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What materials does the earth's crust consist of? Pear figure - what should you wear and what should you refuse? Functions of the earth's crust

The earth's crust is of great importance for our life, for the exploration of our planet.

This concept is closely related to others that characterize the processes occurring inside and on the surface of the Earth.

What is the earth's crust and where is it located

The earth has an integral and continuous shell, which includes: the earth's crust, troposphere and stratosphere, which are the lower part of the atmosphere, hydrosphere, biosphere and anthroposphere.

They closely interact, penetrating each other and constantly exchanging energy and matter. It is customary to call the earth's crust the outer part of the lithosphere - the solid shell of the planet. Most of its outer side is covered by the hydrosphere. The rest, a smaller part, is affected by the atmosphere.

Under the Earth's crust is a denser and more refractory mantle. They are separated by a conditional border, named after the Croatian scientist Mohorovich. Its feature is a sharp increase in the speed of seismic vibrations.

Various scientific methods are used to gain insight into the earth's crust. However, obtaining specific information is possible only by means of drilling to a greater depth.

One of the objectives of such a study was to establish the nature of the boundary between the upper and lower continental crust. The possibilities of penetration into the upper mantle with the help of self-heating capsules made of refractory metals were discussed.

The structure of the earth's crust

Under the continents, its sedimentary, granite and basalt layers are distinguished, the thickness of which in the aggregate is up to 80 km. Rocks, called sedimentary rocks, were formed as a result of the deposition of substances on land and in water. They are predominantly in layers.

  • clay
  • shales
  • sandstones
  • carbonate rocks
  • rocks of volcanic origin
  • coal and other rocks.

The sedimentary layer helps to learn more about the natural conditions on earth that were on the planet in time immemorial. Such a layer may have a different thickness. In some places it may not exist at all, in others, mainly in large depressions, it may be 20-25 km.

The temperature of the earth's crust

An important energy source for the inhabitants of the Earth is the heat of its crust. The temperature increases as you go deeper into it. The 30-meter layer closest to the surface, called the heliometric layer, is associated with the heat of the sun and fluctuates depending on the season.

In the next, thinner layer, which increases in continental climates, the temperature is constant and corresponds to the indicators of a particular measurement site. In the geothermal layer of the crust, the temperature is related to the internal heat of the planet and increases as you go deeper into it. It is different in different places and depends on the composition of the elements, the depth and conditions of their location.

It is believed that the temperature rises on average by three degrees as it deepens for every 100 meters. Unlike the continental part, the temperature under the oceans is rising faster. After the lithosphere, there is a plastic high-temperature shell, the temperature of which is 1200 degrees. It is called the asthenosphere. It has places with molten magma.

Penetrating into the earth's crust, the asthenosphere can pour out molten magma, causing volcanic phenomena.

Characteristics of the Earth's crust

The Earth's crust has a mass of less than half a percent of the total mass of the planet. It is the outer shell of the stone layer in which the movement of matter occurs. This layer, which has a density half that of the Earth. Its thickness varies within 50-200 km.

The uniqueness of the earth's crust is that it can be of continental and oceanic types. The continental crust has three layers, the upper of which is formed by sedimentary rocks. The oceanic crust is relatively young and its thickness varies little. It is formed due to the substances of the mantle from oceanic ridges.

earth's crust characteristic photo

The thickness of the crust under the oceans is 5-10 km. Its feature is in constant horizontal and oscillatory movements. Most of the crust is basalt.

The outer part of the earth's crust is the hard shell of the planet. Its structure is distinguished by the presence of mobile areas and relatively stable platforms. Lithospheric plates move relative to each other. The movement of these plates can cause earthquakes and other cataclysms. The regularities of such movements are studied by tectonic science.

Functions of the earth's crust

The main functions of the earth's crust are:

  • resource;
  • geophysical;
  • geochemical.

