaska block of the North American Plate. It apparently extends from the Arctic Ocean from the rift of the Gakkel Ridge to the young depressions cutting through the Chersky Highlands. This is one of the seismic zones in Russia.
The rise and fall of individual land areas led to increased erosion-accumulation activity: rivers deeply eroded mountain systems and created terraces. Their alluvial strata contain placer deposits of gold, tin and other minerals. In the river valleys of the North-East there are up to ten terraces with heights ranging from 2-5 to 400 m. Terraces up to 35-40 m in height were formed in post-glacial times. River interceptions are associated with changes in erosion bases.
Thus, in the development of the relief of the Northeast after the Mesozoic mountain building, two periods can be outlined: 1) the formation of widespread planation surfaces (peneplains); 2) the development of intense new tectonic processes that caused splits, deformation and movement of ancient planation surfaces, volcanism, and violent erosion processes. At this time, the formation of the main types of morphostructures took place: 1) folded-block areas of the ancient middle massifs (Alazeya and Yukagir plateaus, Suntar-Khayata, etc.); 2) mountains revived by the latest arch-block uplifts and depressions of the rift zone (Momo-Selennyakh depression); 3) folded and block-folded Mesozoic structures (Verkhoyansk, Sette-Daban, Anyui mountains, etc., Yanskoye and Elga plateaus, Oymyakon highlands); 4) stratified-accumulative, sloping plains created mainly by subsidence (Yana-Indigirka and Kolyma lowlands); 5) folded-block ridges and plateaus on the sedimentary-volcanic complex (Anadyr Plateau, Kolyma Plateau, ridges - Yudomsky, Dzhugdzhur, etc.). As we see, neotectonic movements determined the basic plan of the modern relief.
By the beginning of the Quaternary glaciation the territory had a dissected topography with significant contrasts in heights. This had a significant impact on the development of various types of glaciation. Traces of several ancient glaciations are known on the plains and mountains of the Northeast. Many researchers have been and are studying the ancient glaciation of this territory, but there is still no consensus on the number and types of glaciation, the size of the ice sheets, and their relationship with the glaciations of Siberia and all of Eurasia.
According to V.N. Sachs (1948), there were three glaciations in the mountains and plains: maximum, Zyryansky and Sartan. In the work of D.M. Kolosov (1947) said that in the North-East there were two types of ancient glaciation - mountain and plain-cover.
Glaciations developed differently on different landforms, and therefore several types of mountain glaciation formed. The glaciation of mountain ranges resulted in the development valley glaciers with ice collection in karas and through valleys on passes (the length of glaciers reached 300-350 km). On separate mountain domes formed ice caps, from which valley glaciers extended along radii. Huge developments developed on the plateaus pass ice fields, combined with valley glaciers of dissected plateaus. In the highlands, glaciation took on a varied character: ice collections formed at the tops of mountain ranges and massifs, glaciers descended along the slopes of the ridges and then emerged on the surface of the plateau base, and even lower valley glaciers descended to the edge of the plateau base. At the same time, under the influence of climate in different parts of the mountains, the same types of mountain glaciation reached different stages of development. Glaciation of the outer edge of mountain structures, which is under oceanic influence, developed to its maximum. Modern glaciation of the southern parts of the Chersky and Verkhoyansky mountain systems is also developing on these same mountain slopes.
For the northern plains, one glaciation is assumed, preserved as a relic of the Lower Quaternary ice sheet until the end of the Pleistocene. The reason for this is that there were no conditions for a complete interglacial. Several glacial and interglacial eras have been recorded in mountain structures. Their number has not yet been established. There is an opinion about a double glaciation, and many authors reject the existence of glaciation on the northern plains east of the Lena. However, a number of authors (Groswald M.G., Kotlyakov V.M. et al., 1989) convincingly prove the spread of the Zyryansky ice sheet in the Yana-Indigirskaya and Kolyma lowlands. The glaciers, in their opinion, descended south of the New Siberian Islands and the East Siberian Sea.
In the mountains of the Northeast, glaciation, depending on the relief, had a different character: semi-cover, valley-network, valley-cirque and cirque. During maximum development, glaciers reached foothill plains and shelves. The glaciation was synchronous with the glaciations of the entire Siberia and, apparently, was caused by global climate fluctuations.
The morphological and geological activity of glaciers and their meltwater in conditions of a cold continental climate and permafrost determined the main types of morphosculpture and Quaternary deposits of the entire territory. The mountains are dominated by relict cryogenic-glacial denudation morphosculptures with erosional reworking and Upper Pleistocene glacial deposits, above which colluvial accumulations of different ages are common on the mountain slopes. The plains are covered with lacustrine-alluvial deposits with cryogenic and erosive landforms.
Relief
The North-East of Russia, in contrast to other physical-geographical countries of Siberia, is characterized by sharp orographic contrasts: medium-altitude mountain systems predominate, along with them there are plateaus, highlands and lowlands.
In the west, the country’s orographic barrier is the Verkhoyansk mountain system. To the south of Verkhoyansk stretch the Sette-Daban and Yudomsky ridges, separated by the Yudomo-May Plateau, and further along the coast of the Sea of Okhotsk, the Dzhugdzhur ridge runs. The Chersky ridge stretches 1800 km in the eastern Verkhoyansk Mountains in a northwestern direction.
Between the Chaun Bay and the Sea of Okhotsk there is a medium-altitude mountain system consisting of numerous, differently oriented ridges. This entire regional system of mountains and highlands forms the eastern and southern orographic barriers for the interior regions of the Northeast. The main Pacific-Arctic divide runs along them, where maximum altitudes of about 2000 m are concentrated. Between the mountains lie deep tectonic basins that open to the sea or are separated from it by a mountain barrier. The intermountain basins are lowered in relation to the watersheds by 1000-1600 m. The eastern Chaunskaya Bay, and the Chukotka Highlands with altitudes of 1600-1843 m extend to the shores of the Bering Strait. It also serves as a watershed for two oceans.
