Geography. Relief of the earth. Factors influencing the formation of relief. Internal process that affects the formation of relief

14.10.2019

Over time, it changes under the influence of various forces. Places where there were once great mountains become plains, and in some areas volcanoes arise. Scientists are trying to explain why this happens. And already a lot modern science known.

Reasons for transformation

The Earth's topography is one of the most interesting riddles nature and even history. Because of the way the surface of our planet changed, the life of mankind also changed. Changes occur under the influence of internal and external forces.

Among all landforms, large and small ones stand out. The largest of them are continents. It is believed that hundreds of centuries ago, when there was no man yet, our planet had a completely different appearance. Perhaps there was only one continent, which over time was split into several parts. Then they separated again. And all those continents that exist now appeared.

Another major form was the oceanic trenches. It is believed that there were also fewer oceans before, but then there were more. Some scientists argue that hundreds of years later new ones will appear. Others say that the water will flood some areas of the land.

The relief of the planet has been changing over many centuries. Even though people sometimes greatly harm nature, their activities are not capable of significantly changing the relief. This requires such powerful forces that only nature has. However, man cannot not only radically transform the planet’s topography, but also stop the changes that nature itself produces. Despite the fact that science has made great strides forward, it is not yet possible to protect all people from earthquakes, volcanic eruptions and much more.

Basic information

The Earth's topography and major landforms attract close attention many scientists. The main varieties include mountains, highlands, shelves and plains.

The shelf is those areas of the earth's surface that are hidden under water. Very often they stretch along the banks. A shelf is a type of landform that is found only underwater.

Highlands are isolated valleys and even systems of ridges. Much of what is called mountains is actually highlands. For example, the Pamir is not a mountain, as many people believe. Also, the Tien Shan is a highland.

Mountains are the most ambitious landforms on the planet. They rise above the land by more than 600 meters. Their peaks are hidden behind the clouds. It happens that in warm countries you can see mountains whose peaks are covered with snow. The slopes are usually very steep, but some daredevils dare to climb them. Mountains can form chains.

The plains are stability. Residents of the plains are least likely to experience changes in relief. They hardly know what earthquakes are, which is why such places are considered the most favorable for life. A true plain is the flattest possible surface of the earth.

Internal and external forces

The influence of internal and external forces on the Earth's topography is enormous. If you study how the surface of the planet has changed over several centuries, you will notice how what seemed eternal disappears. It is being replaced by something new. External forces are not capable of changing the Earth's topography as much as internal ones. Both the first and second are divided into several types.

Inner forces

The internal forces that change the Earth's topography cannot be stopped. But in modern world scientists from different countries they are trying to predict when and in what place there will be an earthquake, where a volcanic eruption will occur.

Internal forces include earthquakes, movements and volcanism.

As a result, all these processes lead to the appearance of new mountains and mountain ranges on land and on the ocean floor. In addition, geysers, hot springs, chains of volcanoes, ledges, cracks, depressions, landslides, volcanic cones and much more appear.

External forces

External forces are not capable of producing noticeable transformations. However, you should not lose sight of them. Those that shape the Earth's topography include the following: the work of wind and flowing water, weathering, melting glaciers and, of course, the work of people. Although man, as mentioned above, is not yet capable of greatly changing the appearance of the planet.

The work of external forces leads to the creation of hills and ravines, basins, dunes and dunes, river valleys, rubble, sand and much more. Water can very slowly destroy even a great mountain. And those stones that are now easily found on the shore may turn out to be part of a mountain that was once great.

Planet Earth is grandiose creation, in which everything is thought out to the smallest detail. It has changed over the centuries. Cardinal transformations of the relief took place, and all this was under the influence of internal and external forces. In order to better understand the processes occurring on the planet, it is imperative to know about the life it leads, not paying attention to humans.

>> Internal (endogenous) processes of formation of the Earth's relief

§ 2. Internal (endogenous) processes

formation of the Earth's relief

Relief is a collection of irregularities in the earth's surface of different scales, called landforms.

Folds- wave-like bends of the layers of the earth's crust, created by the combined action of vertical and horizontal movements in the earth's crust. A fold whose layers are bent upward is called an anticlinal fold, or anticline. A fold whose layers are bent downwards is called a synclinal fold, or syncline. Synclines and anticlines are the two main forms of folds. Small and relatively simple in structure folds are expressed in the relief by low compact ridges (for example, the Sunzhensky ridge of the northern slope Greater Caucasus).

Larger and more complex folded structures are represented in the relief by large mountain ranges and depressions separating them (the Main and Side ranges of the Greater Caucasus). Even larger folded structures, consisting of many anticlines and synclines, form mega relief forms such as a mountainous country, for example the Caucasus Mountains, the Ural Mountains, etc. These mountains are called folded.

Faults- these are various discontinuities in rocks, often accompanied by movement of broken parts relative to each other. The simplest type of ruptures are single, more or less deep cracks. The largest faults, extending over a significant length and width, are called deep faults.

Depending on how the broken blocks moved in the vertical direction, faults and thrusts are distinguished (Fig. 16). Sets of normal faults and thrusts make up horsts and grabens (Fig. 17). Depending on their size, they form individual mountain ranges (for example, the Table Mountains in Europe) or mountain systems and countries (for example, Altai, Tien Shan).

In these mountains, along with grabens and horsts, there are also folded massifs, so they should be classified as folded-block mountains.

In the case when the movement of rock blocks was not only in the vertical direction, but also in the horizontal direction, shifts are formed.

In the process of developing the sciences Earth Many different hypotheses have been put forward about the development of the earth's crust.

The theory of lithospheric plates is based on the idea that all Lithosphere divided by narrow active zones - deep faults - into separate rigid plates floating in the plastic layer of the upper mantle.

The boundaries of lithospheric plates, both in places of their rupture and in places of collision, are moving sections of the earth's crust, to which most active volcanoes are confined, where earthquakes are frequent. These areas, which are areas of new folding, form the Earth's seismic belts.

The further from the boundaries of the moving areas to the center of the plate, the more stable the sections of the earth's crust become. Moscow, for example, is located in the center of the Eurasian plate, and its territory is considered seismically quite stable.

