Lesson topic: "Eastern Siberia: general features of nature." North-East of Siberia. Relief, geological structure of North-Eastern Siberia

Physiography Russia and the USSR
Asian part: Central Asia and Kazakhstan, Siberia, Far East

Northeast Siberia

general characteristics

A vast territory lying to the east of the lower reaches of the Lena, north of the lower reaches of the Aldan and bounded in the east by the mountain ranges of the Pacific watershed, forms the country of North-Eastern Siberia. Its area (together with the islands of the Arctic Ocean that make up the country) exceeds 1.5 million square kilometers. km 2. The eastern part of the Yakut Autonomous Soviet Socialist Republic and the western regions of the Magadan Region are located within North-Eastern Siberia.

Northeastern Siberia is located in high latitudes and is washed by the seas of the Arctic Ocean in the north. The extreme northern point of the mainland - Cape Svyatoy Nos - lies almost at 73 ° N. sh. (and Henrietta Island in the De Long archipelago - even at 77 ° N); the southernmost regions in the Mai River basin reach 58°N. sh. Approximately half of the country's territory lies north of the Arctic Circle.

North-Eastern Siberia is a country with a varied and contrasting relief. Within its limits are mountain ranges and plateaus, and in the north - flat lowlands, stretching along the valleys of large rivers far to the south. All this territory belongs to the Verkhoyansk-Chukotka region of the Mesozoic folding. The main processes of folding took place here mainly in the second half of the Mesozoic, but the formation of the modern relief is mainly due to the latest tectonic movements.

The climate of the country is harsh, sharply continental. The amplitudes of absolute temperatures are in places 100-105°; in winter there are frosts down to -60 -68 °, and in summer the heat sometimes reaches 30-36 °. On the plains and in the low mountains of the country, there is little precipitation, and in the extreme northern regions their annual amount is as small as in the desert regions of Central Asia (100-150 mm). Permafrost is found everywhere, holding down soils to a depth of several hundred meters.

On the plains of northeastern Siberia, zonality is clearly expressed in the distribution of soils and vegetation: zones of arctic deserts (on islands), continental tundra and monotonous swampy larch woodlands are distinguished.

The mountainous regions are characterized altitudinal zoning. Sparse forests cover only the lower parts of the slopes of the ridges; their upper limit only in the south rises above 600-1000 m. Therefore, significant areas are occupied by mountain tundra and thickets of shrubs - alder, undersized birch and elfin cedar.

The first information about the nature of the Northeast was delivered in the middle of the 17th century. explorers Ivan Rebrov, Ivan Erastov and Mikhail Stadukhin. AT late XIX in. the expeditions of G. A. Maidel and I. D. Chersky conducted reconnaissance studies of mountainous regions, and the northern islands were studied by A. A. Bunge and E. V. Toll. However, information about the nature of the Northeast remained very incomplete until research in the Soviet era.

Expeditions of S. V. Obruchev in 1926 and 1929-1930. significantly changed the ideas even about the main features of the country's orography: the Chersky Range was discovered with a length of more than 1000 km, the Yukagir and Alazeya plateaus, the position of the sources of the Kolyma was clarified, etc. The discovery of large deposits of gold, and then other metals, necessitated geological research. As a result of the work of Yu. A. Bilibin, S. S. Smirnov, specialists from Dalstroy, the North-Eastern Geological Administration and the Arctic Institute, the main features of the geological structure of the territory were clarified and many mineral deposits were discovered, the development of which caused the construction of workers' settlements, roads and the development of shipping on the rivers.

At present, on the basis of aerial survey materials, detailed topographic maps have been compiled and the main geomorphological features of North-Eastern Siberia have been elucidated. New scientific data have been obtained as a result of studies of modern glaciation, climate, rivers and permafrost.

North-Eastern Siberia is a predominantly mountainous country; lowlands occupy a little more than 20% of its area. The most important orographic elements are the mountain systems of the marginal ranges Verkhoyansk and Kolyma highlands- form an arc convex to the south with a length of 4000 km. Inside it are chains elongated parallel to the Verkhoyansk system Chersky Ridge, ridges Tas-Khayakhtakh, Tas-Kystabyt (Sarychev), Momsky and etc.

The mountains of the Verkhoyansk system are separated from the Chersky ridge by a lowered strip Jansky, Elginsky and Oymyakon plateau. East located Nerskoye Plateau and Upper Kolyma Highlands, and in the southeast, the Verkhoyansk ridge adjoins the ridge Sette-Daban and the Yudomo-Maya Highlands.

The highest mountains are located in the south of the country. Average Height them - 1500-2000 m, however, in the Verkhoyansk, Tas-Kystabyt, Suntar Khayata and Chersky, many peaks rise above 2300-2800 m, and the highest of them is Mount Pobeda in the ridge Ulakhan-Chistai- reaches 3147 m. The mid-mountain relief here is replaced by alpine peaks, steep rocky slopes, deep river valleys, in the upper reaches of which there are firn fields and glaciers.

In the northern half of the country, the mountain ranges are lower and many of them stretch in a direction close to meridional. Along with low ridges ( Kharaulakhsky, Selennyakhsky) there are flat ridge-like hills (ridge half-moustache, Ulakhan-Sis) and plateaus (Alazeyskoye, Yukagirskoe). A wide strip of the coast of the Laptev Sea and East Siberian Sea It is occupied by the Yano-Indigirskaya lowland, from which, along the valleys of the Indigirka, Alazeya and Kolyma, the intermountain Sredne-Indigirskaya (Abyiskaya) and Kolyma lowlands extend far to the south. Most of the islands of the Arctic Ocean also have a predominantly flat relief.

Orographic scheme of North-Eastern Siberia

Geological structure and history of development

The territory of the current North-Eastern Siberia in the Paleozoic and the first half of the Mesozoic was a site of the Verkhoyansk-Chukotka geosynclinal marine basin. This is evidenced by the large thickness of the Paleozoic and Mesozoic deposits, in some places reaching 20-22 thousand km. m, and intensive manifestation of tectonic movements that created the folded structures of the country in the second half of the Mesozoic. Especially typical are deposits of the so-called Verkhoyansk complex, whose thickness reaches 12-15 thousand tons. m. It includes Permian, Triassic, and Jurassic sandstones and shales, usually intensely dislocated and intruded by young intrusions. In some areas, terrigenous rocks are interbedded with effusives and tuffs.

The most ancient structural elements are the Kolyma and Omolon median massifs. Their base is composed of Precambrian and Paleozoic deposits, and the Jurassic suites covering them, unlike other areas, consist of weakly dislocated carbonate rocks, occurring almost horizontally; effusives also play a prominent role.

The remaining tectonic elements of the country are of younger age, predominantly Upper Jurassic (in the west) and Cretaceous (in the east). These include the Verkhoyansk folded zone and the Sette-Dabansky anticlinorium, the Yana and Indigirsko-Kolyma synclinal zones, as well as the Tas-Khayakhtakhsky and Momsky anticlinoria. The extreme northeastern regions are part of the Anyui-Chukotka anticline, which is separated from the median massifs by the Oloy tectonic depression filled with volcanic and terrigenous Jurassic deposits. Mesozoic fold-forming movements, as a result of which these structures were formed, were accompanied by ruptures, outpourings of acidic and basic rocks, intrusions, which are associated with various mineralization (gold, tin, molybdenum).

