There are inner and outer shells interacting with each other.

The internal structure of the Earth

To study the internal structure of the Earth, drilling of ultra-deep wells is used (the deepest Kola - 11,000 m. has passed less than 1/400 of the earth's radius). But most of the information about the structure of the Earth was obtained using the seismic method. Based on the data obtained by these methods, a general model of the Earth's structure was created.

In the center of the planet is the earth's core - (R = 3500 km) presumably consists of iron with an admixture of lighter elements. There is a hypothesis that the core consists of hydrogen, which under high can go into a metallic state. The outer layer of the core is a liquid, molten state; the inner core with a radius of 1250 km is solid. The temperature in the center of the core, apparently, is up to 5 - 6 thousand degrees.

The core is surrounded by a shell - the mantle. The mantle has a thickness of up to 2900 km, the volume is 83% of the planet's volume. It consists of heavy minerals rich in magnesium and iron. Despite the high temperature (above 2000?), most of the mantle substance is in a solid crystalline state due to the enormous pressure. The upper mantle at a depth of 50 to 200 km has a mobile layer called the asthenosphere (weak sphere). It is characterized by high plasticity, due to the softness of the substance that forms it. It is with this layer that other important processes on Earth are associated. Its thickness is 200-250 km. The substance of the asthenosphere, penetrating into the earth's crust and pouring out to the surface, is called magma.

The Earth's crust is a hard layered outer shell of the Earth with a thickness of 5 km under the oceans to 70 km under the mountain structures of the continents.

• Continental (mainland)
• Oceanic

The continental crust is thicker and more complex. It has 3 layers:

• Sedimentary (10-15 km, mostly sedimentary rocks)
• Granite (5-15 km., the rocks of this layer are mostly metamorphic, similar in properties to granite)
• Balsat (10-35 km., the rocks of this layer are igneous)

The oceanic crust is heavier, there is no granite layer in it, the sedimentary layer is relatively thin, it is mostly balsatic.

In the areas of transition from the mainland to the ocean, the crust has a transitional character.

The earth's crust and the upper part of the mantle form a shell, which is called (from the Greek litos - stone). The lithosphere is a solid shell of the Earth, including the earth's crust and the upper layer of the mantle, lying on the hot asthenosphere. The thickness of the lithosphere is on average 70–250 km, of which 5–70 km falls on the earth's crust. The lithosphere is not a continuous shell, it is divided into giant faults. Most plates include both continental and oceanic crust. There are 13 lithospheric plates. But the largest are: American, African, Indo-Australian, Pacific.

Under the influence of processes occurring in the bowels of the earth, the lithosphere makes movements. Lithospheric plates slowly move relative to each other at a speed of 1 - 6 cm per year. In addition, their vertical movements are constantly occurring. The set of horizontal and vertical movements of the lithosphere, accompanied by the occurrence of faults and folds of the earth's crust, are called. They are slow and fast.

The forces causing the divergence of lithospheric plates arise when the mantle substance moves. Powerful ascending flows of this substance push apart the plates, break the earth's crust, forming deep faults in it. Where this material rises outward, faults appear in the lithosphere, and the plates begin to move apart. The magma that intrudes along the faults, solidifying, builds up the edges of the plates. As a result, swells appear on both sides of the fault, and . They are found in all oceans and form a single system with a total length of 60,000 thousand km. The height of the ridges is up to 3000 m. Such a ridge reaches its greatest width in the southeastern part, where the rate of plate expansion is 12 - 13 cm / year. It does not occupy a middle position and is called the Pacific Rise. At the fault site, in the axial part of the mid-ocean ridges, there are usually gorges - rifts. Their width varies from several tens of kilometers in the upper part to several kilometers at the bottom. At the bottom of the rifts are small volcanoes and hot springs. In rifts, rising magma creates new oceanic crust. The farther from the rift, the older the crust.

Collision of lithospheric plates is observed along other plate boundaries. It happens in different ways. When a plate collides with the oceanic crust and the plate with the continental crust, the first subsides under the second. In this case, deep-sea trenches, island arcs, and mountains on land appear. If two plates collide with the continental crust, then there is a collapse in, volcanism and the formation of mountainous areas (for example, these are complex processes that occur during the movement of magma, which is formed in separate chambers and at different depths of the asthenosphere. It is very rarely formed in the earth's crust. There are two main types of magmas - basaltic (basic) and granitic (acidic).

