Features of the relief of northeastern Siberia. Eastern Siberia

Site arrangement 22.09.2019

Site arrangement

Open Lesson Plan

Eastern Siberia

in 8th grade

Prepared and conducted

geography teacher Biche-ool O.Kh.

Boyarovka, 2015

Theme: Eastern Siberia

Goals and objectives of the lesson:

Educational : to study the features of the composition of the territory, geographical location, geographical structure of the relief and climate of Eastern Siberia. Formulate an idea of the severity of the nature of the area.

Educational : create the basis for a comprehensive harmonious development, develop observation, abstract thinking (analysis, synthesis, abstraction, generalization), practical actions, encourage students to use various ways to complete tasks.

Educational : on the concrete examples to form students' knowledge about the role of natural conditions in people's lives; cultivate an aesthetic perception of nature.

Equipment:

Maps of Russia - physical, climatic, tectonic; pictures, diagrams.

During the classes

1. Organized moment

2. Learning a new topic

Relief of Eastern Siberia

This area has long attracted scientists. For Eastern Siberia, the words are really applicable - boundless, harsh, grandiose. Here are the largest rivers, the most unique Lake Baikal, one of the largest in Russia, the Taimyr Reserve, where the acclimatization of musk oxen was carried out, the vast, endless taiga, and the richest natural resources.

Let's start our acquaintance with Eastern Siberia by determining the geographical location.

Eastern Siberia is located between the rivers Yenisei, Lena and Aldan. From the north it is washed by the Arctic Ocean, here is the northernmost point - Cape Chelyuskin, in the south the region borders on Mongolia and China. Eastern Siberia occupies an area of more than 7 million square meters. km.

According to the orographic scheme, Eastern Siberia is divided into Central Siberia, North-Eastern Siberia and the Mountains of Southern Siberia.

The region includes Krasnoyarsk region, Irkutsk and Chita regions, the Republic of Sakha (Yakutia), Buryatia, Tyva, Khakassia.

The relief of Eastern (Middle and North-Eastern Siberia) is diverse. There are both plains and mountains. The plains are also different in height-lowlands - the North Siberian and the plateau (Middle Siberian). The mountains are of medium height (Verkhoyansky-Chersky Ridge) and low (Byrranga).

Eastern Siberia differs from the Russian Plain and the West Siberian Plains, not only in the diversity of the relief, but also in the much greater general elevation of the territory above the ocean level.

Determine the absolute height of the plain - the Central Siberian Plateau.

And what is the height of the West Siberian Plain? (From 0 to 200m.)

The relief of Eastern Siberia has another feature: there are many intermountain basins. Find on the map, name them: Minusinsk, Kuznetsk, Tuva, Baikal.

So, let's open the secret of the diversity of the relief of Siberia. What could be the reason for the diversity of the relief of Eastern Siberia? (In the geological structure, in the history of the development of the earth's crust.)

Let's look at the tectonic map. The Central Siberian Plateau is located on the Siberian Platform, as ancient as the Russian Platform. Why does the Central Siberian Plateau have heights of more than 500 m, and the Russian Plain is less than 500 m (200-300 m)? (The Siberian platform was rising more actively than the Russian one.)

The Central Siberian Plateau has another feature: there are spills of igneous erupted rocks. Lava poured out along the cracks, and such outpourings occurred repeatedly. Igneous rocks solidified in the thickness of sedimentary rocks. A stepped relief was formed - traps.

Anabar plateau and Aldan Highlands connected with platform foundation ledges. Do you remember what the outcrops of crystalline rocks of the platform foundation to the surface are called? (Shields: there are 2 of them - Anabar and Aldan.)

The mountains of southern Siberia were formed in the Baikal, Caledonian era, the mountains were rejuvenated as a result of blocky uplifts and faults. The height of the mountains has increased significantly as a result of neotectonic movements. This is how modern folded-block mountains were formed - Altai, Sayans, Ridges of the Baikal and Transbaikalia.

Mountain building in these mountains is not completed, because. earthquakes still occur today. In 1995, an earthquake occurred in Buryatia, in 2002 - in Altai.