By the end of the Cretaceous, Northeastern Siberia was already a consolidated territory elevated above the neighboring regions. The processes of denudation of mountain ranges under conditions warm climate The Upper Cretaceous and Paleogene led to the leveling of the relief and the formation of flat surfaces of alignment, the remains of which have been preserved in many ranges.

The formation of modern mountain relief is due to differentiated tectonic uplifts of the Neogene and Quaternary time, the amplitude of which reached 1000-2000 m. In areas of the most intense uplifts and there were especially high ridges. Their strike usually corresponds to the direction of the Mesozoic structures, i.e., it is inherited; however, some ridges of the Kolyma Highlands are distinguished by a sharp discrepancy between the strike of folded structures and modern mountain ranges. Areas of Cenozoic subsidence are currently occupied by lowlands and intermountain basins filled with strata of loose deposits.

During the Pliocene the climate was warm and humid. On the slopes of the then low mountains there were coniferous-deciduous forests, which included oak, hornbeam, hazel, maple, and gray walnut. Among conifers, Californian forms prevailed: Western American mountain pine (Pinus monticola), Vollosovich spruce (Picea wollosowiczii), members of the family Taxodiaceae.

Early Quaternary uplifts were accompanied by a noticeable cooling of the climate. The forests that covered the southern regions of the country at that time consisted mainly of dark conifers, close to those currently found in the North American Cordillera and the mountains of Japan. From the middle of the Quaternary, glaciation began. Large valley glaciers appeared on the mountain ranges that continued to rise, and on the plains, where, according to D. M. Kolosov, glaciation was of an embryonic nature, firn fields formed. On the far north- in the archipelago of the New Siberian Islands and on the coastal lowlands - in the second half of the Quaternary, the formation of permafrost and ground ice began, the thickness of which in the cliffs of the Arctic Ocean reaches 50-60 m.

Thus, the glaciation of the plains of the Northeast was passive. Most of the glaciers were inactive formations; they carried some loose material, and their exaration effect had little effect on the relief.

Erosion valley in the low-mountain massif of the Tuora-sis ridge. Photo by O. Egorov

The traces of mountain-valley glaciation are much better expressed in the outlying mountain ranges, where well-preserved forms of glacial exaration are found in the form of kars and trough valleys, often crossing the watershed parts of the ridges. The length of valley glaciers descending in the Middle Quaternary from the western and southern slopes of the Verkhoyansk Range to neighboring areas of the Central Yakut Lowland reached 200-300 km. According to most researchers, there were three independent glaciations in the mountains of the Northeast: the Middle Quaternary (Tobychansky) and the Upper Quaternary - Elga and Bokhapcha.

The fossil flora of interglacial deposits testifies to the progressive increase in the severity and continentality of the country's climate. Already after the first glaciation, Siberian species appeared in the composition of forest vegetation along with some North American species (for example, hemlock). coniferous trees, including the now dominant Dahurian larch.

During the second interglacial epoch, mountain taiga prevailed, which is now typical of the more southern regions of Yakutia; the vegetation of the time of the last glaciation, among which there were no dark coniferous trees, already differed little in species composition from the modern one. According to A.P. Vaskovsky, the firn line and the forest boundary then descended in the mountains by 400-500 m lower, and the northern limit of forest distribution was noticeably shifted to the south.

Main types of relief

The main relief types of North-Eastern Siberia form several distinct geomorphological tiers. The most important features of each of them are associated primarily with the hypsometric position, due to the nature and intensity of the latest tectonic movements. However, the country's location in high latitudes and its harsh, sharply continental climate cause other than in the more southern countries, the altitudinal limits of the distribution of the corresponding types of mountainous relief. Moreover, in their formation greater value acquire the processes of nivation, solifluction and frost weathering. The forms of permafrost relief formation also play a significant role here, and fresh traces of Quaternary glaciation are characteristic even of plateaus and areas with low mountain relief.

In accordance with the morphogenetic features within the country, the following types of relief are distinguished: accumulative plains, erosion-denudation plains, plateaus, low mountains, mid-mountain and high-mountain alpine relief.

Accumulative plains occupy areas of tectonic subsidence and accumulation of loose Quaternary deposits - alluvial, lacustrine, marine and glacial. They are characterized by slightly rugged topography and slight fluctuations in relative heights. Forms are widespread here, which owe their origin to permafrost processes, the large ice content of loose deposits and the presence of thick ground ice: thermokarst basins, permafrost heaving mounds, frost cracks and polygons, and on the sea coasts high ice cliffs intensively collapsing (for example, the famous Oyegos Yar, more than 70 km).

Accumulative plains occupy vast areas of the Yano-Indigirskaya, Sredneindigirskaya and Kolyma lowlands, some islands of the seas of the Arctic Ocean ( Faddeevsky, Lyakhovsky, Land Bunge and etc.). Small areas of them are also found in depressions in the mountainous part of the country ( Momo-Selennyakhskaya and Seimchanskaya depressions, Yanskoye and Elga plateaus).

Erosion-denudation plains are located at the foot of some northern ranges (Anyuysky, Momsky, Kharaulakhsky, Kulara), on the peripheral sections of the Polousny ridge, the Ulakhan-Sis ridge, the Alazeysky and Yukagirsky plateaus, as well as on Kotelny Island. Their surface height usually does not exceed 200 m, but near the slopes of some ridges it reaches 400-500 m.

In contrast to the accumulative plains, these plains are composed of bedrock of various ages; the cover of loose sediments is usually thin. Therefore, rubble placers, sections of narrow valleys with rocky slopes, low hills prepared by denudation processes, as well as spots-medallions, solifluction terraces and other forms associated with the processes of permafrost relief formation are often found.

Plateau relief it is most typically expressed in a wide strip separating the systems of the Verkhoyansk ridge and the Chersky ridge (Yanskoye, Elginskoye, Oymyakonskoye and Nerskoye plateaus). It is also characteristic of the Upper Kolyma Highlands, the Yukagir and Alazeya Plateaus, large areas of which are covered with Upper Mesozoic effusive rocks, which occur almost horizontally. However, most of the plateaus are composed of folded Mesozoic deposits and represent denudation leveling surfaces currently located at an altitude of 400 to 1200-1300 m. In places, higher remnant massifs also rise above their surface, typical, for example, for the upper reaches of the Adycha and especially the Upper Kolyma Uplands, where numerous granite batholiths protrude in the form of high domed hills prepared by denudation. Many rivers in regions with a flat mountainous relief are mountainous in nature and flow in narrow rocky gorges.

Upper Kolyma Highlands. In the foreground is Jack London Lake. Photo by B. Vazhenin

lowlands occupy areas subjected in the Quaternary to uplifts of moderate amplitude (300-500 m). They are located mainly on the outskirts of high ridges and are dissected by a dense network of deep (up to 200-300 m) river valleys. The low mountains of North-Eastern Siberia are characterized by relief forms due to nival-solifluction and glacial processing, as well as an abundance of stony placers and rocky peaks.

Middle mountain relief is especially characteristic of most massifs of the Verkhoyansk Range, the Yudomo-Maya Highlands, the Chersky Range, Tas-Khayakhtakh and Momsky. Significant areas are occupied by mid-mountain massifs also in the Kolyma Uplands and the Anyui Range. Modern medium-altitude mountains arose as a result of the latest uplifts of denudation plains of leveling surfaces, parts of which have been preserved here in places to this day. Then, in the Quaternary, the mountains were vigorously eroded by deep river valleys.

