Geological structure and relief of Eurasia. Geological structure of Eurasia Why is the relief of Eurasia so complex and diverse?

It was a ball consisting of only gases. Gradually, heavy metals such as iron and nickel sank to the center and became denser. Light rocks and minerals floated to the surface, cooled and solidified.

Structurally, the Earth consists of three layers: core, mantle and earth's crust.

Core- the center of the Earth, its diameter is 6964 km, mass 1.934 * 10^24 kg, volume - 1.752 * 10^20 m3 (16.2% of the Earth's volume). The core consists of two parts: the subcore (solid part) and the outer core (liquid part). The core is characterized by high (up to 5000 °C) temperatures. It contains about 89% iron and 6% nickel. The movement of matter in the core creates a magnetic field on Earth that protects the planet from cosmic radiation.

Mantle(from the Greek mantion - cover) - the middle layer connecting the core and the earth's crust. The mantle has a thickness of 2865 km, a mass of 4.013 * 10^24 kg, its volume is 8.966 * 10^20 m3 (83% of the Earth's volume).

The mantle consists of three layers: the Golitsyn layer, the Gutenberg layer and the substrate. The upper part of the mantle, called magma, contains a layer with reduced viscosity, density and hardness - the asthenosphere, on which areas are balanced earth's surface. The boundary between the mantle and core is called the Guttenberg layer.

The outer solid layer of the planet. Its mass is 2.85*10^22 kg, volume is 1.02*10^19 m3 (0.8% of the Earth's volume). Its average thickness is 25-30 km, thinner under the oceans (3-10 km), in mountainous areas it reaches 70 km. The earth's crust consists of three layers: basalt, granite and sedimentary. Composition of the earth's crust: oxygen (49%), silicon (26%), aluminum (7%), iron (5%), calcium (4%); the most common minerals are feldspar and quartz. The boundary between the earth's crust and mantle is called the Moho surface (named after the Yugoslav scientist A. Mohorovicic).

Rocks that make up the earth's crust

By definition, a stable composition of a set of minerals located in different states of aggregation. Based on their origin, rocks are classified into igneous, sedimentary, metamorphic, volcanic and metastatic rocks.

Igneous rocks are formed when magma cools and crystallizes, penetrating into the earth's crust through cracks. They make up about 60% of the earth's crust. If their formation occurred at greater depths without reaching the surface, then such rocks are called intrusive. They cool slowly, crystallization takes a long time, and coarse-crystalline rocks (granite, diorite, gabbro) are obtained. If magma erupts and freezes on the surface of the earth, igneous rocks are formed. Due to relatively rapid cooling, small crystals are formed in the rock, for example: basalt, andesite, liparite. Igneous rocks are usually composed of silicates (S1O2). They are divided into ultrabasic (silica less than 40%), basic (silica from 40% to 50%), intermediate (silica from 50-65%) and acidic (silica more than 65%).

Sedimentary rocks were formed by the deposition of matter into aquatic environment, less commonly from the air and as a result of glacial activity. They make up 75% of the thickness of the earth's crust and 10% of its mass, usually occurring in layers. According to the conditions of formation, sedimentary rocks are divided into the following categories:

• Clastic, arose from the destruction of another type of rock - sand, sandstones, clay,
• Chemical, arose as a result chemical reactions V aqueous solutions- salts, gypsum, phosphorites,
• Organic, arose as a result of the accumulation of calcareous or plant residues - limestone, chalk, peat, coal.

Metamorphic rocks are formed as a result of alteration of sedimentary or igneous rocks with a complete or partial change in their mineral composition and structure. These include gneisses (transformed granite), quartzites (transformed sandstone), marble (modified limestone), and various ores.

Volcanic rocks are formed as a result of volcanic eruptions. There are eruptive or effusive (basalt, andesite, trachyte, liparite, diabase) and volcanic-clastic or pyroclastic (tuffs, volcanic breccias) volcanic rocks.

Metasomatic rocks are formed as a result of metasomatism. In this case, the following stages of their formation occur: early alkaline (magnesian and calcareous skarns), acidic (geysers and secondary quartzites), late alkaline (berezite, listvenite).

Due to the unevenness of the earth's surface, land and ocean are distinguished in its structure. Within their boundaries there are grandiose mountain ranges and deep oceanic depressions, vast plains and underwater plateaus, lowlands, ravines, basins, dunes, etc.

The earth's crust has different thickness, composition, and structure on continents and under the oceans. There are continental, oceanic and transitional crusts.

The continental crust is three-layered (layer of sedimentary rocks, granite, basalt), its thickness on the plains is 30-50 km, in the mountains - up to 70-80 km. The oceanic crust is thinner (5-15 km) and consists of two layers - upper sedimentary and lower basaltic. At the border of continents and oceans, in the areas of islands, the thickness of the earth’s crust is 15-30 km, the granite layer pinches out, and the earth’s crust is of a transitional nature.

The transitional crust is an intermediate zone between the continental and oceanic crust, its thickness varies between 30-50 km.

The earth's crust is in constant motion. The first hypothesis about continental drift (i.e., horizontal movement of the earth's crust) was put forward at the beginning of the 20th century by A. Wegener. A theory was created on its basis. According to this theory, it is not a monolith, but consists of seven large and several smaller plates “floating” on the asthenosphere. The boundary areas between lithospheric plates are called seismic belts - these are the most “restless” areas of the planet.

The earth's crust is divided into stable and mobile areas.

Stable sections of the earth's crust - platforms - are formed in place of geosynclines that have lost mobility. The platform consists of a crystalline basement and sedimentary cover. Depending on the age of the foundation, ancient (Precambrian) and young (Paleozoic, Mesozoic) platforms are distinguished. At the base of all continents lie ancient platforms.
Mobile, highly dissected areas of the earth's surface are called geosynclines (folded areas). There are two stages in their development: at the first stage, the earth’s crust experiences subsidence, sedimentary rocks accumulate and metamorphose. Then the earth's crust begins to rise, and the rocks are crushed into folds. There were several eras of intense mountain building on Earth: Baikal, Caledonian, Hercynian, Mesozoic, Cenozoic. In accordance with this, various folding areas are distinguished.

The distribution and age of platforms and geosynclines is shown on a tectonic map (a map of the structure of the earth's crust).