The first of them indicates the presence of the resource potential of the Earth. It is primarily a set of mineral reserves located in the lithosphere. In addition, the resource function includes a number of environmental factors that ensure the life of humans and other biological objects. One of them is the tendency to form a hard surface deficit.

you can't do that. save our earth photo

Thermal, noise and radiation effects realize the geophysical function. For example, there is a problem of natural radiation background, which is generally safe on the earth's surface. However, in countries such as Brazil and India, it can be hundreds of times higher than the allowable one. It is believed that its source is radon and its decay products, as well as some types of human activity.

The geochemical function is associated with problems of chemical pollution harmful to humans and other representatives of the animal world. Various substances with toxic, carcinogenic and mutagenic properties enter the lithosphere.

They are safe when they are in the bowels of the planet. Zinc, lead, mercury, cadmium and other heavy metals extracted from them can be very dangerous. In processed solid, liquid and gaseous form, they enter the environment.

What is the Earth's crust made of?

Compared to the mantle and core, the Earth's crust is fragile, tough, and thin. It consists of a relatively light substance, which includes about 90 natural elements in its composition. They are found in different places of the lithosphere and with varying degrees of concentration.

The main ones are: oxygen silicon aluminum, iron, potassium, calcium, sodium magnesium. 98 percent of the earth's crust is made up of them. Including about half is oxygen, more than a quarter - silicon. Due to their combinations, minerals such as diamond, gypsum, quartz, etc. are formed. Several minerals can form a rock.

  • An ultra-deep well on the Kola Peninsula made it possible to get acquainted with mineral samples from a depth of 12 km, where rocks similar to granites and shale were found.
  • The greatest thickness of the crust (about 70 km) was revealed under the mountain systems. Under the flat areas it is 30-40 km, and under the oceans - only 5-10 km.
  • A significant part of the crust forms an ancient low-density upper layer, consisting mainly of granites and shales.
  • The structure of the earth's crust resembles the crust of many planets, including those on the Moon and their satellites.

A characteristic feature of the evolution of the Earth is the differentiation of matter, the expression of which is the shell structure of our planet. The lithosphere, hydrosphere, atmosphere, biosphere form the main shells of the Earth, differing in chemical composition, power and state of matter.

The internal structure of the Earth

The chemical composition of the Earth(Fig. 1) is similar to the composition of other terrestrial planets, such as Venus or Mars.

In general, elements such as iron, oxygen, silicon, magnesium, and nickel predominate. The content of light elements is low. The average density of the Earth's matter is 5.5 g/cm 3 .

There is very little reliable data on the internal structure of the Earth. Consider Fig. 2. It depicts the internal structure of the Earth. The earth consists of the earth's crust, mantle and core.

Rice. 1. The chemical composition of the Earth

Rice. 2. The internal structure of the Earth

Core

Core(Fig. 3) is located in the center of the Earth, its radius is about 3.5 thousand km. The core temperature reaches 10,000 K, i.e., it is higher than the temperature of the outer layers of the Sun, and its density is 13 g / cm 3 (compare: water - 1 g / cm 3). The core presumably consists of alloys of iron and nickel.

The outer core of the Earth has a greater power than the inner core (radius 2200 km) and is in a liquid (molten) state. The inner core is under enormous pressure. The substances that compose it are in a solid state.

Mantle

Mantle- the geosphere of the Earth, which surrounds the core and makes up 83% of the volume of our planet (see Fig. 3). Its lower boundary is located at a depth of 2900 km. The mantle is divided into a less dense and plastic upper part (800-900 km), from which magma(translated from Greek means "thick ointment"; this is the molten substance of the earth's interior - a mixture of chemical compounds and elements, including gases, in a special semi-liquid state); and a crystalline lower one, about 2000 km thick.

Rice. 3. Structure of the Earth: core, mantle and earth's crust

Earth's crust

Earth's crust - the outer shell of the lithosphere (see Fig. 3). Its density is approximately two times less than the average density of the Earth - 3 g/cm 3 .

Separates the earth's crust from the mantle Mohorovicic border(it is often called the Moho boundary), characterized by a sharp increase in seismic wave velocities. It was installed in 1909 by a Croatian scientist Andrey Mohorovichich (1857- 1936).

