Internal and external processes of the earth. Internal (endogenous) processes and their influence on the formation of relief

Forces constantly act on the earth's surface, changing, contributing to the formation. All these processes are different, but they can be combined into two groups: external (or exogenous) and internal (or endogenous). Exogenous processes act on the surface of the Earth, while endogenous processes are deep processes, the sources of which are located in the bowels of the planet. From the outside, the forces of attraction and the Sun act on the Earth. The force of attraction of other celestial bodies is very small, but some scientists believe that in the geological gravitational influences from space may increase. Many scientists also refer to external, or exogenous, forces as the earth's gravity, due to which landslides, landslides in the mountains occur, and people move from the mountains.

Exogenous forces destroy, transform the earth's crust, transfer loose and soluble products of destruction carried out by water, glaciers. Simultaneously with destruction, there is also a process of accumulation, or products of destruction. 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, destroy crops. Landslides are also dangerous, which also lead to the destruction of various buildings, thereby causing damage to the economy, taking the lives of people. Among the exogenous processes, it is necessary to note -i, which leads to the leveling of the relief, as well as the role of the wind.

Endogenous processes raise separate sections earth's crust. They contribute to the formation of large landforms - megaforms and macroforms. The main source of energy for endogenous processes is internal heat in. These processes cause movement, slow. Internal forces work in the bowels of the planet and are completely hidden from our eyes.

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

Questions for students:

Teacher's story.

landform

Plains

Lowlands - up to 200 m

Hills - 200-500 m

Plateau - more than 500 m

The mountains

Low - 500-1000 m

Medium - 1000 - 2000 m

High - 2000 - 5000 m

The highest - more than 5000 m

Relief of the oceans

2. Formation of plains and mountains

Rice. 2. Formation of plains

Rice. 4. Ural Mountains

Fig.7. young mountains

Rice. 8. Caucasus. Dombay.

Questions for students:

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

The absolute master of open spaces is the wind. Encountering obstacles on its way, it forms majestic hills - dunes and dunes. In the Sahara desert, some of them are up to 200-300 meters high. In the mountain ranges located in the desert, there is almost never loose material that fills the depressions and cracks. That is why aeolian landforms appear, reminiscent of towers, pillars and bizarre castles.

Rice. 16. Sand dunes.

Rice. 17. Barkhan

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The external processes that form the Earth's relief include:

INTERNAL FORCES OF THE EARTH

The movement of lithospheric plates leads to the formation of folded areas, deflections, and extensions in the earth's crust. Tectonic movements lead to splits in the earth's crust, the appearance of discontinuous disturbances in its layers and the formation of folds. Surface areas rise and fall along fault lines. Volcanism creates its own special landforms. Earthquakes can catastrophically change the already created relief.

THE OUTER FORCES OF THE EARTH

The activity of external forces as a whole leads to the destruction of the rocks that make up the earth's surface, and the demolition of the products of destruction from high places to lower ones. This process is called denudation. Demolished material accumulates in low places - valleys, hollows, depressions. This process is called accumulation - approx. from geoglobus.ru. The destruction of rocks near the Earth's surface under the influence of various factors - weathering prepares the material for movement.

The role of water that has fallen into cracks, which are almost always present in rocks, is especially great. Freezing, it expands, pushes the edges of the crack; thawing, flows out of it, taking with it the destroyed particles.

The wind, carrying sand from place to place, not only expands the cracks, but also polishes them, grinds the surfaces of the rocks, creating bizarre figures. Where the wind subsides, in the wind "shadow", for example, behind a rock or behind a bush, sand accumulates. Created new form relief, which over time will give rise to a dune - a sandy hill. Such formations are called eolian landforms, after the ancient Greek god Aeolus, the lord of the winds.

Sea waves and tides contribute to the change in relief. They destroy the shores, carry away the destroyed material and move it to different distances along the coast, forming coastal ramparts and beaches, constantly changing coastline.

Rock fragments, sand, dust from surrounding rocks and valley slopes move on the surface of mountain glaciers and in their thickness. When a glacier melts, all this material falls on the earth's surface - approx. from geoglobus.ru. The ice mass itself is capable of exerting a strong shaping effect on the relief. Under its influence, trough-shaped glacial valleys are formed - troughs, pointed peaks - carlings, huge bulk shafts - moraines.

In recent centuries, man has been so actively influencing the environment natural environment that itself becomes a powerful external force. Harmful emissions into the atmosphere industrial enterprises lead to acid rain.