(from French relief, lat. televo - lift) - a set of irregularities in the earth's surface. The relief is made up of positive (convex) and negative (concave) shapes. The largest negative landforms on Earth are ocean basins, while positive ones are continents. This is of the first order. Landforms of the second order - and (both on land and on the bottom of the oceans). The surface of the mountains and plains has a complex topography consisting of smaller forms.

Morphostructures are large elements of the relief of land, the bottom of oceans and seas, the leading role in the formation of which belongs to endogenous processes. The largest irregularities in the Earth's surface form continental protrusions and ocean trenches. The largest elements of land relief are flat-platform and mountainous areas.

Plain-platform areas include the flat parts of ancient and young platforms and occupy about 64% of the land area. Among the plain-platform regions there are low ones, with absolute heights of 100-300 m (East European, West Siberian, Turanian, North American plains), and high, elevated the latest movements crust to a height of 400-1000 m (African-Arabian, Hindustan, significant parts of the Australian and South American plain regions).

Mountainous regions occupy about 36% of the land area.

The underwater margin of the continent (about 14% of the Earth's surface) includes a generally shallow flat strip of continental shallows (shelf), a continental slope and a continental foot located at depths from 2500 to 6000 m. The continental slope and continental foot separate the continental protrusions, formed by the combination of land and shelf, from the main part of the ocean floor, called the ocean floor.

Island arc zone - transition zone ocean bed. The ocean floor itself (about 40% of the Earth's surface) is mostly occupied by deep-sea (average depth 3-4 thousand m) plains that correspond to oceanic platforms.

Elements of the relief of the earth's surface, in the formation of which the leading role belongs to exogenous processes. The work of rivers and temporary streams plays the greatest role in the formation of morphosculptures. They create widespread fluvial (erosive and accumulative) forms (river valleys, ravines, ravines, etc.). Glacial forms are widespread, caused by the activity of modern and ancient glaciers, especially the cover type (northern part of Eurasia and North America). They are represented by trough valleys, “ram’s foreheads” and “curly” rocks, moraine ridges, eskers, etc. vast territories Asia and North America, where permafrost rock strata are common, have developed various forms of frozen (cryogenic) relief.

The largest landforms are continental ridges and ocean basins. Their distribution depends on the presence of a granite layer in the earth's crust.

The main landforms are mountains and plains. Approximately 60% of the land is occupied by plains - vast areas of the earth's surface with relatively small (up to 200 m) fluctuations in elevation. Based on absolute height, plains are divided into lowlands (height 0-200 m), hills (200-500 m) and plateaus (above 500 m). According to the nature of the surface - flat, hilly, stepped.
Mountains are elevations of the earth's surface (more than 200 m) with clearly defined slopes, bases, and peaks. By appearance mountains are divided into mountain ranges, chains, ridges and mountainous countries. Free-standing mountains are rare, representing either volcanoes or the remains of ancient destroyed mountains. The morphological elements of mountains are: base, or sole; slopes; peak or ridge (at ridges).

The base of a mountain is the boundary between its slopes and the surrounding area, and it is quite clearly expressed. With a gradual transition from the plain to the mountains, a strip is distinguished, which is called the foothills.

Slopes occupy most of the mountain surface and are extremely varied in appearance and steepness.

The summit is the highest point of a mountain (mountain ranges), the pointed top of a mountain is a peak.

Mountain countries (mountain systems) are large mountain structures that consist of mountain ranges - linearly elongated mountain uplifts intersecting slopes. The points of connection and intersection of mountain ranges form mountain nodes. These are usually the highest parts of mountainous countries. The depression between two mountain ranges is called a mountain valley.

Highlands are areas of mountainous countries consisting of heavily destroyed ridges and high plains covered with destruction products.

By height, mountains are divided into low (up to 1000 m), medium-low (1000-2000 m), high (over 2000 m). Based on their structure, folded, folded-block and block mountains are distinguished. Based on their geomorphological age, they distinguish between young, rejuvenated and revived mountains. Mountains of tectonic origin predominate on land, while mountains of volcanic origin predominate in the oceans.

(from Latin vulcanus - fire, flame) - a geological formation that arises above channels and cracks in the earth's crust, through which lava, ash, flammable gases, water vapor and rock fragments erupt onto the earth's surface. There are active, dormant and extinct volcanoes. The volcano consists of four main parts: the magma chamber, the vent, the cone and the crater. There are about 600 volcanoes around the world. Most of them are located along plate boundaries, where red-hot magma rises from the Earth's interior and bursts to the surface.
A typical volcano is a hill with a pipe running through its thickness, called a volcano vent, with a magma chamber (an area of ​​magma accumulation) from which the vent rises. In addition to the vent, small channels with magma, called sills and dikes, can also extend from the magma chamber. When high pressure is created in a magma chamber, a mixture of magma and hard rocks - lava - rises up the vent and is thrown into the air. This phenomenon is called a volcanic eruption. If the lava is very thick, it can solidify in the crater of a volcano, forming a plug. However, enormous pressure from below bursts the plug, spewing large chunks of rock called volcanic bombs high into the air. After each, the lava hardens into a hard crust. Volcanic hills with steep slopes are called conical, while those with gentle slopes are called shield hills. Modern active volcanoes: Klyuchevskaya Sopka, Avachinskaya Sopka (,), Isalko (), Mauna Loa (Hawaii), etc.

Geological chronology is the study of the chronological sequence of formation and age of the rocks that make up the earth's crust. Geological processes occur over many millennia. The identification of various stages and periods in the life of the Earth is based on the sequence of accumulation of sedimentary rocks. The time in which each of the five groups of rocks accumulated is called an era. The last three eras are divided into periods, because... In the sediments of these times, the remains of animals and plants were better preserved. In the eras there were eras of intensification of mountain-building processes - folding.

A distinction is made between relative and d. Relative age is easily established in the case of horizontal occurrence of rock layers within the same exposure. The absolute age of rocks is quite difficult to determine. To do this, they use the method of radioactive decay of a number of elements, the principle of which does not change under the influence of external conditions and comes with constant speed. This method was introduced into science at the beginning of the 20th century by Pierre Curie and Ernest Rutherford. Depending on the final decay products, lead, helium, argon, calcium, strontium and radiocarbon methods are distinguished.