The mountains of the North-East of Siberia - the Verkhoyansk, Chersky, Oymyakon highlands, the Suntar-Khayat Ridge were formed in the Mesozoic era. These are medium-altitude mountains, the most high peak North-East of Siberia - Mount Pobeda, its height is 3147 m in the Chersky ridge.

Output: the relief of Eastern Siberia is diverse, because. the geological history of the development of the territory and the resulting geological structure are diverse.

Minerals

- This region is very diverse in minerals. The bowels of Eastern Siberia are especially rich in coal. Their reserves make up almost 70% of the all-Russian ones. Here are the coal-bearing basins - Lensky, Tunguska, Irkutsk, Taimyr and others. Of great importance are metallic minerals. In the region of Norilsk there are copper-nickel ores, the formation of which is associated with trap magmatism. In Transbaikalia - the center of Bodaibo - gold is mined. Diamond deposits are of particular importance. Graphite, rock salt, etc. are also of great importance in the economy..

Climate of Eastern Siberia

The relief and geological structure, as we found out, are diverse. What unites the territory of Eastern Siberia into one region.

What do all parts of Eastern Siberia have in common? (The climate is sharply continental everywhere.)

What is the difference between a sharply continental climate and a continental and temperate continental climate? (In a sharply continental climate, winters are colder, there is less precipitation, and the amplitude of winter and summer temperatures is greater.)

What conditions affect the climate of Eastern Siberia?

1. Remoteness from the oceans (Atlantic), closed ranges (from the Pacific).

2. The climate of Eastern Siberia is influenced by its huge length from north to south. The southern regions of Siberia are located at the latitude of Ukraine, the Middle and Lower Volga regions and receive a large amount of total radiation, so summer is hot here.

Determine the average July temperatures in southern Siberia. (+16̊С, but can reach +37̊С.)

The extreme northern regions are located north of the Arctic Circle, and receive much less total radiation during the year. Why? (The angle of incidence of the rays is small. In winter, the polar night, and there is absolutely no heat and light from the sun. In spring and summer, a lot of heat is spent on melting snow and permafrost. Cold Arctic air comes in from the Arctic Ocean.)

3. The winter of Eastern Siberia is the coldest in Russia and in the northern hemisphere.

Remember where the "poles of cold" of the northern hemisphere are located? (Oymyakon and Verkhoyansk with absolute minimum temperatures: -71̊С and -68̊С, respectively.)

Determine the average January temperatures in Eastern Siberia. (From -24̊С in the southwest to -48̊С in the northeast.)

What is the reason for such a harsh winter in Eastern Siberia? (In winter, the land cools quickly, and since it is located in the center of the mainland, the oceans do not have a warming effect.)

In winter, the pressure rises (cold air is heavy), an anticyclone (Siberian) is formed with a center over Mongolia. The anticyclone captures the whole of Eastern Siberia and has two spurs: one to the northeast of Siberia, and the other to the west (Voyeikov axis).

In the anticyclone, the weather is windless, dry, and sunny. Frost at -30°C is tolerated here more easily than frost at -20°C near Moscow. The snow cover is thin. At -50°C, students study in schools in Yakutia.

Why are the lowest winter temperatures recorded in Oymyakon and Verkhoyansk, and not on the northernmost Taimyr Peninsula? (Here in the hollows, under the conditions of an anticyclone, the air flows down and cools down. The phenomenon is called an increase in air temperature with altitude inversion.)

All Eastern Siberia is occupied by permafrost. Why? What is the reason for such an extensive distribution of permafrost soils? (Because of the very low temperatures in winter and the short, albeit warm, summer - the average annual temperature in Eastern Siberia is below 0 degrees everywhere - this is a condition for the preservation of permafrost. The snow cover is thin and does not protect the soil from deep freezing.)

biological resources.

Fur resources of the taiga - squirrel, sable; tundra - arctic fox.

The fur of the Barguzin sable is especially valued for its beauty and durability. To protect this valuable animal, the Barguzinsky Reserve was created on the slopes of the Barguzinsky Range.

Fish resources. There are many valuable species of fish in the rivers of Eastern Siberia - grayling, whitefish, pike, etc., but, of course, the most valuable fish is found in Lake Baikal - the Baikal omul.