Lesson topic : External processes that form the relief and

associated natural phenomena

Lesson objectives : to form knowledge about the change in landforms as a result of erosion,

weathering and other external relief-forming processes, their role

in shaping the appearance of the surface of our country. Let the students down

to the conclusion about the constant change, the development of the relief under the influence of

only internal and external processes, but also human activities.

1. Repetition of the studied material.

1. As a result of what is the surface of the Earth changing?

2. What processes are called endogenous?

2. What parts of the country experienced the most intense uplifts in the Neogene-Quaternary?

3. Do they coincide with earthquake distribution areas?

4. What are the main active volcanoes on the territory of the country.

5. In what parts Krasnodar Territory more often internal processes are manifested?

2. Learning new material.

The activity of any external factor consists of the process of destruction and demolition of rocks (denudation) and the deposition of materials in depressions (accumulation). This is preceded by weathering. There are two main types of exposure: physical and chemical, as a result of which loose deposits are formed that are convenient for moving by water, ice, wind, etc.

As the teacher explains the new material, the table is filled

Examples of certain types of external processes - pp. 44-45 Ermoshkin "Geography Lessons"

3. FIXING THE NEW MATERIAL

external processes that form the relief of the earth include:

Name the main types of exogenous processes.

2. Which of them are the most developed in the Krasnodar Territory?

3. What anti-erosion measures do you know?

4. HOME TASK: prepare for a general lesson on the topic "Geological structure,

relief and minerals of Russia" pp. 19-44.

1. land relief

   Lesson

   - on which tecton.structure the following landforms are located: East European Plain, Sredenesib.flat., Amazonian lowland, Great Plains, Andes, Himalayas,

2. Decree of the Administration of the Altai Territory No. 551 dated 14. 12. 10 approved a departmental target program

   Program

   The main educational program of general education was developed by the teaching staff of the secondary school No. 102 of Barnaul, taking into account the recommendations of the Exemplary Basic Educational Program of an educational institution,

3. The work program of the teacher Krovyakova Svetlana Viktorovna, category I Full name, category geography, grade 6 Subject, class, etc. Considered at the meeting

   Working programm

   1. Organization and training in the methods of educational work: observation of the weather, phenological phenomena; measuring the height of the sun above the horizon, orientation to the sun.

4. Kucheryavenko Lyubov Nikolaevna St. Petersburg 2008 lesson

   Lesson

   State educational institution secondary school No. 389 "Center for Environmental Education" of the Kirovsky district of St. Petersburg.

5. Lithosphere and land relief

   Lesson

   A physical map of the hemispheres, a map of the structure of the earth's crust, collections of rocks and minerals, contours of modern continents that allow modeling their movement; diagrams, pictures, etc.

Other related documents..

FOUNDATIONS OF GEOLOGY. GENERAL INFORMATION ABOUT THE EARTH.

Geology is the science of the earth. It studies the composition, structure and patterns of the development of the Earth. Modern geology is a complex science that combines several interconnected disciplines (branches of geology). All disciplines that make up modern geology have their own objects and methods of cognition of the Earth.

At present, the level of development of this discipline is such that it is divided into a number of independent scientific branches.

landform

Geochemistry— studies chemical composition the earth's crust, the laws of distribution and movement of chemical elements and their isotopes.

2. Mineralogy- considers natural chemical compounds - minerals, studies the physico-chemical properties and processes associated with their formation in the earth's crust.

3. Petrography- describes the composition and structure of rocks - natural accumulations of minerals that make up the earth's crust, the forms of their occurrence, origin and location.

4. dynamic geology– considers the processes occurring in the bowels of the planet and on its surface (earthquakes, volcanism, wind, sea, rivers, glaciers, etc.)

5. historical geology- produces a restoration of the past, which is very important for the search for various minerals.

6. Geophysics- a science that uses various physical methods to study the deep bowels of the Earth.

7. Hydrogeology— studies The groundwater contained in the bowels of our planet.

8. Engineering geology- a science that studies soils, geological and engineering-geological processes that affect the conditions for the construction and operation of structures and reclamation systems.

The surface layers of the Earth have been most fully studied at present. One of the main methods for studying the upper surface of the earth's crust is the method of field geological surveys. The essence of the method is a thorough field study of modern geological processes, natural outcrops of rocks, slopes of river valleys, ravines, etc. The composition of rocks, the nature of their occurrence, fossil remains of organisms, etc. are studied. When studying the earth's crust, it is necessary to take into account what it was before and what changes it has undergone. To this end, scientists have proposed a comparative lithological method based on the idea of ​​an irreversible and directed process of the Earth's development, on the idea of ​​the evolution of sedimentation conditions in the history of the Earth.

