Eastern Siberia: the grandeur and severity of nature. Mountains of northeastern Siberia
And on the tops are located. It prevails here, and sometimes drops to -70°C.
In the mountains of North-Eastern Siberia it is clearly visible (and the vegetation depends on the altitude above sea level). For example, three high-altitude landscape zones are distinguished.
The third is the belt of perennial snow and glaciers. The snow line is located at an altitude of 2250-2450 meters. The temperature in this zone does not rise above zero almost throughout the year. However, winters are milder than in neighboring valleys and plateaus. The average temperature of the warmest month at an altitude of 2800 meters is approximately +3°C. In addition, at such a high altitude, quite strong and cold winds blow. Around the glaciers there is permafrost with a small layer of seasonal thawing.
Approximately the same zonality is observed in other mountains of North-Eastern Siberia. The lower altitudinal zone is dominated by larch northern taiga open-layer forests (in hollows and valleys) and mountain larch open forests (on the slopes of valleys and ridges), and in the upper altitude zone - mountain tundra and char. In the south, thickets of dwarf cedar and alder-cedar thickets are widespread.
Chersky Ridge– one of the largest mountain systems in North-Eastern Siberia on the territory of the Republic of Sakha (Yakutia) and the Magadan region. It stretches from the lower reaches of the Yana to the upper reaches of the Kolyma for a distance of about 1500 km. The width of the ridge reaches 400 km. The Charsky ridge consists of two independent chains (Bilibina and Obruchev), which are separated by the Momo-Selennyakh and Indigirka valleys.
The Bilibin chain includes the Selennyakhsky ridge (length about 240 km, height up to 1460 m), the continuation of which on the right bank of the Indigirka River (length about 470 km, height up to 2530 m). The Obruchev chain is part of a mountain system with a complex relief; two mountain regions can be distinguished inside: northwestern and southeastern.
A chain of ridges in the northwestern region, beginning with the Burkat ridge (height up to 1150 m). Its continuation is the Khadaranya ridges (height 2185 m) and the Tas-Khayakhtakh ridge (height 2355 m). The chain is completed by the Chemalginsky ridge (height 2550 m), which separates the Momo-Selennyakh depression from the valley of the Chibagalakh River. Other mountain ranges of the Obruchev chain are located on the left bank of the Indigirka River (Porozhny, Inyalinsky, Silyapsky, Uolchansky). They are located parallel to the high-mountain Chibagapakh ridge (length 250 km, height 2450 m), which serves as a watershed for the Chibagalakh and Adycha rivers. Between the Yana and Indigirka basins there are the Elga Plateau (height up to 1590 m) and (height up to 1400 m).
In the southeastern part of the chain, the Ulakhan-Chistai ridge (length 250 km) stands out, the peak of which, Mount Pobeda (3147 m), is the highest point of the entire mountain system. It is located in the highland Buordakh massif, separated from the ridge by the through gorge of the Tirekhtyakh River. The Ulakhan-Chistai ridge is divided into separate massifs and serves as the watershed of Moma and Mera, Indigirka and Kolyma. It continues with a chain of short mid-mountain ridges. The valley of the Erikit River separates the Ulakhan-Chistai ridge from two short typically mid-mountain ridges - Khayargastakh (height up to 2193 m) and Erikitsky (height up to 2341 m), forming the northeastern and eastern borders of the entire mountain system. Its western border is the Tas-Kystabyt ridge (height up to 2341 m).
On the Ulakhan-Chistai ridge there are about 100 glaciers, the total area of which is 85 km2 (90% is concentrated in the Buordakh massif). In general, on the territory of the Chersky ridge there are over 350 glaciers with a total area of about 157 km2. There are 69 passes and 4 peaks in the Chersky ridge system.
Verkhoyansk ridge formed by a large number of individual mountain ranges, massifs and depressions separating them. The Verkhoyansk ridge forms a watershed with Yana and Omoloy. It stretches for 1200 km from the Lena delta to the Tompo River (the right tributary of the Aldan), forming an arc convex to the southeast. The width of the Verkhoyansk Range ranges from 100 to 250 km. The southeastern continuation of the ridge is called the Sette-Daban ridge, which is distinguished by a different topography and. The northern end is formed by the Tuora-Sis and Kharaulakhsky ridges (height 1000-1250 m).
The highest points are located within the Orulgan ridge 2100-2300 m (highest point 2389 m). From the Orulgan ridge, the narrow and long Kular ridge branches off to the east, the height of which reaches 1300 m. In the latitudinal section of the Verkhoyansk ridge, the heights exceed 2000 m. The passes lie at altitudes of 1300-1500 m. The river valleys of the western and southern slopes are deep. On the tops of ridges and massifs there are areas of ancient leveled relief, better preserved in the Yana basin. The Verkhoyansk ridge is composed of siltstones, sandstones, shales, and less commonly limestones.
On the tops of the highest ridges the cold prevails. Below on the gravelly and loamy slopes, mountain-tundra vegetation appears in small quantities. In the south, the lower parts of the mountain slopes up to an altitude of 800-1200 m are covered with larch forests. Sometimes there are steppe areas and forests formed by pine and birch, occasionally spruce, poplar, and also thickets of bushes.
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 slightly more than 20% of its area. The most important orographic elements - the marginal mountain systems of the Verkhoyansk Range and the Kolyma Plateau - form a convex arc to the south, 4000 km long. Inside it are located the chains of the Chersky ridge, Tas-Khayakhtakh, Tas-Kystabyt (Sarycheva), Momsky and others, stretched parallel to the Verkhoyansk system.
The mountains of the Verkhoyansk system are separated from the Chersky ridge by a low strip of the Yana, Elga and Oymyakon plateaus. In the east are the Nerskoye Plateau and the Upper Kolyma Highlands, and in the southeast the Sette-Daban Range and the Yudomo-Mayskoye Highlands adjoin the Verkhoyansk Range.
The highest mountains are located in the south of the country. Their average height is 1500-2000 m, but in the Verkhoyansk, Tas-Kystabyt, Suntar-Khayat and Chersky ranges, many peaks rise above 2300-2800 m, and the highest of them - Mount Pobeda in the Ulakhan-Chistai range - reaches 3003 m.
In the northern half of the country, the mountain ranges are lower and many of them extend in a nearly meridional direction. 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 Yana-Indigirskaya lowland, from which the intermountain Middle Indigirskaya (Abyyskaya) and Kolyma lowlands extend along the valleys of the Indigirka, Alazeya and Kolyma, far to the south.
Thus, Northeast Siberia is a huge amphitheater inclined towards the Arctic Ocean;
b) The basic 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 planation surfaces (peneplains); and the development of intense new tectonic processes that caused splits, deformation and movement of ancient planation surfaces, volcanism, and violent erosion processes. At this time, the formation of the main types of morphostructures took place: folded-block areas of the ancient middle massifs (Alazeya and Yukagagir plateaus, Suntar-Khayata, etc.); mountains, revived by the latest arch-block uplifts, and depressions of the rift zone (Mom-Selennyakh depression); folded middle mountains of Mesozoic structures (Verkhoyansk, Sette-Daban, Anyui mountains, etc., Yanskoye and Elga plateaus, Oymyakon highlands); stratified-accumulative, inclined plains created mainly by subsidence (Yano-Indigirka and Kolyma lowlands); folded-block ridges and plateaus on the sedimentary-volcanic complex (Anadyr Plateau, Kolyma Highlands, ridges - Yudomsky, Dzhugdzhur, etc.);
c) The territory of present-day North-Eastern Siberia in the Paleozoic and the first half of the Mesozoic was a section of the Verkhoyansk-Chukchi geosynclinal sea basin. This is evidenced by the large thickness of Paleozoic and Mesozoic sediments, in some places reaching 20-22 thousand m, and the intense manifestation of tectonic movements that created folded structures in the country in the second half of the Mesozoic. Particularly typical are the deposits of the so-called Verkhoyansk complex, the thickness of which reaches 12-15 thousand m. It includes Permian, Triassic and Jurassic sandstones and shales, usually intensively dislocated and intruded by young intrusions.
