What is called the internal forces of the Earth? The relief of the earth and its main forms

Simultaneously with internal, tectonic processes, external processes operate on the Earth. Unlike internal ones, covering the entire thickness of the lithosphere, they act only on the surface of the Earth. The depth of their penetration into the earth's crust does not exceed a few meters, and only in caves - up to several hundred meters. The source of the origin of forces that cause external processes is thermal solar energy.

External processes are very diverse. These include the weathering of rocks, the work of wind, water and glaciers.

Weathering. It is divided into physical, chemical and organic.

physical weathering- this is mechanical crushing, grinding of rocks.

It occurs when there is a sudden change in temperature. When heated, the rock expands; when cooled, it contracts. Since the coefficient of expansion of different minerals included in the rock is not the same, the process of its destruction is enhanced. At first, the rock breaks up into large blocks, which are crushed over time. The accelerated destruction of the rock is facilitated by water, which, penetrating into the cracks, freezes in them, expands and breaks the rock into separate parts. Physical weathering is most active where there is a sharp change in temperature, and solid igneous rocks come to the surface - granite, basalt, syenites, etc.

chemical weathering- this is the chemical effect on rocks of various aqueous solutions.

In this case, unlike physical weathering, various chemical reactions occur, and as a result, a change chemical composition and possibly the formation of new rocks. Chemical weathering operates everywhere, but it proceeds especially intensively in easily soluble rocks - limestone, gypsum, dolomite.

organic weathering is the process of destruction of rocks by living organisms - plants, animals and bacteria.

Lichens, for example, settling on rocks, wear away their surface with the released acid. Plant roots also secrete acid, and in addition, root system acts mechanically, as if tearing the rock. earthworms passing through inorganic substances, transform the rock and improve the access of water and air to it.

weathering and climate. All types of weathering occur simultaneously, but act with different intensity. It depends not only on the constituent rocks, but also mainly on the climate.

In the polar countries, frosty weathering is most actively manifested, in temperate countries - chemical, in tropical deserts - mechanical, in the humid tropics - chemical.

Wind work. The wind is capable of destroying rocks, carrying and depositing their solid particles. How stronger wind and the more often it blows, the more work it can do. Where rocky outcrops come to the surface of the Earth, the wind bombards them with grains of sand, gradually erasing and destroying even the most hard rocks. Less resistant rocks are destroyed faster, specific, eolian landforms- stone lace, aeolian mushrooms, pillars, towers.

AT sandy deserts and along the shores of the seas and large lakes, the wind creates specific forms relief - dunes and dunes.

dunes- These are mobile sandy hills of crescent shape. Their windward slope is always gentle (5-10°), and the leeward slope is steep - up to 35-40° (Fig. 27). The formation of dunes is associated with the deceleration of the wind flow carrying sand, which occurs due to any obstacles - surface irregularities, stones, bushes, etc. The wind strength weakens, and sand deposition begins. The more constant the winds and the more sand, the faster the dune grows. The highest dunes - up to 120 m - were found in the deserts of the Arabian Peninsula.

Rice. 27. The structure of the dune (the arrow shows the direction of the wind)

The dunes move in the direction of the wind. The wind drives the grains of sand down a gentle slope. Having reached the ridge, the wind flow swirls, its speed decreases, the grains of sand fall out and roll down the steep leeward slope. This causes the movement of the entire dune at a speed of up to 50-60 m per year. Moving, dunes can fill up oases and even entire villages.

On sandy beaches, the waving sands form dunes. They stretch along the coast in the form of huge sandy ridges or hills up to 100 m or more high. Unlike dunes, they do not have a permanent shape, but can also move inland from the beach. In order to stop the movement of the dunes, trees and shrubs are planted, primarily pines.

The work of snow and ice. Snow, especially in the mountains, does a lot of work. Huge masses of snow accumulate on the slopes of the mountains. From time to time they break down from the slopes, forming snow avalanches. Such avalanches, moving at great speed, capture fragments of rocks and carry them down, sweeping away everything in their path. For the formidable danger posed by snow avalanches, they are called "white death".

The solid material that remains after the snow melts forms huge rocky mounds that block and fill intermountain depressions.

Doing even more work glaciers. They occupy vast areas on Earth - more than 16 million km2, which is 11% of the land area.