The deeper layers of the earth's crust and the earth as a whole are studied mainly by indirect methods - geophysical.

To geophysical methods include: seismic, gravimetric, magnetometric and others.

seismic method allows to study the composition and properties of the deep layers of the Earth by changing the speed of passage of seismic waves that occur during earthquakes.

gravimetric method based on the study of the distribution of gravity on the Earth's surface. In theoretical calculations, the force of gravity of the Earth is assumed to be homogeneous.

magnetometric method based on the study of changes magnetic field Earth in its various parts, depending on the composition and structure of the earth's crust.

landform

Questions for students:

- Who remembers from the 6th grade course what relief is? (Relief - a set of irregularities of the earth's surface). Students write 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 inverted cards with terms:

Fig.1. Flowchart “Earth Relief”

Students complete the chart in their notebooks.

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 height difference on it from the Himalayas to the Mariana Trench reaches two tens of kilometers. The relief of our planet continues to form even now: lithospheric plates collide, crushing into the folds of mountains, volcanoes erupt, rivers and rains wash away rocks. If we were 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 during this time would have changed beyond recognition. All processes that form the Earth's relief can be divided into two large groups: internal and external. Otherwise, internal 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.

landform

Plains

Lowlands - up to 200 m

Hills - 200-500 m

Plateau - more than 500 m

The mountains

Low - 500-1000 m

Medium - 1000 - 2000 m

High - 2000 - 5000 m

The highest - more than 5000 m

Relief of the oceans

Basins - depressions in the bed of the oceans

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 the mantle itself. At their bottom goes ongoing process spreading - 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 constructs an explanation according to this scheme. In the course of the teacher's story, the students transfer the diagram to their notebooks.

Rice. 2. Formation of plains

Planation. The oceanic crust (soft and thin) is easily folded into folds, and mountains can form in its place. Then the rocks that compose 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.

Barely born, the mountains begin to slowly but steadily collapse under the influence of external forces - wind, water flows, glaciers, and simply temperature changes. In the foothill and intermountain troughs accumulates a large number of clastic rocks, with smaller ones below, and increasingly coarser ones at the top.

Old (blocky, revived) mountains. The oceanic crust was crumpled into folds, they collapsed to the state of plains, then the Alpine era of folding revived mountainous relief on the site of the destroyed mountain structures. These low mountains have a small height and the appearance of blocks. Further, students, working with tectonic and physical maps, give examples of ancient mountains (Ural, Appalachian, Scandinavian, Draconian, Great Dividing Range, etc.)

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

Rice. 4. Ural Mountains

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

Rice. 5. Medium (blocky-folded and folded-blocky renewed) mountains.

Rice. 6. North Santiago. Cordillera

Young mountains are still being formed. Being young mountains, they do not bear signs of destruction. Basically, these are high mountains, they look like folds. Often their peaks are sharp, covered with snow caps. Vivid examples of young mountains are the Alps, the Himalayas, the Andes, the 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? (the internal forces of the Earth act)

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

- So, what forces of the Earth influence the shape of the relief of our planet? (internal and external).

Since ancient times, granite has been the embodiment of durability and strength. A strong-willed, unbending person and an indestructible, faithful friendship can equally be compared with granite. However, even granite will crumble into small gravel, crumbs and sand if it experiences temperature changes, the influence of wind, the activity of living organisms and humans for a long time.

Temperature fluctuations. With the first rays of the sun, snow and ice begin to melt high in the mountains. Water penetrates into all cracks and depressions of rocks. At night, temperatures drop a few degrees below zero and the water turns to ice. At the same time, it increases in volume by 9% and pushes the cracks apart, expanding and deepening them. This goes on day after day, year after year, until some crack separates a piece of rock from the main massif and it rolls down the slope. Rocks are also subjected to heating and cooling. The minerals they contain have different thermal conductivity. Expanding and contracting, they break strong bonds between themselves. When these bonds are completely destroyed, the rock turns into sand.

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

The active impact of plant and animal organisms on rocks causes biogenic weathering. The roots of plants perform mechanical destruction, and the acids released in the course of their vital activity perform 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 calcareous skeletons of marine animals.

11. Coral atoll - the result of the activity of marine organisms

Rivers and the World Ocean also leave their mark on the Earth's topography: the river forms the channel and the river valley, the waters of the ocean form the coastline. surface water leave scars of ravines on the surface of hills and plains. Ice during its movement furrows the adjacent territories.