The most ancient structural elements are the Kolyma and Omolon middle 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 lying 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-Daban anticlinorium, the Yansk and Indigirka-Kolyma synclinal zones, as well as the Tas-Khayakhtakh and Mom anticlinoriums. The extreme northeastern regions are part of the Anyui-Chukchi anticline, which is separated from the middle massifs by the Oloi tectonic depression, filled with volcanogenic and terrigenous Jurassic deposits;
d) The main types of relief of North-Eastern Siberia form several clearly defined geomorphological stages. The most important features of each of them are associated, first of all, with the hypsometric position, determined by the nature and intensity of recent tectonic movements. However, the country's location in high latitudes and its harsh, sharply continental climate determine the altitudinal limits of distribution of the corresponding types of mountainous relief that are different from those in more southern countries. In addition, the processes of nivation, solifluction and frost weathering become more important in their formation. 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 characteristics 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 sediments - alluvial, lacustrine, marine and glacial. They are characterized by slightly rugged terrain and slight fluctuations in relative heights. Forms that owe their origin to permafrost processes, high ice content of loose sediments and the presence of thick underground ice are widespread here: thermokarst basins, frozen heaving mounds, frost-breaking cracks and polygons, and on the sea coasts intensively collapsing high ice cliffs. Accumulative plains occupy vast areas of the Yana-Indigirka, Middle Indigirsk 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 the depressions of the mountainous part of the country (Momo-Selennyakh and Seymchan basins, Yanskoye and Elga plateaus).
Erosion-denudation plains are located at the foot of some northern ridges (Anyuysky, Momsky, Kharaulakhsky, Kular), 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. Unlike accumulative plains, these plains are composed of bedrock of various ages; the cover of loose sediments is usually thin. Therefore, there are often gravelly placers, sections of narrow valleys with rocky slopes, low hills prepared by denudation processes, as well as medallion spots, solifluction terraces and other forms associated with the processes of permafrost relief formation.
The flat-mountain relief is most typically expressed in a wide strip separating the systems of the Verkhoyansk ridge and the Chersky ridge (Yanskoye, Elginskoye, Oymyakonsky and Nerskoye plateaus). It is also characteristic of the Upper Kolyma Highlands, the Yukagir and Alazeya plateaus, significant areas of which are covered with Upper Mesozoic effusives, lying almost horizontally. However, most of the plateaus are composed of folded Mesozoic sediments and represent denudation leveling surfaces, currently located at an altitude of 400 to 1200-1300 m. In places, higher remnant massifs rise above their surface, typical, for example, of the upper reaches of the Adycha and especially The Upper Kolyma Highlands, where numerous granite batholiths appear in the form of high dome-shaped hills prepared by denudation. Many rivers in areas with flat mountain topography are mountainous in nature and flow through narrow rocky gorges.
Low mountains are occupied by areas that were subject 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 typical relief forms caused by nival-solifluction and glacial processing, as well as an abundance of rocky placers and rocky peaks.
Mid-mountain relief is especially characteristic of most of the massifs of the Verkhoyansk ridge system, the Yudomo-Maisky highlands, the Chersky ridge, Tas-Khayakhtakh and Momsky. Significant areas are occupied by mid-mountain massifs also in the Kolyma Highlands and the Anyui Range. Modern mid-altitude mountains arose as a result of recent uplifts of denudation plains of planation surfaces, sections of which in some places have been preserved here to this day. Then, in Quaternary times, the mountains were subjected to vigorous erosion by deep river valleys.
The height of mid-mountain massifs ranges from 800-1000 to 2000-2200 m, and only at the bottom of deeply incised valleys do the elevations sometimes drop to 300-400 m. In the interfluve spaces, relatively flat landforms predominate, 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 throughout. The development and preservation of these forms is facilitated by the harsh climate, since, unlike more southern mountainous countries, many mid-mountain massifs of the Northeast are located above the upper limit of tree vegetation, in a strip of 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, upper valleys usually have wide, flat bottoms and shallower slopes.
The high alpine relief is 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, Chersky Tas-Kystabyt ridge. Ulakhan-Chistai), as well as the central 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;
Eastern Siberia is part of the Asian territory of the Russian Federation. It is located from the borders of the Pacific Ocean to the Yenisei River. This zone is characterized by an extremely harsh climate and limited fauna and flora.
Geographical description
Eastern and occupy almost two-thirds of the territory of Russia. Situated on a plateau. The eastern zone covers an area of about 7.2 million square meters. km. Her possessions extend all the way to the Sayan mountain ranges. Most of the territory is represented by tundra lowland. The mountains of Transbaikalia play a significant role in the formation of the relief.
Despite the harsh climatic conditions, there are quite a lot of large cities in Eastern Siberia. The most attractive from an economic point of view are Norilsk, Irkutsk, Chita, Achinsk, Yakutsk, Ulan-Ude, etc. Within the zone are the Trans-Baikal and Krasnoyarsk territories, the republics of Yakutia, Buryatia, Tuva and other administrative regions.
The main type of vegetation is taiga. It stretches from Mongolia to the borders of the forest-tundra. Occupies more than 5 million square meters. km. Most of the taiga is represented by coniferous forests, which make up 70% of the local vegetation. Soils develop unevenly relative to natural zones. In the taiga zone the soil is favorable and stable, in the tundra it is rocky and frozen.
Within the interfluve and lowlands, minor swamps are observed. However, there are much fewer of them than in Western Siberia. But in the eastern region arctic deserts and deciduous plantations are often found.
Relief characteristics
Eastern Siberia of Russia is located at a high level above the sea. The plateau, which is located in the middle part of the zone, is to blame. Here the height of the platform varies from 500 to 700 meters above sea level. The relative averaging of the region is noted. The highest points are considered to be the interfluve of the Lena and the Vilyui plateau - up to 1700 meters.
The base of the Siberian platform is represented by a crystalline folded basement, on which there are huge sedimentary layers up to 12 kilometers thick. The north of the zone is determined by the Aldan shield and the Anabar massif. The average thickness of the soil is about 30 kilometers.
Today, the Siberian platform contains several main types of rocks. This includes marble, crystalline slate, charnockite, etc. The oldest deposits date back to 4 billion years. Igneous rocks are formed as a result of eruptions. Most of these deposits are found in the Tunguska depression.
The modern relief is a combination of lowlands and hills. Rivers flow in the valleys, swamps form, and coniferous trees grow better on the hills.
Features of the water area
It is generally accepted that the Far East faces the Arctic Ocean with its “façade”. The eastern region borders on the Kara, Siberian and Laptev seas. Of the largest lakes, it is worth highlighting Baikal, Lama, Taimyr, Pyasino and Khantayskoye.
Rivers flow in deep valleys. The most significant of them are the Yenisei, Vilyui, Lena, Angara, Selenga, Kolyma, Olekma, Indigirka, Aldan, Lower Tunguska, Vitim, Yana and Khatanga. The total length of the rivers is about 1 million km. Most of the region's internal basin belongs to the Arctic Ocean. Other external water areas include rivers such as Ingoda, Argun, Shilka and Onon.
The main source of nutrition for the inland basin of Eastern Siberia is snow cover, which melts in large quantities under the influence of sunlight from the beginning of summer. The next most important role in the formation of continental waters is played by rain and groundwater. The highest level of basin flow is observed in summer.
The largest and most important river in the region is the Kolyma. Its water area occupies more than 640 thousand square meters. km. The length is about 2.1 thousand km. The river originates in the Upper Kolyma Highlands. The annual water consumption exceeds 120 cubic meters. km.
Eastern Siberia: climate
The formation of meteorological features of a region is determined by its territorial location. The climate of Eastern Siberia can be briefly described as continental, consistently harsh. There are significant seasonal fluctuations in cloudiness, temperature, and precipitation levels. The Asian anticyclone forms vast areas of high pressure in the region, this phenomenon is especially common in winter. On the other hand, severe frost makes air circulation changeable. Because of this, temperature fluctuations at different times of the day are more significant than in the west.
The climate of North-Eastern Siberia is represented by variable air masses. It is characterized by increased precipitation and dense snow cover. This area is dominated by continental flows, which rapidly cool in the surface layer. That is why in January the temperature drops to a minimum. Arctic winds predominate at this time of year. Often in winter you can observe air temperatures down to -60 degrees. Basically, such minimums are characteristic of basins and valleys. On the plateau, the indicators do not drop below -38 degrees.
Warming is observed with the arrival of air flows from China and Central Asia into the region.
winter time
It is not for nothing that it is believed that Eastern Siberia has the heaviest and most severe conditions. The table of temperature indicators in winter is proof of this (see below). These indicators are presented as average values over the last 5 years.
Due to the increased dryness of the air, the constancy of the weather and the abundance of sunny days, such low levels are more easily tolerated than in a humid climate. One of the defining meteorological characteristics of winter in Eastern Siberia is the absence of wind. Most of the season there is moderate calm, so there are practically no blizzards or blizzards here.