Geochronological scale

Eras	Periods	Folding	Events
Cenozoic. 68 million years	Quaternary, 2 million years	Alpine folding	Formation of modern relief under the influence of massive land uplift. Glaciation, sea level changes. Human Origins.
	Neogene, 25 million years		Powerful volcanic eruptions, uplift of the Alpine mountains. Mass distribution of flowering plants.
	Paleogene, 41 million years		Destruction of mountains, flooding of young platforms by seas. Development of birds and mammals.
Mesozoic, 170 million years	Chalky. 75 million years	Mesozoic folding	The rise of destroyed mountains formed in the Baikal fold. The disappearance of giant reptiles. Origin of angiosperms.
	Jurassic, 60 million years		The emergence of faults on continents, massive input of igneous rocks. The beginning of the exposure of the bed of modern seas. Hot humid climate.
	Triassic. 35 million years		Recession of the seas and increase in land area. Weathering and lowering of Paleozoic mountains. Formation of flat terrain.
Paleozoic. 330 million years	Permian, 45 million years	Hercynian folding	The end of the Hercynian mountain formation, the intensive development of life in the mountains. The appearance of amphibians, simple reptiles and insects on land.
	Carboniferous, 65 million years		Lowering the land. Glaciation on the continents of the Southern Hemisphere. Expansion of swamp areas. The emergence of a tropical climate. Intensive development of amphibians.
	Devonian, 55 million years	Caledonian folding	Retreat of the seas. The accumulation on land of thick layers of red continental sediment. Predominance of hot, dry climate. Intensive development of fish, emergence of life from the sea to land. The appearance of amphibians and open-seeded plants.
	Silurian, 35 million years old	Beginning of the Caledonian folding	Rising sea levels, appearance of fish.
	Ordovician, 60 million years		Strong volcanic eruptions, decrease. An increase in the number of invertebrate animals, the appearance of the first invertebrates.
	Cambrian. 70 million years	Baikal folding	Subsidence of land and the appearance of large swampy areas. Invertebrates develop intensively in the seas.
Proterozoic, 2 billion years		The beginning of the Baikal folding	Powerful volcanic eruptions. Formation of the foundations of ancient platforms. Development of bacteria and blue-green algae.
Archean. 1 billion years			The beginning of the formation of the continental crust and the intensification of magmatic processes. Powerful volcanic eruptions. The first appearance of life is the period of bacteria.

The territory of Eurasia was formed over hundreds of millions of years. The structure of the earth's crust of Eurasia is more complex than that of other continents. Eurasia is located within three large lithospheric plates: Eurasian(most of the area), Indo-Australian(in the south) and North American(in the north-east). The lithospheric plates are based on several ancient and young platforms. Ancient platforms formed in the Archean and Proterozoic eras, their age is several billion years. These are the remains of the former continent of Laurasia. These include: Eastern European, Siberian, Chinese-Korean, South Chinese. Also on the mainland there are ancient platforms that joined Eurasia later, having separated from the Gondwanaland mainland - Arabian(part of the African Arabian Platform) and Indian.

Young platforms in Eurasia occupy large areas. The largest of them are West Siberian And Turanskaya. Their foundation, which is several hundred million years old, lies at enormous depths. That is, these platforms were formed at the end of the Paleozoic era. Material from the site

When lithospheric plates converged or diverged along their boundaries, folding, volcanism and earthquakes occurred. As a result, gigantic fold belts Eurasia, within which high mountains and deepest depressions alternate. In the central part of the continent between the platform areas lies an ancient Ural-Mongolian belt, within which active mountain building occurred during the Paleozoic era. Young seismically active belts continue to form in the south and east of Eurasia - Alpine-Himalayan And Pacific. Numerous earthquakes occur within their borders. IN Lately Destructive earthquakes occurred in Armenia in the Caucasus (1988), in Turkey on the Asia Minor Peninsula (1999), in Indonesia on the Greater Sunda Islands (2004). They claimed the lives of tens and hundreds of thousands of people. Active volcanoes are confined to young folding belts: Vesuvius. Etna, Klyuchevskaya Sopka (fig.. 168), Fuji, Krakatoa.

There is an island on the boundary of lithospheric plates Iceland (Fig. 169). This island with an oceanic type of earth's crust represents the upper parts of the North Atlantic Ridge protruding above the water. Due to the divergence of lithospheric plates, fissure-type volcanoes formed on the island. The biggest one is Hekla. Volcanism is accompanied by the emergence of hot springs and geysers.

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On this page there is material on the following topics:

• what part of the crust lies in the Eurasian region
• Eurasia is located on three large lithospheric plates

Eurasia

Goals:

Educational: formation of ideas about the relief of Eurasia; show the features of the relief of Eurasia (general amplitude of heights, ancient platforms, mountain building) consider the main stages of the formation of the continental relief; establish the features of the placement of large relief forms;

Educational: formation of emotional and sensory perception of the surrounding world, development of visual memory

Educational: developing the ability to work with various sources geographic information

Equipment:Physical map of continents and oceans, physical map of the Eurasian continent, map “Structure of the Earth’s Crust”, textbooks, atlases, contour maps, computer, projector, interactive whiteboard.

During the classes:

1. Organizational moment (30 sec.)

The topic of our lesson is the relief of Eurasia, in order to begin studying it we need to remember geographical position mainland.

2. Survey (10 min.)

Cards

Card 1

Arabian Peninsula, Bay of Bengal, Laptev Sea, Kamchatka Peninsula, Yamal Peninsula, Hindustan Peninsula, Red Sea, Caspian Sea, Black Sea, English Channel, Kara Sea, Okhotsk Sea, Baltic Sea, Norwegian Sea, Apennine Peninsula

Card 2

Check geographical names on contour map

Balkan Peninsula, Balkan Peninsula, Kola Peninsula, East China Sea, Bay of Bengal, Red Sea, Bay of Biscay, Norwegian Sea, Sea of ​​Japan, Arabian Sea, Scandinavian Peninsula.

Card 3

Find extreme points Eurasia and determine their coordinates

Oral survey

A) Characterize the g.p. mainland (5 students)

B) List the main features of the mainland (1 student or more)

Q) What parts is Eurasia divided into? Where is the border?