Fig.12. Bryce Canyon in the USA, formed as a result of the activity of flowing waters

Rice. 13. 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 absolute master of open spaces is the wind. Encountering obstacles on its way, it forms majestic hills - dunes and dunes.

How relief is formed

In the Sahara desert, some of them are up to 200-300 meters high. In the mountain ranges located in the desert, there is almost never loose material that fills the depressions and cracks. That is why aeolian landforms appear, reminiscent of towers, pillars and bizarre castles.

Rice. 15. The remains in the desert resemble fairy-tale castles.

Rice. 16. Sand dunes.

Rice. 17. Barkhan

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

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landform

Relief is a set of irregularities on the Earth's surface, which differ in height above sea level, origin, and other characteristics. The presence of such irregularities is due to the unique appearance of various regions of our planet. The relief is formed under the influence of both internal (tectonic) and external forces. Tectonic processes provoke the appearance of large surface irregularities, such as mountains, plateaus, etc., while external forces, on the contrary, destroy them and create smaller relief forms, for example, river valleys, dunes, ravines, etc.

Landforms

All existing forms relief is conditionally divided into convex(mountain systems, volcanoes, hills, etc.) and concave(river valleys, beams, depressions, ravines, etc.), as well as horizontal and inclined surfaces.

Their sizes vary widely: from a few tens of centimeters to hundreds and thousands of kilometers.
Depending on the magnitude, scientists distinguish planetary, macroforms, meso- and microforms of the earth's surface relief. Planetary forms include protrusions of the continents and depressions of the oceans. In this respect, continents and oceans are antipodes. For example, Antarctica is located opposite the North Arctic Ocean, Australia - against the Atlantic, North America - opposite the Indian.

The depths of oceanic trenches differ significantly. The average depth is 3.8 km, and the maximum in the Mariinsky depression is 11.022 km. Knowing that the height of the highest point of land (mountain Chomolungma) is 8.848 km, it can be easily determined that the amplitude of heights on Earth reaches about 20 km.

The depth of most of the ocean is between 3 and 6 km, and the height of the land is usually less than 1 km. Deep-water depressions and high mountains make up no more than 1% of the Earth's surface.

The average height of the continents above sea level also differs greatly: Eurasia - 635 m, North America- 600 m, South America- 580 m, Africa - 640 m, Australia - 350 m, Antarctica - 2300 m. Thus, the average land height is 875 m.

The relief of the ocean floor includes the continental shelf (shelf), the continental slope, and the ocean floor. The main components of the land relief are plains and mountains that form the macrorelief of the earth's surface.

Related content:

Lithosphere

The internal structure of the Earth

Landforms of the continents
The relief of the ocean floor

Factors of external and internal influence

1. Concepts of influence factors

Before starting a discussion of the concepts of factors of external and internal influence, let's find out what is meant by external and, accordingly, internal. Soviet encyclopedic Dictionary states that “External and internal are philosophical categories. The external expresses the properties of the object as a whole and characterizes its interaction with the environment, the internal expresses the structure, the essence of the object. Thus, we can assume that in dynamics, the external characterizes the processes of interaction of an object with the environment, and the internal characterizes the processes within the object itself.

As is known, any material object of the universe in which we exist, after its synthesis (ie creation or emergence) is in interaction with its environment. This interaction continues throughout the entire life cycle and ends with the decay of the object. It should be noted here that the term life cycle" is quite technical and is used in technology to denote the period of existence of any technical product or systems.

The agents through which an object interacts with the environment coincide with the forms of existence of matter. In the known universe, this different kind fields and flows of matter particles. All types of influence of one object on another just come down to these two varieties.

Depending on its (i.e. inherent in it) features, the object affects its environment. The features of the object that we are talking about are mainly determined by its organization, i.e. the materials of which the object consists, its structure, the interaction of its constituent parts, types of energy conversion within its limits, a way to remove the products of its vital activity outside the object, or simply the loss of matter and energy during the interaction of the object with the external environment. It is known that the impact of an object on its environment inevitably, to a greater or lesser extent, changes it, and, consequently, the nature and degree of its impact on the object, i.e. this process is said to be self-consistent. In engineering, the term "feedback" is used to refer to such processes.

People are so arranged that they try to simplify any phenomenon of the surrounding world, most often by breaking the complex into simpler ones, that is, into constituent elements. So the process of interaction with the environment is divided into separately considered processes of the influence of the environment on the object and the object on the environment. Further, in the process of the influence of the environment on the object, its (process) separate aspects or factors are distinguished. The partitioning process does not end there, but we will talk about this later.