In the interior regions of the North-East there are large highlands and plateaus: Yukaghirskoye, Alazeyskoye, Oymyakonskoye, etc. The lowlands occupy coastal areas or enter the intermountain spaces to the south in narrow “bays”.
Thus, the Northeast is a huge amphitheater inclined towards the Arctic Ocean. The complex combination of large relief forms is predetermined by the long history of the development of this largest peninsula of Eurasia, located in the contact zones of the main continental and oceanic lithospheric plates of the Earth (Eurasian, North American and Pacific).
Climate
The climate of North-East Siberia is sharply continental. Its formation is influenced by many factors. The large extent of the territory from north to south between 73 and 55° N latitude. predetermines the uneven arrival of solar heat: a large amount of solar insolation in summer and its almost complete absence in most of the territory in winter. The structure of the relief and the cold water areas surrounding the territory determine the free penetration of cold continental Arctic air masses of the Arctic Ocean. Sea air comes from the Pacific Ocean temperate latitudes, bringing the bulk of precipitation, but its supply to the territory is limited to coastal ridges. The climate is influenced by the Asian maximum, the Aleutian minimum, as well as circulation processes on the Arctic front.
The Northeast is located in three latitudinal climatic zones: arctic, subarctic and temperate. Most of the territory is located in the subarctic zone.
Harsh winter Northeast Siberia lasts about seven months. North of the Arctic Circle the polar night begins. On the Arctic coast it lasts from mid-November to the end of January. At this time, the Arctic region of the Northeast does not receive solar heat, and south of the Arctic Circle the sun is low on the horizon and sends out little heat and light, so the radiation balance is negative from October to March.
The northeast cools greatly in winter, and an area of high pressure forms there, which is the northeastern spur of the Asian High. The mountainous terrain also contributes to strong cooling of the area. Cold and dry arctic air is formed here. The Arctic front passes along the coast of the Sea of Okhotsk. Therefore, the anticyclonic type of weather with a predominance of calms and very low temperatures is typical for intermountain basins and valleys. Isotherms of the coldest month -40...-45°C outline many intermountain basins. In the areas of Verkhoyansk and Oymyakon, the average January temperature is about -50°C. The absolute minimum temperature reaches -71°C in Oymyakon, and -68°C in Verkhoyansk. The interior regions of the Northeast are characterized by temperature inversions. For every 100 m rise, winter temperatures here increase by 2°C. For example, in the basin of the upper part of the Indigirka on the Oymyakon Highlands and on the adjacent slope of the Suntar-Khayata ridge, the average January temperature at an altitude of 777 m is -48 ° C, at an altitude of 1350 m it is already -36.7 ° C, and at an altitude of 1700 m - only -29.5°C.
To the east of the Omolon Valley, winter temperatures increase: an isotherm of -20°C passes through the eastern part of the Chukotka Peninsula. On the coastal plains it is warmer in winter than in the Verkhoyansk area, by about 12-13°C. In the mountains, tundra and on the coast of the Sea of Okhotsk, low temperatures are combined with strong winds. Cyclonic activity manifests itself on the Okhotsk coast and Chukotka in connection with the development of the Arctic front.
In the interior regions of the Northeast, all types of frosty weather form in winter, but weather with increased frostiness (hard, severe and extremely frosty) predominates. On the coast, moderate to significantly frosty weather is more common. The cold and windy weather that characterizes these areas creates significant winter severity in coastal areas.
Stable snow cover lasts 220-260 days, its height is about 30 cm on the coast of the Laptev Sea and in the Verkhoyansk area; to the east and south it increases to 60-70 cm, on the windward slopes of the mountains of the Okhotsk-Chukchi arc it reaches 1-1.5 m. During the period of maximum snow accumulation (March-April), avalanches occur in all mountains. Areas with significant avalanche danger include the Verkhoyansk and Chersky mountain systems. There, avalanches are widespread in many places and occur year-round. Favorable conditions for avalanches are a sufficient amount of precipitation in the mountains and its redistribution under the influence of strong winds (creation of multi-meter snow faces and snow cornices), intense solar insolation in the summer, promoting the recrystallization of snow into firn, slight cloudiness and forest cover of the slopes, as well as the spread clay shales, the moistened surface of which facilitates the sliding of avalanches.
In summer solar heat gain increases. The territory is filled mainly with continental air of temperate latitudes. The Arctic front passes over the northern coastal lowlands. Summer in most of the territory is moderately cool, but in the tundra it is cloudy and cold, with a very short frost-free period. In the mountains from an altitude of 1000-1200 m there is no frost-free period, strong winds prevail and temporary snow cover can form at all times. summer months. The average July temperature in most of the territory is about 10°C, in Verkhoyansk 15°C. However, on some days the temperature can rise in the internal intermountain basins to 35°C. When arctic air masses invade, warm weather may give way to cold snaps, and then the average daily temperature drops below 10°C. In the coastal lowlands, summers are cooler than in inland areas. The weather is changeable, with strong winds. Sum active temperatures reaches its maximum in basins, but is only 600-800°C.
The following types of weather are typical for the summer period: cloudy and rainy, with daytime cloudiness and strong heating of the underlying surface; with night clouds (typical for coastal areas). In July, partly cloudy, dry weather occurs in the basins for up to 10-12 days. Many mountainous regions are characterized by frosty weather during advective cooling.
Summer precipitation is highly variable from year to year. There are dry years and years are wet and rainy. Thus, in Verkhoyansk, over 40 years of observations, the minimum amount of precipitation was 3 mm, and the maximum was 60-80 mm.
The distribution of annual precipitation over the territory is determined by atmospheric circulation and relief. In the Pacific Ocean basin, a lot of precipitation falls when southern and southeastern air currents predominate. That's why greatest number they (up to 700 mm per year) are received by the eastern slopes of the mountains of the Taygonos Peninsula and the southern slopes of the Okhotsk-Kolyma watershed. In the Arctic Ocean basin, precipitation falls with the arrival of northwestern air masses.