D) Name the scientists who explored the continent of Eurasia (Semyonov Tien-shansky, Przhevalsky) (1 student)

D) What contribution did P.P. make to the study of the mainland? Semyonov-Tianshansky? Why did he receive the prefix to his surname - Tianshansky? (1 student)

E) What contribution did Przhevalsky make to the study of the continent? (1 student)

3. Learning new material (20 min)

The topic of our lesson is the relief of Eurasia

Remember the concepts of “relief”, “slab”, “platform”, “landforms”, “seismically active zone”.

Relief - a set of irregularities on the earth's surface

Plate – large region of lithosphere

The platform is an extensive tectonic structure with relatively low mobility.

Landforms - mountains and plains

A seismically active zone is a zone in which intense movements of the earth's crust occur, accompanied by earthquakes and volcanism.

The diversity and complexity of the relief of Eurasia are explained primarily by the history of its formation. Eurasia is part of the ancient continent of Pangea, which split into two large parts. The northern part was called Laurasia, the southern - Gondwana. Laurasia then split into North America and Eurasia, and Gondwana into a number of smaller landmasses.

At the base of the Eurasian continent lies the Eurasian lithospheric plate, which is bordered on the east by the Pacific plate, on the west by the North American plate, on the south by the African and Indo-Australian plates. Along the entire line of their collision, the longest belt of alpine folding (young folded mountains) on Earth is formed, stretching across the entire continent: Pyrenees - Alps - Carpathians - Crimea - Caucasus - Pamir - Tien Shan - Himalayas (Alpine-Himalayan seismic belt). The belt extends from Atlantic Ocean in the latitudinal direction to the Pacific. We see further manifestation of the interaction of two plates in the form of island arcs - Japanese, Kuril, Marquesas, Philippine. The islands are of volcanic origin. Island arcs, as well as the bottom, are characterized by earthquakes and volcanoes, accompanied by tsunamis. Volcanoes: Klyuchevskaya Sopka, Fuji on the island. Honshu, Apo in the Philippine Islands, Etna, Vesuvius, Kazbek, Elbrus.

Young folding – (30 million years)

Pyrenees, Alps, Carpathians, Caucasus, Himalayas, Apennines, Pamirs, Tibet, Altai, Iranian Plateau.

Ancient folding (460-230 million years)

Scandinavian mountains, Ural mountains

Folding

Basic forms

relief

Ancient areas

folding

Highlands Tibet

Ural Mountains, Scandinavian Mountains

New areas

folding

Altai, Tien Shan

Pyrenees, Alps, Caucasus,
Himalayas

Apennines, Carpathians

Pamir Highlands, Iranian Highlands (Alpine-Himalayan belt)

However, the continent consists not only of mountainous regions, but also of platforms - East European, Siberian, Indian, Chinese-Korean, South Chinese, African-Arabian. Indian and African joined much later. It is typical for platforms high position above sea level. The platforms are covered with sedimentary cover, but sometimes protrusions of the crystalline basement are visible, for example, Baltic, Voronezh, Putorana Plateau, Aldan Shield.

Platforms

Basic landforms

Eastern European

the East European Plain

Siberian

Central Siberian Plateau

Indian

PlateauDean

Chinese-Korean

Great Chinese Plain

In external relief Plains and plateaus appear on the platforms.

East European Platform - East European Platform

Siberian – Central Siberian platform

Indian – Deccan Plateau

Sino-Korean – Great Chinese Plain

Ups and downs can be seen on the continent. Northern and Baltic Sea are falling, and the north of the Scandinavian Peninsula is rising.

Glaciation also played an important role, the surface leveled out, became hilly, and lakes formed.

Relief features

1. Eurasia is significantly higher than other continents

2. The highest mountain systems on earth are located on the territory of Eurasia

3. The plains of Eurasia are enormous in size

4. Elevation fluctuations are especially large in Eurasia

In general, the surface of Eurasia is distinguished by contrast: here are the highest mountains on Earth - the Himalayan (peak - Everest, 8848 m) and the deepest depression on land, the Dead Sea (-402 m) - on the eastern coast of the Mediterranean Sea; as well as the most extensive of those lying below sea level, the Caspian Lowland.

We know that the highest mountains in the world are located on the mainland - the Himalayas. The Himalayas are studied and admired not only by geographers, geologists, and biologists. Many famous writers and poets admired the beauty of these majestic mountains, such as the young poetess Irena Artemyeva. Let's listen to her poem, which Anya Ivanova will tell us.

Verse "On the top of a mountain in the Himalayas"

Artemyeva Irena

If only I knew what would lure us into the distance,
if only we knew what awaits us in the future.
On top of a mountain in the Himalayas
in the moonlight - a snow-covered grotto.

An angel in white stands at the entrance,
calls with a majestic gesture.
And it flickers and sparkles blue,
amazing, secret entrance.

A white light loomed in the distance,
suddenly flared up
we descend into the depths of the mountains:
trembling in the knees, fear in the soul.

Touch the stocks with this
alas, we have not yet been given it!
In parting, I’ll say it’s a treasure trove
secret knowledge, rare sciences!

Presentation on the Himalayas (4 min.)

4. Consolidation(5 minutes.)

1. Name the main features of the continent’s topography.

2. What plate lies at the base of the Eurasian continent?

3. How is the interaction of lithospheric plates reflected on the relief?

4. What landforms are located on the platforms? List them.

5. Name the young mountains of Eurasia.

6. Name the old mountains of the mainland.

7. Name the greatest mountain system in the world located on the mainland and its highest point.

8. What is the total area of ​​the Himalayas? (650)

9. How is the name Himalaya translated (stronghold of snow, home of snow)

10. Name three names of the highest point of the Himalayas (Qomolungma, Everest, Sagarmatha)

11. Which famous traveler, artist visited the Himalayas?

5. Grading for the lesson (2 minutes.)

6. Homework: § 60-61, pp. 233-238 .
On the contour map, mark the following landforms of Eurasia:

plains: East European (Russian), West Siberian, Central Siberian Plateau, Great Chinese, Deccan Plateau, Indo-Gangetic Lowland, Mesopotamian Lowland, Turanian Lowland;

mountains: Alps, Ural, Caucasus, Tibetan Plateau (Tibet), Himalayas, Pamir, Tien Shan, Iranian Plateau;

highest point: Mount Chomolungma (8848 m);

volcanoes: Klyuchevskaya Sopka, Fuji, Krakatau, Elbrus;

lowest point of the continent : Dead Sea level.