Volcano- a set of processes and phenomena caused by the penetration of magma into the earth’s crust and its outpouring onto the surface. From deep magma chambers, lava, hot gases, water vapor and rock fragments erupt onto the earth. Depending on the conditions and paths of magma penetration to the surface, three types of volcanic eruptions are distinguished.

Area eruptions led to the formation of vast lava plateaus. The largest of them are the Deccan Plateau on the Hindustan Peninsula and the Columbia Plateau.

Fissure eruptions occur along cracks, sometimes of great length. Currently, volcanism of this type occurs in Iceland and on the ocean floor in the area of mid-ocean ridges.

Central eruptions are associated with certain areas, usually at the intersection of two faults, and occur along a relatively narrow channel called a vent. This is the most common type. Volcanoes formed during such eruptions are called layered or stratovolcanoes. They look like a cone-shaped mountain with a crater on top.

Examples of such volcanoes: Kilimanjaro in Africa, Klyuchevskaya Sopka, Fuji, Etna, Hekla in Eurasia.

"Pacific Ring of Fire". About 2/3 of the Earth's volcanoes are concentrated on islands and the shores of the Pacific Ocean. The most powerful eruptions volcanoes and earthquakes took place in this region: San Francisco (1906), Tokyo (1923), Chile (1960), Mexico City (1985).

Sakhalin Island, the Kamchatka Peninsula and the Kuril Islands, located in the very east of our country, are links in this ring.

In total, there are 130 extinct volcanoes and 36 active volcanoes in Kamchatka. The largest volcano is Klyuchevskaya Sopka. There are 39 volcanoes on the Kuril Islands. These places are characterized by destructive earthquakes, and the surrounding seas are characterized by seaquakes, typhoons, volcanoes and tsunamis.

Tsunami translated from Japanese - “wave in the bay”. These are waves of gigantic size generated by an earthquake or sea quake. In the open ocean they are almost invisible to ships. But when the path of the tsunami is blocked by the mainland and islands, the wave hits the land from a height of up to 20 meters. So, in 1952, such a wave completely destroyed the Far Eastern city of Severokurilsk.

Hot springs and geysers are also associated with volcanism. In Kamchatka, in the famous Valley of Geysers, there are 22 large geysers.

Earthquakes They are also a manifestation of endogenous earth processes and represent sudden underground impacts, tremors and displacements of layers and blocks of the earth's crust.

Studying earthquakes. At seismic stations, scientists study these formidable natural phenomena, using special instruments, and look for ways to predict them. One of these devices, the seismograph, was invented at the beginning of the 20th century. Russian scientist B.V. Golitsyn. The name of the device comes from the Greek words seismo (oscillation), grapho (writing) and speaks of its purpose - to record the vibrations of the Earth.

There may be earthquakes different strengths. Scientists agreed to determine this force on an international 12-point scale, taking into account the degree of damage to buildings and changes in the Earth's topography. Here is a fragment of this scale (Table 5).

Table 5

Earthquakes are accompanied by tremors, following one after another. The place where the shock occurs in the depths of the earth's crust is called the hypocenter. The place on the earth's surface located above the hypocenter is called the epicenter of an earthquake.

Earthquakes cause the formation of cracks on the earth's surface, displacement, lowering or raising of individual blocks, landslides; cause damage to the economy and lead to the death of people.

Maksakovsky V.P., Petrova N.N., Physical and economical geography peace. - M.: Iris-press, 2010. - 368 pp.: ill.

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Forces constantly act on the earth's surface, changing the earth's crust and contributing to the formation of relief. All these processes are different, but they can be combined into two groups: external (or exogenous) and internal (or endogenous). Exogenous processes operate on the surface of the Earth, and endogenous processes act on the surface of the Earth, the sources of which are located in the bowels of the planet. The gravitational forces of the Moon and the Sun act on the Earth from the outside. The gravitational force of other celestial bodies is very small, but some scientists believe that in geological history Earth's gravitational influences from space may increase. Many scientists also consider gravity to be an external, or exogenous, force, which causes landslides, mountain falls, and glaciers to move from mountains.

Exogenous forces destroy and transform the earth's crust, transporting loose and soluble products of destruction carried out by water, wind, and glaciers. Simultaneously with destruction, there is also a process of accumulation, or accumulation of destruction products. The destructive effects of exogenous processes are often undesirable and even dangerous for humans. Such dangerous phenomena include, for example, mudflows and stone flows. They can demolish bridges, dams, and destroy crops. Landslides are also dangerous, which also lead to the destruction of various buildings, thereby causing damage to the economy and killing people. Among the exogenous processes, it is necessary to note weathering, which leads to relief leveling, as well as the role of wind.

Endogenous processes raise individual sections of the earth's crust. They contribute to the formation of large relief forms - megaforms and macroforms. Main source of energy endogenous processes- internal heat in the bowels of the Earth. These processes cause the movement of magma, volcanic activity, earthquakes, and slow vibrations of the earth's crust. Internal forces work in the bowels of the planet and are completely hidden from our eyes.

Thus, the development of the earth's crust and the formation of relief are the result of the combined action of internal (endogenous) and external (exogenous) forces and processes. They act as two opposite sides of a single process. Thanks to endogenous, mainly creative processes, large relief forms are formed - plains, mountain systems. Exogenous processes predominantly destroy and level the earth's surface, but at the same time form smaller (microforms) relief forms - ravines, river valleys, and also accumulate destruction products.

Processes influencing the formation of the earth's crust Wikipedia
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Lithosphere platforms

Platforms are relatively stable areas of the earth's crust. They arise on the site of pre-existing folded structures of high mobility, formed during the closure of geosynclinal systems, through their successive transformation into tectonically stable areas.

A characteristic feature of the structure of all lithospheric platforms of the Earth is their structure of two tiers or floors.

The bottom structural floor is also called the foundation. The foundation is composed of highly dislocated metamorphosed and granitized rocks, penetrated by intrusions and tectonic faults.

Based on the time of foundation formation, platforms are divided into ancient and young.

Ancient platforms, which also form the cores of modern continents and are called cratons, are Precambrian in age and formed mainly by the beginning of the Late Proterozoic. Ancient platforms are divided into 3 types: Laurasian, Gondwanan and transitional.