The height of the mid-mountain massifs - from 800-1000 to 2000-2200 m, and only at the bottom of deeply incised valleys do the marks sometimes drop to 300-400 m. Relatively gentle relief forms predominate in the interfluve spaces, and fluctuations in relative heights usually do not exceed 200-300 m. Forms created by Quaternary glaciers, as well as permafrost and solifluction processes, are widespread everywhere. The development and preservation of these forms is facilitated by the harsh climate, since, unlike the more southern mountainous countries, many mid-mountain massifs of the Northeast are located above the upper limit of woody vegetation, in the mountain tundra.

River valleys are quite diverse. Most often these are deep, sometimes canyon-like gorges (the depth of the Indigirka valley reaches, for example, 1500 m). However, the upper reaches of the valleys usually have a wide flat bottom and less high slopes.

High Alpine relief associated with areas of the most intense Quaternary uplifts, located at an altitude of more than 2000-2200 m. These include the crests of the highest ridges (Suntar-Khayata, Tas-Khayakhtakh, the Chersky Tas-Kystabyt ridge, Ulakhan-Chistai), as well as the central regions of the Verkhoyansk ridge. Due to the fact that the activity of Quaternary and modern glaciers played the most significant role in the formation of the alpine relief, it is characterized by deep dissection and large amplitudes of heights, the predominance of narrow rocky ridges, as well as cirques, cirques and other glacial landforms.

Climate

The harsh, sharply continental climate of North-Eastern Siberia is due to the fact that this country is located mainly within the Arctic and subarctic regions. climatic zones, at a considerable height above sea level and isolated by mountain ranges from the effects of the seas of the Pacific Ocean.

The total solar radiation per year, even in the south, does not exceed 80 kcal/cm 2. Radiation values ​​vary greatly by season: in December and January they are close to 0, in July they reach 12-16 kcal/cm 2. Within seven to eight months (from September - October to April), the radiation balance earth's surface negative, and in June and July it is 6-8 kcal/cm 2 .

Average annual temperatures are everywhere below -10°, and on the New Siberian Islands and in the highlands, even -15-16°. Such low temperatures are due to the long duration of winter (six to eight months) and its extreme severity.

Already in early October, an area begins to form over North-Eastern Siberia. high blood pressure Asian anticyclone. Throughout the winter, very cold continental air dominates here, formed mainly as a result of the transformation of Arctic air coming from the north. air masses. In conditions of cloudy weather, high dryness of the air and a short duration of daylight hours, an intensive cooling of the earth's surface occurs. Therefore, the winter months are characterized by extremely low temperatures and the absence of thaws. The average January temperatures are everywhere, except for the northern lowlands, below -38, -40°. Most very coldy occur in intermountain basins, where stagnation and especially intense cooling of the air occur. It is in such places that Verkhoyansk and Oymyakon are located, which are considered the pole of cold in the northern hemisphere. Average January temperatures here are -48 -50°; on some days frosts reach -60 -65° (the minimum temperature observed in Oymyakon is -69.8°).

Mountain regions are characterized by winter temperature inversions in the lower layer of air: the increase in temperature with height reaches in some places 1.5-2 ° for every 100 m lift. For this reason, it is usually less cold on the slopes than at the bottom of intermountain basins. In places this difference reaches 15-20°. Such inversions are typical, for example, for the upper reaches of the Indigirka, where average temperature January in the village of Agayakan, located at an altitude of 777 m, equal to -48 °, and in the mountains of Suntar-Khayat, at an altitude of 2063 m, rises to -29.5°.

Mountain ranges in the north of the Kolyma Highlands. Photo by O. Egorov

During the cold period of the year, relatively little precipitation falls - from 30 to 100-150 mm, which is 15-25% of their annual amount. In intermountain depressions, the thickness of the snow cover usually does not exceed 25 (Verkhoyansk) - 30 cm(Oymyakon). It is approximately the same in the tundra zone, but on the mountain ranges of the southern half of the country, the snow thickness reaches 50-100 cm. There are great differences between closed basins and the tops of mountain ranges in relation to the wind regime. Very weak winds prevail in the basins in winter, and calm weather is often observed for several weeks in a row. In particularly severe frosts near settlements and highways, fogs are so dense here that even during the day you have to turn on the lights in the houses, and turn on the headlights in cars. Unlike the basins, peaks and passes are often strong (up to 35-50 m/s) winds and blizzards.

Spring everywhere is short, friendly, with little rainfall. The spring month here is only May (in the mountains - the beginning of June). At this time, the sun shines brightly, daily air temperatures rise above 0 °, the snow melts quickly. True, at night in early May there are still frosts down to -25, -30 °, but by the end of the month maximum temperatures air during the day sometimes reach 26-28 °.

After a short spring comes a short but relatively warm summer. At this time, low pressure is established over the mainland of the country, and higher pressure over the northern seas. Located near the northern coast, the Arctic front separates the masses of warm continental air and colder air that forms over the surface of the seas of the Arctic Ocean. The cyclones associated with this front often break south, into the coastal plains, causing a noticeable decrease in temperature and precipitation. The warmest summer is in the intermountain depressions of the upper reaches of the Yana, Indigirka and Kolyma. The average July temperature here is about 14-16°, on some days it rises to 32-35°, and the soil warms up to 40-50°. However, it is cold at night, and frosts are possible in any summer month. Therefore, the duration of the frost-free period does not exceed 50-70 days, although the sum of positive average daily temperatures reaches 1200-1650 ° during the summer months. In the northern tundra regions and on mountain ranges rising above the tree line, summers are cooler and the average temperature in July is below 10-12°C.

During the summer months, the main amount of precipitation falls (65-75% of the annual amount). Most of them come with air masses coming in July and August from the west, northwest and north. The greatest amount of precipitation falls on the Verkhoyansk and Chersky ridges, where at altitudes of 1000-2000 m during the summer months their sum reaches 400-600 mm; much less of them in areas of flat tundra (150-200 mm). There is very little precipitation in closed intermountain basins (Verkhoyansk - 80 mm, Oymyakon - 100 mm, Seymchan - 115 mm), where, due to the dryness of the air, high temperatures and significant evaporation, plant vegetation occurs under conditions of a noticeable lack of moisture in the soil.

The first snowfalls are possible already at the end of August. September and the first half of October can be considered autumn months. In September, there are often clear, warm and windless days, although frosts are already common at night. At the end of September, the average daily temperatures drop below 0°, frosts at night in the north reach -15 -18°, blizzards often occur.

Permafrost and glaciation

The harsh climate of the country causes intense freezing of rocks and the continuous spread of permafrost, which has a significant impact on the formation of landscapes. Northeastern Siberia is distinguished by a very large thickness of permafrost, which in places in the northern and central regions is more than 500 m, and in most mountainous areas - from 200 to 400 m. Very low temperatures are also characteristic. rocks. At the bottom of the layer of annual temperature fluctuations, located at a depth of 8-12 m, they rarely rise above -5 -8°, and within the coastal plain -9 -10°. The depth of the seasonal thawing horizon ranges from 0.2-0.5 m in the north up to 1-1.5 m on South.

On the lowlands and in intermountain depressions, underground ice is widespread - both syngenetic, formed simultaneously with the host rocks, and epigenetic, formed in rocks deposited earlier. Especially typical for the country are syngenetic polygonal vein ice, which form the largest accumulations of underground ice. On the coastal lowlands, their thickness reaches 40-50 m, and on Bolshoi Lyakhovsky Island - even 70-80 m. Some ices of this type can be considered "fossils", since their formation began as early as the Middle Quaternary.