It is interesting that in the central part of Russia a frost of -15 degrees is felt much stronger than in Siberia -35 C. Nevertheless, such low temperatures significantly worsen the living conditions and activities of local residents. All living areas have thickened walls. Expensive fuel boilers are used to heat buildings. The weather begins to improve only with the onset of March.
Warm seasons
In fact, spring in this region is short, as it arrives late. The eastern one, which changes only with the arrival of warm Asian air currents, begins to wake up only by mid-April. It is then that the stability of positive temperatures during the daytime is noted. Warming begins in March, but it is insignificant. By the end of April the weather begins to change for the better. In May, the snow cover completely melts and the vegetation blooms.
In the summer in the south of the region the weather becomes relatively hot. This is especially true for the steppe zone of Tuva, Khakassia and Transbaikalia. In July the temperature here rises to +25 degrees. The highest rates are observed on flat terrain. It is still cool in the valleys and highlands. If we take the whole of Eastern Siberia, then the average summer temperature here is from +12 to +18 degrees.
Climate features in autumn
Already at the end of August, the first frosts begin to envelop the Far East. They are observed mainly in the northern part of the region at night. During the day the bright sun shines, there are rains with sleet, and sometimes the wind increases. It is worth noting that the transition to winter occurs much faster than from spring to summer. In the taiga, this period takes about 50 days, and in the steppe area - up to 2.5 months. All these are characteristic features that distinguish Eastern Siberia from other northern zones.
The climate in autumn is also represented by an abundance of rain coming from the west. Humid Pacific winds most often blow from the east.
Precipitation level
The relief is responsible for atmospheric circulation in Eastern Siberia. Both the pressure and the speed of air mass flow depend on it. The region receives about 700 mm of precipitation annually. The maximum indicator for the reporting period is 1000 mm, the minimum is 130 mm. The level of precipitation is not clearly defined.
On the plateau in the middle zone it rains more often. Due to this, the amount of precipitation sometimes exceeds 1000 mm. The driest region is considered to be Yakutia. Here the amount of precipitation varies within 200 mm. The least amount of rain falls between February and March - up to 20 mm. The western regions of Transbaikalia are considered optimal zones for vegetation relative to precipitation.
Permafrost
Today there is no place in the world that can compete in terms of continentality and meteorological anomalies with the region called Eastern Siberia. The climate in some areas is striking in its severity. In the immediate vicinity of the Arctic Circle lies a permafrost zone.
This area is characterized by light snow cover and low temperatures throughout the year. Because of this, mountain weather and soil lose a huge amount of heat, freezing to depths of meters. The soil here is predominantly rocky. Groundwater is poorly developed and often freezes for decades.
Vegetation of the region
The nature of Eastern Siberia is mostly represented by taiga. Such vegetation extends for hundreds of kilometers from the Lena River to Kolyma. In the south, the taiga borders on the local property, untouched by man. However, due to the arid climate, the threat of large-scale fires always hangs over them. In winter, the temperature in the taiga drops to -40 degrees, but in summer the readings often rise to +20. Precipitation is moderate.
The nature of Eastern Siberia is also represented by the tundra zone. This zone is adjacent to the Arctic Ocean. The soils here are bare, the temperature is low, and the humidity is excessive. In mountainous areas, flowers such as cotton grass, grass grass, poppy, and saxifrage grow. Trees in the region include spruce, willow, poplar, birch, and pine.
Animal world
Almost all regions of Eastern Siberia are not distinguished by the richness of their fauna. The reasons for this are permafrost, lack of food and underdeveloped deciduous flora.
The largest animals are brown bear, lynx, elk and wolverine. Sometimes you can see foxes, ferrets, stoats, badgers and weasels. The central zone is home to musk deer, sable, deer and bighorn sheep.
Due to the perpetually frozen soil, only a few species of rodents are found here: squirrels, chipmunks, flying squirrels, beavers, marmots, etc. But the feathered world is extremely diverse: wood grouse, crossbill, hazel grouse, goose, crow, woodpecker, duck, nutcracker, sandpiper, etc. .
North-Eastern Siberia is located east of the Lena valleys and the lower reaches of the Aldan, from the Verkhoyansk Range to the shores of the Bering Sea and is washed by the seas of the Arctic and Pacific oceans in the north and south. It is located in the eastern and western hemispheres. On the Chukotka Peninsula is the easternmost point of Russia and all of Eurasia - Cape Dezhnev.
The geographical position in the subpolar and subpolar latitudes near the cold seas and the dissected relief with a semi-circular orographic barrier from the south, west and east and a slope to the north predetermined the harsh natural conditions of the country with bright, unusually contrasting physical and geographical processes, typical only for this territory.
North-Eastern Siberia is a country of young and ancient structures, expressed by mountain systems, ridges, highlands, plateaus, coastal and intermountain plains. The relief combines ancient glacial forms and modern mountain glaciers, deep terraced valleys with numerous thermokarst lakes. The subarctic climate prevails, almost continuous permafrost, fossil ice and giant ice dams are developed. Here, many rivers freeze to the bottom in winter, and in some valleys, on the contrary, sub-permafrost warm waters emerge and feed non-freezing watercourses all winter. Rare larch taiga and dwarf pine thickets are widespread. Large areas are occupied by flat and mountain tundras. There are areas of steppe vegetation up to the north of the Chukotka Peninsula. All these are specific features of the nature of the Northeast as an independent physical and geographical country.
Geological structure
North-Eastern Siberia belongs to the area of Mesozoic folding. The direction of Mesozoic structures was significantly influenced by ancient massifs - Paleozoic and pre-Paleozoic - located within the Northeast and in neighboring territories. The intensity and direction of tectonic processes in Mesozoic times depended on their stability, tectonic activity and configuration. In the west, the Northeast borders the Siberian Precambrian platform, the eastern edge of which had a decisive influence on the direction and intensity of folds in the Verkhoyansk anticlinal zone. The structures of Mesozoic folding were formed in the Early Cretaceous as a result of the collision of the ancient Siberian continent with the microcontinents of Chukotka and Omolon.
In the Northeast, rocks of different ages are found, but Mesozoic and Cenozoic ones are especially widespread. The protrusions of the pre-Riphean basement are composed of gneisses, granite gneisses, crystalline schists and marbled limestones and are overlain by Paleozoic and Mesozoic sediments. They are located in the northeastern and southeastern parts of the Chukotka Peninsula (Chukchi Massif), in the upper reaches of the Omolon River (Omolon Massif), on the Taigonos Peninsula (Taigonos Massif) and in the Okhota River basin (Okhotsk Massif). The Kolyma massif is located in the central part of the North-East. It lies at the base of the Alazeya and Yukagir plateaus, the Kolyma and Abyi lowlands. Its pre-Riphean foundation is overlain by marine and continental sediments of the Paleozoic and Mesozoic. Along the edges of the Kolyma massif there are outcrops of Mesozoic granitoids.
Between the ancient massifs and the Siberian platform there are geostructures of Mesozoic folding. Mesozoic folded areas and ancient massifs are bordered on the south and east by the Okhotsk-Chukotka volcanogenic belt. Its length is about 2500 km, width - 250-300 km. All rocks within its boundaries are intruded and overlain by volcanogenic dislocated formations of the Lower and Upper Cretaceous, the thickness of which reaches several thousand meters. Cenozoic effusive rocks are poorly developed and distributed mainly off the coast of the Sea of Okhotsk. The emergence of the Okhotsk-Chukchi belt is apparently associated with the subsidence and fragmentation of the marginal part of the Mesozoic land in connection with the movements of the continental Eurasian, North American and Pacific oceanic lithospheric plates.
Mesozoic-Cenozoic magmatism covered vast areas of North-East Siberia. The metallogeny of this region is associated with it - numerous deposits of tin, tungsten, gold, molybdenum and other metals.
After the completion of folding, the uplifted territory of the Northeast was subject to erosion. In the Upper Mesozoic and Paleogene, there apparently was a hot climate. This is confirmed by the composition of plant remains (deciduous and evergreen forms) of the Upper Mesozoic and Paleogene deposits, the carbon content of these deposits and the presence of a laterite-type weathering crust.
In the Neogene, under conditions of tectonic quiescence, the formation of planation surfaces occurs. The subsequent tectonic uplifts led to the dismemberment of the planation surfaces, their movement to different heights, and sometimes deformation. The regional mountain structures and the Chersky highlands rose most intensively, and some coasts sank below sea level. Traces of marine transgressions are known at the mouths of rivers in the eastern part of the Chukotka Peninsula. At this time, the northern shallow part of the Sea of Okhotsk sank, the land of Beringia, and the New Siberian Islands separated from the mainland.