The first type includes the North American (Laurentia), East European and Siberian (Angarida) platforms, formed as a result of the breakup of the supercontinent Laurasia, which in turn formed after the breakup of the protocontinent Pangea.

To the second: South American, African-Arabian, Hindustan, Australian and Antarctic. Before the Paleozoic era, the Antarctic platform was divided into the Western and Eastern platforms, which were united only in the Paleozoic era. The African platform in the Archean was divided into the protoplatforms of Congo (Zaire), Kalahari (South African), Somalia (East African), Madagascar, Arabia, Sudan, and Sahara. After the collapse of the supercontinent Pangea, the African protoplatforms, with the exception of the Arabian and Madagascar ones, united. The final unification occurred in the Paleozoic era, when the African Plate turned into the African-Arabian Plate as part of Gondwana.

The third intermediate type includes small-sized platforms: Sino-Korean (Huang He) and South China (Yangtze), which different time were both part of Laurasia and part of Gondwana.

The foundation of ancient platforms involves Archean and Early Proterozoic formations. Within the South American and African platforms, some of the formations date back to the Upper Proterozoic. The formations are deeply metamorphosed (amphibolite and granulite facies of metamorphism); main role Among them are gneisses and crystalline schists, and granites are widespread. Therefore, such a foundation is called granite-gneiss or crystalline.

Young platforms formed in Paleozoic or Late Cambrian times, they border ancient platforms. Their area is only 5% of the total area of the continents. The foundation of the platforms is composed of Phanerozoic sedimentary-volcanic rocks that have undergone weak (greenschist facies) or even only initial metamorphism. There are blocks of more deeply metamorphosed ancient, Precambrian, rocks. Granites and other intrusive formations, among which ophiolite belts should be noted, play a subordinate role in the composition. Unlike the foundation of ancient platforms, the foundation of young ones is called folded.

Depending on the time of completion of the foundation deformations, the division of young platforms into epibaikalian (the most ancient), epicaledonian and epihercynian.

The first type includes the Timan-Pechora and Mizian platforms of European Russia.

The second type includes the West Siberian and East Australian platforms.

To the third: Ural-Siberian, Central Asian and Cis-Caucasian platforms.

Between the foundation and the sedimentary cover of young platforms, an intermediate layer is often distinguished, which includes formations of two types: sedimentary, molasse or molasse-volcanic filling of intermountain depressions of the last orogenic stage of development of the mobile belt that preceded the formation of the platform; clastic and clastic-volcanogenic fill of grabens formed during the transition from the orogenic stage to the early platform

The upper structural floor or platform cover is composed of non-metamorphosed sedimentary rocks: carbonate and shallow sandy-clayey in platform seas; lakes, alluvial and swamps in humid climates on the site of former seas; aeolian and lagoonal in arid climates. The rocks lie horizontally with erosion and unconformity at the base. The thickness of the sedimentary cover is usually 2-4 km.

In a number of places, the sedimentary layer is absent as a result of uplift or erosion and the foundation comes to the surface. Such sections of platforms are called shields.

The influence of internal and external processes on the formation of relief

The Baltic, Aldan and Anabar shields are known on the territory of Russia. Within the shields of ancient platforms, three complexes of rocks of Archean and Lower Proterozoic age are distinguished:

Greenstone belts, represented by thick strata of regularly alternating rocks from ultrabasic and basic volcanics (from basalts and andesites to dacites and rhyolites) to granites. Their length is up to 1000 km and their width is up to 200 km.

Complexes of ortho- and para-gneisses, forming granite gneiss fields in combination with granite massifs. Gneisses are similar in composition to granites and have a gneiss-like texture.

Granulite (granulite-gneiss) belts, which are metamorphic rocks formed under conditions of medium pressure and high temperatures (750-1000 ° C) and containing quartz, feldspar and garnet.

Areas where the foundation is covered everywhere by a thick sedimentary cover are called slabs. For this reason, most young platforms are sometimes simply called slabs.

The largest elements of the platforms are syneclises: extensive depressions or troughs with inclination angles of only a few minutes, which correspond to the first meters per kilometer of movement. As an example, we can name the Moscow syneclise with its center near the city of the same name and the Caspian one within the Caspian lowland. In contrast to syneclises, large platform uplifts are called anteclises. On the European territory of Russia, the Belarusian, Voronezh and Volga-Ural anteclises are known.

Large negative elements of platforms are also grabens or aulacogens: narrow extended areas, linearly oriented and limited by deep faults. They can be simple or complex. IN the latter case Along with troughs, they include uplifts - horsts. Along the aulacogens, effusive and intrusive magmatism is developed, which is associated with the formation of volcanic covers and explosion pipes. All igneous rocks within platforms are called traps.

Smaller elements are shafts, domes, etc.

Lithospheric platforms experience vertical oscillatory movements: they rise or fall. Transgressions and regressions of the sea that have repeatedly occurred throughout the geological history of the Earth are associated with such movements.

In Central Asia, the formation of the mountain belts of Central Asia: Tien Shan, Altai, Sayan, etc. is associated with the latest tectonic movements of platforms. Such mountains are called regenerated (epiplatforms or epiplatform orogenic belts or secondary orogens). They are formed during the era of orogenesis in areas adjacent to geosynclinal belts.

1. Changes in relief under the influence of internal processes

Klestov Svyatoslav, Sadovnikov Danil 8b

2.

Relief is a set of irregularities in the earth
surfaces of different scales called shapes
relief.
The relief is formed as a result of the impact on
lithosphere of internal (endogenous) and external
(exogenous) processes.
Processes that form the relief and related to them
natural phenomena.

3. Processes changing the relief

Volcanism –
a set of processes and phenomena associated with the movement of magma (together with
gases and steam) in the upper mantle and earth's crust, its outpouring in the form of lava or
released to the surface during volcanic eruptions
Earthquakes –
These are tremors and vibrations of the earth's surface. According to modern
In our opinion, earthquakes reflect the process of geological transformation
planets.
Tectonic movements –
these are mechanical movements of the earth's crust caused by forces that act
in the earth's crust and mainly in the earth's mantle, leading to deformation
rocks that make up the crust.