Underground ice has a significant impact on the formation of relief, the regime of rivers and conditions economic activity population. So, for example, the processes of ice melting are associated with the phenomena of flow and subsidence of soils, as well as the formation of thermokarst basins.

The climatic conditions of the country's highest ranges contribute to the formation of glaciers. In places here at an altitude of more than 2000-2500 m drops up to 700-1000 mm/year sediments, most of them in solid form. Snow melting occurs only during two summer months, which are also characterized by significant cloudiness, low temperatures (the average temperature in July is from 3 to 6-7 °) and frequent night frosts. More than 650 glaciers with a total area of ​​over 380 km 2. The centers of the most significant glaciation are located in the Suntar-Khayat ridge and in Buordakh massif. The snow line lies high here - at elevations from 2100 to 2600 m, which is explained by the predominance of a fairly continental climate even at these altitudes.

Most of the glaciers occupies the slopes of the northern, northwestern and northeastern exposure. Among them, car and hanging ones predominate. There are also firn glaciers and large snowfields. However, all the largest glaciers are valley ones; their tongues descend to a height of 1800-2100 m. The maximum length of these glaciers reaches 6-7 km, area - 20 km 2 , and the ice power is 100-150 m. Almost all glaciers in the Northeast are now in retreat.

Rivers and lakes

Northeastern Siberia is dissected by a network of many rivers flowing to the Laptev and East Siberian seas. The largest on them - Yana, Indigirka and Kolyma - flow almost in a meridional direction from south to north. Cutting through mountain ranges in narrow deep valleys and receiving numerous tributaries here, they, already in the form of high-water streams, go to the northern lowlands, where they acquire the character of flat rivers.

In terms of their regime, most of the country's rivers belong to the East Siberian type. They feed mainly on melting snow cover in early summer and summer rains. A certain role in the nutrition of rivers is played by groundwater and the melting of "eternal" snow and glaciers in high mountains, as well as icing, the number of which, according to O. N. Tolstikhin, exceeds 2700, and their total area is 5762 km 2. More than 70% of the annual river flow falls on three calendar summer months.

Freezing on the rivers of the tundra zone begins already in late September - early October; mountain rivers freeze at the end of October. In winter, ice forms on many rivers, and small rivers freeze to the bottom. Even on such large rivers as the Yana, Indigirka, Alazeya and Kolyma, the runoff during the winter is from 1 to 5% per annum.

Ice drift begins in the last decade of May - early June. At this time, on most rivers there is the most high level water. In some places (for example, in the lower reaches of the Yana), as a result of ice jams, the water sometimes rises by 15-16 m above winter levels. During the flood period, the rivers intensively erode their banks and clutter up the channels with tree trunks, forming numerous creases.

The largest river in North-Eastern Siberia - Kolyma(basin area - 643 thousand sq. km 2 , length - 2129 km) - begins in the Upper Kolyma Highlands. Somewhat below the mouth of the Korkodon River, the Kolyma enters the Kolyma Lowland; its valley widens sharply here, the fall and speed of the current decrease, and the river gradually acquires a flat appearance. Near Nizhnekolymsk, the width of the river reaches 2-3 km, and the average annual consumption is 3900 m 3 /sec(for a year, Kolyma takes out to the East Siberian Sea about 123 km 3 water). At the end of May, a high spring flood begins, but by the end of June, the flow of the river decreases. Summer rains cause a number of less significant floods and provide a fairly high level of the river until the onset of freeze-up. The distribution of the Kolyma runoff in its lower reaches is as follows: in spring - 48%, in summer - 36%, in autumn - 11% and in winter - 5%.

Sources of the second major river - Indigirki(length - 1980 km, the basin area is over 360 thousand sq. km 2) - located in the area of ​​the Oymyakon Plateau. Crossing the Chersky Range, it flows in a deep (up to 1500-2000 m) and a narrow valley with almost steep slopes; rapids are often found here in the channel of the Indigirka. Near the village of Krest-Mayor, the river enters the plain of the Sredneindigirskaya lowland, where it breaks into branches separated by sandy islands. Below the village of Chokurdakh, the delta begins, the area of ​​\u200b\u200bwhich is about 7700 km 2. In the feeding of the river, the most prominent role is played by summer rains (78%), melted snow (17%), and in the upper reaches - glacial waters. Indigirka annually brings to the Laptev Sea about 57 km 3 water (its average annual consumption is 1800 m 3 /sec). The main runoff (about 85%) falls on summer and spring.

Lake of Dancing Graylings. Photo by B. Vazhenin

The western regions of the country are drained by Yana (length - 1490 km 2, basin area - 238 thousand sq. km 2). Its sources - the Dulgalakh and Sartang rivers - flow down from the northern slope of the Verkhoyansk Range. After their confluence within the Yan Plateau, the river flows in a wide valley with well-developed terraces. In the middle part of the current, where the Yana crosses the spurs of the mountain ranges, its valley narrows, and rapids appear in the channel. The lower reaches of the Yana are located on the territory of the coastal lowland; at its confluence with the Laptev Sea, the river forms a large delta (with an area of ​​about 5200 km 2).

The Yana belongs to the rivers of the Far Eastern type and is characterized by a long summer flood, which is due to the gradual melting of the snow cover in the mountainous regions of its basin and the abundance of summer rains. The highest water levels are observed in July and August. The average annual consumption is 1000 m 3 /sec, and the stock for the year is over 31 km 3 , of which more than 80% occur in summer and spring. Yana's expenses vary from 15 m 3 /sec in winter up to 9000 m 3 /sec during the summer flood.

Most of the lakes of North-Eastern Siberia are located on the northern plains, in the basins of the Indigirka and Alazeya. Here there are places where the area of ​​the lakes is not less than the area of ​​the land separating them. The abundance of lakes, of which there are several tens of thousands, is due to the small ruggedness of the lowland relief, difficult runoff conditions, and the widespread permafrost. Most often, lakes occupy thermokarst basins or depressions in floodplains and on river islands. All of them are distinguished by their small size, flat banks, shallow depths (up to 4-7 m). For seven to eight months, the lakes are bound by a powerful ice cover; very many of them freeze to the bottom in the middle of winter.

Vegetation and soils

In accordance with the harsh climatic conditions in the territory of North-Eastern Siberia, landscapes of northern taiga sparse forests and tundra prevail. Their distribution depends on the geographical latitude and height of the area above sea level.

In the far north, on the islands of the Arctic Ocean, arctic deserts with poor vegetation on primitive thin arctic soils. To the south, on the mainland coastal plain, is located tundra zone- arctic, hummocky and shrubby. Here, gleyed tundra soils are formed, which are also thin. Only to the south of 69-70 ° N. sh. on the tundra plains of the Yano-Indigirka and Kolyma lowlands in the river valleys, the first groups of undersized and oppressed Dahurian larch appear.

In the more southern regions, in the Sredne-Indigirskaya and Kolyma lowlands, such copses emerge from the valleys to the interfluves, forming either larch “gap forests” or very monotonous sparse low-grade forests of the northern taiga appearance on gley-frozen-taiga soils.