Since the processes occurring in the uppermost part of the mantle affect the movement of matter in the earth's crust, they are combined under the general name lithosphere(stone shell). The thickness of the lithosphere varies from 50 to 200 km.

Below the lithosphere is asthenosphere- less hard and less viscous, but more plastic shell with a temperature of 1200 °C. It can cross the Moho boundary, penetrating into the earth's crust. The asthenosphere is the source of volcanism. It contains pockets of molten magma, which is introduced into the earth's crust or poured onto the earth's surface.

The composition and structure of the earth's crust

Compared to the mantle and core, the earth's crust is a very thin, hard, and brittle layer. It is composed of a lighter substance, which currently contains about 90 natural chemical elements. These elements are not equally represented in the earth's crust. Seven elements—oxygen, aluminum, iron, calcium, sodium, potassium, and magnesium—account for 98% of the mass of the earth's crust (see Figure 5).

Peculiar combinations of chemical elements form various rocks and minerals. The oldest of them are at least 4.5 billion years old.

Rice. 4. The structure of the earth's crust

Rice. 5. The composition of the earth's crust

Mineral is a relatively homogeneous in its composition and properties of a natural body, formed both in the depths and on the surface of the lithosphere. Examples of minerals are diamond, quartz, gypsum, talc, etc. (You will find a description of the physical properties of various minerals in Appendix 2.) The composition of the Earth's minerals is shown in fig. 6.

Rice. 6. General mineral composition of the Earth

Rocks are made up of minerals. They can be composed of one or more minerals.

Sedimentary rocks - clay, limestone, chalk, sandstone, etc. - formed by the precipitation of substances in the aquatic environment and on land. They lie in layers. Geologists call them pages of the history of the Earth, because they can learn about the natural conditions that existed on our planet in ancient times.

Among sedimentary rocks, organogenic and inorganic (detrital and chemogenic) are distinguished.

Organogenic rocks are formed as a result of the accumulation of the remains of animals and plants.

Clastic rocks are formed as a result of weathering, the formation of destruction products of previously formed rocks with the help of water, ice or wind (Table 1).

Table 1. Clastic rocks depending on the size of the fragments

Breed name

Size of bummer con (particles)

Over 50 cm

5 mm - 1 cm

1 mm - 5 mm

Sand and sandstones

0.005 mm - 1 mm

Less than 0.005mm

Chemogenic rocks are formed as a result of sedimentation from the waters of the seas and lakes of substances dissolved in them.

In the thickness of the earth's crust, magma forms igneous rocks(Fig. 7), such as granite and basalt.

Sedimentary and igneous rocks, when immersed to great depths under the influence of pressure and high temperatures, undergo significant changes, turning into metamorphic rocks. So, for example, limestone turns into marble, quartz sandstone into quartzite.

Three layers are distinguished in the structure of the earth's crust: sedimentary, "granite", "basalt".

Sedimentary layer(see Fig. 8) is formed mainly by sedimentary rocks. Clays and shales predominate here, sandy, carbonate and volcanic rocks are widely represented. In the sedimentary layer there are deposits of such mineral, like coal, gas, oil. All of them are of organic origin. For example, coal is a product of the transformation of plants of ancient times. The thickness of the sedimentary layer varies widely - from complete absence in some areas of land to 20-25 km in deep depressions.

Rice. 7. Classification of rocks by origin

"Granite" layer consists of metamorphic and igneous rocks similar in their properties to granite. The most common here are gneisses, granites, crystalline schists, etc. The granite layer is not found everywhere, but on the continents, where it is well expressed, its maximum thickness can reach several tens of kilometers.

"Basalt" layer formed by rocks close to basalts. These are metamorphosed igneous rocks, denser than the rocks of the "granite" layer.

The thickness and vertical structure of the earth's crust are different. There are several types of the earth's crust (Fig. 8). According to the simplest classification, oceanic and continental crust are distinguished.

Continental and oceanic crust are different in thickness. Thus, the maximum thickness of the earth's crust is observed under mountain systems. It is about 70 km. Under the plains, the thickness of the earth's crust is 30-40 km, and under the oceans it is the thinnest - only 5-10 km.