Volcanic eruptions occurred along the faults. The volcanoes are confined to a strip of tectonic faults extending from the Momo-Selennyakh depression to the Kolyma valley. The depression arose as a rift zone at the site of the moving apart Eurasian Plate and the Chukotka - Alaska block of the North American Plate. It apparently extends from the Arctic Ocean from the rift of the Gakkel Ridge to the young depressions cutting through the Chersky Highlands. This is one of the seismic zones in Russia.
The rise and fall of individual land areas led to increased erosion-accumulation activity: rivers deeply eroded mountain systems and created terraces. Their alluvial strata contain placer deposits of gold, tin and other minerals. In the river valleys of the North-East there are up to ten terraces with heights ranging from 2-5 to 400 m. Terraces up to 35-40 m in height were formed in post-glacial times. River interceptions are associated with changes in erosion bases.
Thus, in the development of the relief of the Northeast after the Mesozoic mountain building, two periods can be outlined: 1) the formation of widespread planation surfaces (peneplains); 2) the development of intense new tectonic processes that caused splits, deformation and movement of ancient planation surfaces, volcanism, and violent erosion processes. At this time, the formation of the main types of morphostructures took place: 1) folded-block areas of the ancient middle massifs (Alazeya and Yukagir plateaus, Suntar-Khayata, etc.); 2) mountains revived by the latest arch-block uplifts and depressions of the rift zone (Momo-Selennyakh depression); 3) folded and block-folded Mesozoic structures (Verkhoyansk, Sette-Daban, Anyui mountains, etc., Yanskoye and Elga plateaus, Oymyakon highlands); 4) stratified-accumulative, sloping plains created mainly by subsidence (Yana-Indigirka and Kolyma lowlands); 5) folded-block ridges and plateaus on the sedimentary-volcanic complex (Anadyr Plateau, Kolyma Plateau, ridges - Yudomsky, Dzhugdzhur, etc.). As we see, neotectonic movements determined the basic plan of the modern relief.
By the beginning of the Quaternary glaciation the territory had a dissected topography with significant contrasts in heights. This had a significant impact on the development of various types of glaciation. Traces of several ancient glaciations are known on the plains and mountains of the Northeast. Many researchers have been and are studying the ancient glaciation of this territory, but there is still no consensus on the number and types of glaciation, the size of the ice sheets, and their relationship with the glaciations of Siberia and all of Eurasia.
According to V.N. Sachs (1948), there were three glaciations in the mountains and plains: maximum, Zyryansky and Sartan. In the work of D.M. Kolosov (1947) said that in the North-East there were two types of ancient glaciation - mountain and plain-cover.
Glaciations developed differently on different landforms, and therefore several types of mountain glaciation formed. The glaciation of mountain ranges resulted in the development valley glaciers with ice collection in karas and through valleys on passes (the length of glaciers reached 300-350 km). On separate mountain domes formed ice caps, from which valley glaciers extended along radii. Huge developments developed on the plateaus pass ice fields, combined with valley glaciers of dissected plateaus. In the highlands, glaciation took on a varied character: ice collections formed at the tops of mountain ranges and massifs, glaciers descended along the slopes of the ridges and then emerged on the surface of the plateau base, and even lower valley glaciers descended to the edge of the plateau base. At the same time, under the influence of climate in different parts of the mountains, the same types of mountain glaciation reached different stages of development. Glaciation of the outer edge of mountain structures, which is under oceanic influence, developed to its maximum. Modern glaciation of the southern parts of the Chersky and Verkhoyansky mountain systems is also developing on these same mountain slopes.
For the northern plains, one glaciation is assumed, preserved as a relic of the Lower Quaternary ice sheet until the end of the Pleistocene. The reason for this is that there were no conditions for a complete interglacial. Several glacial and interglacial eras have been recorded in mountain structures. Their number has not yet been established. There is an opinion about a double glaciation, and many authors reject the existence of glaciation on the northern plains east of the Lena. However, a number of authors (Groswald M.G., Kotlyakov V.M. et al., 1989) convincingly prove the spread of the Zyryansky ice sheet in the Yana-Indigirskaya and Kolyma lowlands. The glaciers, in their opinion, descended south of the New Siberian Islands and the East Siberian Sea.
In the mountains of the Northeast, glaciation, depending on the relief, had a different character: semi-cover, valley-network, valley-cirque and cirque. During maximum development, glaciers reached foothill plains and shelves. The glaciation was synchronous with the glaciations of the entire Siberia and, apparently, was caused by global climate fluctuations.
The morphological and geological activity of glaciers and their meltwater in conditions of a cold continental climate and permafrost determined the main types of morphosculpture and Quaternary deposits of the entire territory. The mountains are dominated by relict cryogenic-glacial denudation morphosculptures with erosional reworking and Upper Pleistocene glacial deposits, above which colluvial accumulations of different ages are common on the mountain slopes. The plains are covered with lacustrine-alluvial deposits with cryogenic and erosive landforms.
Relief
The North-East of Russia, in contrast to other physical-geographical countries of Siberia, is characterized by sharp orographic contrasts: medium-altitude mountain systems predominate, along with them there are plateaus, highlands and lowlands.
In the west, the country’s orographic barrier is the Verkhoyansk mountain system. To the south of Verkhoyansk stretch the Sette-Daban and Yudomsky ridges, separated by the Yudomo-May Plateau, and further along the coast of the Sea of Okhotsk, the Dzhugdzhur ridge runs. The Chersky ridge stretches 1800 km in the eastern Verkhoyansk Mountains in a northwestern direction.
Between the Chaun Bay and the Sea of Okhotsk there is a medium-altitude mountain system consisting of numerous, differently oriented ridges. This entire regional system of mountains and highlands forms the eastern and southern orographic barriers for the interior regions of the Northeast. The main Pacific-Arctic divide runs along them, where maximum altitudes of about 2000 m are concentrated. Between the mountains lie deep tectonic basins that open to the sea or are separated from it by a mountain barrier. The intermountain basins are lowered in relation to the watersheds by 1000-1600 m. The eastern Chaunskaya Bay, and the Chukotka Highlands with altitudes of 1600-1843 m extend to the shores of the Bering Strait. It also serves as a watershed for two oceans.
In the interior regions of the North-East there are large highlands and plateaus: Yukaghirskoye, Alazeyskoye, Oymyakonskoye, etc. The lowlands occupy coastal areas or enter the intermountain spaces to the south in narrow “bays”.
Thus, the Northeast is a huge amphitheater inclined towards the Arctic Ocean. The complex combination of large relief forms is predetermined by the long history of the development of this largest peninsula of Eurasia, located in the contact zones of the main continental and oceanic lithospheric plates of the Earth (Eurasian, North American and Pacific).
Climate
The climate of North-East Siberia is sharply continental. Its formation is influenced by many factors. The large extent of the territory from north to south between 73 and 55° N latitude. predetermines the uneven arrival of solar heat: a large amount of solar insolation in summer and its almost complete absence in most of the territory in winter. The structure of the relief and the cold water areas surrounding the territory determine the free penetration of cold continental Arctic air masses of the Arctic Ocean. Temperate sea air comes from the Pacific Ocean, bringing the bulk of precipitation, but its supply to the territory is limited to the coastal ridges. The climate is influenced by the Asian maximum, the Aleutian minimum, as well as circulation processes on the Arctic front.
The Northeast is located in three latitudinal climatic zones: arctic, subarctic and temperate. Most of the territory is located in the subarctic zone.
Harsh winter Northeast Siberia lasts about seven months. North of the Arctic Circle the polar night begins. On the Arctic coast it lasts from mid-November to the end of January. At this time, the Arctic region of the Northeast does not receive solar heat, and south of the Arctic Circle the sun is low on the horizon and sends out little heat and light, so the radiation balance is negative from October to March.
The northeast cools greatly in winter, and an area of high pressure forms there, which is the northeastern spur of the Asian High. The mountainous terrain also contributes to strong cooling of the area. Cold and dry arctic air is formed here. The Arctic front passes along the coast of the Sea of Okhotsk. Therefore, the anticyclonic type of weather with a predominance of calms and very low temperatures is typical for intermountain basins and valleys. Isotherms of the coldest month -40...-45°C outline many intermountain basins. In the areas of Verkhoyansk and Oymyakon, the average January temperature is about -50°C. The absolute minimum temperature reaches -71°C in Oymyakon, and -68°C in Verkhoyansk. The interior regions of the Northeast are characterized by temperature inversions. For every 100 m rise, winter temperatures here increase by 2°C. For example, in the basin of the upper part of the Indigirka on the Oymyakon Highlands and on the adjacent slope of the Suntar-Khayata ridge, the average January temperature at an altitude of 777 m is -48 ° C, at an altitude of 1350 m it is already -36.7 ° C, and at an altitude of 1700 m - only -29.5°C.