Sparse larch forests usually occupy the lower parts of the mountain slopes. Under a sparse cover of low (up to 10 - 15 m) larches are thickets of undersized shrubs - birches (skinny - Betula exilis, shrub - B. fruticosa and Middendorf - B. middendorffii), alder (Alnaster fruticosus), juniper (Juniperus sibirica), rhododendrons (Rhododendron parvifolium and R. adamsii), various willows (Salix xerophila, S. glauca, S. lanata)- or the soil is covered with an almost continuous carpet of mosses and bushy lichens - cladonia and cetraria. Sparse forests are dominated by peculiar mountain taiga-frozen soils with an acidic reaction and without clearly defined genetic horizons (with the exception of the humus one). The features of these soils are associated with shallow permafrost, low temperatures, weak evaporation, the development of permafrost phenomena in the soil. In summer, such soils experience temporary waterlogging, which causes their weak aeration and the appearance of signs of gleying.

The mountains of North-Eastern Siberia are characterized by low vertical limits of distribution of tree species. The upper limit of woody vegetation is located at a height of only 600-700 m, and in the extreme northern mountainous regions it does not rise above 200-400 m. Only in the southernmost regions - in the upper reaches of the Yana and Indigirka, as well as in the Yudomo-Maya Highlands - larch forests occasionally reach 1100-1400 m.

They differ sharply from the monotonous light forests of the mountain slopes of the forests that occupy the bottom of deep river valleys. Valley forests develop on well-drained alluvial soils and consist mainly of fragrant poplar (Populus suaveolens), whose height reaches 25 m, and the thickness of the trunk - 40-50 cm, and Chosenia (Chosenia macrolepis), which has a direct high (up to 20 m), but thin (20-30 cm) stem.

Above the mountain-taiga zone on the slopes are dense thickets of Siberian dwarf pine (Pinus pumila) or alder forest, gradually changing into a zone mountain tundra, in which in some places there are small areas of sedge-cereal alpine meadows. Tundra occupies approximately 30% of the area of ​​mountainous regions.

The crests of the highest massifs, where climatic conditions prevent the existence of even the most unpretentious plants, are a lifeless cold desert and are covered with a continuous cloak of stone placers and screes, over which rocky peaks rise.

Animal world

The fauna of North-Eastern Siberia differs markedly from the fauna of the neighboring regions of Siberia. To the east of the Lena, some animals common to the Siberian taiga disappear. There is no column, Siberian ibex, etc. Instead of them, mammals and birds appear in the mountains and on the plains, close to those widespread in North America. Of the 45 species of mammals living in the mountains of the Kolyma basin, more than half are very closely related to the animals of Alaska. Such, for example, are the yellow-bellied lemming (Lemmus chrysogaster), light wolf, huge Kolyma elk (Alces americanus). Some American fish are found in the rivers (for example, dallium - Dallia pectoralis, Chukuchan - catostomus catostomus). The presence of North American animals in the composition of the fauna of the Northeast is explained by the fact that even in the middle of the Quaternary, there was land on the site of the current Bering Strait, which sank only in the Upper Quaternary.

Other characteristic fauna of the country - the presence in its composition of steppe animals, nowhere in other places so far in the north are not found. In the high-mountainous rocky tundra, one can often meet the Verkhoyansk black-capped marmot - tarbagan (Marmota camtschatica), and on the dry glades of the mountain taiga zone - the long-tailed Kolyma ground squirrel (Citellus undulatus buxtoni). During the winter, which lasts at least seven to eight months, they sleep in their burrows in the frozen ground. The closest relatives of the black-capped marmot, as well as the bighorn sheep (Ovis nivicola) live in the mountains of Central Asia and Transbaikalia.

The study of the remains of fossil animals found in the Middle Quaternary deposits of northeastern Siberia shows that even then the woolly rhinoceros and reindeer, musk ox and wolverine, tarbagan and arctic fox are animals of areas with a very continental climate, close to the modern climate of the highlands of Central Asia. According to zoogeographers, within the boundaries of ancient Beringia, which included the territory of the North-East of the USSR, the formation of modern taiga fauna began in the Quaternary. It was based on: 1) local species adapted to the cold climate; 2) immigrants from North America; and 3) immigrants from the mountains of Central Asia.

Mammals in the mountains are now dominated by various small rodents and shrews; there are more than 20 species of them. Of the predators, the large Beringian bear, wolverine, East Siberian lynx, Arctic fox, Beringian fox are characteristic, there are also sable, weasel, ermine and East Siberian wolf. Among the birds are typical stone capercaillie (Tetrao urogalloides), hazel grouse (Tetrastes bonasia kolymensis), nutcracker (Nucifraga caryocatactes), ptarmigan (Lagopus mutus), Asiatic ash snail (Heteractitis incana). In summer, many waterfowl are found on the lakes: scoter (Oidemia fusca), bean goose (Anser fabalis) and etc.

Snow sheep. Photo by O. Egorov

Natural resources

Of the natural wealth of North-Eastern Siberia, minerals are of the greatest importance; especially important are ore deposits associated with Mesozoic intrusive rocks.

In the mountains of the Yano-Kolyma Territory, which are part of the Pacific metallogenic belt, there are well-known gold-bearing regions - Verkhneindigirsky, Allah-Yunsky and Yansky. A large tin-bearing province has been explored within the Yana-Indigirka interfluve. The largest deposits of tin - Deputatskoe, Ege-Khaiskoe, Kesterskoe, Ilintas, etc. - are associated with the Upper Jurassic and Cretaceous granite intrusions; a lot of tin is also found here in alluvial placers. The deposits of polymetals, tungsten, mercury, molybdenum, antimony, cobalt, arsenic, coal and various building materials are also of significant importance. AT last years prospects for the discovery of oil and gas fields have been identified in intermountain depressions and on coastal lowlands.

Dredging on one of the rivers of the Upper Kolyma Highlands. Photo by K. Kosmachev

Large rivers of North-Eastern Siberia are navigable for a long distance. The total length of currently operated waterways is about 6000 km(of which in the Kolyma basin - 3580 km, Yany - 1280 km, Indigirki - 1120 km). The most significant shortcomings of rivers as means of communication are a short (only three months) navigation period, as well as an abundance of rapids and riffles. Hydropower resources are also significant here (Indigirka - 6 mln. kW, Yana - 3 million. kW), but their use is difficult due to the exceptionally large fluctuations in the water content of the rivers according to the seasons of the year, freezing in winter and the abundance of inland ice. The engineering-geological conditions for the construction of structures on permafrost are also complex. At present, the Kolyma hydroelectric power station, the first in the Northeast, is being built in the upper reaches of the Kolyma.

In contrast to other Siberian countries, the reserves of high-quality timber are relatively small here, since the forests are usually sparse and their productivity is low. The average stock of timber in the forests of even the most developed southeastern regions is no more than 50-80 m 3 /ha.

The harsh climate also limits the possibilities for the development of agriculture. In the tundra zone, where the sum of average daily temperatures above 10° even in the south barely reaches 600°, only radishes, lettuce, spinach and onions can be grown. To the south, turnips, turnips, cabbage, and potatoes are also cultivated. In especially favorable conditions, mainly on the gentle slopes of the southern exposure, it is possible to sow early varieties of oats. More favorable conditions for animal husbandry. Significant areas of the plain and mountain tundra are good reindeer pastures, and the meadows of the river valleys serve food base for a major cattle and horses.

Before the Great October revolution Northeastern Siberia was the most backward outskirts of Russia. The development of its natural resources and all-round development began only in the conditions of a socialist society. Widespread exploration work led to the discovery of ore deposits in the upper reaches of the Kolyma and Yana and the emergence of numerous mines and large workers' settlements here. Good highways were laid through the mountain ranges, and boats and steamboats appeared on the large rivers of the region. The mining industry has now become the basis of the economy and provides the country with many valuable metals.