The greatest amount of them is received by the western slopes of the Verkhoyansk mountain system and Suntar-Khayat (718 mm at an altitude of 2063 m), in the mountain system of the Chersky ridge - 500-400 mm. Intermountain basins and plateaus, as well as the coast of the East Siberian Sea, receive the least amount of precipitation per year - about 200 mm (in Oymyakon - 179 mm). Maximum precipitation occurs during the short warm period of the year - July and August.
Modern glaciation and permafrost
Modern glaciation developed in many mountain systems: the Suntar-Khayata, Verkhoyansk, Chersky (Ulakhan-Chistai ridge) and the Chukotka Plateau. The total area of glaciation formed by glaciers and large snowfields is about 400 km 2. The number of glaciers is more than 650. The largest center of glaciation is the Suntar-Khayata ridge, where there are more than 200 glaciers with a total area of approximately 201 km 2. The mountains of the Indigirka basin contain the largest number of glaciers. This is explained great height mountains, rugged terrain and abundance of snow.
The formation of glaciation is influenced big influence moist air masses coming from the Pacific Ocean and its seas. Therefore, this entire territory is classified as a glaciological region of predominantly Pacific nutrition.
The snow line in the Indigirka basin runs at an altitude of 2350-2400 m, on the Suntar-Khayat glaciers it reaches about 2200-2450 m. The ends of the glaciers are located in the Indigirka basin at an altitude of about 2000 m. Numerous snowfields are located at various levels. The most common are cirque and valley glaciers. The length of glaciers is up to 8 km. There are many hanging glaciers on the steep, steep mountain slopes. Currently, the size of glaciers is decreasing. This is evidenced by the division of large glaciers into smaller ones and the retreat of glacier tongues from the terminal moraine to a distance of 400-500 m. However, some glaciers advance, block even the terminal moraine and descend below it.
The modern harsh climate favors conservation and development permafrost(underground glaciation). Almost the entire Northeast is covered with low-continuous (almost continuous) permafrost, and only small areas of the coast of the Sea of Okhotsk have patches of permafrost among the thawed soil. The thickness of frozen soil reaches 200-600 m. The greatest freezing of soil with minimum temperatures is in the middle part of the country, in its mountainous region - from Lena to Kolyma. There the permafrost thickness is up to 300 m under the valleys and 300-600 m in the mountains. The thickness of the active layer is determined by slope exposure, vegetation, local hydrological and climatic conditions.
Water
Rivers from the territory of the Northeast they flow into the Arctic and Pacific oceans. The watershed between them runs along the Dzhugdzhur, Suntar-Khayata ridges, the Kolyma Plateau, the Anadyr Plateau and the Chukotka Plateau, therefore, the watershed is close to Pacific Ocean. The largest rivers - Kolyma and Indigirka - flow into the East Siberian Sea.
River Kolyma begins on the slopes of the southern ridges of the Chersky mountain system, has a length of 2130 km and a basin area of about 643 thousand km 2. Its main tributary, the Omolon River, has a length of 1114 km. Flood of the rivers of the entire basin occurs in June, which is associated with melting snow. The water level at this time is high, since much more snow falls in its basin than in the Yana and Indigirka basins. The high levels are partly due to ice jams. The formation of powerful floods is associated with heavy rains, especially in early summer. The river's winter flow is insignificant. The average annual water flow is 4100 m3/s.
River Indigirka It originates on the slopes of the Suntar-Khayata ridge, flows through the Oymyakon Highlands, cuts through the Chersky mountain system through deep gorges and exits into the Momo-Selennyakh depression. There it receives a large tributary - the Moma River and, going around the Momsky ridge, comes out to the Abyi lowland, and then to the Yano-Indigirskaya lowland. The length of the river is 1726 km, the basin area is about 360 thousand km 2. Its main tributaries are the Seleniyakh and Moma rivers. Indigirka is fed by snow and rainwater, melting snowfields and glaciers. The rise of water and the main flow (about 85%) occurs in spring and summer. In winter, the river has low water and in some places on the plain it freezes to the bottom. The average annual flow is 1850 m3/s.
River Yana begins in the Verkhoyansk Mountains and flows into the Laptev Sea. Its length is 879 km, the basin area is 238 thousand km 2. In some places it flows through wide ancient valleys filled with alluvium. There are outcrops of fossil ice in the coastal cliffs. Ice intrusions - hydrolaccoliths - are widespread in lacustrine-alluvial deposits. The spring flood is weakly expressed, since an insignificant amount of snow falls in the Yana basin. Floods usually occur in the summer when it rains. The average annual water flow is about 1000 m 3 /s.
The Kolyma, Indigirka and Yana rivers at their confluence form vast low-lying swampy deltas with numerous small lakes. Buried ice lies in deltas at shallow depths from the surface. The area of the Yana delta is 528 km 2 , the Indigirka delta is 7700 km 2 . In the mountains, rivers have predominantly narrow valleys, fast current, thresholds. In the lower reaches, all the valleys are wide, the rivers flow through vast swampy lake lowlands.
The rivers of the Northeast freeze in October and open in late May - early June. The water temperature reaches 10°C, but in places in June-August it can rise to 20°C. In many areas in the lower reaches of the river, the river freezes to the bottom in winter. An interesting and important feature of the winter regime of rivers in the Northeast is widespread distribution of aufeis(in Yakut - taryn).
Naledi is a complex geographical concept. It develops under a combination of hydrological, climatic, permafrost and other conditions. But the ice itself influences the morphology, the nature of sediments, the microclimate and vegetation of the valley, and also creates its own natural complex.
The ice dams of the Northeast are among the largest in the world. Some of them occupy areas of more than 100 km2. Their formation occurs most intensively in tectonically mobile areas, where they are associated with places of disturbances rocks caused by faults. Ice deposits grow throughout the winter, filling river beds and floodplains, especially in the mountainous areas of the Yana, Indigirka and Kolyma basins. The largest of them - Momskaya naledi - is located on the Moma River and has an area of 150 km 2. Almost all large ground ice dams are fed by sub-permafrost waters emerging along tectonic fault lines. Powerful rising springs in places of tectonic fracturing overcome the cooled layer of soil, come to the surface, form ice and feed them all winter, even at frosts of -40°C and below. In summer, large ice fields persist for a long time, and some remain into the next winter.