4. Volcanism

In Russia, the vast majority of volcanic mountains and all active volcanoes
located in the east of the country - on the Kamchatka Peninsula and the Kuril Islands.
This territory belongs to the so-called “Ring of Fire”, within
which contains more than 2/3 of the planet's active volcanoes. Here
there is a grandiose tectonic process of interaction between two large
lithospheric plates - Pacific and Sea of Okhotsk. At the same time, the earth's crust of the Pacific
ocean, more ancient and heavier, sinks (subducts) under the Sea of Okhotsk and,
melting at great depths, it gives rise to magma chambers that feed
volcanoes of Kamchatka and Kuril Islands.
About 30 active and more than 160 extinct volcanoes are now known in Kamchatka.
Most often, strong and catastrophic eruptions occurred in the Holocene (over the last 10
thousand

years) occurred on two volcanoes - Avachinskaya Sopka and Shiveluch.
Klyuchevskaya Sopka Volcano is the largest active volcano Eurasia (4,688 m) -
known for its perfect, extraordinarily beautiful cone. First
the eruption of the Klyuchevskaya Sopka volcano was described in 1697 by the pioneer of Kamchatka
Vladimir Atlasov. On average, a volcanic eruption occurs once every five years, and in
certain periods - annually, sometimes for several years, and
accompanied by explosions and ash falls.

5. Eruption of the Klyuchevskaya Sopka volcano

6.
internal and external processes of the earth

Earthquakes

In Russia, earthquakes occur in mountainous areas, at the junction
tectonic plates - Caucasus, Altai, Western Siberia, Eastern Siberia, Kamchatka.
Most earthquakes in Russia occur in remote, sparsely populated areas
areas, but those earthquakes that occur in populated areas average 5-6
once a century they take away a lot human lives, houses and villages are being destroyed. So
during the earthquake on Sakhalin in 1995, the village was completely destroyed
Neftegorsk Most earthquakes occur in Kamchatka and the Kuril Islands
islands, sometimes accompanied by tsunamis. Due to the earthquake in the Pacific Ocean
a tsunami formed off the coast of Kamchatka in 1952, which completely destroyed
city of Severo-Kurilsk.
Earthquakes occur due to the collision of lithospheric plates, as in the Caucasus
The Arabian Plate is moving north onto the Eurasian Plate. In Kamchatka
The Pacific plate collides with the Eurasian plate, also volcanic activity
is one of the causes of small tremors occurring in
in the immediate vicinity of the volcano or on it itself.

7. Neftegorsk earthquake (1995)

8. Tectonic movements of Russia

As a result of the long history of geological development on the territory of Russia,
main types of geotextures - flat-platform areas and large orogenic mobile
belts

However, within the same geotextures, completely different
relief (low basement plains of Karelia and the Aldan Highlands on the shields of ancient platforms;
low Ural Mountains and high Altai within the Ural-Mongolian belt, etc.);
on the contrary, similar relief can form within different geotextures (high mountain
Caucasus and Altai). This is due to the great influence on the modern relief of neotectonic
movements that began in the Oligocene (Upper Paleogene) and continue to the present
time.
After a period of relative tectonic quiescence at the beginning of the Cenozoic, when
low plains and practically no mountains preserved (only in the area of Mesozoic folding
in some places, apparently, small hills and low mountains were preserved), vast areas of Western
Siberia and the south of the East European Plain were covered with shallow sea waters
swimming pools. In the Oligocene, a new period of tectonic activation began - neotectonic
a stage that led to a radical restructuring of the relief.
The latest tectonic movements and morphostructures. Neotectonics, or the latest
tectonic movements, V.A. Obruchev defined as the movements of the earth's crust that created
modern relief. It is with the latest (Neogene-Quaternary) movements that the
formation and placement of morphostructures - large relief forms - across the territory of Russia,
arising as a result of the interaction of endogenous and exogenous processes with a leading role
first.

9.

Altai Mountains

Changes in relief under the influence of internal processes

English РусскийRules

Relief is formed mainly as a result of long-term simultaneous effects on the earth's surface of endogenous (internal) and exogenous (external) processes.

Processes influencing the formation of the earth's crust

Relief is the study of geomorphology. Endogenous processes are relief-forming processes that occur mainly in the bowels of the Earth and are determined by its internal energy, gravity and forces arising during the rotation of the Earth. Endogenous processes manifest themselves in the form of tectonic movements, magmatism, in the activity of mud volcanoes, etc. Endogenous processes play a major role in the formation of large landforms. Exogenous processes are relief-forming processes occurring on the surface of the Earth and in the uppermost parts of the earth's crust: weathering, erosion, denudation, abrasion, glacial activity, etc. Exogenous processes are caused mainly by the energy of solar radiation, gravity and the vital activity of organisms. Exogenous processes predominantly form meso and microrelief forms.

what forces created the continents

Supermind from above)

1) human activity 2) weathering 3) activity of groundwater 4) movement of lithosphere plates 5) activity of flowing waters

Geological processes of formation and development of the earth's crust and relief

When studying this topic, it is important to understand the essence of endogenous and exogenous processes, to have a correct understanding of the interaction of endogenous and exogenous forces and the role of this interaction in creating the relief of the earth's surface and soil-forming rocks.

Geological processes take place on the surface of the Earth and in its interior, which are usually divided into two large groups according to energy sources: 1) endogenous and 2) exogenous.

Exogenous processes arise as a result of external influences on the globe (atmosphere, hydrosphere, biosphere) and appear on its surface. They are mainly generated by the thermal energy of the Sun entering the earth and transformed into other types of energy.

Endogenous processes manifest themselves when the internal forces of the Earth act on the solid shell. They are caused by the energy that accumulates in the bowels of the Earth. Endogenous processes include: magmatism, metamorphism, tectonic movements of the earth's crust (epeirogenesis and orogenesis) and earthquakes.

You should know that many hot springs (therms) and their variety - geysers (periodically gushing) are associated with the activity of volcanoes, which bring to the surface a large amount of mineral substances that form mineral cones (geyserites).

In conclusion, it should be pointed out that volcanism plays a large role in soil formation processes and affects the properties of modern soil cover.

With intrusive magmatism (plutonism), magma penetrates into the earth's crust, without reaching the Earth's surface, it immediately solidifies, forming magmatic bodies of various shapes - intrusions (batholiths, stocks, laccoliths, phacoliths, lopoliths, chonoliths).

Igneous activity is the main cause of mountainous terrain.