Some success has been achieved Agriculture. The state farms set up in the upper reaches of the Indigirka and Kolyma meet part of the population's needs for fresh vegetables, milk and meat. In the Yakut collective farms of the northern and mountainous regions, reindeer breeding, fur trade and fishing are developing, giving significant marketable products. Horse breeding is also developed in some mountainous regions.

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Nature of Eastern Siberia

Features of nature

Eastern Siberia

• Eastern Siberia striking in its scale. From west to east, it stretches from the Ob-Yenisei interfluve to the mountain ranges of the Pacific watershed, in the north it goes to the Arctic Ocean in a wide front, in the south it borders on Mongolia and China.

• Eastern Siberia includes the Krasnoyarsk Territory, the Trans-Baikal Territory, the Irkutsk and Chita regions, Buryatia, Tuva and Yakutia. The area of ​​each of these administrative units could accommodate several large European states. The area of ​​the entire Eastern Siberia is about 7.2 million square meters. km.

• High-water rivers stretching for 1000 kilometers, endless taiga, mountain ranges and plateaus, occupying 3/4 of the entire territory, low-lying plains of the tundra strip - this is Eastern Siberia.

The main feature of the relief

throughout the territory.

• The main feature of the relief of Eastern Siberia is its general significant elevation above sea level and the predominance of spaces with mountainous terrain: mountain ranges and plateaus occupy 3/4 throughout the territory.

• Most of the territory is occupied by the highly elevated and strongly dissected Central Siberian Plateau, located at an average height of 500-700 m (but some peaks, for example, in the Putorana Mountains, reach 1700 m).

• In the north and east of Eastern Siberia there are two lowlands: North Siberian and Central Yakut.

• In the south and west of Eastern Siberia, there are mountains - Transbaikalia, the Western and Eastern Sayans, the Yenisei Ridge.

Morning in Siberia. Hanging stone in Ergaki

Climate

The climatic conditions of Eastern Siberia are largely determined by its geographical location within the Asian continent. A great influence on the climatic conditions of the region is exerted by the winter time in the center of Asia, the Siberian anticyclone is an area high pressure, a powerful spur of which occupies the whole of Eastern Siberia. Under the conditions of a stable anticyclonic weather type, winter is characterized by low cloudiness and a predominance of calm, which entails a strong cooling.

Clear, severe, little snow, stable and long winter and rather arid, short and hot summer - these are the main features of the climate of Eastern Siberia. Frosts, for example, in the region of Verkhoyansk and Oymyakon reach -60, -70 °. These are the lowest air temperatures that are observed in a habitable area. the globe, so the region of Verkhoyansk and Oymyakon is called "pole of cold".

Average monthly temperatures air of the coldest month - January - fluctuate 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 most warm month - July - in the northern part of the region (in the tundra zone) about 10°, in the south, in the upper reaches of the Yenisei (Minusinsk depression), up to 20.8°. The transition of air temperature through 0 ° in the far north is observed in mid-June, in autumn - in mid-September, and in southern parts district (Minusinsk depression) - on the twentieth 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 Russia.

precipitation little falls out. In the predominant part of the district, their number does not exceed 200-400 mm per year. The Leno-Vilyui lowland (200 mm) is extremely poor in precipitation. Even less precipitation falls in the north, in the Subpolar Lowland, where their annual amount does not exceed 100 mm. So, for example, in the region of the river delta. Lena falls only about 90 mm per year. Most of the precipitation (70-80%) falls in the summer in the form of rains, which are usually of a continuous nature. In the cold part of the soda, there is little precipitation - no more than 50 mm.

permafrost

A characteristic feature of the climate of Eastern Siberia is the widespread distribution 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 basin of the upper Yenisei), the permafrost thickness decreases, more or less significant areas devoid of permafrost (taliks) appear.

The presence of permafrost creates complex hydrogeological conditions. Groundwater reserves in most of Eastern Siberia are very poor; groundwater is represented mainly by perched water, which does not feed the rivers. Outcrops of subpermafrost waters are relatively rare and confined to areas of young faults. earth's crust and karst regions (upper reaches of the Aldan).

• In a number of places (the Leno-Vilyui lowland, the lowlands of the mouth sections of the Kolyma and Indigirka rivers, etc.), buried ice is found at a small depth from the surface, occupying large areas; their thickness sometimes reaches 5-10 m and more.

Studies carried out in recent years have shown that modern glaciation is widespread in Eastern Siberia. It is found in the most elevated parts of the Verkhoyansk and Chersky ranges - in the upper reaches of the Yana and Indigirka basins. The area of ​​glaciation reaches 600-700 km2, which is approximately equal to the area of ​​modern Altai glaciation. Glaciers are small. The largest glacier of the Sauntarskaya group (on the watershed of Indigirka and Okhota) is up to 10 km long.

Inland waters

Rivers of Eastern Siberia

• It belongs to the basins of the marginal seas of the Arctic Ocean - the Kara, Laptev, East Siberian and Chukchi. The main rivers of this region - the Yenisei and the Lena - are also the largest rivers in Russia. Significant rivers also include the Pyasina, Khatanga, Kolyma, Yana and Indigirka.

• The rivers of Eastern Siberia, mainly in the upper reaches, are of a mountainous nature, on the average they are transitional, and in the lower reaches of the rivers they usually go to the plain, where they acquire the features of typical lowland rivers.

These are, for example, the Yenisei, the upper reaches of which are located in the Sayano-Baikal mountainous country, and the lower reaches among the vast plains, the Lena, which has a mountainous character in the upper reaches, and flows in the lower reaches among the Leno-Vilyui lowland, Yana, Indigirka, Kolyma, sources which are located within the Verkhoyansk-Kolyma mountainous country, and the mouth areas - in the Subpolar Lowland, etc.

Lena

• Lena - the largest of the Russian rivers, whose basin lies entirely within the country.

• Length 4,480 km.

• Basin area 2 million 490 thousand km²

Yenisei

• Yenisei - the bottom of the greatest rivers of Russia and the world. It flows into the Kara Sea of ​​the Arctic Ocean.

• Length 4287 km.

• Basin area 2 million 580 thousand km²

Baikal - the pearl of Siberia

• Baikal is a lake of tectonic origin in the southern part of Eastern Siberia, the deepest lake on the planet Earth, the largest natural reservoir of fresh water.

• Length 636 km; width 79.5 km; area 31,722 km²; volume 23,615.39 km³; coastline length 2000 km; the greatest depth is 1642 m.

• Siberians say: "He who has not seen Baikal has never been to Siberia."

Beauty of Baikal

Flora and fauna

Compared with the Russian Plain and even neighboring Western Siberia, the boundaries of the zones here are significantly shifted to the north: sparse deciduous forests spread in Taimyr up to 70-72 ° N. sh. - much north of the Arctic Circle. In general, the flora and fauna of Eastern Siberia are more diverse than the flora and fauna of the plains of the western part of the country; they contain many relic and endemic species of plants and animals related to East Asian and Central Asian ones.

The modern vegetation of Eastern Siberia was formed mainly during the Quaternary. Earlier, in the Neogene, on the plains of Eastern Siberia in conditions of warm and humid climate first, broad-leaved and mixed forests of beech, chestnut, maple, swamp cypress, hazel grew, and then dark coniferous taiga from relatively heat-loving North American trees: Volosovich spruce, mountain pine, as well as oak, walnut, hazel, hemlock and other broad-leaved species.