Lithospheric plates - This large blocks the earth's crust and parts of the upper mantle that make up the lithosphere.

What is the lithosphere composed of?

At this time, on the boundary opposite to the fault, collision of lithospheric plates. This collision can proceed in different ways depending on the types of colliding plates.

• If oceanic and continental plates collide, the first one sinks under the second one. This creates deep-sea trenches, island arcs (Japanese islands) or mountain ranges (Andes).
• If two continental lithospheric plates collide, then at this point the edges of the plates are crushed into folds, which leads to the formation of volcanoes and mountain ranges. Thus, the Himalayas arose on the border of the Eurasian and Indo-Australian plates. In general, if there are mountains in the center of the continent, this means that it was once the site of a collision between two lithospheric plates fused into one.

Thus, the earth's crust is in constant motion. In its irreversible development, the moving areas are geosynclines- are transformed through long-term transformations into relatively quiet areas - platforms.

Lithospheric plates of Russia.

Russia is located on four lithospheric plates.

• Eurasian plate– most of the western and northern parts of the country,
• North American Plate– northeastern part of Russia,
• Amur lithospheric plate– south of Siberia,
• Sea of ​​Okhotsk plate– Sea of ​​Okhotsk and its coast.

Figure 2. Map of lithospheric plates in Russia.

In the structure of lithospheric plates, relatively flat ancient platforms and mobile folded belts are distinguished. In stable areas of the platforms there are plains, and in the area of ​​fold belts there are mountain ranges.

Figure 3. Tectonic structure of Russia.

Russia is located on two ancient platforms (East European and Siberian). Within the platforms there are slabs And shields. A plate is a section of the earth's crust, the folded base of which is covered with a layer of sedimentary rocks. Shields, as opposed to slabs, have very little sediment and only a thin layer of soil.

In Russia, the Baltic Shield on the East European Platform and the Aldan and Anabar Shields on the Siberian Platform are distinguished.

Figure 4. Platforms, slabs and shields on the territory of Russia.

Eurasia– the largest continent on Earth, consisting of two parts of the world: Europe and Asia. Together with the islands, Eurasia occupies an area of ​​about 54 million km 2 or 37% of the land. The islands account for 2.75 million km 2. Its territory extends over 90° in latitude and 190° in longitude. Extreme continental points: in the north - Cape Chelyuskin, 77 about 43 "N; in the south - Cape Piai, 1 about 16" N; in the east - Cape Dezhnev, 169 o 40 "W; in the west - Cape Roka, 9 o 34" W.

The distance between the extreme points in the east and west is 8100 km, in the north and east – 8500 km. The archipelagos in southeastern Eurasia are located in the southern hemisphere. They are united common name The Malay archipelago, which is the largest collection of islands on Earth (about 10 thousand). Eurasia is separated from North America by the Atlantic (in the west), Arctic (in the north) and Pacific (in the east) oceans.

In the northeast, the Bering Strait separates it from North America, in the southwest - Gibraltar watering with Africa. In the south, the Mediterranean and Red Seas are confined between Eurasia and Africa, which are connected by the Isthmus of Suez. The south of Eurasia is washed by the waters of the Indian Ocean. The Torres Strait, with its many islands, rocks and reefs, separates the southernmost large island of Eurasia, New Guinea, from Australia.

The gigantic territory of Eurasia is a continuous landmass, the formation of which occurred throughout the history of the geological development of the Earth, leading to the modern tectonic consolidation of the continental-type earth's crust.

Eurasian sharp relief contrasts. More than 75% of its territory is occupied by mountains, highlands and plateaus, including the largest mountain systems on the globe. Within this continent is the highest peak, Chomolungma (8848 m). Eurasia is home to one of the largest low-lying accumulative plains on the planet - the West Siberian Lowland. This continent is home to the deepest tectonic basin (1620 m), filled with the waters of Baikal, and the deepest depression on land - the Dead Sea, or El Ghor (-395 m), the water edge of which is 40-60 m below sea level.

Eurasia is located in all climatic zones of the Northern Hemisphere - from the Arctic to the equatorial. The internal natural differences of this gigantic territory are determined by its position in relation to the surrounding oceans. Eurasia is characterized by the predominance of a huge Atlantic sector in a temperate climate zone with westerly transport of air masses and a narrowed Pacific sector with a monsoon climate.

The remoteness of inland areas from the surrounding oceans and the barrier role of the highest mountain systems led to the widespread development of inland sectors in climatic zones and areas of internal drainage. A distinctive feature of the continent is the presence of permafrost (permafrost), especially in the Russian part of Asia.

Eurasia is characterized by a significant commonality in the development of the organic world. It is also an arena for development ancient civilizations. Thousands of years of agricultural culture have transformed the natural landscapes of many territories, especially Europe, Southeast, South, Central and Central Asia. In addition to natural unity, the need to take into account the importance of territorial integrity for assessing socio-historical phenomena gave rise to the need for a name that unites the entire continent. The most convenient name turned out to be “Eurasia,” introduced by the Austrian scientist and paleontologist E. Suess (1831-1914) into geology and geography.

Geological structure Eurasia is determined by the formation within the continental part of several Precambrian platform structures, on which lies a sedimentary cover of Paleozoic, Mesozoic and Cenozoic rocks.

The ancient core of the consolidation of the European part of Eurasia includes the East European Platform. Its western half is characterized by the presence of shields (Baltic, Ukrainian) and anteclises (Belarusian and Voronezh). In the area of ​​development, syneclises correspond to: in the west – the Polish-German and Baltic lowlands, in the east – the Meshcherskaya and in the south – the Caspian lowlands. The basins of the southern Baltic Sea, the Jutland Peninsula and the eastern part of the North Sea are also located within the syneclises.

The Asian part has several platform cores: the Siberian, Chinese, Arabian and Hindustan platforms. The Siberian Platform in its borders almost corresponds to the Central Siberian Plateau. The Chinese platform includes several separate massifs (platforms of smaller dimensions): North China, Tarim, Sinai (Chinese-Korean), South China and, according to latest research, Tibetan. In Precambrian times, these massifs probably represented a single whole.