The processes of change and transformation of rocks occurring inside the Earth were called metamorphism. When studying this process, pay attention to the causes and main types of metamorphism, among which contact metamorphism, regional and dynamometamorphism are distinguished.

Tectonic movements are the movements of matter in the earth's crust under the influence of processes occurring in the interior of the Earth (in the mantle, in the deep and upper parts of the earth's crust).

Tectonic movements of the earth's crust create over a long period of time the main forms of the earth's surface - mountains and depressions.

There are two types of tectonic movements: folded and faulty, or orogenic(creating mountains), and oscillating, or epeirogenic(creating continents).

All tectonic movements are interconnected, fold and fault movements can transform into each other, as a result of their action earthquakes occur in the earth's crust, and the formation of deposits of many minerals (oil, coal, etc.) is associated with them.

Oscillatory (epeirogenic) movements – the most common form of tectonic movement. These are slow secular uplifts and subsidences that the earth's crust constantly experiences.

Secular oscillatory movements have great importance in the life of humanity.

A gradual rise in land level changes the topographic, hydrological, geochemical conditions of soil formation, leads to increased processes of erosion, leaching, and the emergence of new relief forms. The sinking of the land leads to the accumulation of mechanical, chemical, and biogenic sediments and swamping of the area.

Along with centuries-long phenomena, there are phenomena of modern seismotectonics - earthquakes and seaquakes.

When studying this phenomenon, one should consider the geographical distribution of earthquakes, the causes, consequences of earthquakes and their prediction.

In conclusion, it should be emphasized that movements of the earth’s crust (both slow and relatively fast) play a decisive role in the formation of the modern topography of the earth’s surface and lead to the division of the surface into two qualitatively different areas - geosynclines And platforms.

Exogenous processes– these are processes external dynamics. They occur on the surface of the Earth or at shallow depths in the earth’s crust under the influence of forces caused by the energy of solar radiation, gravity, the vital activity of plant and animal organisms and human activity. Exogenous processes that transform the relief of continents include: weathering, various slope processes, the activity of flowing water, the activity of oceans and seas, lakes, ice and snow, permafrost processes, the activity of wind, groundwater, processes caused by human activity, biogenic processes.

When considering exogenous processes, it is necessary to understand not only the essence of each of them, but also to understand their role in the formation of relief and the formation of sediments and to study them.

It should be clearly understood that weathering, which is the first link in the system of exogenous processes, contributes to the transformation of rocks into loose material and prepares it for transport.

As a result of the destruction of rocks, various weathering products are formed: mobile, which are carried away under the influence of gravity, planar washout, and residual, which remain at the site of destruction and are called eluvium.

Eluvium is one of the important genetic types of continental sediments. Eluvial formations that make up the most top part lithosphere are called weathering bark.

As a result of weathering, rocks undergo profound physical and chemical changes and acquire a number of new properties favorable for plant life (air permeability, water permeability, porosity, moisture capacity, absorption capacity, supply of ash nutrients available to organisms).

Weathering has little effect directly on the relief, but weathering processes destroy rocks, thereby facilitating the impact of denudation agents on them.

Wind activity consists of the processes of deflation (blowing and fluttering), corrosion (grinding), transfer and accumulation (deposition).

Having mastered the main features of wind activity, you should study the forms of aeolian relief (deflationary and accumulative) and aeolian deposits (sands and loess).

Activity of surface flowing waters(fluvial processes). Consideration of this issue should begin with the study of surface runoff, which is widespread on the surface of the continents and determines the main features of their landscapes in almost all physical-geographical zones (excluding the zone of deserts and eternal snow) both in the mountains and on the plains.

When studying the activity of surface waters, first of all, it should be understood that their work consists of flushing, erosion of the surface (erosion), transportation and accumulation of erosion products (accumulation). The combination of erosion and accumulation processes determines the formation of erosional and accumulative relief forms.

Temporary flows in the form of non-channel runoff (planar washout) transport material along the slope and lead to the formation of deluvial and proluvial deposits, which are a unique genetic type of continental deposits.

It is important to understand that planar washout can easily turn into linear washout where unevenness appears on the slopes, the vegetation cover is disturbed, and there are cracks in the soil. Flowing water, collecting in depressions, lingers and erodes the soil. At the site of the beginning of erosion, a pothole first forms, then a gulley and finally a ravine.

Unlike temporary streams, rivers are permanent channel streams. Rivers constantly perform not only the work of erosion, but also the work of transporting and deposition of material.

When studying the structure of a river valley from a textbook, you should draw a profile (longitudinal and transverse), showing the floodplain, terraces, and bedrock slopes.

It is necessary to consider the formation of characteristic forms of floodplain relief (microrelief), which includes riverbed banks, ridges and interridge depressions, oxbow depressions, and study the main types of alluvium (channel, floodplain).

It is important to understand that the floodplain, terraces, bedrock banks and valley as a whole are the result of river channel migration both horizontally and vertically. The direction of displacement and its intensity are entirely determined by the position of the erosion base, tectonic movements and the hydrological regime of the watercourse, which depends on climate.

The study of fluvial processes should be completed by considering the role of flowing waters in transforming the relief of the earth's surface.

Activity of seas and lakes. The sea occupies about 71% of the earth's surface and carries out a variety of work on the destruction of rocks, the transfer of destroyed material and its accumulation and the creation of new rocks, with the processes of sediment accumulation predominating.

Repeated replacement of land by sea, especially transgressions in the Neogene and Quaternary periods, played a role in the formation of the modern coastal topography. The result of these transgressions are the marine accumulative plains of the North of Russia and the Caspian lowland.

The activity of lakes is similar to the activity of the sea and differs from it mainly only in its scale.

To underground waters includes all water located in the pores and cracks of rocks. Groundwater is a special type of mineral resource. They are becoming increasingly important in the national economy. Various manifestations of their activity and interaction with soil waters represent specific objects of observation by soil scientists and agronomists. Particular attention should be paid to karst, suffosion, landslide and solifluction processes and landforms, various types chemogenic accumulation and mineralization of groundwater.

The depth of groundwater and the degree of its mineralization have a great influence on the properties of soils, the nature of vegetation and the processes occurring in them (gleyization, swamping, salinization), and shape the landscape features of the area.