There are continental, or integumentary, and mountain glaciers. continental ice occupy vast areas in Antarctica, Greenland, and on many polar islands. The ice thickness of continental glaciers is not the same. For example, in Antarctica it reaches 4000 m. Under the influence of enormous gravity, the ice slides into the sea, breaks off, and forms icebergs- ice floating mountains.

At mountain glaciers two parts are distinguished - areas of nutrition or accumulation of snow and melting. Snow is accumulating in the mountains above snow line. The height of this line is not the same in different latitudes: the closer to the equator, the higher the snow line. In Greenland, for example, it lies at an altitude of 500-600 m, and on the slopes of the Chimborazo volcano in the Andes - 4800 m.

Above the snow line, snow accumulates, compacts and gradually turns into ice. Ice has plastic properties and under the pressure of the overlying masses begins to slide down the slope. Depending on the mass of the glacier, its saturation with water and the steepness of the slope, the speed of movement varies from 0.1 to 8 m per day.

Moving along the slopes of the mountains, glaciers plow out potholes, smooth out rock ledges, and widen and deepen valleys. The clastic material that the glacier captures during its movement, during the melting (retreat) of the glacier, remains in place, forming a glacial moraine. Moraine- these are piles of fragments of rocks, boulders, sand, clay left by the glacier. There are bottom, lateral, surface, middle and terminal moraines.

Mountain valleys, through which a glacier has ever passed, are easy to distinguish: in these valleys, the remains of moraines are always found, and their shape resembles a trough. Such valleys are called touches.

Work of flowing waters. Flowing waters include temporary rain streams and snow melt, streams, rivers and The groundwater. The work of flowing waters, taking into account the time factor, is grandiose. It can be said that the entire appearance of the earth's surface is to some extent created by flowing water. All flowing waters are united by the fact that they produce three types of work:

destruction (erosion);

Transfer of products (transit);

Attitude (accumulation).

As a result, various irregularities are formed on the surface of the Earth - ravines, furrows on slopes, cliffs, river valleys, sandy and pebble islands, etc., as well as voids in the thickness of rocks - caves.

The action of gravity. All bodies - liquid, solid, gaseous, located on the Earth - are attracted to it.

The force with which a body is attracted to the earth is called gravity.

Under the influence of this force, all bodies tend to take the lowest position on the earth's surface. As a result, water flows in rivers, rain water seep into the depths earth's crust, snow avalanches fall, glaciers move, fragments of rocks move down the slopes. Gravity - necessary condition actions of external processes. Otherwise, the weathering products would have remained at the site of their formation, covering the underlying rocks like a cloak.

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§ 19. Volcanoes and earthquakes§ 21. Minerals and rocks

Earth. Slow uplifts and subsidences of parts of the earth's surface cause changes in the outlines of land and sea. Plate movements lead to the formation of mountains, volcanoes and earthquakes.

Movements of the earth's crust

Already the ancient Greeks and Romans, who lived on the shores of the Mediterranean Sea, knew that the earth's surface can experience ups and downs. Long-term observations with the help of modern instruments have proved this. The earth's crust really moves in a vertical direction: somewhere it slowly sinks, somewhere it slowly rises. At the same time, each section of the earth's crust moves in a horizontal direction along with the lithospheric plates.

Mountain formation

Rocks on the surface of slowly moving ones accumulate in horizontal layers. When the plates collide, the rock strata are bent and crushed into folds of various sizes and steepness. Convex folds form mountain ranges, and concave folds form intermountain depressions. That is why many formed during the collision lithospheric plates mountains of land are called folded.

Gradually, the folded mountains are destroyed, and only the folded base remains of them. Plains form on this leveled base.

During the formation of mountains, rock strata are not only crushed into folds, but also torn, split by faults. Separated by faults into separate blocks, sections of the earth's crust are shifted up or down relative to each other. This is how faults, horsts and grabens arise. The mountains consisting of them are called folded-blocky and blocky.

The movement of giant plates of the lithosphere leads not only to the formation of mountains, but also to the occurrence of earthquakes and, which often carry mortal danger for people.

Volcanism

Volcanism- this is an outpouring of magma on the surface of the land or the bottom of the oceans but cracks in the earth's crust or pipe-like channels - vents. On land, magma erupts, as a rule, through vents around which cone-shaped mountains rise - volcanoes.