To the east of the Omolon Valley, winter temperatures increase: an isotherm of -20°C passes through the eastern part of the Chukotka Peninsula. On the coastal plains it is warmer in winter than in the Verkhoyansk area, by about 12-13°C. In the mountains, tundra and on the coast of the Sea of Okhotsk, low temperatures are combined with strong winds. Cyclonic activity manifests itself on the Okhotsk coast and Chukotka in connection with the development of the Arctic front.
In the interior regions of the Northeast, all types of frosty weather form in winter, but weather with increased frostiness (hard, severe and extremely frosty) predominates. On the coast, moderate to significantly frosty weather is more common. The cold and windy weather that characterizes these areas creates significant winter severity in coastal areas.
Stable snow cover lasts 220-260 days, its height is about 30 cm on the coast of the Laptev Sea and in the Verkhoyansk area; to the east and south it increases to 60-70 cm, on the windward slopes of the mountains of the Okhotsk-Chukchi arc it reaches 1-1.5 m. During the period of maximum snow accumulation (March-April), avalanches occur in all mountains. Areas with significant avalanche danger include the Verkhoyansk and Chersky mountain systems. There, avalanches are widespread in many places and occur year-round. Favorable conditions for avalanches are a sufficient amount of precipitation in the mountains and its redistribution under the influence of strong winds (creation of multi-meter snow faces and snow cornices), intense solar insolation in the summer, promoting the recrystallization of snow into firn, slight cloudiness and forest cover of the slopes, as well as the spread clay shales, the moistened surface of which facilitates the sliding of avalanches.
In summer solar heat gain increases. The territory is filled mainly with continental air of temperate latitudes. The Arctic front passes over the northern coastal lowlands. Summer in most of the territory is moderately cool, but in the tundra it is cloudy and cold, with a very short frost-free period. In the mountains from an altitude of 1000-1200 m there is no frost-free period, strong winds prevail and temporary snow cover can form during all summer months. The average July temperature in most of the territory is about 10°C, in Verkhoyansk 15°C. However, on some days the temperature can rise in the internal intermountain basins to 35°C. When arctic air masses invade, warm weather may give way to cold snaps, and then the average daily temperature drops below 10°C. In the coastal lowlands, summers are cooler than in inland areas. The weather is changeable, with strong winds. The sum of active temperatures reaches a maximum in the basins, but is only 600-800°C.
The following types of weather are typical for the summer period: cloudy and rainy, with daytime cloudiness and strong heating of the underlying surface; with night clouds (typical for coastal areas). In July, partly cloudy, dry weather occurs in the basins for up to 10-12 days. Many mountainous regions are characterized by frosty weather during advective cooling.
Summer precipitation is highly variable from year to year. There are dry years and wet and rainy years. Thus, in Verkhoyansk, over 40 years of observations, the minimum amount of precipitation was 3 mm, and the maximum was 60-80 mm.
The distribution of annual precipitation over the territory is determined by atmospheric circulation and relief. In the Pacific Ocean basin, a lot of precipitation falls when southern and southeastern air currents predominate. Therefore, the largest amount of them (up to 700 mm per year) is received by the eastern slopes of the mountains of the Taygonos Peninsula and the southern slopes of the Okhotsk-Kolyma watershed. In the Arctic Ocean basin, precipitation falls with the arrival of northwestern air masses.
The greatest amount of them is received by the western slopes of the Verkhoyansk mountain system and Suntar-Khayat (718 mm at an altitude of 2063 m), in the mountain system of the Chersky ridge - 500-400 mm. Intermountain basins and plateaus, as well as the coast of the East Siberian Sea, receive the least amount of precipitation per year - about 200 mm (in Oymyakon - 179 mm). Maximum precipitation occurs during the short warm period of the year - July and August.
Modern glaciation and permafrost
Modern glaciation developed in many mountain systems: the Suntar-Khayata, Verkhoyansk, Chersky (Ulakhan-Chistai ridge) and the Chukotka Plateau. The total area of glaciation formed by glaciers and large snowfields is about 400 km 2. The number of glaciers is more than 650. The largest center of glaciation is the Suntar-Khayata ridge, where there are more than 200 glaciers with a total area of approximately 201 km 2. The mountains of the Indigirka basin contain the largest number of glaciers. This is explained by the high altitude of the mountains, the dissected terrain and the abundance of snow.
The formation of glaciation is greatly influenced by moist air masses coming from the Pacific Ocean and its seas. Therefore, this entire territory is classified as a glaciological region of predominantly Pacific nutrition.
The snow line in the Indigirka basin runs at an altitude of 2350-2400 m, on the Suntar-Khayat glaciers it reaches about 2200-2450 m. The ends of the glaciers are located in the Indigirka basin at an altitude of about 2000 m. Numerous snowfields are located at various levels. The most common are cirque and valley glaciers. The length of glaciers is up to 8 km. There are many hanging glaciers on the steep, steep mountain slopes. Currently, the size of glaciers is decreasing. This is evidenced by the division of large glaciers into smaller ones and the retreat of glacier tongues from the terminal moraine to a distance of 400-500 m. However, some glaciers advance, block even the terminal moraine and descend below it.
The modern harsh climate favors conservation and development permafrost(underground glaciation). Almost the entire Northeast is covered with low-continuous (almost continuous) permafrost, and only small areas of the coast of the Sea of Okhotsk have patches of permafrost among the thawed soil. The thickness of frozen soil reaches 200-600 m. The greatest freezing of soil with minimum temperatures is in the middle part of the country, in its mountainous region - from Lena to Kolyma. There the permafrost thickness is up to 300 m under the valleys and 300-600 m in the mountains. The thickness of the active layer is determined by slope exposure, vegetation, local hydrological and climatic conditions.
Water
Rivers from the territory of the Northeast they flow into the Arctic and Pacific oceans. The watershed between them runs along the Dzhugdzhur, Suntar-Khayata ridges, the Kolyma Plateau, the Anadyr Plateau and the Chukotka Plateau, therefore, the watershed is close to the Pacific Ocean. The largest rivers - Kolyma and Indigirka - flow into the East Siberian Sea.
River Kolyma begins on the slopes of the southern ridges of the Chersky mountain system, has a length of 2130 km and a basin area of about 643 thousand km 2. Its main tributary, the Omolon River, has a length of 1114 km. Flood of the rivers of the entire basin occurs in June, which is associated with melting snow. The water level at this time is high, since much more snow falls in its basin than in the Yana and Indigirka basins. The high levels are partly due to ice jams. The formation of powerful floods is associated with heavy rains, especially in early summer. The river's winter flow is insignificant. The average annual water flow is 4100 m3/s.
River Indigirka It originates on the slopes of the Suntar-Khayata ridge, flows through the Oymyakon Highlands, cuts through the Chersky mountain system through deep gorges and exits into the Momo-Selennyakh depression. There it receives a large tributary - the Moma River and, going around the Momsky ridge, comes out to the Abyi lowland, and then to the Yano-Indigirskaya lowland. The length of the river is 1726 km, the basin area is about 360 thousand km 2. Its main tributaries are the Seleniyakh and Moma rivers. Indigirka is fed by snow and rainwater, melting snowfields and glaciers. The rise of water and the main flow (about 85%) occurs in spring and summer. In winter, the river has low water and in some places on the plain it freezes to the bottom. The average annual flow is 1850 m3/s.
River Yana begins in the Verkhoyansk Mountains and flows into the Laptev Sea. Its length is 879 km, the basin area is 238 thousand km 2. In some places it flows through wide ancient valleys filled with alluvium. There are outcrops of fossil ice in the coastal cliffs. Ice intrusions - hydrolaccoliths - are widespread in lacustrine-alluvial deposits. The spring flood is weakly expressed, since an insignificant amount of snow falls in the Yana basin. Floods usually occur in the summer when it rains. The average annual water flow is about 1000 m 3 /s.