Aufeis contain a large amount of water, which summer period enters rivers and is an additional source of their nutrition. In winter, polynyas form on some mountain rivers. Their occurrence is also associated with the release of warm sub-permafrost waters. Fogs appear above them and ice and frost forms. Sources of sub-permafrost waters, especially in winter, are of great practical importance for water supply to the population and the mining industry.
All major rivers of the Northeast in the lower reaches are navigable: Kolyma - from the mouth of the Bakhapchi River (Sinegorye village), Indigirka - below the mouth of the Moma River, and along the Yana, ships go from Verkhoyansk. The duration of navigation on them is 110-120 days. The rivers are rich in valuable species of fish - nelma, muksun, whitefish, sturgeon, grayling, etc.
Lakes. In the lowlands, especially in the lower reaches of the Yana, Indigirka, Alazeya and Kolyma, there are a lot of lakes and swamps. Most lake basins are of thermokarst origin. They are associated with the thawing of permafrost and underground ice. The lakes freeze in September - early October and are covered with thick ice (up to 2-3 m) during the long winter, which leads to frequent frosts and death of the ichthyofauna. Ice melts in May and early June, and floating ice on large lakes they also occur in July.
Soils, vegetation and fauna
A variety of physical and geographical conditions (mountainous and flat terrain, low air and soil temperatures, varying amounts of precipitation, small thickness of the active layer, excess moisture) contribute to the formation of variegated soil cover. Harsh climatic conditions and permafrost delay the development of chemical and biological weathering processes, and therefore soil formation occurs slowly. The soil profile is thin (10-30 cm), gristly, with a low humus content, peaty and moist. Common in lowlands tundra-gley, humus-peat-bog and gley-taiga permafrost soils. On the floodplains of river valleys there are developed floodplain humus-turf, frozen-gley or frozen-marsh soils. In the floodplains of tundra rivers, permafrost lies at shallow depths, and sometimes layers of ice appear in the coastal cliffs. The soil cover is poorly developed.
In the mountains under forests they predominate mountain podburs, taiga are also common permafrost soils, among which are found on gentle slopes, gley-taiga permafrost. On the southern slopes, permafrost-taiga soils with slight podzolization are common. The mountains of the Okhotsk coast are dominated by mountain podzolic soil. In mountain tundras, underdeveloped rough-skeletal mountain tundra soils, turning into rocky placers.
Vegetation North-East Siberia consists of representatives three floras: Okhotsk-Kamchatka, East Siberian and Chukotka. The most diverse in species composition is the Okhotsk-Kamchatka flora, which occupies the coast of the Sea of Okhotsk. Most of the mountains are covered with northern taiga sparse forests and mountain tundra. The lowlands are occupied by tundra, turning into forest-tundra.
The history of the development of the Northeast and adjacent territories (the ancient landmass of Beringia, Okhotia and Eoarctic, connecting the Northeast with Alaska), as well as the climate, predetermined the modern appearance of the vegetation cover of the tundra, forest-tundra and taiga, therefore they differ in species composition from similar zones of neighboring territories Siberia.
On far north, on the coastal lowland, located tundra. Lichen tundras are not typical for it, since clay soils are heavily waterlogged and bog-peat and peat-gley soils predominate. The hummocky-hypnum-sphagnum tundra dominates here. Its surface is formed by dense hummocks of cotton grass. The height of the grass stand is up to 30-50 cm. The hummocky tundra occupies approximately 30-50% of the area of tundra groups. Uneven thawing and freezing of the soil leads to soil deformation, soil rupture and the formation of bare spots (0.5-1 m in diameter) around hummocks, in the cracks of which mosses, lichens, saxifrage, and creeping polar willow nest.
South there's a streak coming forest-tundra. It is formed by alder, willow, and birch shrubs, which alternate with tussocks of cotton grass and individual specimens of oppressed Cajander larch.
All the rest of the plains and lower parts of the mountains covered larch forests on gley-taiga abominable soils and mountain taiga podburs. The main forest-forming tree species is the Cajander larch. Among the deciduous species in floodplain forests, there are fragrant poplar and relict Korean willow Chozenia. Pine and spruce are common only on the southern slopes of the mountains of the Verkhoyansk Range and rise into the mountains only to a height of 500 m.
In the undergrowth of larch forests, dwarf cedar, shrubby alder, blue currant, or spruce grouse, and thickets of Middendorf and lean birches are common; The ground cover consists of lingonberry shrubs, crowberries and lichens. There are few lichens on the northern slopes; mosses dominate there. The tallest larch forests grow on southern-facing slopes. On the slopes of northern exposure, forest-tundra is predominantly common.
On the slopes of the southern exposure of valleys and high terraces, steppe plots. They are known in the wide valleys of the Yana (between the mouths of its tributaries Dulgalakh and Adycha), Indigirka (in the mouth parts of the Moma, etc.) and Kolyma, as well as in the Chukotka tundra. The vegetation of the steppes on the slopes consists of steppe sedge, bluegrass, typica, wheatgrass, and forbs - speedwell, cinquefoil. Thin, gravelly soils close to chestnut soils formed under the steppes. On the terraces above the floodplain there are grass-forb steppes, developing in drained areas, and sedge-grass-forb steppes, located in the lowest areas. Among the steppe vegetation, local species are distinguished, genetically related primarily to the vegetation of the mountainous regions of Southern and Central Siberia, other species came along river valleys from Central Asia during the warm interglacial period, and species preserved from the “tundra-steppe” past of the Beringian North.