The Arabian and Hindu platforms are believed (according to the new global tectonics) to be “splinters” of Gondwana, which adjoined the mainland in Tertiary times. In some areas, the ancient foundation of Eurasia comes to the surface, forming a system of shields - Arabian (Nubian), Aldan, Anabar and others.

Asian platforms belong to the group of movable ancient platforms. They are characterized by a high position above sea level, which determines the dominance within their boundaries of processes of demolition or accumulation of continental sediments. In such platforms, deep faults are not limited to the foundation and penetrate into the sedimentary cover, reach the surface and are accompanied by intense volcanic activity, the products of which are trap formations of various ages: Late Triassic and Jurassic traps on the Hindustan Peninsula (area 1 million km 2, thickness 3-4 km ), Cretaceous and Tertiary in the north-west of the Arabian Platform, post-Permian - in the south-west of the Chinese Platform.

The main geostructures of Eurasia also include folded (geosynclinal) belts: Atlantic, Mediterranean, Eurasian (Alpine-Himalayan), Ural-Mongolian, Arctic and Pacific. The Atlantic belt includes the Scandinavian mountains and the north of Great Britain, the Mediterranean can be traced across the entire continent from the Atlantic to Indochina, including the Hercynian (Central European midlands) and Alpine-Carpathian Europe, the European Mediterranean, Asia Minor, the Caucasus, the Iranian Plateau, the Pamirs, the Tien Shan, Himalayas, Tibet and Indochina.

The Ural-Mongolian belt is created by the mountain systems of the Urals, the Kazakh small hills, the Altai, the Sayans, the Yablonovy and Stanovoy ranges, the Greater Khingan and the Sikhote-Alin. The Arctic belt includes the islands of the Arctic Ocean and the Taimyr Peninsula; in the northeast of Asia it meets the Pacific (Verkhoyansk and Chersky ridges, Chukotka Peninsula, Kamchatka, Japanese Islands, Malay Archipelago). The geological record of nature includes several stages.

Archaea(4.5-2.5 billion years ago). The primary earth's crust initial stage existence was presumably of great power. Its formation was of a general nature and was accompanied by the outpouring of masses of volcanic rocks - basaltic magma, whose composition was close to modern basaltic magma in mid-ocean ridges. Tectonic processes were poorly differentiated, and the main role in the formation of the structural plan belonged to the gravitational differentiation of the substance of the protocrust ( primary cortex) and mantle. This process was slow and long-lasting, which led to the formation of thick layers of Archean deposits of terrigenous, volcanic and chemical origin.

The processes of chemical and gravitational differentiation of matter, intensifying during the growth of the earth's crust, led to the vertical and spatial separation of various differentiates - the accumulation of heavier ones at the bottom and the rise of lighter ones, enriched in volatile components. The latter, rising upward, influenced the still plastic earth's crust, which, under conditions of its isostasy and in the absence of hard crotons, led to the formation of arched dome uplifts and interdome troughs, different in size and configuration.

The period of early doming stimulated the emergence of circular and linear faults. This period was followed by cratonization of the primary earth's crust - the formation of consolidated areas with a continental structure, including a granite-metamorphic layer. These areas are not capable of folding transformation. Maximum magmatic activity manifested itself in the junction zone of active zones (protoaulacogens). Since the formation of consolidated sections of the earth's crust, the style of tectonics and magmatism has changed, expressed in the emergence of eras of tectonic-magmatic activation. The most ancient of them - the Kola (pre-Karelian, about 3 billion years ago) was expressed in the formation of the most ancient cores of the continents. Relics of these nuclei were found in all ancient platforms (East European and Siberian), except for the Chinese-Korean and South Chinese ones.

Proterozoic(2.5 billion - 570 million years ago). In the Proterozoic, several eras of folding and tectonic-magmatic activation had planetary significance, which played a decisive role in the formation of all ancient platforms, including Eurasia. The final one in Eurasia was the Baikal one, which began about 800 million years ago. The Baikalites, formed as a result of the Baikal folding, frame the Siberian Platform from the south and west. They form the ancient cores of many Paleozoic folded massifs of the Urals, Taimyr, Kazakhstan and, probably, significant areas of the basement of the West Siberian Lowland.

Ancient massifs, transformed to one degree or another by Alpine tectonic movements, are established throughout the entire Mediterranean fold belt - in Western Europe, Caucasus, Afghanistan, Turkey, Tien Shan, etc. Within the ancient platforms, the Baikal folding manifested itself in the formation of aulacogens - intraplatform linear mobile zones with the basement lowering to 5-10 km, which were filled with masses of sedimentary and sedimentary-volcanic rocks. The structural plan of the Earth, created during the Baikal folding, predetermined the placement of the most important structural elements planet throughout its subsequent geological history.

Paleozoic(570-230 million years ago). At the beginning of the Paleozoic (Cambrian, 570-500 million years ago), the northern hemisphere was similar to the modern southern one, i.e. was oceanic. A single continental plate formed in the southern hemisphere - Gondwana, extending from the South Pole to the equator. The largest fragments of present-day Eurasia - the microcontinents of Europe, Siberia, China and Kazakhstan - were located in the tropical region and were separated by seas.

In the Ordovician (500-440 million years ago), the general arrangement of Gondwana and microcontinents was preserved. Between the European and Siberian plates there is the Ural Ocean. At the end of the Ordovician and in the following periods - the Silurian (440-495 million years ago) and the Devonian (405-350 million years ago) - the Caledonian folding led to the formation of mountain ranges on the Scandinavian Peninsula, Spitsbergen, Kazakhstan, Western Sayan, Altai , Tien Shan, etc. In the French Massif Central, Southern Europe In the Asia Minor and Iranian plateaus, scattered blocks (median massifs) were formed, included in younger folded areas of Hercynian and Alpine age.

The enormous Hercynian folding, which began in the Carboniferous (350-265 million years ago) and continued in the Permian (265-230 million years ago), formed the mountain structures of the south of the British Isles, the Iberian Peninsula, France, the Central European Middle Mountains, the Urals-Tien -Shan belt. Scattered continental masses (Gondwana and microcontinents) were “fused” into a huge continent Pangea, stretching from the North Pole to the South Pole.