The Kolyma, Indigirka and Yana rivers at their confluence form vast low-lying swampy deltas with numerous small lakes. Buried ice lies in deltas at shallow depths from the surface. The area of the Yana delta is 528 km 2 , the Indigirka delta is 7700 km 2 . In the mountains, rivers have predominantly narrow valleys, fast currents, and rapids. In the lower reaches, all the valleys are wide, the rivers flow through vast swampy lake lowlands.
The rivers of the Northeast freeze in October and open in late May - early June. The water temperature reaches 10°C, but in places in June-August it can rise to 20°C. In many areas in the lower reaches of the river, the river freezes to the bottom in winter. An interesting and important feature of the winter regime of rivers in the Northeast is widespread distribution of aufeis(in Yakut - taryn).
Naledi is a complex geographical concept. It develops under a combination of hydrological, climatic, permafrost and other conditions. But the ice itself influences the morphology, the nature of sediments, the microclimate and vegetation of the valley, and also creates its own natural complex.
The ice dams of the Northeast are among the largest in the world. Some of them occupy areas of more than 100 km2. Their formation occurs most intensively in tectonically mobile areas, where they are associated with places of rock disturbances caused by faults. Ice deposits grow throughout the winter, filling river beds and floodplains, especially in the mountainous areas of the Yana, Indigirka and Kolyma basins. The largest of them - Momskaya naledi - is located on the Moma River and has an area of 150 km 2. Almost all large ground ice dams are fed by sub-permafrost waters emerging along tectonic fault lines. Powerful rising springs in places of tectonic fracturing overcome the cooled layer of soil, come to the surface, form ice and feed them all winter, even at frosts of -40°C and below. In summer, large ice fields persist for a long time, and some remain into the next winter.
A large amount of water is concentrated in the aufeis, which flows into the rivers in the summer and is an additional source of their nutrition. In winter, polynyas form on some mountain rivers. Their occurrence is also associated with the release of warm sub-permafrost waters. Fogs appear above them and ice and frost forms. Sources of sub-permafrost waters, especially in winter, are of great practical importance for water supply to the population and the mining industry.
All major rivers of the Northeast in the lower reaches are navigable: Kolyma - from the mouth of the Bakhapchi River (Sinegorye village), Indigirka - below the mouth of the Moma River, and along the Yana, ships go from Verkhoyansk. The duration of navigation on them is 110-120 days. The rivers are rich in valuable species of fish - nelma, muksun, whitefish, sturgeon, grayling, etc.
Lakes. In the lowlands, especially in the lower reaches of the Yana, Indigirka, Alazeya and Kolyma, there are a lot of lakes and swamps. Most lake basins are of thermokarst origin. They are associated with the thawing of permafrost and underground ice. The lakes freeze in September - early October and are covered with thick ice (up to 2-3 m) during the long winter, which leads to frequent frosts and death of the ichthyofauna. Ice melting occurs in May and early June, and floating ice on large lakes occurs in July.
Soils, vegetation and fauna
A variety of physical and geographical conditions (mountainous and flat terrain, low air and soil temperatures, varying amounts of precipitation, small thickness of the active layer, excess moisture) contribute to the formation of variegated soil cover. Harsh climatic conditions and permafrost delay the development of chemical and biological weathering processes, and therefore soil formation occurs slowly. The soil profile is thin (10-30 cm), gristly, with a low humus content, peaty and moist. Common in lowlands tundra-gley, humus-peat-bog and gley-taiga permafrost soils. On the floodplains of river valleys there are developed floodplain humus-turf, frozen-gley or frozen-marsh soils. In the floodplains of tundra rivers, permafrost lies at shallow depths, and sometimes layers of ice appear in the coastal cliffs. The soil cover is poorly developed.
In the mountains under forests they predominate mountain podburs, taiga are also common permafrost soils, among which are found on gentle slopes, gley-taiga permafrost. On the southern slopes, permafrost-taiga soils with slight podzolization are common. The mountains of the Okhotsk coast are dominated by mountain podzolic soil. In mountain tundras, underdeveloped rough-skeletal mountain tundra soils, turning into rocky placers.
Vegetation North-East Siberia consists of representatives three floras: Okhotsk-Kamchatka, East Siberian and Chukotka. The most diverse in species composition is the Okhotsk-Kamchatka flora, which occupies the coast of the Sea of Okhotsk. Most of the mountains are covered with northern taiga sparse forests and mountain tundra. The lowlands are occupied by tundra, turning into forest-tundra.
The history of the development of the Northeast and adjacent territories (the ancient landmass of Beringia, Okhotia and Eoarctic, connecting the Northeast with Alaska), as well as the climate, predetermined the modern appearance of the vegetation cover of the tundra, forest-tundra and taiga, therefore they differ in species composition from similar zones of neighboring territories Siberia.
On far north, on the coastal lowland, located tundra. Lichen tundras are not typical for it, since clay soils are heavily waterlogged and bog-peat and peat-gley soils predominate. The hummocky-hypnum-sphagnum tundra dominates here. Its surface is formed by dense hummocks of cotton grass. The height of the grass stand is up to 30-50 cm. The hummocky tundra occupies approximately 30-50% of the area of tundra groups. Uneven thawing and freezing of the soil leads to soil deformation, soil rupture and the formation of bare spots (0.5-1 m in diameter) around hummocks, in the cracks of which mosses, lichens, saxifrage, and creeping polar willow nest.
South there's a streak coming forest-tundra. It is formed by alder, willow, and birch shrubs, which alternate with tussocks of cotton grass and individual specimens of oppressed Cajander larch.
All the rest of the plains and lower parts of the mountains covered larch forests on gley-taiga abominable soils and mountain taiga podburs. The main forest-forming tree species is the Cajander larch. Among the deciduous species in floodplain forests, there are fragrant poplar and relict Korean willow Chozenia. Pine and spruce are common only on the southern slopes of the mountains of the Verkhoyansk Range and rise into the mountains only to a height of 500 m.
In the undergrowth of larch forests, dwarf cedar, shrubby alder, blue currant, or spruce grouse, and thickets of Middendorf and lean birches are common; The ground cover consists of lingonberry shrubs, crowberries and lichens. There are few lichens on the northern slopes; mosses dominate there. The tallest larch forests grow on southern-facing slopes. On the slopes of northern exposure, forest-tundra is predominantly common.
On the slopes of the southern exposure of valleys and high terraces, steppe plots. They are known in the wide valleys of the Yana (between the mouths of its tributaries Dulgalakh and Adycha), Indigirka (in the mouth parts of the Moma, etc.) and Kolyma, as well as in the Chukotka tundra. The vegetation of the steppes on the slopes consists of steppe sedge, bluegrass, typica, wheatgrass, and forbs - speedwell, cinquefoil. Thin, gravelly soils close to chestnut soils formed under the steppes. On the terraces above the floodplain there are grass-forb steppes, developing in drained areas, and sedge-grass-forb steppes, located in the most low-lying areas. Among the steppe vegetation, local species are distinguished, genetically related primarily to the vegetation of the mountainous regions of Southern and Central Siberia, other species came along river valleys from Central Asia during the warm interglacial period, and species preserved from the “tundra-steppe” past of the Beringian North.
The predominance of mountainous terrain within the Northeast determines altitudinal zone in the placement of vegetation. The nature of the mountains is extremely diverse. It determines the structure of the zonality of each system while maintaining the general type of altitudinal belts, characteristic only of the North-East of Siberia. They are clearly shown on maps of soils and vegetation, as well as on an altitudinal diagram. The altitudinal zone in the lower parts of the slopes begins with light coniferous taiga (except for the Kharaulakh Mountains and the Chukotka Plateau), but it does not rise high into the mountains: in the Chersky ridge system - up to 650 m, and in the Dzhugdzhur ridge - about 950 m. Above the taiga, a closed shrub belt forms dwarf cedar up to 2 m high with an admixture of dwarf birch.
Northeast is one of the main growing areas cedar dwarf- a nut-bearing plant adapted to the harsh subarctic climate and thin gravelly soils. Its life forms are different: bushes 2–2.5 m high grow along river valleys, and single-trunked trees spread on the top plateaus and hills. With the onset of frost, all branches are pressed to the ground and are covered with snow. In spring, the warm rays of the sun “raise” them. Elfin nuts are small, with a thin shell and very nutritious. They contain up to 50-60% oil, a large amount of protein, B vitamins, and young shoots of the plant are rich in vitamin C. On the slopes of hills and ridges, elfin wood is an important regulator of runoff. Elfin forests are favorite places for many animals of all altitudinal zones; here they find shelter and abundant food.
