EASTERN SIBERIA, a natural region located mainly in Russia. It is located in Siberia, between the valley of the Yenisei River and the watershed ranges along the Pacific coast, stretching south of the Chukotka Peninsula. In the north it is washed by the Kara, Laptev and East Siberian seas.

Naturally complex Eastern Siberia includes the following physical and geographical countries: Central Siberia, partly the Altai-Sayan country (with the Eastern Sayan mountain system), North-Eastern Siberia, the Baikal region and Transbaikalia. The relief is dominated by low and middle mountains. In the west, the Central Siberian Plateau, the largest in Russia, stands out. In the east, complex mountain systems (the Verkhoyansky and Chersky ridges, etc.) are combined with plateaus (Yanskoye, Elginskoye, Alazeyskoye, Yukagirskoye, etc.) and uplands (Oymyakonskoye, Kolymskoye, etc.). In the south there are also a number of vast uplands (Stanovoe, Aldan, Patom, etc.). In some high-mountain ranges, alpine landforms with modern glaciation are developed (Orulgan, Momsky, Sunta-Khayata, etc.). In the north, a number of large lowlands stretch - the North Siberian, Yano-Indigirskaya, Kolyma, etc.

The tectonic structures of Eastern Siberia are represented by the Siberian platform and its folded framing: in the north - the Early Mesozoic structure of Taimyr; in the west - the system of the Yenisei Ridge of the Baikal age; in the southeast - the structures of the Salair-Caledonian-Hercynian Altai-Sayan folded region. In the south is the Baikal-Mongol-Okhotsk region, in which the time of the main folding in various mountain systems varies from the late Proterozoic to the late Mesozoic. To the east of the Siberian Platform is the late Mesozoic Verkhoyansk-Chukotka folded region. Mountain building covered the southern part of Eastern Siberia in the Cenozoic. The eastern regions are experiencing active uplift. One of the largest continental rift systems in the world, the Baikal rift system, is located in the south of Eastern Siberia. High seismicity is characteristic of the southern (Lake Baikal basin with adjacent territories, Eastern Sayan) and eastern (Verkhoyansky and Chersky ridges) regions. Strong destructive earthquakes occurred in 1862 (in the delta of the Selenga River), 1927 (Bulun in the Verkhoyansk Range), 1950 (in the Eastern Sayan), 1957 (Muiskoye in Transbaikalia), 1959 (Middle Baikal), 1971 (Artykskoye in the Chersky Range). Known deposits of oil and natural combustible gas, coal, iron ores, gold, uranium, platinum, tin, copper, nickel, cobalt, antimony, mercury, niobium, rare earth elements, as well as diamonds, phlogopite, muscovite, asbestos, stone and potash salt, etc.

The climate of Eastern Siberia is sharply continental. In the regions of Oymyakon and Verkhoyansk, there is the cold pole of Eurasia (absolute minimum -68 °C). Permafrost is ubiquitous, reaching a maximum thickness of 1500 m (the Markha River basin). Thermokarst lakes are numerous in the north and northeast. The largest rivers of Russia flow through the territory of Eastern Siberia: Lena, Yenisei, Kolyma, Indigirka; there is a unique Lake Baikal. The northern lowlands of Eastern Siberia are occupied by tundra: arctic, moss-lichen and shrubs on peat-cryozems. To the south, a narrow strip of forest-tundra without a sharp transition gives way to the northern subzone of taiga larch forests on coarsely humus cryozems. Larch forests are widespread in the middle and southern subzones of the taiga on cryoturbated pale soils and coarsely humus light soils. In the south of the Central Siberian Plateau there are forest-steppe islands. The zonal distribution of the soil and vegetation cover is disturbed in the Byrranga mountains and on the Putorana Plateau, as well as in high areas of the plateaus. The structure of altitudinal zonality in the northeastern part of Eastern Siberia differs sharply from the southern part, where it is more diverse.

The active development of natural resources, the development of large industrial centers has led to the emergence of regions with a tense ecological situation (Norilsk, Kemerovo, Irkutsk, etc.), which is aggravated by the poor ability of the natural environment of this region to self-purify. A number of nature reserves (Taimyrsky, Barguzinsky, Central Siberian, Vitimsky, etc.) and national parks (Pribaikalsky, Zabaikalsky, Tunkinsky, etc.) have been created. The World Heritage List includes: Lake Baikal, the Ubsunur Hollow (most of it is in Mongolia).