From the foregoing, it is clear how the concepts of "External Influence Factors" or, as they are sometimes called, "External Influencing Factors" arise. (It should be noted that these concepts are absolutely identical). Thus, under the factors of external influence we understand the side, process, mechanism, etc. of the influence of the environment on the object under consideration, separated from the totality.

But the functioning of an object is not limited only to its interaction with the external environment, very often the interactions of its constituent parts are more important in terms of their influence on the functioning of the object and the change in parameters over time. Here we come to the emergence of the concept of "Internal Influence Factors". These should include changes in time of the properties of the materials that make up the object, types of its organization, etc.

2. Classification of impact factors

It is known that the quality of products, and by the term "product" we mean technical systems of various purposes, is laid down at the development stage, ensured in the production process and maintained at the operation stage. When developing products, it is necessary to take into account the conditions of their operation, storage and transportation, which are characterized by the influence of external and internal factors.

External factors in engineering include the action of the environment and the features of operation associated with the installation site of the product and (or) the conditions of its transportation. These external influences can cause a limitation or loss of performance of the product or its components during operation.

Internal factors for technical objects are the processes of aging and wear. Aging processes occur continuously, and they occur both during operation and during storage and transportation of products. Wear is manifested mainly during operation and depends on the influence of external factors, on the operating modes and operation of products. The probability of the influence of internal factors increases as the duration of operation increases and in case of violation of operating modes, which can be characterized by: the frequency of switching on and switching, causing transient processes in products; overvoltages; shocks, etc. Frequent switching on and switching of some products can also affect the mechanical wear of their structural elements. In products designed for cyclic operation, a significant effect on thermal regimes provide a ratio of the duration of work and breaks. The action of internal factors in many cases depends on the schemes and designs of products.

According to the time and nature of the impact, the modes of operation and operation of products can be:

continuous,

periodic (cyclical),

aperiodic (disposable),

repeatedly - discontinuous,

random.

In classifications, factors are usually grouped according to some attribute, therefore, mechanical, climatic, etc. factors are distinguished.

The corresponding GOST divides all external influencing factors (WWF) into the following classes: mechanical, climatic, biological, radiation, electromagnetic, special media and thermal.

In turn, each class is divided into groups, and each group into types, which, by the way, correspond to certain types tests. For example, the class of climatic impacts is divided into groups:

Atmosphere pressure,

environment temperature.

humidity of air or other gases, etc.

Groups, in turn, are divided into the following types:

atmospheric high or low pressure,

change atmospheric pressure or its difference

elevated and, accordingly, low temperature environments

change in ambient temperature, etc.

Thus, the classification of factors of external influence is most often built according to the scheme

True, sometimes there are deviations from this scheme - another gradation or level is introduced - a subgroup. An example of such an exception takes place in the above classification in relation to mechanical FVM.

Some types, groups and classes of influences are determined by the purpose of products and their interaction with environments created by man in the course of his activities. These classes include the WWF classes:

special environments

radiation,

electromagnetic,

thermal.

Space exploration has led to the need to allocate another class (not provided for by the standards), which includes all types of so-called space impacts.

One of the possible classifications of FVM is shown in Figure 1.

As we can see from the classification, mechanical factors include two groups: static impact factors and dynamic impact factors. Static impact factors include such types as:

stretching,

torsion,

indentation.

It is obvious that here the FVM classification repeats the types of deformation of materials.

The mechanical factors of dynamic impact include such types of them as the impact:

acceleration - linear or angular, which causes overloads or a state of complete or partial weightlessness,

vibration,

acoustic noise,

Among the climatic factors, impacts are usually distinguished:

solar radiation (in the near-surface layers of the atmosphere);

moisture contained in the air or any other mixture of gases (by moisture it is not necessary to understand only water vapor - it can also be vapor of any other liquid, for example, in the atmosphere of Jupiter, the role of water, apparently, is played by methane, in inner atmosphere This role can be performed by a liquid working fluid of some of its systems that got inside the apparatus as a result of the flow of highways);

precipitation, which is usually referred to as rain, frost, snow, ice, etc.

atmosphere ( gas composition, the presence of impurities in the form of liquid and solid aerosols, dust particles, sand.),

aerostatic or hydrostatic pressure (normal, increased, decreased), its changes or drops.

Climatic factors include such, in general, a mechanical factor in nature, as the effect of the movement of the medium, i.e. wind, wave motion of a liquid, etc.