Soil resources

The territory of Eastern Siberia is not suitable for agriculture, as the soils - permafrost-taiga are cooled by permafrost. But there are areas of valuable, fertile chernozems in Siberia.

What do you guys think, where can chernozems form? (In the basins of southern Siberia along the steppe landscapes.)

Recreational resources

The recreational resources of Eastern Siberia are, first of all, the mountains of the South of Siberia. These are beautiful mountain-forest landscapes, clean air, rivers rich in fish.

In addition, it is a World Natural Heritage site - Lake Baikal; Baikal's younger brother is Lake Teletskoye in Altai.

3. Fixing

(Working with a card)

Eastern Siberia covers an area of more than ____________ (7 million km 2 .)
The territory stretched from the river __________ (Yenisei) in the west to ______________________ (Pacific Divide) in the east. In the north, the region is washed by _______________________________ (Arctic Ocean), and in the south it borders on _______________ (China) _____________________ and (Mongolia.)
A significant part of the territory is located beyond the Arctic Circle. The city ____________ (Kyzyl) is the center of Asia.

The territory of the region consists of three parts:

Central Siberian Plateau;

Northeast Siberia;

Mountain belts of Southern Siberia.

And now, guys, I propose to draw up a nomenclature route. It is necessary to distribute the landforms in alphabetical order. I start.

Homework

Parag. 36; answer the questions.

It occupies an area of about 7 million square kilometers. Eastern Siberia is called the area located east of, to the mountains that form the watershed between and. largest area takes . In the north and east there are two lowlands: North Siberian and Central Yakut. In the south and west there are mountains (, Yenisei Ridge). The length of this region from north to south is about 3 thousand kilometers. In the south there is a border with and, and the northernmost point is Cape Chelyuskin.

During the Mesozoic period, most of Central Siberia experienced uplift. It is no coincidence that the highest point of the Central Siberian Plateau is located in this area - (its height is 1700 meters above sea level). In the Cenozoic, surface uplift continued. At the same time, a river network was being created on the surface. In addition to the Putorana plateau, the Byrranga, Anabar and Yenisei massifs rose most intensively. Subsequently, active tectonic processes that took place in this territory led to a change in the river system. Traces of river systems that existed in ancient times have survived to our time. At the same time, river terraces and deep river valleys of the central part of Siberia were formed.

Cape Chelyuskin

The vast majority of river valleys in Central Siberia are canyon-like and asymmetrical. Their characteristic feature is also a large number of terraces (six to nine), which indicates repeated tectonic uplifts of the territory. The height of some terraces reaches 180-250 m. On and in the North Siberian lowland, the river valleys are younger, and the number of terraces is somewhat less. Even the largest rivers have here three or four terraces.

Four relief groups can be distinguished on the territory of the Central Siberian Plateau:

plateaus, ridgesplateaus, ridges, and mid-mountain massifs on ledges of the crystalline basement
bedded uplands and plateaus on sedimentary Paleozoic rocks;
plateau
and reservoir-accumulative

Most of the tectonic processes that took place in antiquity and in modern times, on the territory Eastern Siberia matched in direction. However, this did not happen throughout the entire territory of the Central Siberian Plateau. As a result of these discrepancies, depressions similar to the Tunguska were formed. There is no permafrost (the Lena-Angara and Lena-Aldan plateaus). But the main small relief forms on the territory of the Central Siberian plateau are still erosive and cryogenic.

Due to the strongest monsoons, sharply continental, characteristic of Eastern Siberia, here you can find a large number of stony placers and screes in mountain ranges, on the slopes of river valleys and on plateau surfaces.

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

Federal State Budgetary Educational Institution of Higher Professional Education "National Mineral and Raw Materials University "Gorny"

Faculty of secondary vocational education

(College of Geodesy and Cartography)

TEST

by geography

Option number 8

Completed:

1st year student of PG-15z group

FULL NAME. Konyaev Artur Georgievich

Lecturer: Dashicheva A.V.

St. Petersburg-2015

TASK 1: Biogenic landforms. Relief-forming activity of animals and plants.

TASK 2: North-Eastern Siberia of Russia, physical and geographical characteristics

The relief is a set of forms of the earth's surface, different in shape, size, origin, age and history of development. The relief influences the formation of the climate, the nature and direction of the flow of rivers depend on it, the features of the distribution of flora and fauna are associated with it. The relief significantly affects the life and economic activity of a person.