At the upper limits of the belt, the elfin forest gradually thins out, is more and more pressed to the ground and is gradually replaced by mountain tundra with rocky placers. Above 800-1200 m, tundras and cold deserts with many snowfields dominate. The tundra descends in separate spots into lower belts of dwarf cedar and larch woodlands.
There is no such combination of altitudinal zones in any mountain system in Russia. The proximity of the cold Sea of Okhotsk determined a decrease in altitudinal zones in the coastal ranges, and even at the foot of the mountains of the Taigonos Peninsula, cedar tundras give way to hummocky tundras - analogues of the northern lowland tundras (this happens at the latitude of southern Timan and northern Lake Onega).
Animal world North-East Siberia belongs to the Arctic and European-Siberian subregions of the Paleoarctic region. The fauna consists of tundra and taiga forms. However, many animal species typical of the taiga do not live in the eastern Verkhoyansk Mountains. The fauna of the Chukotka Peninsula is very similar to the fauna of Alaska, since the Bering Strait was formed only at the end of the Ice Age. Zoogeographers believe that the tundra fauna formed on the territory of Beringia. The Northeast moose is close to the moose of North America. The white-tailed goose nests on the Chukotka Peninsula and winters off the rocky coasts of Alaska and the Aleutian Islands. The guillemot is endemic to the Northeast and Alaska. Dallia (black pike) from the order Salmonidae is found in small rivers, lakes and swamps of the Chukotka Peninsula and in northwestern Alaska. This is the most frost-resistant fish breed. In winter, when water bodies freeze, it buries itself in the ground and overwinters there in a frozen state. In the spring, the dallia thaws and continues to live normally.
Mountain tundra species of animals penetrate far to the south through the char, into the forest zone. Of these, the most typical is the endemic yellow-bellied lemming, which does not penetrate east of Indigirka. Next to them, in the mountain tundras of the Northeast, open-space animals of Central Asian origin live. They penetrated here during the xerothermal period and are now preserved here. These include, for example, the black-capped marmot (tarbagan). During the cold season (eight to nine months) it falls asleep in burrows located in permafrost soil. The Kolyma ground squirrel, an inhabitant of the forest zone, also falls asleep for the same long period. The mountain finch has penetrated the open high-mountain landscapes to the Lena delta. Predators in the taiga include bear, fox, and ermine. Lynx and wolverine are sometimes found. Sable was almost completely destroyed. But now it has been restored and there are separate pockets of its habitat in the Kolyma, Oloy, Yana basins and on the Koni Peninsula.
Of the ungulates, wild reindeer is widespread in the taiga and tundra, and elk is widespread in the taiga. Musk deer live on the rocky forested slopes of the mountains. Bighorn sheep (Chukchi subspecies) live in the mountain tundra. It lives at altitudes from 300-400 to 1500-1700 m and prefers rocks when choosing sediments. The most common rodent in mountain forests is the squirrel, which is the main game animal. In the past, the Asian river beaver lived in the Kolyma and Omolon basins; the northern border of its distribution was about 65° N. Currently, there is a variety of small rodents: red-backed vole, root vole, forest lemming, northern pika. The white hare is common in the thickets of river valleys.
Of the birds, it should be noted the stone grouse, hazel grouse, shura, kuksha, nutcracker and tundra partridge living on stone placers. A very beautiful bird, the pink gull, is called the pearl of the Arctic. The little swan, the white goose, the beautiful Siberian crane, the white-billed loon, the falcons - the falcon, the gyrfalcon and the salvage, the hawks - the white-tailed eagle and the golden eagle have become rare.
Mountainous regions and provinces
In the Northeast, natural complexes of plains and mountains are developed. The lowlands contain natural zones of tundra, forest-tundra and sparse taiga. On the territory of the plains, two physical-geographical provinces are distinguished: tundra and forest-tundra Yano-Indigiro-Kolyma and Abyisko-Kolyma northern taiga. The rest of the territory is occupied by mountains and is divided into mountainous regions.
The Yana-Indigir-Kolyma province is located along the Arctic coast within the Yano-Indigir and Kolyma lowlands.
Zoning appears in the distribution of vegetation and soils. The coast is occupied by Arctic tundra on gley, peaty-gley and swamp soils. To the south they are replaced by typical moss-lichen soils, which turn into forest-tundra with gley-permafrost soils. A specific feature of the Northeast is the absence of the shrub tundra subzone. Within their distribution zone, open larch forests also appear, which is due to the sharp continental climate. Larch open forests and shrub tundras alternate with areas of sedge-cotton grass hummocky tundras.
The Yana-Kolyma tundra is the main nesting site for many waterfowl, and among them are the pink gull and the Siberian Crane. The pink gull makes nests on hummocks of sedge-cotton grass tundra and islands near small lakes and channels. After nesting (late July - early August), adult and young birds fly to the north, northwest and northeast. The winter migration area of the pink gull extends from the Bering Strait to the southern islands of the Kuril ridge. The main nesting sites for the Siberian Crane are lowland, heavily moist, lake-filled tundras between Yana and Alazeya. The birds fly to Southeast China for the winter.
The Abyysko-Kolyma province is confined to the largest intermountain depression. The surface of the watersheds here is covered with sparse larch forests, sedge-cotton grass swamps and lakes. Along the river valleys there are swampy meadows and thickets of bushes, and in drier areas there are forests of larch, sweet poplar and choicenia.
Verkhoyansk region occupies a marginal western position. The altitudinal zonation of the soil and vegetation cover is most fully expressed on the Suntar-Khayata and Setta-Daban ridges. The lower zone here is represented by northern taiga sparse larch forests, which rise on the northern slopes to 1200-1300 m, and on the southern slopes to 600-800 m. The ground cover is dominated by lichens; The shrub layer is formed by lingonberries, crowberries and wild rosemary. A dwarf birch has been developed from the Middendorf birch. Along the river valleys on sand and pebble deposits stretch gallery forests of fragrant poplar and choicenia with an admixture of larch, birch, aspen and Siberian mountain ash.
Above the upper boundary of the larch forest, thickets of dwarf birch, shrubby alder and dwarf cedar, combined with lichen-shrub tundras, dominate. The next belt is mountain-tundra with taryns. Its upper limit should be drawn at the ends of the glaciers (1800-2100 m). Higher up are high mountain deserts with glaciers and snowfields. Avalanches occur in autumn, winter and spring.
Anyui-Chukotka region extends from the lower reaches of the Kolyma to the Bering Strait for almost 1500 km.
The tundra of Chukotka differs from other tundras of the Arctic coast of Russia in that its main part is mountain tundra with rocky placers, rocks and thickets of bushes, and the coastal part is flat tundra of grass-shrubs and hummocks with cotton grass and creeping wild rosemary.
The flora of vascular plants of the Chukotka tundra contains about 930 species and subspecies. This is the richest flora of the Arctic region. Chukotka was part of Megaberingia, and this had a significant impact on the composition of the flora of its plant communities. On the southern slopes of the ridges and above-floodplain terraces, mountain-steppe vegetation has been preserved - the remains of the Beringian tundra-steppe landscapes. North American plant species grow there: among the dryad tundras on the limestones there are Meckenzie's pennywort, dense cat's paw, and in the willow-herbaceous communities there are balsam poplar and edible viburnum. Primula egalikensis is common in the nival tundra. Lena fescue is common in steppe areas. B.A. Yurtsev calls it the emblem of the steppe complexes of North-East Siberia. Once upon a time, horses, bison, saiga and other herbivores lived in the tundra and steppes of Beringia. Now the problem of the sunken Beringia is attracting the attention of various specialists.
In Chukotka, off the Bering coast, there are thermal springs with temperatures ranging from 15 to 77°C. They create favorable conditions for the development of lush and diverse vegetation. There are up to 274 plant species here. In harsh climatic conditions, the flora at hot springs has a subarctic and temperate character with a predominance of arctic-alpine elements - mountain shrub-moss communities. Among them grow cassiopeia, diapensia, loiselaria, phyllodoce, Kamchatka rhododendron, etc., as well as mountain-tundra Asian-American or Beringian species - anemone, chrysanthemum, primrose, saxifrage, sedge, etc.
Anthropogenic impact on nature
The nature of the Northeast is experiencing significant anthropogenic impact due to off-road transport (all-terrain vehicles), construction, geological surveys and mining, deer grazing and frequent fires.
Fur farming and fur fishing for squirrel, arctic fox, ermine, mountain hare, and muskrat are developed in the territory. Plain and mountain tundras and forest-tundras serve as good pastures for deer. One of the main food for reindeer in winter is bushy lichen-cladonia (reindeer moss). The restoration of its reserves takes five to seven years. Due to anthropogenic impact, the pasture fund is declining, so strict adherence to pasture load and careful attitude of the entire population to reindeer pastures is necessary.