When studying the activity of groundwater, it is important to understand the essence of karst phenomena and the conditions that favor their development, and to understand the general features of karst landforms. In karst areas, the leading processes are the dissolution and leaching of rocks, which occur under conditions of prevailing vertical circulation of groundwater, in easily soluble and permeable rocks.

Snow and ice activity. Glaciers do a lot of destructive and creative work. Thanks to their activity, the topography of the earth's surface changes, a significant amount of clastic material moves and a variety of sediments accumulate.

When studying this issue, you should pay attention to a number of general issues activity of glaciers, namely: the concept of the snow boundary, conditions for the formation and development of glaciers. Without a good understanding of these concepts, it is difficult to understand the remaining issues of the topic.

The relief of areas dominated by glacial demolition is represented by forms of glacial processing, shading and polishing: curly rocks, sheep's foreheads and forms of glacial gouging: depressions, basins.

The relief of areas where glacial accumulation predominates is represented by hilly-moraine, terminal moraine, and drumlin landscapes.

The relief of non-glacial areas is associated with the activity of melted glacial waters and is represented by outwash plains, periglacial lakes, eskers and kamas.

In post-glacial times, the moraine and fluvio-glacial relief changed under the influence of planar washout, solifluction, erosion and tectonic movements (smoothing of hills and filling of lake depressions, descent of lakes, development of a gully-beam network, formation of floodplains and terraces, formation of dunes).

At the end of the section, carefully study the properties of all types of sediments associated with the activity of the glacier and water-glacial flows.

Beneath the permafrost understand the state of rocks in which they retain negative temperatures for a long time (hundreds and thousands of years).

When considering this issue, it is necessary to study the causes and boundaries of permafrost.

The presence of frozen rocks at shallow depths causes the development of special phenomena (thermokarst and solifluction) and creates a unique complex of relief forms - solifluction terraces (sintered forms), upland terraces (stepped forms of mountain slopes), large peat mounds (during heaving processes), aufeis, hydrolaccoliths, polygonal formations.

When studying this issue, the student must understand not only the causes, essence and boundaries of the distribution of permafrost, but also the influence that the presence of permafrost has on the soil-forming process, the specifics of agriculture and the features of the organization and implementation of engineering work in areas where permafrost is distributed.

Self-test questions

Endogenous and exogenous processes of transformation of the earth's crust, features of their manifestation. Their unity and interconnection and energy sources.

2. Fold disturbances, folds, their types (synclines and anticlines), significance in the formation of minerals.

3. Fractures in the earth’s crust, their types, significance for soil formation and accumulation of minerals.

4. Chemical weathering of rocks. Name the main ones chemical reactions. Give the concept of eluvium and weathering crust.

5. Name the types of deserts.

6. Compare glacial and fluvioglacial landforms and sediments.

7. Describe the main links of the hydrographic network (ravine, ravine, gully, valley).

Development of landforms

Make a schematic sketch of the river valley and show the floodplain, terrace, bedrock slopes.

9. Geological activity of lakes and swamps, their types, sediments, economic significance.

10. What are the features of relief formation in permafrost conditions?

11. Name the types of relief (morphological and genetic) and categories of relief by dimension.

12. Study individual landforms in your area and explain their origins.

13. The concept of landscape and its evolution in connection with the evolution of relief.

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Relief of the Earth

Questions for students:

— Who remembers from the 6th grade course what relief is? (Relief is a set of irregularities on the earth's surface). Students write down this definition in the dictionary, which is located on the back of the notebook.

- Remember what landforms you know and fill in the diagram on the board. On the board, the teacher hangs a diagram of upside-down cards with terms:

Fig.1. Block diagram “Earth Relief”

Students fill out the diagram in their notebook.

Teacher's story.

Relief - the totality of all the irregularities of the earth's surface

The surface of the Earth, of course, is not completely flat. The elevation differences on it from the Himalayas to the Mariana Trench reach two tens of kilometers.

How the relief is formed

The topography of our planet continues to form even now: lithospheric plates collide, crushing into folds of mountains, volcanoes erupt, rivers and rains erode rocks. If we ended up on Earth in a few hundred million years, we would no longer recognize the map of our home planet, and all the plains and mountain systems would have changed beyond recognition during this time. All processes that shape the Earth's topography can be divided into two large groups: internal and external. Otherwise, internal ones can be called endogenous. These include subsidence and uplift of the crust, volcanism, earthquakes, plate movement. External ones are called exogenous - this is the activity of flowing waters, winds, waves, glaciers, as well as animals and plants. The surface of the planet is also increasingly influenced by man himself. The human factor can be divided into another group, calling it anthropogenic forces.

Land relief

Plains

Lowlands - up to 200 m

Hills - 200-500 m

Plateau - more than 500 m

Mountains

Low - 500-1000 m

Medium – 1000 – 2000 m

High – 2000 – 5000 m

The highest - more than 5000 m

Ocean relief

Basins - depressions in the ocean floor

Mid-ocean ridges are faults that form a single mountain system at the bottom of all oceans with a total length of more than 60 thousand km. In the middle part of these faults there are deep gorges reaching all the way to the mantle.

At their bottom there is a constant process of spreading - the outpouring of the mantle with the formation of a new earth's crust.

Deep-sea trenches are long, narrow depressions on the ocean floor that are more than 6 km deep. The deepest in the world is the Mariana Trench, 11 km 22 m deep.

Island arcs are elongated groups of islands rising from the ocean floor above the surface of the water. (For example, the Kuril and Japanese islands) They can be adjacent to a deep-sea trench and are formed as a result of the fact that the oceanic crust next to the trench begins to rise above sea level due to the subduction processes occurring in it - the immersion of one lithospheric plate in this place under another.

2. Formation of plains and mountains

The teacher builds an explanation according to this scheme. As the teacher tells the story, students transfer the diagram to their notebooks.

Rice. 2. Formation of plains

Planation. The oceanic crust (soft and thin) easily folds, and mountains can form in its place. Then the rocks composing it rise to a height of several kilometers above sea level. This happens as a result of intense compression. The thickness of the earth's crust increases to 50 km.