The significance of organisms in the life of the Earth is great and varied. The processes of changing the Earth's surface as a result of the activity of living organisms are called biogeomorphological, and the relief created with the participation of plants and animals is called biogenic. These are mainly nano-, micro- and mesoforms of relief.

A grandiose process, carried out largely due to organisms, is the formation of sediments (for example, limestones, caustobioliths and other rocks).

Plants and animals are also involved in a complex universal process - weathering. rocks, both as a result of direct impact on rocks, and due to the products of their vital activity. Not without reason, sometimes, along with physical and chemical weathering, biological weathering is distinguished.

Plants and animals have a significant impact on various natural processes, such as erosion. The destruction of vegetation on steep slopes, the trampling of plants by animals (the so-called "slaughter trails"), the loosening of soils by burrowing animals - all this increases erosion. This is especially dangerous on the mountain slopes, where distant pasture cattle breeding is carried out. There, due to excessive pasture load, various large-scale slope processes often come to life, the results of which are felt even in the foothills. Grassing of slopes (sowing meadow perennial long-rhizome grasses) holds soil together and reduces erosion.

Abundant aquatic vegetation in the rivers, as well as the inhabitants of water bodies, influence the channel processes. Beaver dams change the hydrological regime of rivers and geomorphological processes in the riverbed. Due to the damming of the rivers, swampy, hummocky floodplains are formed in the areas above the beaver dams.

Vegetation contributes to the overgrowth of lakes, filling them with organic matter. As a result, leveled hummocky surfaces of marshes appear on the site of lake basins. In the tundra, peat mounds are very characteristic.

Plants and animals are actively involved in the creation of some types of accumulative shores. In the equatorial-tropical latitudes, mangrove shores are formed, growing towards the sea due to the death of the plant mass. In temperate latitudes, along the shores of seas and lakes, reed shores similar to them arise.

On the coasts of the seas, shell beaches are created from animal shells with the participation of wave activity. Such accumulative landforms as coral structures are also widely known: coastal, barrier (for example, the Great Barrier Reef off the coast of Australia), ring atolls, which are numerous in the Pacific and Indian Oceans.

Burrowing animals also contribute to the formation of a biogenic relief. As a result of earth emissions, they create molehills, marmots, bobbins - mounds up to a meter high. Termite hills reach up to 4-5 m in height with a diameter of 15-20 m and create a kind of small-hilly relief in the Australian and African savannahs.

Animals and plants perform destructive work, which is often much more diverse and complex than the similar activity of various agents of inanimate nature (wind, water, etc.).

The accumulative activity of animals and plants causes a wide variety of positive landforms. You can, for example, point to marmot bumps, which are ejections of soil from holes. However, the largest positive landforms are formed due to the accumulation of plant residues in the form of peat. Ridges composed of peat are often found on the surface of raised bogs. Together with the depressions separating them (hollows), they create a kind of ridge-hollow surface of the marshes. The height of the ridges above the surface of the hollows ranges from 15 to 30 cm and rarely reaches 50-70 cm.

As a result of the vital activity of animals and plants, various forms relief, which can be divided into the following main groups:

landforms due to their destructive activity;

landforms due to their accumulative activity.

Seven-Eastern Siberia is located in the extreme northeast of Eurasia at the junction of three lithospheric plates - Eurasian, North American and Pacific, which determined the extremely complex relief of the territory. In addition, over the course of a long geological history, cardinal rearrangements of tecto- and morphogenesis have repeatedly occurred here.

If we accept that the territory of North-Eastern Siberia corresponds to the late Mesozoic Verkhoyansk-Chukotka fold-cover region, then its boundaries are: in the west - the Lena valley and the lower reaches of the Aldan, from where, crossing the Dzhugdzhur, the border goes to Sea of Okhotsk; in the southeast, the border runs along the lowland from the mouth of the Anadyr to the mouth of the Penzhina; in the north - the seas of the Arctic Ocean; in the south and east - the seas of the Pacific Ocean. Some geographers do not include the Pacific coast in North-Eastern Siberia, drawing the boundary along the watershed of the rivers of the basins of the Arctic and Pacific Oceans.