Rice. 8. Types of the earth's crust: 1 - water; 2 - sedimentary layer; 3 - interbedding of sedimentary rocks and basalts; 4, basalts and crystalline ultramafic rocks; 5, granite-metamorphic layer; 6 - granulite-mafic layer; 7 - normal mantle; 8 - decompressed mantle

The difference between the continental and oceanic crust in terms of rock composition is manifested in the absence of a granite layer in the oceanic crust. Yes, and the basalt layer of the oceanic crust is very peculiar. In terms of rock composition, it differs from the analogous layer of the continental crust.

The boundary of land and ocean (zero mark) does not fix the transition of the continental crust into the oceanic one. The replacement of the continental crust by oceanic occurs in the ocean approximately at a depth of 2450 m.

Rice. 9. The structure of the continental and oceanic crust

There are also transitional types of the earth's crust - suboceanic and subcontinental.

Suboceanic crust located along the continental slopes and foothills, can be found in the marginal and Mediterranean seas. It is a continental crust up to 15-20 km thick.

subcontinental crust located, for example, on volcanic island arcs.

Based on materials seismic sounding - seismic wave velocity - we get data on the deep structure of the earth's crust. Thus, the Kola superdeep well, which for the first time made it possible to see rock samples from a depth of more than 12 km, brought a lot of unexpected things. It was assumed that at a depth of 7 km, a “basalt” layer should begin. In reality, however, it was not discovered, and gneisses predominated among the rocks.

Change in the temperature of the earth's crust with depth. The surface layer of the earth's crust has a temperature determined by solar heat. This heliometric layer(from the Greek Helio - the Sun), experiencing seasonal temperature fluctuations. Its average thickness is about 30 m.

Below is an even thinner layer, the characteristic feature of which is a constant temperature corresponding to the average annual temperature of the observation site. The depth of this layer increases in the continental climate.

Even deeper in the earth's crust, a geothermal layer is distinguished, the temperature of which is determined by the internal heat of the Earth and increases with depth.

The increase in temperature occurs mainly due to the decay of radioactive elements that make up the rocks, primarily radium and uranium.

The magnitude of the increase in temperature of rocks with depth is called geothermal gradient. It varies over a fairly wide range - from 0.1 to 0.01 ° C / m - and depends on the composition of the rocks, the conditions of their occurrence and a number of other factors. Under the oceans, the temperature rises faster with depth than on the continents. On average, with every 100 m of depth it becomes warmer by 3 °C.

The reciprocal of the geothermal gradient is called geothermal step. It is measured in m/°C.

The heat of the earth's crust is an important energy source.

The part of the earth's crust extending to the depths available for geological study forms bowels of the earth. The bowels of the Earth require special protection and reasonable use.

Before talking about what the earth's crust consists of, we can recall what is supposedly the constituent parts of everything Presumably - because man has not yet been able to penetrate deeper than this earth's crust into the center of the earth. Even the entire thickness of the bark could only be "picked".

Scientists assume, build hypotheses based on the laws of physics, chemistry and other sciences, and according to these data, we have a certain picture of the structure of the entire planet, as well as what large elements the earth's crust consists of. Geography in grades 6-7 gives students precisely these theories in a form facilitated for immature minds.

Thanks to a small share of data and a large baggage of various laws, models of the planets of the solar system, and even stars that are far from us, are built in the same way. What follows from this? Mainly that you have an absolute right to doubt all this.

Layers of planet Earth

In addition to having layers, the entire earth also consists of three layers. Such a layered culinary masterpiece. The first of these is the core; it has a solid part and a liquid part. It is the movement of the liquid part in the core that presumably creates a bit hot here - the temperature reaches values ​​​​up to 5000 degrees Celsius.

The second is the mantle. It connects the core and the earth's crust. The mantle also has several layers, namely three, and the upper one, adjacent to the earth's crust, is magma. It is directly related to the question of what large elements the earth's crust consists of, since hypothetically, these very large elements "float" along it. We can talk about its existence with a more or less high degree of probability, since during volcanic eruptions it is this hot substance that comes to the surface, destroying all plant and animal life that is on the slope of the volcano.