As soon as they are born, mountains begin to slowly but steadily collapse under the influence of external forces - wind, water flows, glaciers, and simply temperature changes. A large number of clastic rocks accumulate in foothill and intermountain troughs, with smaller ones at the bottom and increasingly coarser ones at the top.

Old (blocky, revived) mountains. The oceanic crust was crushed into folds, they were destroyed to the state of plains, then the Alpine era of folding revived the mountainous relief in place of the destroyed mountain structures. These low mountains have a small height and a blocky appearance. Next, students, working with tectonic and physical cards, give examples of ancient mountains (Urals, Appalachians, Scandinavian, Drakensberg, Great Dividing Range, etc.)

Rice. 3. Formation of old (block, revived) mountains

Rice. 4. Ural Mountains

The middle (folded-block) mountains were formed in the same way as the ancient ones, but destruction did not bring them to the state of plains. Their block formation began on the site of dilapidated mountains. This is how the medium block-folded mountains were formed. Next, students, working with tectonic and physical maps, give examples of medium-sized mountains (Cordillera, Verkhoyansk Range).

Rice. 5. Middle (block-folded and folded-block renewed) mountains.

Rice. 6. Northern Santiago. Cordillera

Young mountains are still being formed. Being young mountains, they show no signs of destruction. Basically, these mountains are high and have the appearance of folds. Often their peaks are sharp and covered with snow caps. Vivid examples young mountains are the Alps, Himalayas, Andes, Caucasus, etc.

Fig.7. Young Mountains

Rice. 8. Caucasus. Dombay.

3. Internal and external forces of the Earth

Questions for students:

— Tell me, why does the oceanic crust turn into mountains? (act internal forces Earth)

— Why do mountains turn into plains? (external forces of the Earth act).

— So, what forces of the Earth influence the appearance of the topography of our planet? (internal and external).

For a long time, granite has been the personification of durability and strength. A strong-willed, unbending person and an unbreakable, faithful friendship can be equally compared to granite. However, even granite will crumble into fine crushed stone, crumbs and sand if it experiences temperature changes, wind influences, and the activity of living organisms and humans for a long time.

Temperature changes. With the first rays of the Sun, snow and ice begin to melt high in the mountains. Water penetrates into all cracks and cavities of rocks. At night, the temperature drops several degrees below zero and the water turns to ice. At the same time, it increases in volume by 9% and pushes the cracks apart, widening and deepening them. This continues day after day, year after year, until some crack separates a piece of rock from the main mass and it rolls down the slope. Rocks also undergo heating and cooling. The minerals they contain have different thermal conductivities. Expanding and contracting, they break strong connections between themselves. When these bonds are completely destroyed, the rock turns into sand.

Rice. 10. Destruction of rocks in the mountains under the influence of temperature changes.

The active influence of plant and animal organisms on rocks causes biogenic weathering. Plant roots undergo mechanical destruction, and the acids released during their life activity cause chemical destruction. As a result of many years of activity of living organisms, coral reefs and a special type of islands arise - atolls, formed by the calcareous skeletons of marine animals.

Rice. 11. Coral atoll is the result of the activity of marine organisms

Rivers and the World Ocean also leave their mark on the Earth's topography: a river forms a channel and a river valley, ocean waters form coastline. Surface waters leave scars of ravines on the surface of hills and plains. As the ice moves, it furrows the surrounding areas.

Fig. 12.

Bryce Canyon in the USA, formed as a result of the activity of flowing waters

Rice. 13. The road in Abkhazia to Lake Ritsa, laid along the bottom of a mountain river gorge

Rice. 14. Sand and pebble beach in Crimea, formed as a result of wave activity

The wind is the absolute master of open spaces. Encountering obstacles on its way, it forms majestic hills - dunes and dunes. In the Sahara Desert, the height of some of them reaches 200 - 300 meters. In mountain ranges located in the desert, there is almost never loose material filling the depressions and cracks. This is why aeolian landforms arise that resemble towers, pillars and quaint castles.

Rice. 15. Remains in the desert resemble fairy-tale castles

Rice. 16. Sand dunes.

Rice. 17. Barkhan

Human economic activity also causes changes in relief. Man extracts minerals, resulting in the formation of quarries, builds buildings, canals, makes embankments and fills up ravines. This is all a direct impact, but it can also be indirect, representing the creation of favorable conditions for relief-forming processes (plowing slopes causes rapid growth of ravines).

It is formed as a result of the interaction of internal (endogenous) and external (exogenous) forces. Endogenous and exogenous processes of relief formation operate constantly. In this case, endogenous processes mainly create the main features of the relief, and exogenous ones try to level the relief.

The main sources of energy during relief formation are:

Internal energy of the Earth;
Energy of sun;
Gravity;
The influence of space.

Source of energy endogenous processes is the thermal energy of the Earth associated with processes occurring in the mantle (radioactive decay). Due to endogenous forces, the earth's crust was separated from the mantle with the formation of two types: continental and oceanic.

Endogenous forces cause: movements of the lithosphere, the formation of folds and faults, earthquakes and volcanism. All these movements are reflected in the relief and lead to the formation of mountains and troughs of the earth's crust.

Crustal faults distinguished by: size, shape and time of formation. Deep faults form large blocks of the earth's crust that experience vertical and horizontal displacements. Such faults often determine the outlines of continents.

Large blocks of the earth's crust are cut through a network of small faults. River valleys are often associated with them (for example, the Don River valley). The vertical movements of such blocks are always reflected in the relief. The forms created by modern ( neotectonic) movements. Thus, in our Central Black Earth region, the area of the Central Russian Upland (Belgorod, Voronezh, Kursk regions) is rising at a rate of 4-6 mm/year. At the same time, the Oka-Don lowland (Tambov, Lipetsk and northeast Voronezh regions) decreases by 2 mm annually. Ancient movements of the earth's crust are usually reflected in the nature of the occurrence of rocks.

Exogenous processes associated with the supply of solar energy to the earth. But they proceed with the participation of gravity. This happens:

Weathering of rocks;
Movement of material under the influence of gravity (collapses, landslides, screes on slopes);
Transfer of material by water and wind.

Weathering is a set of processes of mechanical destruction and chemical change of rocks.

The total impact of all processes of destruction and transport of rocks is called denudation. Denudation leads to leveling of the surface of the lithosphere. If there were no endogenous processes on Earth, then it would have long ago had a completely flat surface. This surface is called main level of denudation.