In biological factors, the impact on technical systems is usually distinguished:

mold fungi and other microorganisms,

insects,

rodents.

Sometimes in the form biological factor Reptiles or animals can also act as environmental influences, but the likelihood of such a situation is much lower than for rodents.

It seems expedient to include in this class PEF and human impact, which in its destructiveness and scale can surpass the impact of other biological factors.

Until now, we have considered internal relief-forming factors, such as movements of the earth's crust, folding, etc. These processes are due to the action of the internal energy of the Earth. As a result, large landforms such as mountains and plains are created. In the lesson, you will learn how the relief was formed and continues to form under the influence of external geological processes.

Other forces are also working on the destruction of rocks - chemical. Seeping through cracks, water gradually dissolves rocks (See Fig. 3).

Rice. 3. Dissolution of rocks

The dissolving power of water increases with the content of various gases in it. Some rocks (granite, sandstone) do not dissolve in water, others (limestone, gypsum) dissolve very intensively. If water penetrates along cracks into layers of soluble rocks, then these cracks expand. In those places where water-soluble rocks are close to the surface, numerous sinkholes, funnels and depressions are observed on it. This is karst landforms(see Fig. 4).

Rice. 4. Karst landforms

Karst is the process of dissolution of rocks.

Karst landforms are developed on the East European Plain, Cis-Urals, the Urals and the Caucasus.

Rocks can also be destroyed as a result of the vital activity of living organisms (saxifrage plants, etc.). This is biological weathering.

Simultaneously with the destruction processes, the destruction products are transferred to lower areas, thus, the relief is smoothed out.

Consider how the Quaternary glaciation shaped the modern relief of our country. Glaciers have survived to this day only on the Arctic islands and on the highest peaks of Russia. (See Fig. 5).

Rice. 5. Glaciers in the Caucasus Mountains ()

Going down steep slopes, glaciers form a special, glacial relief. Such a relief is common in Russia and where there are no modern glaciers - in the northern parts of East European and West Siberian Plains. This is the result of an ancient glaciation that arose in the Quaternary era due to a cooling of the climate. (See Fig. 6).

Rice. 6. Territory of ancient glaciers

The largest centers of glaciation at that time were the Scandinavian mountains, the Polar Urals, the islands of Novaya Zemlya, the mountains of the Taimyr Peninsula. The thickness of the ice on the Scandinavian and Kola peninsulas reached 3 kilometers.

Glaciation occurred more than once. It was advancing on the territory of our plains in several waves. Scientists believe that there were about 3-4 glaciations, which were replaced by interglacial epochs. Last glacial period ended about 10 thousand years ago. The most significant was the glaciation on the East European Plain, where the southern edge of the glacier reached 48º-50º N. sh.

To the south, the amount of precipitation decreased, so in Western Siberia glaciation reached only 60º N. sh., and east of the Yenisei, due to the small amount of snow, it was even less.

In the centers of glaciation, from where the ancient glaciers moved, there are widespread traces of activity in the form of special relief forms - Sheep foreheads. These are ledges of rocks with scratches and scars on the surface (slopes facing towards the movement of the glacier are gentle, and the opposite ones are steep) (See Fig. 7).

Rice. 7. Lamb forehead

Under the influence of their own weight, glaciers spread far from the center of their formation. Along the way, they smoothed out the relief. A characteristic glacial relief is observed in Russia on the territory of the Kola Peninsula, the Timan Ridge, the Republic of Karelia. The moving glacier scraped soft loose rocks and even large, hard debris from the surface. Clay and hard rocks frozen into the ice formed moraine(deposits of rock fragments formed by glaciers during their movement and melting). These rocks were deposited in more southerly regions where the glacier was melting. As a result, moraine hills and even entire moraine plains were formed - Valdai, Smolensk-Moscow.

Rice. 8. Moraine formation

When the climate did not change for a long time, the glacier stopped in place and single moraines accumulated along its edge. In the relief, they are represented by curved rows tens or sometimes even hundreds of kilometers long, for example, Northern Uvaly on the East European Plain (see fig. 8).

During the melting of glaciers, streams of melt water were formed, which washed over the moraine, therefore, in the areas of distribution of glacial hills and ridges, and especially along the edge of the glacier, water-glacial sediments accumulated. Sandy flat plains that arose along the outskirts of a melting glacier are called - outwash(from German "zander" - sand). Examples of outwash plains are the Meshcherskaya lowland, the Upper Volga, Vyatka-Kama lowland (see fig. 9).