Routing

Topic No. 57: "Nature of the North of Eastern Siberia"

Organizational stage (writing dates, topics, filling out a journal and attendance records).

Homework check step

Stage of assimilation of new knowledge

East and West, North, South of Siberia

More beautiful in the world can not be found

Our descendants and peers

There are endless paths there.

You can't see her so easily

And you will not count its rich bowels.

Siberia, Siberia - the pearl of Russia

There is nothing more beautiful than the end.

Students characterize the features of the nature of North-Eastern Siberia on their own, using a physical map of Russia and a map of large natural areas placed in the atlas.

Questions and tasks:

Name the borders of North-Eastern Siberia natural area in the north, west, south and east.

5. What minerals are the Mesozoic folding mountains rich in?

Deposits of ore minerals are associated with traps, and deposits of ore minerals are associated with kemberlite pipes. iron ore and diamonds. Interestingly, the discovery of diamonds on the territory of the Siberian platform is an example of a brilliant confirmation of a scientific forecast. Such a forecast was made by V.S. Sobolev in 1937 based on a comparison of the geology of the Siberian and African platforms. The search for diamonds began in 1940, and in 1947 the first diamonds were found in placers, and in 1954 the first kemberlite pipes. A feature of the mountains of North-Eastern Siberia is the formation of alluvial gold deposits. Placers are located in terraces, valleys and riverbeds. They were formed due to the erosion of granitic igneous rocks. Gold is a common companion of deposits of tin, cobalt, arsenic and other ores. The bowels of Eastern Siberia are especially rich in coal. Their reserves make up almost 70% of the all-Russian ones. There are three giant coal-bearing basins here - Lena, Tunguska, Kansko-Achinsk. Great importance have metallic minerals. Copper-nickel deposits are being developed near the city of Norilsk. Large deposits of iron have been explored in the south-west of the region.

6.Characteristics of the climate of the North of Eastern Siberia?

On the territory of North-Eastern Siberia . Almost all of northeastern Siberia lies within and climatic zones. The average temperature is below -10°.

North-Eastern Siberia can be divided into 3 climatic zones.

7. What are the reasons that explain why a sharply continental climate with a very cold winter, the warmest summer and little precipitation compared to other regions of our country at the same latitudes.

They name the climate-forming factors: the northern geographical position, the influence of the Arctic, the distance from Atlantic Ocean, significant absolute heights of the area, strong cooling of the mainland in winter, which contributes to the development of stable anticyclones. The Siberian anticyclone is characterized by stable, very cold, clear, sunny, slightly cloudy, dry and windless winters.

8. Where are the lowest air temperatures observed?

The lowest air temperatures are observed in the interior regions of North-Eastern Siberia, in poorly ventilated intermountain basins, where cold air stagnates and cools down especially strongly. It is in such places that Verkhoyansk and Oymyakon are located. Intermountain basins are characterized by winter temperature inversions in the lower air layer. During inversions, an increase in air temperature with height by 2 ° for every 100 m is observed. For this reason, it is less cold on the slopes of the mountains than in the basins, sometimes this difference is 15 - 20 ° C.

9. Features of permafrost in the North of Eastern Siberia?

A consequence of the sharp continentality of the climate is permafrost, which is almost ubiquitous in Eastern Siberia. The thickness of the permafrost layer in many places exceeds hundreds of meters, for example, in the Vilyui basin it reaches 600 m, and in the extreme south it is 5-10 m. . In turn, permafrost is the cause of swamping of the plains, has a great influence on the regime of inland waters, on the development of landscapes. Permafrost cools the soil and thus slows down the soil-forming process. Permafrost is a consequence climatic conditions, in another case - the reason that determines the development of other components (water, soil, vegetation) and natural phenomena (bogging).

Plants with a shallow root system, such as larch, can grow on permafrost.

10. Features of the natural zone of the Tundra

11. Features of the nature of Yakutia

12. Features East Siberian taiga

13. What parts can be divided into the territory of the North of Eastern Siberia

Central Siberia and Northeast Siberia

14. What are the main features of the nature of the North of Eastern Siberia

Sharply continental climate

Flat terrain elevated above sea level

Here is the northernmost point of Asia - Cape Chelyuskin

4.Homework information stage and student grading

Homework: §52, answer questions and assignments

1. Geographic location.

2. Geological structure and relief.

3. Climate.

4. Water and permafrost.

5. Soils, flora and fauna.

Geographical position

North-East of 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 extreme 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. Almost in the middle of the country passes the Arctic Circle. F.P. Wrangel, A.F. Middendorf, E.V. Toll, I.D. Chersky, S.V. Obruchev, K.A. Salishchev and others.

Geological structure and relief

Geologically, the whole 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. Here are the Verkhoyansk anticlise, the Yamalo-Kolyma synclinal zone, the Chukotka anticlinorium. The surface of these structures is covered with marine sandy-argillaceous deposits, in some places there are coal-bearing strata. Mesozoic granitoids outcrop in places. Mesozoic folded structures and ancient massifs are bordered from 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 big number(up to 10) river terraces. In the mountains of the Northeast, traces of ancient glaciation are known. The mountains are dominated by relic cryogenic-glacial denudation morphosculptures. The plains are covered with lacustrine-alluvial deposits and erosional landforms. In general, the country's relief is characterized by combinations of medium-altitude mountain systems, plateaus, highlands and lowlands. In the west of the country, the Verkhoyanskaya mountain system, with a width of 100-250 km and a height of 500 m in the north to 2400 m in the south. To the southeast of the Verkhoyansk Range lies the Suntar-Khayata Range. To the east of the Verkhoyansk ridge is the Chersky ridge, between which are the Yanskoye and Elga plateaus, and to the south - the Oymyakon highlands. The Chersky Ridge stretches for 1800 km and consists of three parts. To the east of it lies the Yukaghir Plateau. The Kolyma Highlands and the Dzhugdzhur Range stretch along the coast of the Sea of ​​Okhotsk. In the east of the country lie the Anadyr and Chukotka highlands, 1500-1800 m high. The largest lowlands here are Yano-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 contributes to the free penetration of Arctic air deep into the country. The influence of the Pacific Ocean is limited to the coastal mountain ranges. Winter is very severe. To the 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, over the northeast of Siberia, the pressure is increased - a spur of the Asian maximum. The anticyclonic weather regime prevails. Characterized by temperature inversions. In the intermountain basins, the average temperature in winter is about -45˚C (nearly -50˚C in the area of ​​Oymyakon, and the absolute minimum is -71˚C). But for every 100 m you go up, it gets 2˚C warmer. To the east of the Omolon river valley, winter temperatures increase, reaching -20˚C on the Chukchi Peninsula. The coast is characterized by strong winds. The snow cover lies up to 8-9 months, its height varies from 30 cm in the north to 70 cm in the southeast (up to 1.5 m on the windward slopes of the mountains). Summer is cool, in the mountains above 1000 meters there is no frost-free period. Average temperatures in summer are from +5˚C on the northern coast to +15˚C in the continental southern regions. Droughts can occur in summer, but there are also very wet periods. The annual amount of precipitation varies from 200 mm in intermontane basins to 700 mm on the windward slopes of the mountains.

Water and permafrost.