Mesozoic(230-60 million years ago). The Mesozoic was the main era of Cimmerian folding, manifested in tectonic processes and mountain building in the Crimea, Northern Afghanistan, Southeast Asia and Taimyr. Its last phase was particularly active in Far East.

In the Early Triassic (230-195 million years ago), Pangea still remained a single continent. The ascending mantle flow led to its split into Laurasia And Gondwana with the formation of a rift axis of the ocean between them Tethys. In the Jurassic (195-137 million years ago), Laurasia almost came close to North Pole. In the Triassic, the split of Europe and Asia began, but never took place, in the area of ​​​​the present West Siberian Lowland. At this time, the separation of North America from Africa and Europe also began.

In the Jurassic, the fragmentation of ancient continents continued. In the Cretaceous (137-60 million years ago), the Hindustan continent begins to drift towards Eurasia. The Tethys Ocean is slowly closing due to the rapprochement of Africa and Eurasia. Its complete closure occurred in the Cenozoic. Modern Mediterranean, Black and Caspian Sea are its relics. According to paleomagnetic data, by the end of the Mesozoic the continents of the Northern Hemisphere were located at the same latitudes that they currently occupy.

Cenozoic(last 60 million years). In the Cenozoic, the modern natural appearance of Eurasia took shape. After the closure of the Tethys Ocean about 55 million years ago, the collision of the Hindustan Plate with the Eurasian Plate began. As she actively moves towards the part continental crust modern India was pushed under the crust more northern territory or pushed up. The Tibetan Plateau, the highest on Earth, and the highest mountain system, the Himalayas, were formed. During the collision, it is possible that Asia moved counterclockwise and a rift was formed, partially filled by Lake Baikal. In the Paleogene (60-25 million years ago), in addition to the collision of the Hindustan Plate with Eurasia, the modern largest Mediterranean mountain belt was formed. In the Neogene (25-1.6 million years ago), the natural transformation of the continent continued towards an increase in relief contrast. The change in its nature in the anthropogene has already been carried out under the influence of man.

The formation of the geostructural heterogeneity of Eurasia in the Cenozoic, in addition to the movement of lithospheric plates, is associated with the Alpine tectonic era. In the Mediterranean belt, by the end of the Neogene, young folded mountains formed: the Pyrenees, Alps, Apennines, Carpathians, Caucasus, Hindu Kush, Pamir, Himalayas, as well as the mountains of Asia Minor, Iran, Burma and Indonesia. Young folded mountains also formed along the periphery of the Pacific Ocean.

Arch uplifts and block displacements along faults covered large areas of folded structures of various, more early age, causing the formation mountainous terrain on leveled denudation spaces. This is the origin of the mountain belt, which includes the Tien Shan, Altai, Sayan, Yablonevy and Stanovoy ranges, mountains Central Asia, Tibet, the Scandinavian Peninsula and the Urals. The Alpine orogeny is not over, as evidenced by earthquakes and volcanic eruptions. As noted, in the Cenozoic the Baikal rift system was formed, including Lake Baikal and its continuation depressions - grabens.

Throughout the geological history of Eurasia, transgression and regression of the sea, changes in climate conditions, settlement by plants and animals, as well as other processes that accompanied the formation of its natural appearance were characteristic. The diversity and mosaic nature of the continent's relief are associated with a wide variety of morphostructures that have a long history geological history formation. Below listed types of macrorelief(according to Ermakov et al., 1988) are the most common and have the largest area.

Basement and strata platform plains. In the formation of their relief, the main role belongs to the processes of long-term denudation and accumulation in marine and continental conditions. This type of relief includes the Fennoscandian shield, the European and West Siberian plains, as well as the plains of Central, Eastern and South Asia.

Blocky plateaus and highlands. This type of structure is represented in the European part of the continent by the Caledonian uplifts of Scandinavia and Scotland, in the Asian part by the Central Siberian, Arabian, Hindustan and other plateaus.

Folded block mountains and hills. These include: the uplifts of the Central French and Czech massifs, the epiplatform Ural Mountains revived in Hercynian times with gentle western and steep eastern slopes, the Kolyma Highlands with mid-altitude ridges and tectonic depressions; Altai-Sayan mountainous country in the form of ancient peneplains raised to different heights, framed by high ridges; systems of the Tien Shan and Pamir-Alai, representing the Paleozoic peneplain, raised (in places lowered) in the form of blocks to different heights into the Cenozoic folding (syrty). IN Overseas Asia This type of macrorelief includes the ancient middle massifs (Shan Highlands, Korat Plateau) on the Indochina Peninsula and in the People's Republic of China.

Folded and block-folded alpine midlands and highlands. They include the Pyrenees, Alps, Carpathians, Crimean-Caucasian mountain belt, mountainous regions of the Far East with extensive tertiary lava covers of Chukotka and volcanic cones of Kamchatka. In Foreign Asia (in relation to the territory of the USSR), this type of macrorelief includes the Hindu Kush, Karakorum, Himalayas and the mountains of western Indochina.

Block and folded-block mountains. Among them in Europe are the Rilo-Rhodope Mountains, and in Asia - the Western Asian Highlands, consisting of blocks of ancient peneplain of varying heights and the alpine ridges bordering them, the Vitim Plateau and southwestern Transbaikalia.

Particular mention should be made of the Tibetan Plateau, which is distinguished not only by its scale and height (4500-4600 m), but also by the presence of numerous sublatitudinal low ridges in the interior of the plateau. The Upper Paleozoic and Mesozoic blocks of the Tibetan Plateau are bordered by the highest mountain systems, uplifted (Himalayas, Karakoram) or modified (Kunlun) into the Alpine fold.

Accumulative and stratified intermountain and foothill plains and lowlands. Among them: the Amur-Primorsky, Mesopotamian and Indo-Gangetic, Venetian-Padan and Middle Danube lowlands.

Volcanic regions of island arcs. They O They belt the mainland from the east and southeast and are represented by ridges of islands of different sizes: the Kuril ridge, Sakhalin, the Japanese Islands, and the Malay Archipelago.