And, finally, the third layer of the earth is the earth's crust: the solid layer of the planet, located outside the hot "insides" of the Earth, on which we are used to walking, traveling and living in general. The thickness of the earth's crust, in comparison with the other two layers of the earth, is negligible, but nevertheless it is possible to characterize what large elements the earth's crust consists of, and also to understand its composition.

What are the layers of the earth's crust. Its main chemical elements

The earth's crust also consists of layers - there is basalt, granite and sedimentary. Interestingly, in the chemical composition of the earth's crust, 47% is oxygen.

The substance, which is essentially a gas, combines with other elements and creates a solid crust. Other elements in this case are silicon, aluminum, iron and calcium; the remaining elements are present in minute fractions.

Division into parts by thickness in different areas

It has already been said that the earth's crust is much thinner than the lower mantle or core. If we approach the question of what large elements the earth's crust consists of, precisely in relation to thickness, we can divide it into oceanic and continental. These two parts differ significantly in their thickness, and the oceanic one is about three times, and in some places ten times (if we talk about averages) thinner than the mainland.

What is the difference between the continental and oceanic crust

In addition, the zones of land and oceans differ in layers. Different sources indicate different data, we will give one option. So, according to these data, the continental crust consists of three layers, among which there is a basalt layer, a granite layer and a layer of sedimentary rocks. The plains of the earth's continental crust reach a thickness of 30-50 km, in the mountains these figures can rise to 70-80 km. According to the same source, the oceanic crust consists of two layers. A granite ball falls out, leaving only the upper sedimentary and lower basalt. The thickness of the earth's crust in the region of the oceans is approximately from 5 to 15 kilometers.

Simplified and averaged data as the basis for training

These are the most general and simplified descriptions, because scientists are constantly working to study the features of the surrounding world, and the latest data indicate that the earth's crust in different places has a structure that is much more complicated than the usual standard scheme of the earth's crust that we study at school. Here in many places of the continental crust, for example, there is another layer - diorite.

It is also interesting that these layers are not perfectly even, as is schematically depicted in geographical atlases or in other sources. Each layer can be wedged into another, or kneaded in some cut. In principle, there can be no ideal model of the earth's scheme, for the same reason that volcanic eruptions occur: there, under the earth's crust, something is constantly in motion and has very high temperatures.

All this can be learned if you connect your life with the sciences of geology and geophysics. You can try to follow scientific progress through scientific journals and articles. But without a certain amount of knowledge, this can turn out to be a very difficult task, and therefore there is a certain basis that is taught in schools without any explanation that this is just an approximate model.

Presumably, the earth's crust consists of "pieces"

Scientists at the beginning of the 20th century put forward the theory that the earth's crust is not monolithic. Therefore, it is possible to find out what large elements the earth's crust consists of according to this theory. It is assumed that the lithosphere consists of seven large and several small plates that slowly float on the surface of magma.

These movements create a catastrophic kind of phenomena that occur on our earth with great intensity in certain places. There are areas between the lithospheric plates, which are called "seismic belts". It is in these areas that the highest level of anxiety, so to speak. An earthquake and all the ensuing consequences of this is one of the clear signs that demonstrates

Influence of displacements of lithospheric plates on the formation of relief

What large elements the earth's crust consists of, which moving parts are more stable and which are more mobile, throughout the entire creation of the earth's relief, influenced its formation. The structure of the lithosphere and the characteristics of the seismic regime distribute the entire lithosphere into stable areas and mobile belts. The first are characterized by flat planes without huge depressions, hills and similar relief variations. They are also called abyssal plains. In principle, this is the answer to the question of what large elements the earth's crust consists of, what stable primary objects it is formed from. The earth's crust underlies all continents. The boundaries of these plates are easily visible by the zones of mountain formation, as well as by the degree of intensity of earthquakes. The most active places on our planet, where earthquakes and many active volcanoes are located, are the locations of Japan, the islands of Indonesia, the Aleutian Islands, the South American Pacific coast.

Are the continents bigger than we used to think?