Lit .: Plains and mountains of Siberia. M., 1975; Antipova A.V. Geography of Russia. M., 2001.

Eastern Siberia occupies a vast territory from the Yenisei to the Pacific Ocean. It is famous for its large number of natural resources and minerals. The features of the relief and this region made it so valuable in terms of raw materials. Mineral resources of Eastern Siberia are not only oil, coal and iron ores. A significant part of Russia's gold and diamonds, as well as valuable metals, is mined here. In addition, almost half of the country's forest resources are located in this region.

Eastern Siberia

Minerals are not the only feature of this region. Eastern Siberia covers an area of ​​more than 7 million square kilometers, which is about a quarter of the whole of Russia. It stretches from the valley of the Yenisei River to the most mountain ranges on the Pacific coast. The region borders the Arctic Ocean to the north and Mongolia and China to the south.

Eastern Siberia does not include as many regions and settlements as in the European part of Russia, because this area is considered sparsely populated. Here are the country's largest Chita and Irkutsk regions, as well as the Krasnoyarsk and Trans-Baikal regions. In addition, the autonomous republics of Yakutia, Tuva and Buryatia belong to Eastern Siberia.

Eastern Siberia: relief and minerals

The diversity of the geological structure of this region explains such a wealth of its raw materials. Due to their huge number, many deposits have not even been explored. What minerals are Eastern Siberia rich in? It is not only coal, oil and iron ores. The subsoil of the region contains rich reserves of nickel, lead, tin, aluminum and other metals, as well as sedimentary rocks necessary for industry. In addition, Eastern Siberia is the main supplier of gold and diamonds.

This can be explained by the features of the relief and geological structure of this region. Eastern Siberia is located on the ancient Siberian platform. And most of the territory of the region is occupied by the Central Siberian Plateau, elevated above sea level from 500 to 1700 m. The foundation of this platform is the oldest crystalline rocks, whose age reaches 4 million years. The next layer is sedimentary. It alternates with igneous rocks formed as a result of volcanic eruptions. Therefore, the relief of Eastern Siberia is folded, stepped. It contains many mountain ranges, plateaus, terraces, deep river valleys.

Such a variety of geological processes, tectonic shifts, deposits of sedimentary and igneous rocks led to the wealth of minerals in Eastern Siberia. The table allows you to find out that more resources are mined here than in neighboring regions.

Coal reserves

Due to geological processes since the Paleozoic and Mesozoic eras, the largest in Russia coal deposits of minerals in Western and Eastern Siberia are located in the lowlands of the region. These are the Lena and Tunguska basins. There are also a lot of smaller deposits. And although there is less coal in them, they are also promising. These are the Kama-Achinsk and Kolyma-Indigirsk basins, the Irkutsk, Minusinsk, South Yakut deposits.

Hard coal reserves in Eastern Siberia account for 80% of all coal mined in Russia. But many places of its occurrence are very difficult to develop due to the harsh climatic conditions of the region and the features of the relief.

Iron and copper ores

The main minerals of Eastern Siberia are metals. Their deposits are found in the most ancient rocks, even the Precambrian period. Most of all in the region are hematites and magnetites. Their deposits are located in the south of the Yakutsk region, in the basin on and also on the Angara, in Khakassia, Tuva and Transbaikalia.

The largest ore deposits are Korshunovskoye and Abakanskoye. There are also many of them in the Angara-Pitsky district. 10% of all Russian iron ore reserves are concentrated here. In Transbaikalia and in the north of the region there are also large deposits of tin and valuable metals.

The environs of Norilsk are famous for large deposits of copper-nickel ores. Almost 40% of Russian copper and about 80% of nickel are mined here. In addition, there is a lot of cobalt, there are also platinum, silver, tellurium, selenium and other elements. In other places, copper, mercury, manganese, antimony are mined. There are large deposits of bauxite.

Non-metallic minerals

Our country is the world's largest supplier of natural gas, and a lot of oil is produced here. And the first supplier of these minerals is the deposits of Eastern Siberia. In addition, geological processes have led to the emergence of rich deposits of sedimentary rocks.