The predominance of mountainous terrain within the Northeast determines altitudinal zone in the placement of vegetation. The nature of the mountains is extremely diverse. It determines the structure of the zonality of each system while maintaining the general type of altitudinal belts, characteristic only of the North-East of Siberia. They are clearly shown on maps of soils and vegetation, as well as on an altitudinal diagram. The altitudinal zone in the lower parts of the slopes begins with light coniferous taiga (except for the Kharaulakh Mountains and the Chukotka Plateau), but it does not rise high into the mountains: in the Chersky ridge system - up to 650 m, and in the Dzhugdzhur ridge - about 950 m. Above the taiga, a closed shrub belt forms dwarf cedar up to 2 m high with an admixture of dwarf birch.
Northeast is one of the main growing areas cedar dwarf- a nut-bearing plant adapted to the harsh subarctic climate and thin gravelly soils. Its life forms are different: bushes 2–2.5 m high grow along river valleys, and single-trunked trees spread on the top plateaus and hills. With the onset of frost, all branches are pressed to the ground and are covered with snow. In spring, the warm rays of the sun “raise” them. Elfin nuts are small, with a thin shell and very nutritious. They contain up to 50-60% oil, a large amount of protein, B vitamins, and young shoots of the plant are rich in vitamin C. On the slopes of hills and ridges, elfin wood is an important regulator of runoff. Elfin forests are favorite places for many animals of all altitudinal zones; here they find shelter and abundant food.
At the upper limits of the belt, the elfin forest gradually thins out, is more and more pressed to the ground and is gradually replaced by mountain tundra with rocky placers. Above 800-1200 m, tundras and cold deserts with many snowfields dominate. The tundra descends in separate spots into lower belts of dwarf cedar and larch woodlands.
There is no such combination of altitudinal zones in any mountain system in Russia. The proximity of the cold Sea of Okhotsk determined a decrease in altitudinal zones in the coastal ranges, and even at the foot of the mountains of the Taigonos Peninsula, cedar tundras give way to hummocky tundras - analogues of the northern lowland tundras (this happens at the latitude of southern Timan and northern Lake Onega).
Animal world North-East Siberia belongs to the Arctic and European-Siberian subregions of the Paleoarctic region. The fauna consists of tundra and taiga forms. However, many animal species typical of the taiga do not live in the eastern Verkhoyansk Mountains. The fauna of the Chukotka Peninsula is very similar to the fauna of Alaska, since the Bering Strait was formed only at the end of the Ice Age. Zoogeographers believe that the tundra fauna formed on the territory of Beringia. The Northeast moose is close to the moose of North America. The white-tailed goose nests on the Chukotka Peninsula and winters off the rocky coasts of Alaska and the Aleutian Islands. The guillemot is endemic to the Northeast and Alaska. Dallia (black pike) from the order Salmonidae is found in small rivers, lakes and swamps of the Chukotka Peninsula and in northwestern Alaska. This is the most frost-resistant fish breed. In winter, when water bodies freeze, it buries itself in the ground and overwinters there in a frozen state. In the spring, the dallia thaws and continues to live normally.
Mountain tundra species of animals penetrate far to the south through the char, into the forest zone. Of these, the most typical is the endemic yellow-bellied lemming, which does not penetrate east of Indigirka. Next to them, in the mountain tundras of the Northeast, open-space animals of Central Asian origin live. They penetrated here during the xerothermal period and are now preserved here. These include, for example, the black-capped marmot (tarbagan). During the cold season (eight to nine months) it falls asleep in burrows located in permafrost soil. The Kolyma ground squirrel, an inhabitant of the forest zone, also falls asleep for the same long period. The mountain finch has penetrated the open high-mountain landscapes to the Lena delta. Predators in the taiga include bear, fox, and ermine. Lynx and wolverine are sometimes found. Sable was almost completely destroyed. But now it has been restored and there are separate pockets of its habitat in the Kolyma, Oloy, Yana basins and on the Koni Peninsula.
Of the ungulates, wild reindeer is widespread in the taiga and tundra, and elk is widespread in the taiga. Musk deer live on the rocky forested slopes of the mountains. Bighorn sheep (Chukchi subspecies) live in the mountain tundra. It lives at altitudes from 300-400 to 1500-1700 m and prefers rocks when choosing sediments. The most common rodent in mountain forests is the squirrel, which is the main game animal. In the past, the Asian bird lived in the Kolyma and Omolon basins river beaver, the northern border of its distribution was about 65° N. Currently, there is a variety of small rodents: red-backed vole, root vole, forest lemming, northern pika. The white hare is common in the thickets of river valleys.
Of the birds, it should be noted the stone grouse, hazel grouse, shura, kuksha, nutcracker and tundra partridge living on stone placers. A very beautiful bird, the pink gull, is called the pearl of the Arctic. The little swan, the white goose, the beautiful Siberian crane, the white-billed loon, the falcons - the falcon, the gyrfalcon and the salvage, the hawks - the white-tailed eagle and the golden eagle have become rare.
Mountainous regions and provinces
In the Northeast, natural complexes of plains and mountains are developed. In the lowlands there are natural areas tundra, forest-tundra and rare taiga. On the territory of the plains, two physical-geographical provinces are distinguished: tundra and forest-tundra Yano-Indigiro-Kolyma and Abyisko-Kolyma northern taiga. The rest of the territory is occupied by mountains and is divided into mountainous regions.
The Yana-Indigir-Kolyma province is located along the Arctic coast within the Yana-Indigir and Kolyma lowlands.
Zoning appears in the distribution of vegetation and soils. The coast is busy arctic tundra on gley, peaty-gley and marsh soils. To the south they are replaced by typical moss-lichen soils, which turn into forest-tundra with gley-permafrost soils. A specific feature of the Northeast is the absence of the shrub tundra subzone. Within their distribution zone, open larch forests also appear, which is due to the sharp continental climate. Larch open forests and shrub tundras alternate with areas of sedge-cotton grass hummocky tundras.
The Yana-Kolyma tundra is the main nesting site for many waterfowl, and among them are the pink gull and the Siberian Crane. The pink gull makes nests on hummocks of sedge-cotton grass tundra and islands near small lakes and channels. After nesting (late July - early August), adult and young birds fly to the north, northwest and northeast. The winter migration area of the pink gull extends from the Bering Strait to the southern islands of the Kuril ridge. The main nesting sites for the Siberian Crane are lowland, heavily moist, lake-filled tundras between Yana and Alazeya. The birds fly to Southeast China for the winter.