Erupting magma loses gases and water vapor and becomes lava. Gases from magma are released very quickly, so eruptions are often accompanied by powerful explosions. They destroy rocks, turning them into fragments, including very small ones - volcanic ash. The eruptions of different volcanoes are not the same. For some, they proceed calmly; during the eruption of others, strong explosions are observed with the release of hot debris, ash and gases.

earthquakes

earthquakes These are rapid fluctuations in the earth's crust caused by rock shifts. The place in the depths of the earth's crust where these shifts occur is called the focus of the earthquake. From the focus, waves propagate through the earth's crust, creating vibrations. The place on the earth's surface directly above the focus of an earthquake is called the epicenter. Here the tremors are the strongest, with the distance from the epicenter they weaken.
More than 100,000 small and about 100 fairly strong earthquakes occur on Earth every year. Scientists record earthquakes with the help of special instruments - seismographs. For assessment in Russia, a is used on a 12-point scale.

Consequences of earthquakes and volcanism

Areas where earthquakes and volcanic eruptions often recur form seismic belts. They coincide with the boundaries between the lithospheric plates. Volcanic eruptions, and especially strong earthquakes accompanied by destruction and loss of life. Between 2004 and 2011 alone, more than half a million people died as a result of earthquakes. The most destructive earthquakes in these seven years were in South-East Asia in 2004, on the island of Haiti in 2010 and in March 2011.

Formation of the Earth's relief

Features of the Earth's relief

Topic: "Internal Forces of the Earth"

Target:

1. Acquaintance with the internal forces of the Earth.

2. Form an idea about the movements of the earth's surface, earthquakes, the origin and formation of volcanoes.

3. Find out the influence of volcanoes on the life of the planet.

Tasks:

1. Show with examples the destructive power of the internal forces of the Earth.

2. Consolidate students' knowledge of the structure and functioning of volcanoes.

3. Give an idea of ​​the catastrophic nature of eruptions.

4. Find out how the products of volcanic eruptions are used in the economy.

5. Continue to develop the ability to work with the map.

Lesson type: A lesson in learning a new topic.

During the classes.

Organizing time. Guys, check your readiness for the lesson: textbook, notebook, atlas, contour map, pen, pencil.

Announcement of the topic of the lesson.

In Norway, far from the coast, pegs are driven in, to which boats used to be tied. Explain why boat pegs are not at the water's edge? (The earth's surface has risen).

What follows from this? (The earth's crust is moving).

How fast is the earth's surface moving? (Very slow, up to 5 cm per year).

Do you notice these movements?

And what movements of the Earth can a person see? And even to feel, as these are destructive movements, with human casualties. (Earthquakes).

Where are the movements of the Earth formed on the surface of the planet or inside?

Who is ready to name the topic of the lesson? (Internal motions of the Earth).

The movements of the Earth can be called the forces of the Earth. How will the theme sound now?

- Internal forces of the Earth . Write the topic of the lesson in your notebook.

What is our goal? (Name the internal forces, get acquainted with the movements of the earth's crust and identify the causes of movements, identify the causes of earthquakes).

3. Learning a new topic.

Guys, what kind of movements occur inside the planet? (The earth's crust is not whole, it is divided into lithospheric plates that slide along the inner mantle. The inner mantle is viscous, plastic).

What are internal movements? (To the fact that lithospheric plates approach, collide, diverge).

What is formed? Open your textbooks on page 58, 1 point 19 of the paragraph, find the answer.

How can we schematically show these movements with an arrow?

Who will come out and draw on the blackboard? These are horizontal movements.

If there are horizontal movements, what other movements can there be? (Vertical).

Find on page 59 of the textbook among the drawings, examples of vertical movements. (Horst, graben, fault).

Determine from the picture what a horst is? (Elevated area of ​​the earth's surface. Mountains with flat tops). Write down in a notebook.

What is a graben? (This is a section lowered along the faults). Write down in a notebook.

What is a reset? (The ledge occurs when one block of the earth's crust descends along a fault in relation to another). Write down in a notebook.

So what are the movements of the earth's surface? (Horizontal and vertical).

What do we attribute to the internal forces of the Earth? (Internal horizontal and vertical movements of the earth's surface). Write down in a notebook.

Guys, what phenomenon combines fast horizontal and vertical movements? (Earthquake).

What happens during an earthquake? (Displacement, shift of rocks).

What is the name of the place where the rock shift occurs? (The hearth (in the textbook, page 61) is the place where the shift of rocks occurs).

What else does an earthquake consist of? (Epicenter - the place where a seismic vibration occurs, is located directly above the source).

What do earthquakes lead to? (To catastrophic consequences, to destruction, to victims).