Gold and diamonds of Eastern Siberia

The most valuable metal has been mined here for almost the second century. The oldest deposit is Bodaibo in the Irkutsk region. There are rich placer and bedrock deposits of gold in the Aldan, Yan, Allah-Yun regions. Deposits have recently begun to be developed in the region of the Yenisei Ridge, near Minussinsk and in the east of Transbaikalia.

Thanks to the special geological processes that have been going on in this region since the Mesozoic era, many diamonds are now being mined here. The largest deposit in Russia is located in Western Yakutia. They are mined from the so-called diatremes filled with kimberlites. Each such "explosion tube" in which diamonds are found even got its own name. The most famous are "Udachnaya-Vostochnaya", "Mir" and "Aikhal".

Natural resources

The complex topography of the region, vast undeveloped territories covered with taiga forests provide a wealth of natural resources. Due to the fact that the most full-flowing rivers of Russia flow here, the region is provided with cheap and environmentally friendly hydroelectric power. The rivers are rich in fish, the surrounding forests are rich in fur-bearing animals, of which sable is especially valued. But due to the fact that man has become more and more actively interfering with nature, many species of plants and animals are dying out. Therefore, many reserves and national parks have recently been created in the region to preserve natural wealth.

The richest areas

Eastern Siberia occupies almost a quarter of the territory of Russia. But there are not many people living here. In some places, there are more than 100 square kilometers per person. But Eastern Siberia is very rich in minerals and natural resources. Although they are unevenly distributed throughout the region.

• The richest in economic terms is the Yenisei basin. Krasnoyarsk is located here, in which more than half of the entire population of Eastern Siberia is concentrated. The richness of this area in minerals, natural and hydro resources led to the active development of industry.
• The wealth located in the upper reaches of the Angara River began to be used only in the 20th century. A very large polymetallic deposit has been discovered here. And the reserves of iron ore are simply huge. The best magnesites in Russia are mined here, as well as a lot of antimony, bauxites, nephelines, and slates. Deposits of clay, sand, talc and limestone are being developed.
• Evenkia has the richest resources. Here in the Tunguska basin there are such minerals of Eastern Siberia as stone and high-quality graphite is mined in the Noginsk deposit. Icelandic spar deposits are also being developed.
• Khakassia is another richest region. A quarter of East Siberian coal and all iron ore are mined here. After all, the Abakansky mine, located in Khakassia, is the largest and oldest in the region. There is gold, copper, a lot of building materials.
• One of the richest places in the country is Transbaikalia. Mostly metals are mined here. For example, it supplies copper ores, Ononskoye - tungsten, Sherlokogonskoye and Tarbaldzheyskoye - tin, and Shakhtaminskoye and Zhrikenskoye - molybdenum. In addition, a lot of gold is mined in Transbaikalia.
• Yakutia is a treasure trove of minerals in Eastern Siberia. Although only after the revolution, deposits of rock salt, coal and iron ore began to be developed. There are rich deposits of non-ferrous metals, mica. In addition, it is in Yakutia that the richest reserves of gold and diamonds have been discovered.

Problems of development of minerals

Huge, often unexplored territories of the region lead to the fact that many of its natural resources are not developed. There is a very low population density here, therefore, promising mineral deposits in Eastern Siberia are mainly developed in populated areas. After all, the lack of roads over a large area and the huge distance from the center make the development of deposits in remote regions unprofitable. In addition, most of Eastern Siberia is located in the permafrost zone. A sharply continental climate hinders the development of natural resources in the rest of the territory.

Northeastern Siberia and the Far East

Due to the peculiarities of the relief and climatic conditions, the minerals of North-Eastern Siberia are not so rich. There are few forests here, mainly tundra and arctic deserts. Most of the territory is dominated by permafrost and year-round low temperatures. Therefore, the minerals of North-Eastern Siberia are not very developed. Basically, coal is mined here, as well as metals - tungsten, cobalt, tin, mercury, molybdenum and gold.