The Abyysko-Kolyma province is confined to the largest intermountain depression. The surface of the watersheds here is covered with sparse larch forests, sedge-cotton grass swamps and lakes. Along the river valleys there are swampy meadows and thickets of bushes, and in drier areas there are forests of larch, sweet poplar and choicenia.
Verkhoyansk region occupies a marginal western position. The altitudinal zonation of the soil and vegetation cover is most fully expressed on the Suntar-Khayata and Setta-Daban ridges. The lower zone here is represented by northern taiga sparse larch forests, which rise on the northern slopes to 1200-1300 m, and on the southern slopes to 600-800 m. The ground cover is dominated by lichens; The shrub layer is formed by lingonberries, crowberries and wild rosemary. A dwarf birch has been developed from the Middendorf birch. Along the river valleys on sand and pebble deposits stretch gallery forests of fragrant poplar and choicenia with an admixture of larch, birch, aspen and Siberian mountain ash.
Above the upper boundary of the larch forest, thickets of dwarf birch, shrubby alder and dwarf cedar, combined with lichen-shrub tundras, dominate. The next belt is mountain-tundra with taryns. Its upper limit should be drawn at the ends of the glaciers (1800-2100 m). Higher up are high mountain deserts with glaciers and snowfields. Avalanches occur in autumn, winter and spring.
Anyui-Chukotka region extends from the lower reaches of the Kolyma to the Bering Strait for almost 1500 km.
The tundra of Chukotka differs from other tundras of the Arctic coast of Russia in that its main part is mountain tundra with rocky placers, rocks and thickets of bushes, and the coastal part is flat tundra of grass-shrubs and hummocks with cotton grass and creeping wild rosemary.
The flora of vascular plants of the Chukotka tundra contains about 930 species and subspecies. This is the richest flora of the Arctic region. Chukotka was part of Megaberingia, and this had a significant impact on the composition of the flora of its plant communities. On the southern slopes of the ridges and above-floodplain terraces, mountain-steppe vegetation has been preserved - the remains of the Beringian tundra-steppe landscapes. North American plant species grow there: among the dryad tundras on the limestones there are Meckenzie's pennywort, dense cat's paw, and in the willow-herbaceous communities there are balsam poplar and edible viburnum. Primula egalikensis is common in the nival tundra. Lena fescue is common in steppe areas. B.A. Yurtsev calls it the emblem of the steppe complexes of North-East Siberia. Once upon a time, horses, bison, saiga and other herbivores lived in the tundra and steppes of Beringia. Now the problem of the sunken Beringia is attracting the attention of various specialists.
In Chukotka, off the Bering coast, there are thermal springs with temperatures ranging from 15 to 77°C. They create favorable conditions for the development of lush and varied vegetation. There are up to 274 plant species here. In harsh climatic conditions, the flora at hot springs has a subarctic and temperate character with a predominance of arctic-alpine elements - mountain shrub-moss communities. Among them grow cassiopeia, diapensia, loiselaria, phyllodoce, Kamchatka rhododendron, etc., as well as mountain-tundra Asian-American or Beringian species - anemone, chrysanthemum, primrose, saxifrage, sedge, etc.
Anthropogenic impact on nature
The nature of the Northeast is experiencing significant anthropogenic impact due to off-road transport (all-terrain vehicles), construction, geological surveys and mining, deer grazing and frequent fires.
Fur farming and fur fishing for squirrel, arctic fox, ermine, mountain hare, and muskrat are developed in the territory. Plain and mountain tundras and forest-tundras serve as good pastures for deer. One of the main food for reindeer in winter is bushy lichen-cladonia (reindeer moss). The restoration of its reserves takes five to seven years. Due to anthropogenic impact, the pasture fund is declining, so strict adherence to pasture load and careful attitude of the entire population to reindeer pastures is necessary.
The main commercial fish - vendace, muksun, nelma, omul, whitefish, etc. - are concentrated in the lower sections of the Yana, Indigirka and Kolyma rivers. In the warm areas of the valleys of the Yana, Indigirka, Kolyma and other rivers, early varieties of cabbage, potatoes and other vegetables are grown using special agricultural technology.
Active development of the territory contributed to changes in natural landscapes, reduction in the numbers and habitats of many species of animals and plants, for example, the Chukchi bighorn sheep, the Siberian Crane and the Spade-tailed Elder, which nest only in Russia, the Bairdov's sandpiper, the present slipper, etc.
The nature of the Northeast is very vulnerable, therefore, with increased human activity, entire natural complexes (ecosystems) are dying. For example, during the development of placer deposits, significant areas of floodplains are completely destroyed, where a wide variety of animals and plants are concentrated. On the territory of this huge physical-geographical country, there is so far only one reserve - Magadan, several complex and sectoral reserves (nesting waterfowl) and natural monuments, and among them is a protected zone for the location of mammoth fauna.
Scientists propose to create a number of protected areas here, for example, the Buordakhsky Natural Park with the basins of the left tributaries of the Moma and Mount Pobeda. The unique geographical objects of this region include the world's largest ice dam, Ulakhan-Taryn (Momskaya), which does not completely melt every year, and in the valley on the gravelly slopes of the southern exposure - the Yakut mountain steppes, turning into steppe alpine lawns and mountain tundras. It is also proposed to create the Central Yakut Nature Reserve as a biosphere reserve, where the Chukchi bighorn sheep are preserved on the rocky shores of Lake Elgygytgyn, where there are calving grounds for wild reindeer - the only large population in the entire Northeast. Here, poplar-chosenia valley forests are at the limit of their distribution, and steppe areas have been preserved.
1) Using the atlas map, determine the specifics of the geographical location of Eastern Siberia.