In the Precambrian and Paleozoic, median massifs appeared in this area in the form of separate microcontinents (Kolyma-Omolon and others), which during the Mesozoic folding were woven into the lace of folded mountains. At the end of the Mesozoic, the territory experienced peneplanization. At that time, there was an even warm climate with coniferous-broad-leaved forests, and North American flora penetrated here by land on the site of the Bering Strait. During the Alpine folding, the Mesozoic structures were split into separate blocks, some of which rose and others sank. The median massifs rose entirely, and where they split, lava came out. At the same time, the shelf of the Arctic Ocean sank and the relief of North-Eastern Siberia acquired the appearance of an amphitheater. Its highest steps run along the western, southern, and eastern borders of the territory (Verkhoyansk Range, Suntar-Khayata, and the Kolyma Highlands). A step below are numerous plateaus on the site of the median massifs (Yanskoye, Elginskoye, Yukagirskoye, etc.) and the Chersky Range with the highest point of North-Eastern Siberia - Mount Pobeda (3003 m). The lowest step is the marshy Yano-Indigirskaya and Kolyma lowlands.

Arctic desert zone.

Tundra zone.

Taiga zone.

The Arctic Desert is part of the Arctic geographic zone, the Arctic Ocean basin. This is the northernmost of the natural zones, characterized by an arctic climate. The spaces are covered with glaciers, rubble and stone fragments.

It has low air temperatures in winter up to? 60 ° C, on average - 30 ° C in January and +3 ° C in July. It is formed not only due to the low temperatures of high latitudes, but also due to the reflection of heat (albedo) in the daytime from the snow and under the ice crust. The annual amount of atmospheric precipitation is up to 400 mm. In winter, the soil is saturated with layers of snow and barely thawed ice, the level of which is 75-300 mm. [Source not specified 76 days]

The climate in the Arctic is very harsh. Ice and snow cover lasts almost the whole year. In winter, there is a long polar night (at 75 ° N - 98 days; at 80 ° N - 127 days; in the region of the pole - half a year). This is a very harsh time of the year. The temperature drops to −40 °C and below, strong gale-force winds blow, snowstorms are frequent. In summer, there is round-the-clock lighting, but there is little heat, the soil does not have time to completely thaw. The air temperature is slightly above 0 °C. The sky is often overcast with gray clouds, it rains (often with snow), due to the strong evaporation of water from the surface of the ocean, thick fogs form.

Flora and fauna

The Arctic desert is practically devoid of vegetation: there are no shrubs, lichens and mosses do not form a continuous cover. The soils are thin, with patchy (island) distribution mainly only under vegetation, which consists mainly of sedges, some grasses, lichens and mosses. Extremely slow recovery of vegetation. The fauna is predominantly marine: walrus, seal, in summer there are bird colonies. Terrestrial fauna is poor: arctic fox, polar bear, lemming.

Tumndra is a type of natural zones lying beyond the northern limits of forest vegetation, an area with permafrost soil that is not flooded by sea or river waters. The tundra is located north of the taiga zone. By the nature of the surface of the tundra are swampy, peaty, rocky. The southern border of the tundra is taken as the beginning of the Arctic. From the north, the tundra is limited by the zone of arctic deserts. Sometimes the term "tundra" is applied to similar natural areas of Antarctica.

Tundra in Alaska in July

The tundra has a very harsh climate (the climate is subarctic), only those plants and animals live here that endure the cold, strong winds. In the tundra, large fauna is quite rare.

Winter in the tundra is extremely long. Since most of the tundra is located beyond the Arctic Circle, the tundra experiences a polar night in winter. The severity of winter depends on the continentality of the climate.

The tundra, as a rule, is deprived of climatic summer (or it comes for a very short time). The average temperature of the warmest month (July or August) in the tundra is 5-10 °C. With the advent of summer, all vegetation comes to life, as the polar day comes (or white nights in those areas of the tundra where the polar day does not occur).

May and September are the spring and autumn of the tundra. It is in May that the snow cover melts, and already in early October it usually sets again.

In winter, the average temperature is up to? 30 ° C

There can be 8-9 winter months in the tundra.