The easternmost and northern regions of Siberia belong to the Far East. This area is also rich, but also more populated due to its proximity to the ocean and milder climate. Mineral resources of Eastern Siberia and the Far East are similar in many respects. There are also many diamonds, gold, tungsten and other non-ferrous metals, mercury, sulfur, graphite, mica are mined. The region has rich deposits of oil, coal and natural gas.

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.

Altitude zoning is typical for mountainous regions. 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 the end of the XIX century. 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. Their average height is 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 is replaced here 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 the East Siberian Sea is occupied by the Yano-Indigirskaya lowland, from which the intermountain Sredneindigirskaya (Abyiskaya) and Kolyma lowlands protrude far to the south along the valleys of the Indigirka, Alazeya and Kolyma. 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 sediments, and the Jurassic formations 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 in the conditions of the warm climate of 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, especially high ridges arose. 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. In 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

Significantly better are traces of mountain-valley glaciation in the outlying mountain ranges, where well-preserved forms of glacial exaration in the form of kars and trough valleys are found, 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, along with some North American species (for example, hemlock), Siberian conifers appeared in the composition of forest vegetation, including the Daurian larch that is now dominant.

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 location of the country in high latitudes and its severe, sharply continental climate determine the altitudinal limits of the distribution of the corresponding types of mountain relief, which are different from those in more southern countries. In addition, the processes of nivation, solifluction, and frost weathering are of greater importance in their formation. 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 that owe their origin to permafrost processes, large ice content of loose deposits and the presence of thick underground ice are widespread here: thermokarst basins, permafrost heaving mounds, frost cracks and polygons, and on the sea coasts, high ice cliffs are intensively collapsing (for example, the famous Oyegossky Yar with a length of more than 70 km).

Accumulative plains occupy vast areas of the Yana-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 ridges 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 climatic zones, at a considerable height above sea level and is isolated by mountain ranges from the influences of the Pacific Ocean seas.

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. For seven to eight months (from September - October to April), the radiation balance of the earth's surface is 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 of ​​increased pressure of the Asian anticyclone begins to form over North-Eastern Siberia. Throughout the winter, very cold continental air dominates here, formed mainly as a result of the transformation of Arctic air masses coming from the north. 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°. The most severe frosts 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 temperature rise with altitude 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 the average January temperature 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 especially severe frosts near settlements and highways, fogs are so thick that even in the daytime it is necessary to turn on the lights in houses and turn on 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 the maximum air temperatures 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 drop 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 treeline, summers are cooler and the average temperature in July is below 10-12°.

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 dry air, high temperatures and significant evaporation, the vegetation of plants occurs in 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 still 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, 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 of the rock mass are also characteristic. 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. Part of the ice of this type can be considered "fossil", since their formation began in the Middle Quaternary.

Underground ice has a significant impact on the formation of the relief, the regime of rivers and the conditions for the economic activity of the 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 July temperature 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, most rivers have the highest water levels. 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 period of high water, 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 feeding the river, the most prominent role is played by summer rains (78%), snowmelt (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 stream, 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, low evaporation, and 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.

Another characteristic feature of the country's fauna is the presence of steppe animals in its composition, which are not found anywhere else in the far north. 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 North-Eastern Siberia shows that even then the woolly rhinoceros and reindeer, musk ox and wolverine, tarbagan and arctic fox lived here - animals of regions 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 resources 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, Kösterskoe, 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. In recent 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 as a food base for cattle and horses.

Before the Great October Revolution, North-Eastern 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.

Agriculture has also made some progress. 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.

,

a) The North-East of Russia is characterized by sharp orographic contrasts: medium-altitude mountain systems predominate, along with them there are plateaus, highlands and lowlands. North-Eastern Siberia is a predominantly mountainous country; lowlands occupy a little more than 20% of its area. The most important orographic elements - the marginal mountain systems of the Verkhoyansk Range and the Kolyma Highlands - form a 4000 km long arc convex to the south. Inside it are located the chains of the Chersky ridge, elongated parallel to the Verkhoyansk system, the ridges Tas-Khayakhtakh, Tas-Kystabyt (Sarycheva), Momsky, and others.

The mountains of the Verkhoyansk system are separated from the Chersky ridge by a lowered strip of the Yansky, Elginsky and Oymyakonsky plateaus. The Nera plateau and the Upper Kolyma highlands are located in the east, and in the southeast the Sette-Daban ridge and the Yudomo-Maysky highlands adjoin the Verkhoyansk ridge.