The vast territory of Eastern Siberia, occupying a quarter of the area of Russia, stretches from the shores of the Arctic Ocean to the border with Mongolia, from the left bank of the Yenisei to the watershed ridges Far East. The natural features of Eastern Siberia are determined by its size, location in the middle and high latitudes, the general slope of the territory towards the low coast of the Arctic Ocean, and its greater distance from the Atlantic Ocean. In addition, the barrier of mountain ranges almost eliminates the influence of the Pacific Ocean, which explains the continental climate.
2) Compare the area of this region with other regions of Russia, with foreign countries Europe.
Eastern Siberia is the largest natural region in Russia. The area of the listed territories could accommodate several large European states, such as France, Great Britain, Germany, Spain
3) Which federal subjects are part of this natural region?
Krasnoyarsk Territory, Republic of Tyva, Republic of Buryatia, Irkutsk Region, Transbaikal Territory, Yakutia.
Questions in a paragraph
*Using the atlas maps, compare the sizes and heights of the Vitim Plateau, Stanovoy and Aldan Highlands with the mountain ranges of Europe. What conclusions can be drawn?
The size and height of European mountain ranges are generally inferior to the size of the highlands of Eastern Siberia. In terms of heights, only the Alps can be compared with the highlands of Eastern Siberia. The mountains of southern Siberia were formed in Cenozoic times as a result of recent tectonic movements, when folded block mountains formed in place of ancient Precambrian and Paleozoic mountains. Tectonic movements continue to this day. This explains high altitudes uplands and their sizes.
*Tell us about the largest deposits in Eastern Siberia, about the patterns of their location. What are the difficulties associated with their development?
Among the natural resources of Eastern Siberia highest value have mineral ones, among which the most important are fuel and energy. About 80% of the country's hard and brown coal reserves are concentrated in Eastern Siberia (Tunguska, Lensky, Irkutsk-Cheremkhovo, South Yakutsk and other basins). Eastern Siberia is also rich in ore deposits; iron ores of the Korshunovsky and Abakansky deposits, Angara-Pitek region; copper-nickel ores of Norilsk, the formation of which is associated with trap magmatism, polymetals of Altai, bauxites of the Eastern Sayan Mountains.
Known large deposits non-metallic minerals: mica, graphite, Iceland spar, building materials, salts (for example, salt in Usolye-Sibirskoe). Diversity mineral resources due to the complexity of the structure of the earth's crust, as well as geological history formation of territory. Harsh, harsh continental climate Eastern Siberia, the predominance of highly dissected relief, permafrost and weak population of the territory hinder its development.
Questions at the end of the paragraph
2. Determine in which time zones Eastern Siberia is located. With which regions of Russia does it have the most big difference in time?
6,7,8 time zones. The greatest time difference from European part and the Far East.
3. Name the main features of the nature of Eastern Siberia and explain their reasons.
By natural features This is a country with pronounced continental features. The continental climate is manifested in a large range of temperatures between winter and summer (it reaches 50°, and in Eastern Yakutia - 100°), as well as sharp fluctuations in temperature during the day and a relatively small amount of precipitation. main reason the formation of such a climate - central position, remoteness from the coasts, relief. The relief is characterized by a general significant elevation above sea level. Most of the region is occupied by the Central Siberian Plateau, the average height of which is 500-700 m. It was formed within the oldest section of the earth’s crust - Siberian platform. The Central Siberian Plateau in the north, south and east is edged by a giant amphitheater of mountain ranges. These mountains are distinguished by a complex geological structure and large fluctuations in relative heights. The distribution of precipitation is greatly influenced by relief. A striking example of this is the Khamar-Daban ridge: its northwestern slopes facing Lake Baikal receive 800-1400 mm of precipitation per year, and on the southeastern slopes less than 300 mm falls per year.
5. Analyze physical card Eastern Siberia and explain why physical geographers distinguish three independent regions on its territory: 1) Central Siberia; 2) North-Eastern Siberia; 3) mountains of Southern Siberia.
The identification of three independent regions in Eastern Siberia is associated with differences in climate, topography and, accordingly, the formation of various natural complexes.
1. Geographical location.
2. Geological structure and relief.
3. Climate.
4. Water and permafrost.
5. Soils, flora and fauna.
Geographical position
Northeast Siberia is located east of the Lena Valley and the lower reaches of the Aldan to the shores of the Bering Sea. In the north, the country is washed by the seas of the Arctic Ocean. The far east lies already in the western hemisphere, the 180th meridian crosses the country from Wrangel Island to the Gulf of Anadyr. The territory of this physical-geographical country is a giant peninsula of Eurasia with an area of more than 2.5 million km2. The Arctic Circle runs almost through the middle of the country. F.P. studied this territory. Wrangel, A.F. Middendorf, E.V. Toll, I.D. Chersky, S.V. Obruchev, K.A. Salishchev and others.
Geological structure and relief
Geologically, the entire country belongs to the Mesozoic folding. Mesozoic structures were formed in the Early Cretaceous as a result of the collision of the ancient Siberian platform with the microcontinents of Chukotka and Omolon. The Verkhoyansk anticline, the Yamalo-Kolyma synclinal zone, and the Chukotka anticlinorium are located here. The surface of these structures is covered with marine sandy-clayey sediments, and in some places there are coal-bearing strata. Mesozoic granitoids emerge in places. Mesozoic folded structures and ancient massifs are bordered on the south and east by the Okhotsk-Chukotka volcanogenic belt, which is associated with deposits of tin, tungsten, molybdenum, gold and other metals. The river valleys of the northeast are characterized by a large number (up to 10) river terraces. Traces of ancient glaciation are known in the mountains of the Northeast. The mountains are dominated by relict cryogenic-glacial denudation morphosculptures. The plains are covered with lacustrine-alluvial deposits and erosional landforms. In general, the country's topography is characterized by a combination of medium-high mountain systems, plateaus, highlands and lowlands. In the west of the country, the Verkhoyansk mountain system stretches for 1,500 thousand km, 100-250 km wide and from 500 m in the north to 2,400 m in the south. To the southeast of the Verkhoyansk Range lies the Suntar-Khayata Range. To the east of the Verkhoyansk Range is the Chersky Range, between which are the Yanskoye and Elga Plateaus, and to the south are the Oymyakon Uplands. The Chersky Ridge stretches for 1800 km and consists of three parts. To the east of it lies the Yukagir Plateau. The Kolyma Plateau and the Dzhugdzhur ridge stretch along the coast of the Sea of Okhotsk. In the east of the country lie the Anadyr and Chukotka highlands, with an altitude of 1500-1800 m. The lowlands occupy a coastal position or in narrow “bays” enter the intermountain spaces to the south. The largest lowlands here are the Yana-Indigirskaya and Kolyma.