Animal and plant world

The vegetation of the tundra is primarily lichens and mosses; the angiosperms encountered are low grasses (especially from the Grass family), shrubs and shrubs (for example, some dwarf species of birch and willow, berry bushes, princess, blueberry).

Typical inhabitants of the Russian tundra are reindeer, foxes, bighorn sheep, wolves, lemmings and hare. There are few birds: Lapland plantain, white-winged plover, red-throated pipit, plover, snow bunting, snowy owl and ptarmigan.

Rivers and lakes are rich in fish (nelma, broad whitefish, omul, vendace and others).

The swampiness of the tundra allows the development of a large number of blood-sucking insects that are active in summer period. Due to the cold summer, there are practically no reptiles in the tundra: low temperatures limit the ability of cold-blooded animals to live.

Taigam is a biome characterized by the predominance of coniferous forests (boreal species of spruce, fir, larch, pine, including cedar).

Pinezhsky forest.

The taiga is characterized by the absence or weak development of undergrowth (since there is little light in the forest), as well as the monotony of the grass-shrub layer and moss cover (green mosses). Types of shrubs (juniper, honeysuckle, currant, etc.), shrubs (blueberries, lingonberries, etc.) and herbs (oxalis, wintergreen) are not numerous both in Eurasia and in North America.

In the north of Europe (Finland, Sweden, Norway, Russia) spruce forests predominate, in North America (Canada) - spruce forests with an admixture of Canadian larch. The taiga of the Urals is characterized by light coniferous forests of Scots pine. in Siberia and Far East sparse larch taiga dominates with an undergrowth of elfin cedar, Daurian rhododendron, and more.

The fauna of the taiga is richer and more diverse than that of the tundra. Numerous and widespread: lynx, wolverine, chipmunk, sable, squirrel, etc. Of the ungulates, there are reindeer and red deer, elk, roe deer; hares, shrews, rodents are numerous: mice, voles, squirrels and flying squirrels. Of the birds, the following are common: capercaillie, common hazel grouse, nutcracker, crossbills, etc. The taiga of North America is typical of American species of the same genera as in Eurasia.

In the taiga forest, in comparison with the forest-tundra, the conditions for the life of animals are more favorable. There are more settled animals here. Nowhere in the world, except for the taiga, there are so many fur-bearing animals.

IN winter period the vast majority of invertebrate species, all amphibians and reptiles, as well as some species of mammals, are immersed in suspended animation and hibernation, and the activity of a number of other animals is reduced.

Taiga types

According to the species composition, light coniferous (Scots pine, some American species of pine, Siberian and Dahurian larch) and more characteristic and widespread dark coniferous taiga (spruce, fir, stone pine, Korean cedar) are distinguished. Tree species can form pure (spruce, larch) and mixed (spruce-fir) forest stands.

The soil is usually sod-podzolic. Humidity is sufficient. 1-6% humus.

Evaporation 545 mm, precipitation 550 mm, average temperature in July 17°-20 °C, in winter the average temperature in January in the west? 6 °C, and in the east? 13 °C

A sharply continental climate operates on the territory of North-Eastern Siberia. Almost all of North-Eastern Siberia lies within the Arctic and subarctic climatic zones. The temperature is on average below? 10 °.

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

Hydrography

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.

Most of the rivers are fed mainly by melting snow cover in early summer and summer rains. play a role in feeding rivers ground water, melting snow and glaciers in high mountains, as well as icing. More than 70% of the annual river flow falls on three calendar summer months.

The largest river in North-Eastern Siberia - Kolyma (basin area - 643 thousand km2, 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 discharge is 3900 m3/sec (flow of about 123 km3 of water).

The sources of the second major river - the Indigirka (length - 1980 km, basin area - 360 thousand km2) - are located in the region of the Oymyakon Plateau. Crossing the Chersky Range, it flows in a deep and narrow valley with almost steep slopes; rapids are often found here in the channel of the Indigirka. Then 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, with an area of 7700 km2. Indigirka has a runoff of more than 57 km3 per year (an average annual flow is 1800 m3/sec).