The highest mountains are located in the south of the country. Their average height is 1500-2000 m, however, in the Verkhoyansk, Tas-Kystabyt, Suntar-Khayat and Chersky ridges, many peaks rise above 2300-2800 m, and the highest of them, Mount Pobeda in the Ulakhan-Chistai ridge, reaches 3003 m.

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 uplands (Polousny Ridge, Ulakhan-Sis) and plateaus (Alazeysky, Yukagirsky). A wide strip of the coast of the Laptev Sea and the East Siberian Sea is occupied by the Yano-Indigirskaya lowland, from which, along the valleys of the Indigirka, Alazeya and Kolyma, the intermountain Sredneindigirskaya (Abyiskaya) and Kolyma lowlands protrude far to the south.

Thus, the North-East of Siberia is a huge amphitheater, inclined towards the Arctic Ocean;

b) The main plan of the modern relief of North-Eastern Siberia was determined by neotectonic movements. In the development of the relief of the Northeast after the Mesozoic mountain building, two periods are distinguished: the formation of widespread leveling surfaces (peneplains); and the development of intense newest tectonic processes that caused splits, deformation and displacement of ancient alignment surfaces, volcanism, violent erosion processes. At this time, the formation of the main types of morphostructures takes place: folded-block areas of ancient median massifs (Alazeya and Yukagagir plateaus, Suntar-Khayata, etc.); mountains revived by the latest arch-block uplifts and depressions of the rift zone (Moma-Selennyakh depression); folded mid-mountains of Mesozoic structures (mountains Verkhoyansk, Sette-Daban, Anyui, etc., the Yanskoye and Elga plateaus, the Oymyakon highlands); stratal-accumulative, sloping plains, created mainly by subsidence (Yano-Indigirskaya and Kolyma lowlands); fold-block ridges and plateaus on the sedimentary-volcanic complex (the Anadyr plateau, the Kolyma highlands, the ridges - Yudomsky, Dzhugdzhur, etc.);

c) 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 m, and the intense 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 m. It includes Permian, Triassic and Jurassic sandstones and shales, usually intensively dislocated and broken through by young intrusions.

The most ancient structural elements are the Kolyma and Omolon median massifs. Their base is composed of Precambrian and Paleozoic sediments, and the Jurassic formations 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;

d) The main types of relief of North-Eastern Siberia form several distinct geomorphological tiers. The most important features of each of them are associated, first of all, with the hypsometric position, due to the nature and intensity of the latest tectonic movements. However, the location of the country in high latitudes and its severe, sharply continental climate determine the altitudinal limits of the distribution of the corresponding types of mountain relief, which are different from those in more southern countries. In addition, the processes of nivation, solifluction, and frost weathering are of greater importance in their formation. 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 underground ice: thermokarst basins, permafrost heaving mounds, frost cracks and polygons, and high ice cliffs that are intensively collapsing on sea coasts. Accumulative plains occupy vast areas of the Yana-Indigirskaya, Sredneindigirskaya and Kolyma lowlands, some islands of the seas of the Arctic Ocean (Faddeevsky, Lyakhovsky, Bunge Land, etc.). Small areas of them are also found in depressions in the mountainous part of the country (Momo-Selennyakhskaya and Seimchanskaya hollows, Yanskoye and Elga plateaus).

Erosion-denudation plains are located at the foot of some northern ridges (Anyuisky, 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. The height of their surface 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.

The plateau relief is most typically expressed in a wide strip separating the systems of the Verkhoyansk Range and the Chersky Range (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 Mesozoic deposits folded into folds and represent denudation leveling surfaces, currently located at an altitude of 400 to 1200-1300 m. Upper Kolyma Highlands, where numerous granite batholiths appear 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.

The low mountains are occupied by areas subjected to uplifts of moderate amplitude (300-500 m) in the Quaternary. They are located mainly along 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.

The mid-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 is from 800-1000 to 2000-2200 m, and only at the bottom of deeply incised valleys the marks sometimes drop to 300-400 m. Relatively gentle relief forms prevail in the interfluve spaces, and fluctuations in relative heights usually do not exceed 200-300 m Forms created by Quaternary glaciers, as well as by 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.