How to act in case of an earthquake? (Move away from the windows, stand in doorway when running out into the street do not use the elevator).

How is the strength of an earthquake measured? (In points).

You have the international 12-point Richter scale on your desks. Determine the strength of the earthquake on the slides.

What instrument measures the strength of an earthquake? (Seismograph).

What kind of lines does the device draw? (Measures the strength of an earthquake, the greater the force, the greater the trait).

What are the areas of the Earth where earthquakes often occur called? (Seismically active areas, in the textbook page 61).

Who will be able to show on the map the seismically active regions of our planet? Where they are? (At the boundaries of lithospheric plates).

So what other inner forces have we met? (Earthquakes). Write it down in your notebook as the second paragraph.

Listen to the riddle, and name what else can be attributed to the internal forces of the Earth. Listen to the riddle to the end without shouting to raise your hand.

Magma rushes out through the vent

She really needs an exit from the crater

If the passage to the surface is given to her,

So, the terrible woke up ...

(Volcano.)

What will you write down in your notebook in paragraph 3? (Volcanism).

What parts of the volcano sounded in the riddle? (Vent and crater).

What is a crater? (Bowl-shaped depression at the top of the mountain).

What is a vent? (A channel through which magma rises.) Showing the parts of a volcano on a model of a volcano made by grade 5.

What part of the volcano has not been named? (Cone). What is a volcano cone? (A cone is a volcanic mountain formed by solidified lava.)

How is a volcano cone formed? (The cone grows gradually, the first layer of lava pours out and solidifies. Over it, after a while, the second layer pours out, etc. It turns out a layered cone.)

Why is the volcano erupting? (At the upper boundary of the mantle, where the pressure is less than at great depths, in some places the mantle substance melts, a magma chamber is formed. If a crack in the earth's crust reaches the magma chamber, the pressure decreases. Magma, saturated with gases, boils, as it were, turning into a fiery liquid mass, rushes up, expanding the crack, and pours out to the surface. Its temperature is more than 1000 * C. - Who is ready to draw a conclusion: what is the difference between a volcano and a mountain? (magma chamber, crater, vent, layered cone)

What is the substance under the earth's crust called? (Mantle).

The substance in the mouth of a volcano is called ... (Magma).

And the substance on the surface of the Earth is ... (Lava).

Who will correctly place the tablets of the process of transformation of one substance into another? (Magma Lava Mantle).

Look at the screen. Where do volcanoes form? (On land - in the fault zone, at the bottom of the oceans - lava burns through the earth's crust).

Where are the faults in the earth's crust? (Boundaries of lithospheric plates are seismically active areas).

Where do you think there will be more volcanoes - in the ocean or on the mainland? (At the bottom of the ocean, as there is a thin earth's crust, which is easier to burn through.)

Where did the name "Vulcan" come from? (The ancient Romans called the God of fire and blacksmithing Vulcan. According to legend, he forged armor in his forge inside a mountain on the island of Vulcano in the Tyrrhenian Sea, off the coast of Italy. Over time, any fire-breathing mountain began to be called a volcano, like the God of fire.)

On the table I have three-dimensional models of volcanoes, which were made by children of the 5th grade. The models are made from different materials: sweet and salty dough, building foam, polystyrene foam, gypsum, clay. For today's lesson, your guys have prepared models.

And now we will look at the volcano in action. (Student showing a model of a volcanic eruption).

In addition to lava, what else comes to the surface during a volcanic eruption? (Gases, water vapor, volcanic dust, clouds of ash, volcanic bombs and blocks fly out.)

Name the types of volcanoes. (Volcanoes are active, extinct and dormant).

What volcanoes are called active? Volcanoes, the eruption of which took place in the memory of mankind: Etna (Sicily), Krakatoa (Indonesia), Cotopaxi (South America.)

What volcanoes are called extinct? (Volcanoes, about the eruption of which no information has been preserved. For example, Elbrus, Kenya and Kilimanjaro).

Dormant volcanoes? ( long time did not erupt, but suddenly begin to erupt. For example, Vesuvius.)

Volcanoes are formidable neighbors for nearby settlements. They can cause great disasters.

The first such terrible event, information about which has come down to us, is the death of three cities in 79 AD. e. Volcano Vesuvius, which had fallen asleep after several centuries of dormancy, began to erupt and flooded the city of Herculaneum with mud-stone flows, lava - Stabia, and filled up the city of Pompeii with a multi-meter layer of hot ash and stones, thousands of people died.