Rice. 9. Formation of outwash plains

Among the flat-low hills, water-glacial landforms are widespread, ozes(from Swedish "oz" - ridge). These are narrow ridges, up to 30 meters high and up to several tens of kilometers long, resembling railway embankments in shape. They were formed as a result of settling on the surface of loose sediments formed by rivers flowing along the surface of glaciers. (see fig. 10).

Rice. 10. Formation of lakes

All water flowing on land, under the influence of gravity, also forms a relief. Permanent streams - rivers - form river valleys. The formation of ravines is associated with temporary streams formed after heavy rains. (see fig. 11).

Rice. 11. Ravine

Overgrown, the ravine turns into a beam. The slopes of uplands (Central Russian, Volga, etc.) have the most developed ravine network. Well-developed river valleys are characteristic of rivers flowing outside the boundaries of the last glaciations. Flowing waters not only destroy rocks, but also accumulate river sediments - pebbles, gravel, sand and silt (see fig. 12).

Rice. 12. Accumulation of river sediment

They consist of river floodplains, stretching in strips along the riverbeds. (see fig. 13).

Rice. 13. The structure of the river valley

Sometimes the latitude of the floodplains varies from 1.5 to 60 km (for example, near the Volga) and depends on the size of the rivers (see Fig. 14).

Rice. 14. The width of the Volga in various sections

Along the river valleys there are traditional places of human settlement and a special type of economic activity is being formed - animal husbandry in floodplain meadows.

On the lowlands, experiencing slow tectonic subsidence, there are extensive floods of rivers and wanderings of their channels. As a result, plains are formed, built by river sediments. This relief is most common in the south of Western Siberia. (see fig. 15).

Rice. 15. Western Siberia

There are two types of erosion - lateral and bottom. Deep erosion is aimed at cutting flows into the depth and prevails near mountain rivers and rivers of plateaus, which is why deep river valleys with steep slopes are formed here. Lateral erosion is aimed at erosion of the banks and is typical for lowland rivers. Speaking about the impact of water on the relief, we can also consider the impact of the sea. When the seas advance on the flooded land, sedimentary rocks accumulate in horizontal layers. The surface of the plains, from which the sea retreated long ago, is greatly changed by flowing waters, wind, glaciers (see fig. 16).

Rice. 16. Retreat of the sea

The plains, relatively recently abandoned by the sea, have a relatively flat relief. In Russia, this is the Caspian lowland, as well as many flat areas along the shores of the Arctic Ocean, part of the low plains of Ciscaucasia.

The activity of the wind also creates certain landforms, which are called eolian. Aeolian landforms are formed in open spaces. In such conditions, the wind carries a large amount of sand and dust. Often a small bush is a sufficient barrier, the wind speed decreases, and the sand falls to the ground. Thus, at first small, and then large sandy hills are formed - dunes and dunes. In terms of plan, the dune has the shape of a crescent, with its convex side facing the wind. As the direction of the wind changes, so does the orientation of the dune. Wind-related landforms are distributed mainly on the Caspian lowland (dunes), on the Baltic coast (dunes) (see fig. 17).

Rice. 17. Formation of a dune

The wind blows a lot of small fragments and sand from the bare mountain peaks. Many of the grains of sand he carries out again hit the rocks and contribute to their destruction. You can observe bizarre weathering figures - remnants(see fig. 18).

Rice. 18. Remains - bizarre landforms

The formation of special species - forests - is associated with the activity of the wind. - loose, porous, dusty rock (see fig. 19).

Rice. 19. Forest

Forest covers large areas in the southern parts of the East European and West Siberian plains, as well as in the Lena River basin, where there were no ancient glaciers (see fig. 20).

Rice. 20. Russian territories covered with forest (shown in yellow)

It is believed that the formation of the forest is associated with winding dust and strong winds. On the forest, the most fertile soils, however, it is easily washed out by water and the deepest ravines appear in it.

1. The formation of the relief occurs under the influence of both external and internal forces.
2. Internal forces create large landforms, and external forces destroy them, transforming them into smaller ones.
3. Under the influence of external forces, both destructive and creative work is carried out.

Bibliography

1. Geography of Russia. Nature. Population. 1 hour Grade 8 / V.P. Dronov, I.I. Barinova, V.Ya Rom, A.A. Lobzhanidze.
2. V.B. Pyatunin, E.A. Customs. Geography of Russia. Nature. Population. 8th grade.
3. Atlas. Geography of Russia. population and economy. - M.: Bustard, 2012.
4. V.P. Dronov, L.E. Savelyeva. UMK (educational-methodical set) "SPHERES". Textbook “Russia: nature, population, economy. 8th grade". Atlas.