The northeast of Siberia is rich in inland waters. The rivers belong to the basins of two oceans. The watershed runs along the Dzhugdzhur, Suntar-Khayat, Kolyma and Chukchi 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 Range, its length is 2130 km, the basin area is 643 thousand km2. The main tributary is the Omolon River (1114 km.). Meals are mixed, with the leading role of snow. High water in early June, when the snow melts. The water level is very high. Indigirka originates on the slopes of the Suntar-Khayat ridge, flows through the Oymyakon highlands and cuts through the Chersky ridge, receives a tributary - the Moma River and enters the Yano-Indigirskaya lowland. The river is 1726 km long, the basin area is about 360 thousand km2. Food is mixed, snow prevails, rain and glacial in summer. The Yana River begins in the Verkhoyansk Mountains, its length is 880 km, the basin area is 238 thousand km2. The food and regime are similar to the previous rivers, but the flood is less pronounced, since there is little snow in the river basin. All three rivers at their confluence form vast deltas, in which buried ice occurs at a shallow depth from the surface. In winter, the rivers freeze to the bottom in some places. On the rivers, icing (taryns) often form, which fill the floodplain of the river and can persist all summer. There are many lakes and swamps in the lowlands. Most lakes are thermokarst. The lakes are under the ice from October to June, the thickness of the ice reaches 2-3 meters. Mountain glaciation is developed in the mountains (Verkhoyansky ridge, Chersky ridge, Suntar-Khayat ridge, Chukchi highlands). The area of ​​glaciation and snowfields is about 400 km2. The number of glaciers is more than 650. The snow line passes at an altitude of 2200-2500 m. Permafrost is widespread everywhere, its thickness is 300-600 m.

Soils, flora and fauna

Soil formation processes are suppressed by 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 the river valleys. Mountain podburs and gley-taiga permafrost soils predominate in the mountains under forests. On the Okhotsk coast, the soils are podzolic.

The vegetation of the North-East of Siberia consists of representatives of three floras: Okhotsk-Kamchatka, East Siberian and Chukchi. 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 forest-tundra strip of alder, willow, birch, and undersized larch shrubs. The rest of the country, with the exception of the upper belt of mountains, is covered with larch forests. Poplars are found in floodplains, spruce and pine grow on the southern slopes. In the undergrowth of the taiga, elfin 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 from bluegrass, couch grass, 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, higher is the shrub belt of elfin cedar. Above 1000-1200 m - mountain tundra.

The fauna of the country consists of tundra and taiga forms. But there are mountain and steppe species. The Chukchi fauna is close to the fauna of Alaska. Mountain-tundra species penetrate far to the south into the taiga, and steppe species to the north into the tundra. Reindeer, yellow-bellied lemming, bighorn sheep, mountain hare, arctic fox, wolf, black-capped marmot, tundra partridge, pink gull, swans, eiders, geese, ducks, falcons (balaban, gyrfalcon, peregrine falcon), etc. live in the north. In the taiga typical are elk and reindeer, bear, wolf, fox, sable, weasel, forest lemming, voles, pika, capercaillie, hazel grouse, smurf, kuksha, nutcracker, hawks, golden eagle, etc.

Eastern Siberia is a part of Siberia that includes the Asian territory of Russia from the Yenisei in the west to the watershed ranges that run along the Pacific Ocean in the east. The region features a harsh climate, limited flora and fauna, and incredibly rich natural resources. Consider what belongs to Eastern Siberia, where its borders are located, what are the features of the climate and wildlife.

Geographical position of Eastern Siberia

Eastern and Western Siberia occupy almost two thirds of the territory of Russia. The area of ​​Eastern Siberia is 7.2 million km. Most of it is occupied by the taiga Central Siberian Plateau, which is replaced in the north by tundra lowlands, in the south and east by the high mountain ranges of the Western and Eastern Sayans, the mountains of Transbaikalia and the Yano-Kolmyk Territory. Here flow the largest rivers of Russia - the Yenisei and the Lena.

Rice. 1. Eastern Siberia covers an impressive area

Within Eastern Siberia are Krasnoyarsk and Trans-Baikal Territory, Irkutsk region, Republics of Buryatia, Yakutia, Tuva.

The largest city in Eastern Siberia is Krasnoyarsk; large cities - Irkutsk, Ulan-Ude, Chita, Yakutsk, Norilsk.

Due to its great extent, Eastern Siberia includes several natural zones: arctic deserts, taiga, mixed forests and even dry steppes. Swampy tundra areas can also be included in this list, but there are very few of them, and they are found, as a rule, within the lowlands on flat, poorly drained interfluves.

Three time zones operate on the territory of Eastern Siberia - Krasnoyarsk time, Irkutsk time and Yakutsk time.

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Climate

Eastern Siberia lies in the temperate and cold zones. Depending on where this or that region of Eastern Siberia is located, the following types of climate are distinguished:

• the climate of the South of Eastern Siberia is extracontinental(Barguzinsky morphoclimatic region);
• temperate continental(Nazarovsky and Krasnoyarsk-Kansky morphoclimatic regions);
• sharply continental(Angara-Lena and Selenginsky morphoclimatic regions);
• foothill steppe, steppe(Koibal and Uda morphoclimatic regions).

Precipitation is less than western regions Russia, the thickness of the snow cover is usually small, in the north permafrost is widespread.

Winter in the northern regions is long and cold, the temperature reaches -40-50 °C. Summer is warm, hot in the south. July in Eastern Siberia is sometimes warmer than in the same latitudes of the European part of Russia, and sunny days more.

Rice. 2. Winter in Eastern Siberia

The amplitude of fluctuations in summer and winter temperatures reaches 40-65 °C, and in Eastern Yakutia - 100 °C.

Resources

One of the most important characteristics Eastern Siberia - the presence of a huge amount of resources. About half of all forests in Russia are concentrated here. The main amount of wood reserves are valuable conifers: larch, spruce, Scots pine, fir, Siberian cedar.

About 70% of hard and brown coal reserves are located in Eastern Siberia. This region is rich in ore deposits:

• iron ores of the Korshunov and Abakan deposits, Angara-Pitsky district;
• copper-nickel ores of Norilsk;
• polymetals of Altai;
• bauxites of the Eastern Sayan.

The oldest Bodaibo gold deposit is located in Eastern Siberia. Irkutsk region. In the Krasnoyarsk Territory, a significant amount of Russian oil. Eastern Siberia is rich in non-metallic minerals, including mica, graphite, building materials, and salts. There is also largest deposit diamonds on the border of the Krasnoyarsk Territory and Yakutia.

Rice. 3. Diamonds of Yakutia

Live nature

The predominant type of vegetation is taiga. The East Siberian taiga stretches from the borders of the forest-tundra in the north to the border with Mongolia in the south, in an area of ​​about 5,000 thousand square meters. km., of which 3,455 thousand square meters. km is occupied by coniferous forests.

The soils and vegetation of the taiga zone of Eastern Siberia develop under more favorable conditions than in the tundra and forest-tundra zones. The relief is more rugged than in neighboring Western Siberia; stony, often thin soils are formed on bedrock.

To preserve nature in its original form, many reserves, national and natural parks have been opened on the territory of Eastern Siberia.

The Barguzinsky Nature Reserve is the oldest nature reserve in Russia. It was founded before the revolution of 1917 to preserve and increase the number of sable. At the time of creation, there were only 20-30 sable individuals, at present - 1-2 individuals per 1 sq. km. km.

What have we learned?

In grade 8, geography reveals a topic dedicated to Eastern Siberia. She covers incredibly large area, and its length from north to south is about 3 thousand km. Briefly about Eastern Siberia, we can say the following: it is a region with a harsh climate, not very diverse fauna and flora, and with large reserves of natural resources.

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