That is, simply speaking, what the earth's crust consists of is pieces of the lithosphere, which move more or less through magma. And the boundaries of these "pieces" do not always coincide with the boundaries of the continents. Technically, they often never match. In addition, we are used to hearing that the oceans account for approximately 70% of the surface, and the continental component - only 30%. Geographically, it is, but here's what's interesting - in terms of geology, the continents account for about 40%. Ten percent of the continental crust is covered by sea and ocean waters.

The study of the internal structure of the planets, including our Earth, is an extremely difficult task. We cannot physically "drill" the earth's crust down to the core of the planet, so all the knowledge we have received at the moment is knowledge obtained "by touch", and in the most literal way.

How seismic exploration works on the example of oil exploration. We “call” the ground and “listen” to what the reflected signal will bring us

The fact is that the simplest and most reliable way to find out what is under the surface of the planet and is part of its crust is to study the propagation velocity seismic waves in the depths of the planet.

It is known that the velocity of longitudinal seismic waves increases in denser media and, on the contrary, decreases in loose soils. Accordingly, knowing the parameters of different types of rocks and having calculated data on pressure, etc., “listening” to the received answer, one can understand through which layers of the earth’s crust the seismic signal passed and how deep they are under the surface.

Studying the structure of the earth's crust using seismic waves

Seismic vibrations can be caused by two types of sources: natural And artificial. Earthquakes are natural sources of vibrations, the waves of which carry the necessary information about the density of the rocks through which they penetrate.

The arsenal of artificial vibration sources is more extensive, but first of all, artificial vibrations are caused by an ordinary explosion, but there are also more “subtle” ways of working - generators of directed impulses, seismic vibrators, etc.

Conducting blasting and studying the velocities of seismic waves is engaged in seismic exploration- one of the most important branches of modern geophysics.

What did the study of seismic waves inside the Earth give? An analysis of their propagation revealed several jumps in the change in speed when passing through the bowels of the planet.

Earth's crust

The first jump, at which speeds increase from 6.7 to 8.1 km / s, according to geologists, registers bottom of the earth's crust. This surface is located in different places on the planet at different levels, from 5 to 75 km. The boundary of the earth's crust and the underlying shell - the mantle, is called "Mohorovicic surfaces", named after the Yugoslav scientist A. Mohorovichich, who first established it.

Mantle

Mantle lies at depths up to 2,900 km and is divided into two parts: upper and lower. The boundary between the upper and lower mantle is also fixed by the jump in the propagation velocity of longitudinal seismic waves (11.5 km/s) and is located at depths from 400 to 900 km.

The upper mantle has a complex structure. In its upper part there is a layer located at depths of 100-200 km, where transverse seismic waves attenuate by 0.2-0.3 km / s, and the velocities of longitudinal waves, in essence, do not change. This layer is called waveguide. Its thickness is usually 200-300 km.

The part of the upper mantle and the crust overlying the waveguide is called lithosphere, and the layer of low velocities itself - asthenosphere.

Thus, the lithosphere is a rigid hard shell underlain by a plastic asthenosphere. It is assumed that processes arise in the asthenosphere that cause the movement of the lithosphere.

The internal structure of our planet

Earth's core

At the base of the mantle, there is a sharp decrease in the propagation velocity of longitudinal waves from 13.9 to 7.6 km/s. At this level lies the boundary between the mantle and the core of the earth, deeper than which transverse seismic waves no longer propagate.

The radius of the core reaches 3500 km, its volume: 16% of the planet's volume, and mass: 31% of the mass of the Earth.

Many scientists believe that the core is in a molten state. Its outer part is characterized by sharply reduced P-wave velocities, while in the inner part (with a radius of 1200 km), seismic wave velocities increase again to 11 km/s. The density of the core rocks is 11 g/cm 3 , and it is determined by the presence of heavy elements. Such a heavy element can be iron. Most likely, iron is an integral part of the core, since the core of a purely iron or iron-nickel composition should have a density that is 8-15% higher than the existing density of the core. Therefore, oxygen, sulfur, carbon and hydrogen appear to be attached to the iron in the core.