Climate
The climate is sharply continental, arctic in the north, temperate in the extreme south of the country, and the subarctic zone occupies most of the middle part. The structure of the relief facilitates the free penetration of Arctic air into the interior of the country. The influence of the Pacific Ocean is limited to the coastal mountain ranges. Winter is very harsh. North of the Arctic Circle in winter there is a polar night, and to the south of it the sun at noon is low above the horizon, daylight hours are short. The radiation balance from October to March is negative. In winter, the pressure is increased over the northeast of Siberia - a spur of the Asian maximum. Anticyclonic weather conditions prevail. Temperature inversions are characteristic. In the intermountain basins, the average temperature in winter is about -45˚C (in the area of Oymyakon almost -50˚C, and the absolute minimum is -71˚C). But for every 100 m you go up, it becomes 2˚C warmer. East of the Omolon River valley winter temperatures increase, reaching -20˚C on the Chukotka Peninsula. Strong winds are typical on the coast. Snow cover lasts up to 8-9 months, its height varies from 30 cm in the north to 70 cm in the southeast (on the windward slopes of the mountains - up to 1.5 m). Summer is cool; in the mountains above 1000 meters there is no frost-free period. Average temperatures in summer range from +5˚C on the northern coast to +15˚C in the southern continental regions. Droughts can occur in summer, but there are also very wet periods. The annual precipitation varies from 200 mm in intermountain basins to 700 mm on the windward slopes of the mountains.
Water and permafrost.
Northeast Siberia is rich inland waters. Rivers belong to the basins of two oceans. The watershed runs along the Dzhugdzhur, Suntar-Khayata ridges, Kolyma and Chukotka highlands. Therefore, most of the territory belongs to the Arctic Ocean basin, and not to the Pacific Ocean. The largest rivers: Kolyma, Indigirka, Yana. The Kolyma River originates from the southern slopes of the Chersky ridge, its length is 2130 km, the basin area is 643 thousand km2. Main tributary– Omolon River (1114 km.). The diet is mixed, with snow playing a leading role. High water in early June, when the snow melts. The water rise is very high. The Indigirka originates on the slopes of the Suntar-Khayata ridge, flows through the Oymyakon highland and cuts through the Chersky ridge, receives a tributary - the Moma River and goes out onto the Yana-Indigirka lowland. The length of the river is 1726 km, the basin area is about 360 thousand km2. The food is mixed, dominated by snow, in summer rain and glaciers. The Yana River begins in the Verkhoyansk Mountains, its length is 880 km, the basin area is 238 thousand km2. The nutrition and regime are similar to the previous rivers, but the flood is less pronounced, since little snow falls in the river basin. All three rivers at their confluence form extensive deltas in which buried ice lies at a shallow depth from the surface. In winter, in some places the rivers freeze to the bottom. Ice deposits (taryns) often form on rivers, which fill the river floodplain and can persist all summer. There are many lakes and swamps in the lowlands. Most lakes are thermokarst. The lakes are under ice from October to June, the ice thickness reaches 2-3 meters. Mountain glaciation is developed in the mountains (Verkhoyansk Range, Chersky Range, Suntar-Khayata Range, Chukotka Plateau). The area of glaciation and snowfields is about 400 km2. The number of glaciers is more than 650. The snow line runs at an altitude of 2200-2500 m. Permafrost is widespread, its thickness is 300-600 m.
Soils, flora and fauna
Soil-forming processes are suppressed low temperatures, so soil formation is slow. The soil profile is thin, only 10-30 cm. In the north, in the lowlands, tundra-gley soils are common. Permafrost-taiga soils are developed in river valleys. In the mountains under forests, mountain podburs and gley-taiga permafrost soils predominate. On the Okhotsk coast the soils are podzolic.
The vegetation of North-East Siberia consists of representatives of three floras: Okhotsk-Kamchatka, East Siberian and Chukotka. In the far north, on the coastal lowlands, there is a tundra dominated by mosses, cotton grass, saxifrage, as well as lichens and creeping willow. To the south there is a strip of forest-tundra made up of alder, willow, birch, and low-growing larch shrubs. The entire rest of the country, with the exception of the upper mountain belt, is covered with larch forests. Poplars are found in the floodplains of the rivers; spruce and pine grow on the southern slopes. In the undergrowth of the taiga, dwarf cedar, alder, currant, and skinny birch are common; The ground cover consists of lingonberries, crowberries and lichens and mosses. On the slopes of the southern exposure of valleys and river terraces, areas of steppe vegetation of bluegrass, wheatgrass, steppe sedge, crowberry, cinquefoil, etc. (a relic of the tundra-steppe Beringian north) have been preserved. In the mountains, the forest boundary rises to 600-900 m, above which there is a shrub belt of dwarf cedar. Above 1000-1200 m there are mountain tundras.
The country's fauna consists of tundra and taiga forms. But there are mountain and steppe species. The Chukotka fauna is close to the fauna of Alaska. Mountain tundra species penetrate far to the south into the taiga, and steppe species penetrate north into the tundra. In the north live reindeer, yellow-bellied lemming, bighorn sheep, mountain hare, arctic fox, wolf, black-capped marmot, tundra partridge, pink gull, swans, auks, geese, ducks, falcons (balaban, gyrfalcon, peregrine falcon), etc. In the taiga Typical species are elk and reindeer, bear, wolf, fox, sable, weasel, wood lemming, voles, pika, capercaillie, hazel grouse, pike-perch, kuksha, nutcracker, hawks, golden eagle, etc.