This terrible event struck people so much that the artist Karl Bryullov painted the painting “The Last Day of Pompeii”.

Guys, there is no volcano in the picture, how did the artist depict the eruption?

Are there active volcanoes in our country? (On the Kamchatka Peninsula and Kuril Islands. The largest of them, the Klyuchevskaya Sopka volcano, is located in Kamchatka. Its height is 4688 meters).

Who will show on the map?

Open atlases on page 23.

How are volcanoes marked on a map? (*). In the contour map on page 10, label Klyuchevskaya Sopka volcano. Designate the volcano *. On the island of Iceland, mark the volcano Hekla.

Can a volcano appear on the territory of Moscow?

Guys, you have a table on your tables, fill it out using the atlas p.6. Pick up 2 examples of volcanoes on each continent.

Did you manage to complete all the columns? Why? (There are no volcanoes in Australia). Why?

Do you think there are benefits from volcanic eruptions? The products of the volcanic eruption are used in the economy of people. Volcanic ash is a good natural fertilizer for fertile soil. Lava is used in industry and construction, volcanic glass - obsidian - in jewelry, for making dishes, table clocks. (Presentation).

4. Consolidation of the studied topic.

A game for those who closely followed the course of the lesson. You have answer sheets on the tables, your task, having heard the question, is to raise the correct answer.- Pearth shocks and vibrations of the earth's surface? (Earthquakes).

A bowl-shaped depression at the top of a volcano? (Crater).

A channel through which magma rises? (Vernel).

Where do volcanoes form? (On land - in the fault zone, at the bottom of the oceans).

What are volcanoes? (Acting, sleeping, extinct).

The substance that erupts from a volcano is called? (Lava).

The highest volcano in Russia? (Klyuchevskaya Sopka).

Abrupt displacement of rocks? (Earthquake).

Horizontal movements of the earth's surface? (The mountains).

Vertical movements of the earth's surface? (Horsts, grabens).

Name the internal forces of the Earth that form the relief. (Horizontal, vertical movements of the earth's surface, earthquakes, volcanism).

5. Summing up.

Grading.

6. Homework:

paragraph 19, in the contour map, mark and sign the volcanoes recorded in the table.

THE OUTER FORCES OF THE EARTH

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

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

Rock fragments, sand, dust from the surrounding rocks and valley slopes move on the surface and in their thickness. When melting, all this material falls on the earth's surface. The ice mass itself is capable of exerting a strong shaping effect on the relief. Under its influence, trough-shaped 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 in industrial enterprises lead to acid rain.

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Our planet knows how to surprise... Take, for example, the recent earthquake in Bashkiria. Personally, I, like many others, thought that this was unlikely in this region. However, processes invisible to us are constantly going on inside the planet, and internal forces are accumulating. I will remind you what it is.

What are the internal forces of the Earth

Various geological and geochemical processes that occur in the bowels of the planet are recorded by special instruments in different parts of the world. Almost every day we learn from TV news about natural disasters: volcanic eruptions, tsunamis, earthquakes. All of them are caused by energy that arises in the depths of the planet. It is this deep energy that generates the internal (endogenous) forces of the Earth. They accumulate through various chemical reactions that occur with the release of heat, as well as the radioactive decay of elements.

What processes are going on in the bowels

Endogenous forces are at work within the planet and humans cannot see them. However, the result of their action is quite accessible to our view. Mountains and depressions, volcanoes and geysers, mineral deposits appeared due to such internal processes as:

1. The movement of the earth's crust, which is manifested in the raising and lowering of its sections.
2. Magmatism, which is characterized by the accumulation of molten magma in the mantle. It can rise and solidify both inside the earth's crust and outside. When magma comes to the surface, volcanoes form.
3. Metamorphism is the change in rocks within the earth's crust. Thus, minerals are formed in rocks.
4. Earthquakes. This phenomenon occurs due to sudden shifts or breaks in the upper mantle and crust of the Earth.

Earthquakes: types and features

If the eruption of volcanoes is a more or less local phenomenon, then the shocks and vibrations during earthquakes are transmitted over a vast territory. They come in different strengths and are conditionally divided into:

• weak (1-4 points);
• strong (5-7 points);
• destructive (8-12 points).

Fortunately, the earthquake in Ufa was weak, but it showed that scientists know far from everything about the internal forces of the planet.