Geochemical method for studying the structure of planets

There is another way to study the deep structure of planets - geochemical method. The identification of various shells of the Earth and other terrestrial planets by physical parameters finds a fairly clear geochemical confirmation based on the theory of heterogeneous accretion, according to which the composition of the cores of the planets and their outer shells in its main part is initially different and depends on the earliest stage of their development.

As a result of this process, the heaviest ( iron-nickel) components, and in the outer shells - lighter silicate ( chondrite), enriched in the upper mantle with volatiles and water.

The most important feature of the terrestrial planets ( , Earth, ) is that their outer shell, the so-called bark, consists of two types of matter: mainland" - feldspar and " oceanic» - basalt.

Continental (continental) crust of the Earth

The continental (continental) crust of the Earth is composed of granites or rocks similar in composition to them, that is, rocks with a large amount of feldspars. The formation of the "granite" layer of the Earth is due to the transformation of older sediments in the process of granitization.

The granite layer should be considered as specific the shell of the Earth's crust - the only planet on which the processes of differentiation of matter with the participation of water and having a hydrosphere, an oxygen atmosphere and a biosphere have been widely developed. On the Moon and, probably, on the terrestrial planets, the continental crust is composed of gabbro-anorthosites - rocks consisting of a large amount of feldspar, however, of a slightly different composition than in granites.

These rocks form the most ancient (4.0-4.5 billion years) surfaces of the planets.

Oceanic (basalt) crust of the Earth

Oceanic (basalt) crust The earth was formed as a result of stretching and is associated with zones of deep faults, which caused the penetration of the upper mantle to the basalt chambers. Basaltic volcanism is superimposed on the earlier formed continental crust and is a relatively younger geological formation.

Manifestations of basalt volcanism on all terrestrial planets are apparently similar. The wide development of basalt "seas" on the Moon, Mars, and Mercury is obviously associated with stretching and the formation of permeability zones as a result of this process, along which basalt melts of the mantle rushed to the surface. This mechanism of manifestation of basaltic volcanism is more or less similar for all planets of the terrestrial group.

The satellite of the Earth - the Moon also has a shell structure, which on the whole repeats that of the earth, although it has a striking difference in composition.

Heat flow of the Earth. It is hottest in the region of faults in the earth's crust, and colder in the regions of ancient continental plates.

Method for measuring heat flow for studying the structure of planets

Another way to study the deep structure of the Earth is to study its heat flow. It is known that the Earth, hot from the inside, gives off its heat. The heating of deep horizons is evidenced by volcanic eruptions, geysers, and hot springs. Heat is the main energy source of the Earth.

The increase in temperature with deepening from the Earth's surface averages about 15 ° C per 1 km. This means that at the boundary of the lithosphere and asthenosphere, located approximately at a depth of 100 km, the temperature should be close to 1500 ° C. It has been established that at this temperature basalt melts. This means that the asthenospheric shell can serve as a source of basaltic magma.

With depth, the change in temperature occurs according to a more complex law and depends on the change in pressure. According to the calculated data, at a depth of 400 km the temperature does not exceed 1600°C, and at the core-mantle boundary it is estimated at 2500-5000°C.

It is established that the release of heat occurs constantly over the entire surface of the planet. Heat is the most important physical parameter. Some of their properties depend on the degree of heating of rocks: viscosity, electrical conductivity, magneticness, phase state. Therefore, according to the thermal state, one can judge the deep structure of the Earth.

Measuring the temperature of our planet at great depths is a technically difficult task, since only the first kilometers of the earth's crust are available for measurements. However, the internal temperature of the Earth can be studied indirectly by measuring the heat flux.

Despite the fact that the main source of heat on Earth is the Sun, the total power of the heat flow of our planet exceeds the power of all power plants on Earth by 30 times.

The measurements showed that the average heat flow on the continents and in the oceans is the same. This result is explained by the fact that in the oceans, most of the heat (up to 90%) comes from the mantle, where the process of transfer of matter by moving streams occurs more intensively - convection.