The high-mountainous alpine relief is associated with areas of the most intense Quaternary uplifts, located at an altitude of more than 2000-2200 m. areas of the Verkhoyansk Range. Due to the fact that the most significant role in the formation of the Alpine relief was played by the activity of Quaternary and modern glaciers, 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;

e) Among the minerals of this region, one can note numerous deposits of metals, in particular, tin, tungsten, gold, molybdenum, etc. These deposits are associated with Mesozoic-Cenozoic magmatism. Also in the region there are coal and brown coal basins (Zyryansky, Verkhoyansky).

Questions and tasks

1. Compare the relief of Eastern and Western Siberia.

The modern relief of Western Siberia is due to geological development, tectonic structure and the influence of various exogenous relief-forming processes. The main orographic elements are closely dependent on the structural-tectonic plan of the plate, although the prolonged Meso-Cenozoic subsidence and the accumulation of a thick layer of loose deposits largely leveled the unevenness of the basement. The low amplitude of geotectonic movements is due to the low hypsometric position of the plain. The maximum amplitudes of uplifts reach 100–150 m in the peripheral parts of the plain, and in the center and in the north they are replaced by subsidence up to 100–150 m. However, a number of lowlands and uplands stand out within the plain, commensurate in area with the lowlands and uplands of the Russian Plain.

Western Siberia has the form of a stepped amphitheater, open to the north, to the coast of the Kara Sea. Three high-altitude levels are clearly traced within its limits. Almost half of the territory has a height of less than 100 m. The second hypsometric level is located at heights of 100–150 m, the third is mainly in the range of 150–200 m with small areas up to 250–300 m.

The highest level is confined to the marginal parts of the plain, to the Outer Tectonic Belt. It is represented by the North Sosva, Upper Taz and Lower Yenisei uplands, the Ob plateau, the Turin, Ishim, Kulunda, Ket-Tym plains.

Eastern Siberia is located on the ancient Siberian platform. And most of the territory of the region is occupied by the Central Siberian Plateau, elevated above sea level from 500 to 1700 m. The foundation of this platform is the oldest crystalline rocks, whose age reaches 4 million years. The next layer is sedimentary. It alternates with igneous rocks formed as a result of volcanic eruptions. Therefore, the relief of Eastern Siberia is folded, stepped. It contains many mountain ranges, plateaus, terraces, deep river valleys.

2. Explain the climatic features of Eastern Siberia.

The formation of the climate in Eastern Siberia is affected by its territorial location and relief features. Far from the Atlantic Ocean, Eastern Siberia is characterized by pronounced continental climate features. This is manifested in exceptionally large seasonal differences in air temperature, low cloud cover, and low precipitation in the flat area. In winter, the weather in Eastern Siberia is formed under the influence of a vast area of ​​high pressure - the Asian anticyclone. However, the position of the center of the anticyclone, the pressure in it, and the area of ​​distribution change significantly during the cold period. This determines the variability of the circulation, which is also associated with interdiurnal fluctuations in air temperature, which is especially typical for the southwest of Yakutia. Although cyclonic activity is weakened in winter, it significantly affects the weather: air masses change, precipitation falls, and snow cover forms. Continental air prevails here, which cools in the surface layer, and in December - February in the lower layers it becomes colder than the Arctic. The average air temperature in January in the vast expanse of Eastern Siberia varies from -26 in the southwest to -38, -42 ° in the Central Lowland. In valleys and hollows, the air temperature can drop to -60°C. However, against the background of a very low average monthly temperature, with the removal of warmer continental air from Central Asia, China, relative warming is observed in the Baikal and Transbaikal regions, accompanied by an increase in temperature to –15° and above. With a long-term removal of relatively warm air masses, the daytime air temperature in Eastern Siberia can be above 0°. Summer in Eastern Siberia is warm: up to 30-40% of solar heat is spent on air heating, and up to 50% in the south of Transbaikalia and the east of the Central Yakutsk lowland. Therefore, despite the inflow of cold air from the Arctic seas, from the north of Western Siberia and from the Sea of ​​Okhotsk, the average temperatures in July vary across the territory from north to south from 14 to 18°. The highest temperatures in these areas occur during the removal of continental air from China and Mongolia (35 - 38 °). In summer, the frequency of cyclones over Eastern Siberia is greater than in winter. They mainly come from the west, southwest and northwest. In the second half of summer, there are outlets of southern cyclones, which are associated with significant precipitation. The relief and features of atmospheric circulation distribute precipitation over the territory. The annual amount of precipitation varies within 130 - 1000 mm, and there is no well-pronounced, as in the European territory of Russia and Western Siberia, a gradual decrease in precipitation to the south. The combination of heat and moisture contributes to the growth of forests in most of Eastern Siberia. However, the complex relief of this region violates the natural zonality.