The main commercial fish - vendace, muksun, nelma, omul, whitefish, etc. - are concentrated in the lower sections of the Yana, Indigirka and Kolyma rivers. In the warm areas of the valleys of the Yana, Indigirka, Kolyma and other rivers, early varieties of cabbage, potatoes and other vegetables are grown using special agricultural technology.
Active development of the territory contributed to changes in natural landscapes, reduction in the numbers and habitats of many species of animals and plants, for example, the Chukchi bighorn sheep, the Siberian Crane and the Spade-tailed Elder, which nest only in Russia, the Bairdov's sandpiper, the present slipper, etc.
The nature of the Northeast is very vulnerable, therefore, with increased human activity, entire natural complexes (ecosystems) are dying. For example, during the development of placer deposits, significant areas of floodplains are completely destroyed, where a wide variety of animals and plants are concentrated. On the territory of this huge physical-geographical country, there is so far only one reserve - Magadan, several complex and sectoral reserves (nesting waterfowl) and natural monuments, and among them is a protected zone for the location of mammoth fauna.
Scientists propose to create a number of protected areas here, for example, the Buordakhsky Natural Park with the basins of the left tributaries of the Moma and Mount Pobeda. The unique geographical objects of this region include the world's largest ice dam, Ulakhan-Taryn (Momskaya), which does not completely melt every year, and in the valley on the gravelly slopes of the southern exposure - the Yakut mountain steppes, turning into steppe alpine lawns and mountain tundras. It is also proposed to create the Central Yakut Nature Reserve as a biosphere reserve, where the Chukchi bighorn sheep are preserved on the rocky shores of Lake Elgygytgyn, where there are calving grounds for wild reindeer - the only large population in the entire Northeast. Here, poplar-chosenia valley forests are at the limit of their distribution, and steppe areas have been preserved.
The physical-geographical country of North-Eastern Siberia is a gigantic territory located in high-altitude latitudes and covering an area of more than one and a half million kilometers, which is limited: in the east by the bed of the Lena River, and in the west by large mountain ranges belonging to the Pacific watershed. It includes eastern Yakutia and western Magadan region and is washed by the Arctic Ocean.
The extreme points of the region are: Cape St. Helena (in the far north) and the May River basin (in the south). Due to the fact that more than half of the territory that makes up this country is located beyond the Arctic Circle, it is characterized by a varied and contrasting topography. There are plateaus, mountain ranges and flat lowlands located along the valleys of large rivers. Although this geographical country is located almost entirely on the territory of the stable Verkhoyansk-Chukchi fold, its relief continues to form.
North-Eastern Siberia is characterized by a rather harsh climate, prone to sudden temperature changes and relatively low precipitation (one hundred to one hundred and fifty millimeters). For example: in winter, temperatures can range from minus five degrees (in November - December) to minus sixty (in January - February). Summer temperatures are no exception; temperatures range from plus fifteen in May to plus forty in August. The depth of soil freezing in this area reaches several hundred meters. Also, North-Eastern Siberia is characterized by a clearly defined zonation - swampy woodlands, arctic wastelands and tundras.
Despite the fact that North-Eastern Siberia has a varied topography, for the most part it is still a mountainous country, the lowlands of which occupy less than twenty percent of the area. The highest mountain ranges (average height of one and a half thousand meters and above) are located in the south of the region. Many mountain peaks located there in the Verkhoyansk and Chersky mountain ranges reach a height of two and a half thousand meters and higher. The highest point in the region is Mount Pobeda, part of the Ulan-Chistai mountain range. It reaches a height of three thousand two hundred meters above sea level.
We owe the first mention of the nature of this region to the explorers I. Rebrov, I. Erastev and M. Stradukhin. The Northern Islands were discovered by A. Brunche and E. Toll, and they were studied by S. Obruchev only in the thirties.
Geological structure of North-Eastern Siberia
This region, in the Paleozoic and Mesozoic eras, belonged to a geosynclinal sea basin. This statement is proven by the presence of Paleozoic-Mesozoic deposits located at a depth of twenty-two thousand meters. The Kolyma and Omolon middle massifs are considered the most ancient. Younger are: western Upper Jurassic and eastern Cretaceous tectonic elements.
These include:
- Sette-Dabanskaya, Tas-Khayanskaya and Momskaya aticlinoria
- Yana and Indigirka-Kolyma geological zones
- Verkhoyansk zone of increased folding
By the end of the Cretaceous period, North-Eastern Siberia was a territory located on a hill in relation to neighboring regions. The temperate climate of that time and the processes of destruction of mountain ranges smoothed out the relief, forming significant flat surfaces. The folded relief in this area was formed under the influence of powerful tectonic processes characteristic of the Neogene and Quaternary periods. The amplitude of these changes reached two kilometers. Especially high mountain ranges were formed in those areas where tectonic processes were most intense.
Around the end of the Quaternary period, a powerful process of glaciation began. Due to this, large-sized valley glaciers began to form on the mountain ranges that continued to form. In the same period, the formation of permafrost begins in the coastal lowlands and the New Siberian Islands. The thickness of permafrost and intrasoil glaciation reaches fifty meters, and on the steep shores of the Arctic Ocean exceeds sixty meters.
Valley glaciation was more pronounced. On the outskirts of mountain ranges there are cirques, trough valleys and other forms of glacial gouging. In these areas, the thickness of glaciers in some places reached three hundred meters. The Siberian mountain ranges were influenced by three independent waves of glaciation, in the Middle Quaternary and Upper Quaternary geological periods.
These include:
- Tobychan glaciation.
- Elginsky and Bokhapchinsky glaciers.
The first glaciation led to the appearance of coniferous trees in Siberia, including the relict Daurian larch. The second interglacial period that followed was characterized by the predominance of mountain and taiga forests. Which, in our time, are the main representatives of wildlife in this region. The last ice age did not affect the flora and fauna of the region. During this period, the northern limit of the forest gradually shifts to the south.
The flat territories of North-Eastern Siberia are characterized by passive glaciation. A significant part of which was passive, slow-moving glacial formations.
Relief of North-East Siberia
The relief of this region is formed by several well-developed geomorphological stages. Each stage is characterized by a unique intensity of tectonic processes and is associated with a hypsometric position. The altitudinal ranges corresponding to the prevailing types of mountainous relief explain the sharp continental nature of the local climate. Also, the processes of nivation, solifluction and frost weathering take part in its formation.
Within a given geographical country and in accordance with its morphogenetic characteristics, the following are distinguished:
- Accumulative and Erosion-denudation plains;
- Highlands and lowlands;
- Low-mountain and mid-mountain alpine terrain.
Some lowland areas are occupied by weakly rugged accumulative plains, characterized by slight altitudinal fluctuations. Landforms are spreading, which owe their formation to the processes of permafrost and ice content.
Among them are:
- Frost cracks and polygons;
- Thermokarst basins;
- Permafrost mounds;
- Icy sea cliffs.
Accumulative plains include: the Indigirka and Kolyma plateaus.
At the base of the Anyui, Mom, Kharaulakh and Kular mountain ranges, plains of erosion-denudation nature were formed. The surface of these plains has an average height of two hundred meters, and in some places reaches half a kilometer. The rock deposits here are loose and thin.
Between the Verkhoyansk and Chersky mountain ranges there are a number of territories with a pronounced plateau topography. The largest of them are the Elga, Yanskoye, Oymyakon and Nerskoye plateaus. Most of which consist of Mesozoic rocks and have a height of up to one and a half kilometers.
Areas that in the Quaternary period were subject to uplifts of moderate amplitude are occupied by mountain lowlands, up to five hundred meters high. They occupy a position on the outskirts of the region and are dissected by a dense network of river valleys of varying depths. With typical rocky terrain.
Mid-mountain relief is typical mainly for the Verkhoyansk mountain range, the Yudomo-Maysky highlands and the Chersky, Tas-Khayansky, Momsky mountain ranges. In the Kolyma and Anyui highlands there are mid-mountain massifs, with average heights from eight hundred meters to two kilometers. They are located above the upper border of the vegetation massif, in a strip of mountain tundra.
The mountain ridges of the highest ranges - Suntar-Hayat, Tas-Hayat and Ulan-Chistai - are characterized by high-altitude alpine terrain and have heights of more than two thousand meters. They are characterized by elevation changes, narrow rocky ridges, punishments, circuses, etc.