The western regions of the country are drained by Yana (length - 1490 km2, basin area - 238 thousand km2). Its sources - the Dulgalakh and Sartang rivers - flow down from the northern slope of the Verkhoyansk Range. After their confluence within the Yan Plateau, the river flows in a wide valley with well-developed terraces. In the middle part of the current, where the Yana crosses the spurs of the mountain ranges, its valley narrows, and rapids appear in the channel. The lower reaches of the Yana are located on the territory of the coastal lowland; when it flows into the Laptev Sea, the river forms a large delta (about 5200 km2 in area).

Yana is characterized by long summer floods, which is due to the gradual melting of 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 discharge is 1000 m3/s, and the runoff per year is over 31 km3.

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.

On the territory of North-Eastern Siberia there is: gold, tin, polymetals, tungsten, mercury, molybdenum, antimony, cobalt, arsenic, coal.

Unlike other parts of Siberia, the amount of high-quality timber here is relatively small.

relief siberia russia

Literature

1. Lyubushkina S.G. General geography: Proc. allowance for university students enrolled in special. "Geography" / S.G. Lyubushkina, K.V. pashkang, A.V. Chernov; Ed. A.V. Chernov. - M. : Education, 2004. - 288 p.

2. N. A. Gvozdetsky and N. I. Mikhailov, Physical Geography of the USSR. Asian part. - 3rd ed., Rev. and additional Textbook for students geogr. fak. Univ. - M.: "Thought", 1978. 512 p.

3. Davydova M.I., Rakovskaya E.M. Physical geography of the USSR. - M.: Enlightenment, 1990.- 304 p.

Hosted on Allbest.ru

Geological structure and history of development

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

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

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

By the end of the Cretaceous, Northeastern Siberia was already a consolidated territory elevated above the neighboring regions. The processes of denudation of mountain ranges 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.

Formation of modern mountainous terrain 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 glaciers was a sedentary formation; they carried some loose material, and their exaration effect had little effect on the relief.

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

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

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

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

Main types of relief

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

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

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

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

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

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

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

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

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

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

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

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

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

Climate

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

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 dense here that even during the day 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 maximum temperatures air during the day sometimes reach 26-28 °.

After a short spring comes a short but relatively warm summer. At this time, low pressure is established over the mainland of the country, and higher pressure over the northern seas. Located near the northern coast, the Arctic front separates the masses of warm continental air and colder air that forms over the surface of the seas of the Arctic Ocean. The cyclones associated with this front often break south, into the coastal plains, causing a noticeable 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 tree line, summers are cooler and the average temperature in July is below 10-12°C.

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

The first snowfalls are possible already at the end of August. September and the first half of October can 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, the average daily temperatures drop below 0°, frosts at night in the north reach -15 -18°, blizzards often occur.

Permafrost and glaciation

The harsh climate of the country causes intense freezing of rocks and the continuous spread of permafrost, which has a significant impact on the formation of landscapes. Northeastern Siberia is distinguished by a very large thickness of permafrost, which in places in the northern and central regions is more than 500 m, and in most mountainous areas - from 200 to 400 m. Very low temperatures 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. Some ices of this type can be considered "fossils", since their formation began as early as the Middle Quaternary.

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

The climatic conditions of the country's highest ranges contribute to the formation of glaciers. In places here at an altitude of more than 2000-2500 m drops up to 700-1000 mm/year sediments, most of them in solid form. Snow melting occurs only during two summer months, which are also characterized by significant cloudiness, low temperatures (the average 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

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 flood period, the rivers intensively erode their banks and clutter up the channels with tree trunks, forming numerous creases.

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

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

Lake of Dancing Graylings. Photo by B. Vazhenin

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

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

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) trunk.

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 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) native species adapted to cold climates; 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 large reindeer. 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.

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

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

Geographical position of Eastern Siberia

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

Rice. 1. Eastern Siberia covers an impressive area

Within Eastern Siberia are the Krasnoyarsk and Trans-Baikal Territories, the Irkutsk Region, the Republics of Buryatia, Yakutia, and Tuva.

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

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

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

Climate

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

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

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

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

Rice. 2. Winter in Eastern Siberia

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

Resources

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

About 70% of the reserves of stone and brown coal. This region is rich in ore deposits:

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

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

Rice. 3. Diamonds of Yakutia

Nature

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

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

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

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

What have we learned?

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