3. Select from the text the features of the lake-river network of Eastern Siberia. What is their significance for the economic development of the region?

The basis of the river network is formed by the Yenisei and Lena, which are among the greatest rivers in the world. Both of them begin in the mountains of Southern Siberia and flow north almost in a meridional direction.

Both the Yenisei and the Lena are striking in their size and abundance of water; each of them collects water from a pool of more than 2 million square meters. km and has a length of more than 4 thousand km; annually in the seas of the Arctic Ocean they take out over 1100 cubic meters. km of fresh, relatively warm water.

The interfluves of these rivers are drained by a dense network of their tributaries. The upper reaches of many large tributaries are often located close to each other, and this feature of the river network has long been used by the Russian population of Siberia.

There are a huge number of lakes in Eastern Siberia. The main one is the Baikal. This is the deepest lake in the world - 1637 m. It contains the world's largest supply of fresh water (1/5).

Oz. Taimyr is located in the center of the Taimyr Peninsula, beyond the Arctic Circle, at the foot of the Byrranga plateau. This is the northernmost of the large lakes of the USSR. The area of ​​its water surface is 4650 km2. The lake is shallow. Its average depth is 2.8 m, the maximum is 26 m. The river flows into the lake. Upper Taimyr, and the river flows out. Lower Taimyr, which flows into the Taimyr Bay of the Kara Sea. The average monthly surface water temperature in July is 5-7°C. The lake is ice-free for about 3 months.

It should be noted that some lakes of alas-like depressions are significantly saline. The primary mineralization of these lakes is apparently associated with mineral substances contained in buried ice. Other lakes in the region In the north-west of the region, in the lower reaches of the Yenisei, the Khantai group of lakes of glacial origin stands out. The largest of this group is the shallow lake. Pyasino with an area of ​​about 850 km2. Lakes Lama, Glubokoe, Khantaiskoe, Vivi, and others also belong to this group. An exceptional abundance of lakes is characteristic of the region of the Kolyma and Alazeya lowlands. In the Vitim basin, there are groups of Eravna and Arakhlei lakes. A significant number of lakes are located in the Baikal region and in Transbaikalia, as well as in the upper part of the Yenisei basin, in the so-called Minusinsk basin.

4. Name the features of the natural zones of Eastern Siberia, using the text of the paragraph and the maps of the atlas.

The northern plains and mountainous areas are dominated by tundra and forest-tundra, and in the Far North, on the ocean coast of Taimyr and on the Arctic islands (Severnaya Zemlya), arctic deserts dominate.

Most of Eastern Siberia is covered with light coniferous larch forests, the border of which in the north goes quite far - up to 70 s. sh. In the Krasnoyarsk Territory, larch forests occupy half of the entire taiga.

In the Angara basin, large areas are also occupied by pine forests, and in the Western Baikal region - dark coniferous spruce-cedar forests. Only in the southern regions of the region in the basins (Minusinsk, Kuznetsk) there are areas of steppes and forest-steppes. The area has huge reserves of wood raw materials. The total timber stock is almost 40% of the all-Russian fund. However, the main tracts of forests are located in poorly developed areas, where almost no logging is carried out.

An important wealth of the region is fur-bearing animals: sable, squirrel and arctic fox, the main object of hunting for the indigenous population of this region. Agricultural land is concentrated mainly in the southern part of the region, in the steppe and forest-steppe areas and along the banks of rivers in the taiga zone. Severe climatic conditions and the inaccessibility of many areas, a sparse population, despite the innumerable natural resources, are a deterrent to the economic development of Eastern Siberia.