In reality, there are many temporary levels of denudation at which leveling processes can fade for some time.

The manifestation of denudation processes depends on the composition of rocks, geological structure and climate. For example, the shape of ravines in sand is trough-shaped, and in chalk rocks it is V-shaped. However, the greatest importance for the development of denudation processes is the height of the area above sea level, or the distance to erosion basis.

Thus, the relief of the surface of the lithosphere is the result of the counteraction of endogenous and exogenous processes. The former create uneven terrain, and the latter smooth them out. During relief formation, endogenous or exogenous forces can prevail. In the first case, the height of the relief increases. This upward development of relief. In the second case, positive relief forms are destroyed and the depressions are filled. There is a decrease in surface heights and flattening of slopes. This downward development of relief.

Endogenous and exogenous forces are balanced over long geological time. However, in short periods of time, one of these forces predominates. The change of ascending and descending movements of the relief leads to cyclical processes. That is, first positive forms of relief are formed, then weathering of rocks occurs, movement of material under the influence of gravity and water, which leads to leveling of the relief.

Such continuous movement and change of matter is the most important feature of the geographical envelope.

Literature.

Smolyaninov V. M. General geoscience: lithosphere, biosphere, geographic envelope. Educational and methodological manual/ V.M. Smolyaninov, A. Ya. Nemykin. – Voronezh: Origins, 2010 – 193 p.

>>How and why the relief of Russia is changing

§ 14. How and why the relief of Russia changes

The formation of relief is influenced by various processes. They can be combined into two groups: internal (endogenous) and external (exogenous).

Internal processes. Among them, the most recent (neotectonic) ones had the greatest impact on the formation of modern relief. crustal movements, volcanism and earthquakes. Thus, under the influence of internal processes, the largest, large and medium-sized forms relief.

Neotectonic movements are the movements of the earth's crust that have occurred in it over the past 30 million years. They can be both vertical and horizontal. The formation of relief is most influenced by vertical movements, as a result of which the earth’s crust rises and falls (Fig. 20).

Rice. 20. Newest tectonic movements.

The speed and height of vertical neotectonic movements in some areas were very significant. Most of modern mountains on the territory of Russia exist only thanks to the latest vertical uplifts, since even young, relatively recently formed mountains destroyed within a few million years. The Caucasus Mountains, despite the destructive influence of external forces, were raised to a height of 4000 to 6000 m. The Ural Mountains by 200-600 m, Altai by 1000-2000 m. Largest plains Russia also experienced a slight rise - from 100 to 200 m. In those places where the earth's crust sank, depressions of seas and lakes and many lowlands arose.

According to Fig. 20 determine what types of movements prevail on the territory of Russia.

Movements of the earth's crust are still happening. The Greater Caucasus Range continues to rise at a rate of 8-14 mm per year. The Central Russian Upland is growing somewhat slower - about 6 mm per year. And the territories of Tatarstan and the Vladimir region annually fall by 4-8 mm.

Along with the slow movements of the earth's crust, earthquakes and volcanism play a certain role in the formation of large and medium-sized relief forms.

Earthquakes often lead to significant both vertical and horizontal displacements of rock layers, the occurrence of landslides and failures.

During volcanic eruptions, specific landforms such as volcanic cones, lava sheets and lava plateaus are formed.

External Processes, forming modern relief , are associated with the activity of the seas, flowing waters, glaciers, and waters. Under their influence, large relief forms are destroyed and medium and small relief forms are formed.

When seas advance, sedimentary rocks are deposited in horizontal layers. Therefore, many coastal parts of the plains, from which the sea retreated relatively recently, have a flat topography. This is how the Caspian and northern West Siberian Lowlands were formed.

Flowing waters(rivers, streams, temporary water streams) erode the earth's surface. As a result of their destructive activities relief forms called erosional are formed. These are river valleys, ravines, and ravines.

Valleys large rivers have a large width. For example, the Ob valley in its lower reaches is 160 km wide. Amur is slightly inferior to it - 150 km and Lena - 120 km. River valleys are a traditional place for people to settle and conduct special types of farming ( livestock farming on floodplain meadows, gardening).

Gullies are a real problem for agriculture (Fig. 21). By dividing fields into small areas, they make them difficult to cultivate. In Russia there are more than 400 thousand large ravines with a total area of 500 thousand hectares.

Glacier activity. During the Quaternary period, due to climate cooling in many regions of the Earth, several ancient ice sheets arose. In some areas - centers of glaciation - ice accumulated over thousands of years. In Eurasia, such centers were the tori of Scandinavia, the Polar Urals, the Putorana plateau in the north of the Central Siberian Plateau and the Byrranga mountains on the Taimyr Peninsula (Fig. 22).

Using the population map in the atlas, compare the population density in the valleys of the major rivers of Siberia and in the surrounding areas.

The thickness of the ice in some of them reached 3000 m. Under the influence of its own weight, the glacier slid south to the adjacent territories. Where the glacier passed, the earth's surface changed greatly. In places he smoothed it out. In some places, on the contrary, there were depressions. The ice polished the rocks, leaving deep scratches on them. Accumulations of huge stones (boulders), sand, clay, and rubble moved along with the ice. This mixture of various rocks is called moraine. In the southern, warmer regions, the glacier melted. The moraine he carried with him was deposited in the form of numerous hills, ridges, and flat plains.

Wind activity. The wind shapes the relief mainly in arid areas and where sands lie on the surface. Under its influence, dunes, sand hills and ridges are formed. They are common in the Caspian lowland, in the Kaliningrad region (Curonian Spit).

Fig.22. Boundaries of ancient glaciation

Questions and tasks

1. What processes influence the formation of the Earth’s topography at the present time? Describe them.
2. What glacial landforms are found in your area?
3. What landforms are called erosional? Give examples of erosional landforms in your area.
4. What modern relief and forming processes are typical for your area?

Geography of Russia: Nature. Population. Farming. 8th grade : textbook for 8th grade. general education institutions / V. P. Dronov, I. I. Barinova, V. Ya. Rom, A. A. Lobzhanidze; edited by V. P. Dronova. - 10th ed., stereotype. - M.: Bustard, 2009. - 271 p. : ill., map.