Convection is a process in which a heated liquid expands, becomes lighter, and rises, while colder layers sink. Since the mantle substance is closer in its state to a solid body, convection in it proceeds under special conditions, at low material flow rates.

What is the thermal history of our planet? Its initial heating is probably associated with the heat generated by the collision of particles and their compaction in their own gravity field. Then the heat was the result of radioactive decay. Under the influence of heat, a layered structure of the Earth and the terrestrial planets arose.

Radioactive heat in the Earth is released even now. There is a hypothesis according to which, at the boundary of the molten core of the Earth, the processes of splitting of matter continue to this day with the release of a huge amount of thermal energy that heats up the mantle.

In this video lesson, everyone will be able to study the topic "The structure of the Earth." Users will learn about how the earth's crust is studied, what properties it has, what layers our planet consists of. The teacher will talk about the structure of the Earth, how it was studied at different times.

2. Mantle.

As we move deeper into the Earth, temperature and pressure increase. In the center of the Earth is the core, its radius is about 3500 km, and the temperature is more than 4500 degrees. The core is surrounded by a mantle, its thickness is about 2900 km. Above the mantle is the earth's crust, its thickness varies from 5 km (under the oceans) to 70 km (under the mountain systems). The earth's crust is the hardest shell. The substance of the mantle is in a special plastic state; this substance can slowly flow under pressure.

Rice. 1. The internal structure of the Earth ()

Earth's crust- the upper part of the lithosphere, the outer solid shell of the Earth.

The earth's crust is made up of rocks and minerals.

Rice. 2. The structure of the Earth and the earth's crust ()

There are two types of earth's crust:

1. Continental (it consists of sedimentary, granite and basalt layers).

2. Oceanic (it consists of sedimentary and basalt layers).

Rice. 3. The structure of the earth's crust ()

The mantle accounts for 67% of the total mass of the Earth and 87% of its volume. Separate the upper and lower mantle. The material of the mantle can move under pressure. Internal heat from the mantle is transferred to the earth's crust.

The core is the deepest part of the Earth. There is an outer liquid core and an inner solid core.

Most of the earth's crust is covered by the waters of the oceans and seas. The continental crust is much larger than the oceanic and has three layers. The upper part of the earth's crust is heated by the sun's rays. At a depth of more than 20 meters, the temperature practically does not change, and then increases.

The most accessible for human study is the upper part of the earth's crust. Sometimes deep wells are made to study the internal structure of the earth's crust. The deepest well is over 12 km deep. Help to study the earth's crust and mines. In addition, the internal structure of the Earth is studied using special instruments, methods, images from space and sciences: geophysics, geology, seismology.

Homework

Paragraph 16.

1. What parts does the Earth consist of?

Bibliography

Main

1. Initial course of geography: Proc. for 6 cells. general education institutions / T.P. Gerasimova, N.P. Neklyukov. - 10th ed., stereotype. - M.: Bustard, 2010. - 176 p.

2. Geography. Grade 6: atlas. - 3rd ed., stereotype. - M.: Bustard, DIK, 2011. - 32 p.

3. Geography. Grade 6: atlas. - 4th ed., stereotype. - M.: Bustard, DIK, 2013. - 32 p.

4. Geography. 6 cells: cont. cards. - M.: DIK, Bustard, 2012. - 16 p.

Encyclopedias, dictionaries, reference books and statistical collections

1. Geography. Modern illustrated encyclopedia / A.P. Gorkin. - M.: Rosmen-Press, 2006. - 624 p.

Literature for preparing for the GIA and the Unified State Examination

1. Geography: an initial course. Tests. Proc. allowance for students 6 cells. - M.: Humanit. ed. center VLADOS, 2011. - 144 p.

2. Tests. Geography. Grades 6-10: Teaching aid / A.A. Letyagin. - M .: LLC "Agency" KRPA "Olimp": "Astrel", "AST", 2001. - 284 p.

Materials on the Internet

1. Federal Institute of Pedagogical Measurements ().

2. Russian Geographical Society ().

4. 900 presentations for children and 20,000 presentations for schoolchildren ().