1. The influence of internal and external processes on the formation of relief ().
2. External forces that change the relief. Weathering. ().
3. weathering().
4. Glaciation in Russia ().
5. Physics of dunes, or how sand waves are formed ().

Homework

1. Is the statement true: “Weathering is the process of destruction of rocks under the influence of wind”?
2. Under the influence of what forces (external or internal) did the peaks of the Caucasus Mountains and Altai acquire a pointed shape?

External forces are smoothed out, created by the internal forces of the Earth. Destroying the protruding surface irregularities, they fill depressions with sedimentary rocks. Flowing waters, glaciers, man create on land a variety of smaller landforms.

Weathering

One of the main external processes is weathering- the process of destruction and transformation of rocks.

Weathering itself does not lead to the formation of landforms, but only turns solid rocks into loose ones and prepares the material for movement. The result of this movement is various forms relief.

The action of gravity

Under the action of gravity, rocks destroyed by weathering move on the surface of the Earth from elevated areas to lower ones. Stone blocks, crushed stone, sand often rush down from steep mountain slopes, giving rise to landslides and screes.

Under the influence of gravity, landslides and mudflows. They carry huge masses of rocks. Landslides are the sliding of rock masses down a slope. They form along the banks of water bodies, on the slopes of hills and mountains after heavy rains or melting snow. The upper loose layer of rocks becomes heavier when saturated with water and slides along the lower, water-impervious layer. Heavy rains and rapid snowmelt also cause mudflows in the mountains. They move down the slope with destructive force, demolishing everything in their path. Landslides and mudflows lead to accidents and deaths.

Activity of flowing waters

The most important relief changer is moving water, which performs great destructive and creative work. Rivers cut wide river valleys in the plains, deep canyons and gorges in the mountains. Small water streams create a ravine-beam relief on the plains.

Flowing hearths not only create depressions on the surface, but also capture rock fragments, carry them and deposit them in depressions or in their own valleys. So flat plains are formed from river sediments along the rivers.

Karst

In those areas where readily soluble rocks (limestone, gypsum, chalk, rock salt) lie close to the earth's surface, amazing natural phenomena. Rivers and streams, dissolving rocks, disappear from the surface and rush into the depths of the earth's interior. Phenomena associated with the dissolution of surface rocks and are called karst. The dissolution of rocks leads to the formation of karst landforms: caves, abysses, mines, funnels, sometimes filled with water. The most beautiful stalactites (multi-meter lime "icicles") and stalagmites ("columns" of lime growths) form bizarre sculptures in the caves.

wind activity

In open treeless spaces, the wind moves giant accumulations of sand or clay particles, creating eolian landforms (Eolus is the patron god of the wind in ancient Greek mythology). Most of the world's sandy deserts are covered with sand dunes. Sometimes they reach a height of 100 meters. From above, the dune looks like a sickle.

Moving at high speed, particles of sand and gravel process stone blocks like sandpaper. This process is faster at the surface of the earth, where there are more grains of sand.

As a result of wind activity, dense deposits of silt particles can accumulate.
Such homogeneous porous rocks of a grayish-yellow color are called loess.

Glacier activity

Glaciers form a special glacial relief. Moving along the surface of the land, they smooth rocks, plow out hollows, and move destroyed rocks. Deposits of these rocks form moraine hills and ridges. When glaciers melt, sandy plains - sands - are formed from the sand brought by water. The basins formed by glaciers are often filled with water, turning into glacial lakes.

human activity

Man plays an important role in changing the relief. The plains were especially strongly changed by his activity. People have long settled on the plains, they build houses and roads, fill up ravines, build embankments. A person changes the relief during mining: huge quarries are dug out, heaps of waste heaps are poured - heaps of waste rock.

Scales human activity can be compared with natural processes. For example, rivers develop their valleys, carrying out rocks, and a person builds canals comparable in size.

Landforms created by man are called anthropogenic. Anthropogenic change in the relief occurs with the help of modern technology and at a fairly rapid pace.

Moving water and wind do a huge destructive job, which is called erosion (from the Latin word erosio corrosive). Land erosion - natural process. However, it is intensified as a result of economic activities of people: plowing up slopes, deforestation, excessive grazing, laying roads. In the last hundred years alone, a third of all cultivated land in the world has been eroded. These processes have reached the greatest scale in the large agricultural regions of Russia, China and the USA.

Formation of the Earth's relief

Features of the Earth's relief