The modern relief of Eurasia, as a result of the long-term geological development of the continent, is not fully formed. It undergoes further changes under the influence of endogenous and exogenous factors. Among the most important endogenous processes, which determine the transformation of the modern macrorelief, stand out, first of all, the latest tectonic (neotectonic) movements and volcanism.

Neotectonic movements- these are rhythmic oscillatory movements tectonic structures of various sizes, influencing the formation of modern relief. The time of their manifestation covers the Neogene and Quaternary periods (the last 25 million years).

As a result of neotectonic movements, powerful mountain systems arose in the Mediterranean fold belt with contrasting relief. In the modern era, neotectonic movements are most strongly manifested during earthquakes in this folded belt, as well as in the eastern branch of the Ural-Mongolian belt (Altai, Tuva, Eastern Sayan, Baikal region, Stanovoye Highlands and Chersky Ridge).

Earthquakes of the same intensity (8-9 points on a 12-point scale) periodically repeat on the eastern flank of Eurasia in the Pacific belt (Kamchatka). In the coastal waters of the Japanese and Kuril Islands, underwater earthquakes (seaquakes) cause giant waves - tsunamis. The formation of mountainous terrain here is accompanied by active volcanism and the formation of various volcanic landforms.

Less significant earthquakes with a magnitude of 5-7 are quite common on the plains adjacent to seismically active mountain systems in the zone ranging from the foot of the latter to 250 km. Ancient and young platforms, as well as the Urals and the Kazakh small hills are characterized by low intensity earthquakes (up to 5 points).

Exogenous processes on land everywhere lead to the formation of sculptural (relatively small) relief forms. These include Quaternary glaciations, the activity of watercourses (rivers, streams and temporary ones), the accumulation of continental sediments in non-glacial areas and marine transgressions.

The most important event in the Quaternary history of Eurasia was continental glaciations. Glaciations were repeated many times, glacial epochs alternated with interglacial ones. The most significant glaciations were on the European part of the continent, occupying an area up to 48°N. (along the Dnieper valley). IN Western Siberia their southern border did not fall south of 60°N.

East of the Yenisei, ice cover was developed only in Taimyr and the north-west of the Central Siberian Plateau. In North-Eastern Siberia and Chukotka, glaciation was mountainous in nature. In the Alps, Pyrenees, Carpathians, Caucasus, mountains of Central Asia and the Himalayas there were local centers of mountain glaciations. The relief of the territory that experienced glaciations most fully reflects the traces of the last one - the Würm or Valdai glaciation, which ended about 8-10 thousand years ago.

The product of Quaternary glaciations is perennial cryolithozone (permafrost) in northern Europe and Western Siberia, the Central Siberian Plateau and the Far East. Its formation in Tibet is also caused by the high altitude of this highland above sea level, which is sufficient for this purpose.

In areas of accumulation and spreading of ice masses (Fennoscandia, New Earth, the northern part of the Urals, the Byrranga Mountains and the Putorana Plateau) hollows and gouging hollows arose ( excision relief forms), as well as curly rocks. In areas where glacier movement slowed down or stopped, formations formed. accumulative forms. Finite moraine ridges, main moraine fields with medium and small hilly relief on the territory of Belarus are the result of the last continental glaciation.

The melting of the glacier was accompanied by the appearance of glacial rivers and lakes on its surface, the filling of which with clastic material (gravel, pebbles and sand) led to the formation of positive relief forms on the modern earth's surface: eskers (linear) and kames (oval in terms of relief forms). At the marginal zones of the melting and retreating continental glacier, water-glacial, outwash, ancient lake and ancient alluvial plains formed.

Widespread in Eurasia loess and loess-like(resembling loess) sedimentary rocks, which served as the lithogenic basis for the formation of unique landscapes. The question of the origin of these breeds has not yet received a generally accepted solution. Most likely, they are characterized by a polygenetic origin from the aeolian transfer of dust and soil-forming processes to the aqueous accumulation of glacial turbidity in water-glacial and alluvial flows.

According to aeolian hypothesis, the origin of loess is the result of the combined activity of wind, rain and vegetation. Proponents of this hypothesis distinguish two types of aeolian loess: “warm” and “cold”. Warm loess was formed as a result of the removal of dust from deserts and its deposition in the bordering steppes. This is how loess could have formed in Central Asia. The thickness of loess on the Loess Plateau in China, bordered in the north by the Ordos Desert and in the northwest by the Alashan Desert, ranges from 100-250 m.

“Cold” loess and loess-like loams cover sedimentary rocks in the periglacial (pereglacial) zone with a cover ranging in thickness from several tens of centimeters to several meters. Its origin is dust brought by an anticyclone from the surface of a glacier and blown from periglacial deposits during dry glacial periods. Such a cover is characteristic of the landscapes of central Belarus, including the Orshano-Mogilev plateau.

Other hypotheses the origin of loess and loess-like rocks suggests the participation of soil-forming processes or the accumulation of turbidity in water flows in a particular area. The abundance of suffusion funnels significantly complicates the use in agriculture these territories well developed by humans. In addition, in conditions of rugged terrain, water erosion has become widespread.

The contrasting relief of Eurasia, which arose as a result of recent tectonic movements, contributed to the development erosion activity temporary watercourses, rivers and streams. In the mountains and uplands, this led to the formation of erosional relief, and in the intermountain basins, foothills and depressions lying among the plains, to the accumulation of sediment and the formation of proluvial, alluvial and lacustrine plains. In an arid climate, many of them turned into modern sandy, clayey and other deserts.

The Quaternary period was characterized change in sea level– decrease as a result of water accumulation in continental glaciers and increase during interglacial periods. The regression of the sea during the last glaciation led to the formation of Berengia - land between Eurasia and North America on the site of the modern shelf of the Arctic Ocean and the northern part of the Bering Sea.

Transgression of sea water from the Arctic Ocean reached the Siberian ridges of the West Siberian Plain; the North Siberian (Taimyr) Lowland and the valleys of the northern rivers of the East European Plain were filled with water. Traces of transgression have been preserved on the shores of the Baltic, Caspian and Black Seas. Quaternary transgressions formed the relatively flat relief characteristic of marine plains.

The morphostructural and morphosculptural heterogeneity of Eurasia served as the arena in which the evolution of its organic world took place, natural zonation and regional spatial differentiation of soils, vegetation and fauna were formed under the influence of changing climatic conditions.

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