As magma erupts on the Earth's surface, it forms volcanoes. Such magmatism is called effusive. But more often, magma is introduced into the earth's crust along cracks. Such magmatism is called intrusive.

Methods for studying the internal structure and composition of the Earth

Methods for studying the internal structure and composition of the Earth can be divided into two main groups: geological methods and geophysical methods. Geological methods are based on the results of a direct study of rock strata in outcrops, mine workings (mines, adits, etc.) and boreholes. At the same time, researchers have at their disposal the entire arsenal of methods for studying the structure and composition, which determines the high degree of detail of the results obtained. At the same time, the possibilities of these methods in studying the depths of the planet are very limited - the deepest well in the world has a depth of only -12262 m (Kola superdeep in Russia), even smaller depths have been achieved when drilling the ocean floor (about -1500 m, drilling from the American research vessel "Glomar Challenger"). Thus, depths not exceeding 0.19% of the planet's radius are available for direct study.

Information about the deep structure is based on the analysis of indirect data obtained geophysical methods, mainly the patterns of change with depth of various physical parameters (electrical conductivity, mechanical figure of merit, etc.) measured during geophysical surveys. The development of models of the internal structure of the Earth is based primarily on the results of seismic studies based on data on the laws of propagation of seismic waves. In the centers of earthquakes and powerful explosions, seismic waves arise - elastic vibrations. These waves are divided into volume waves - propagating in the bowels of the planet and "translucent" them like X-rays, and surface waves - propagating parallel to the surface and "probing" the upper layers of the planet to a depth of tens to hundreds of kilometers.
Body waves, in turn, are divided into two types - longitudinal and transverse. Longitudinal waves with a high propagation speed are the first to be recorded by seismic receivers, they are called primary or P-waves ( from English. primary - primary), the "slower" transverse waves are called S-waves ( from English. secondary - secondary). Transverse waves, as is known, have an important feature - they propagate only in a solid medium.

At the boundaries of media with different properties, waves are refracted, and at the boundaries of sharp changes in properties, in addition to refracted, reflected and converted waves arise. Shear waves can be offset perpendicular to the plane of incidence (SH waves) or offset in the plane of incidence (SV waves). When crossing the boundary of media with different properties, the SH waves experience ordinary refraction, and the SV waves, except for the refracted and reflected SV waves, excite P-waves. This is how a complex system of seismic waves arises, "seeing through" the bowels of the planet.

Analyzing the patterns of wave propagation, it is possible to identify inhomogeneities in the bowels of the planet - if at a certain depth an abrupt change in the propagation velocities of seismic waves, their refraction and reflection is recorded, we can conclude that at this depth there is a boundary of the Earth's inner shells, differing in their physical properties.

The study of the ways and speed of propagation of seismic waves in the bowels of the Earth made it possible to develop a seismic model of its internal structure.

Seismic waves, propagating from the source of the earthquake into the depths of the Earth, experience the most significant jumps in velocity, refract and reflect on seismic sections located at depths 33 km and 2900 km from the surface (see fig.). These sharp seismic boundaries make it possible to divide the bowels of the planet into 3 main internal geospheres - the earth's crust, mantle and core.

The earth's crust is separated from the mantle by a sharp seismic boundary, on which the velocity of both longitudinal and transverse waves increases abruptly. Thus, the velocity of transverse waves sharply increases from 6.7-7.6 km/s in the lower part of the crust to 7.9-8.2 km/s in the mantle. This boundary was discovered in 1909 by the Yugoslavian seismologist Mohorovičić and was subsequently named Mohorovicic border(often abbreviated as the Moho or M boundary). The average depth of the boundary is 33 km (it should be noted that this is a very approximate value due to different thicknesses in different geological structures); at the same time, under the continents, the depth of the Mohorovichich section can reach 75-80 km (which is fixed under young mountain structures - the Andes, Pamir), under the oceans it decreases, reaching a minimum thickness of 3-4 km.

An even sharper seismic boundary separating the mantle and core is fixed at depth 2900 km. At this seismic section, the P-wave velocity abruptly drops from 13.6 km/s at the base of the mantle to 8.1 km/s at the core; S-waves - from 7.3 km / s to 0. The disappearance of transverse waves indicates that the outer part of the core has the properties of a liquid. The seismic boundary separating the core and mantle was discovered in 1914 by the German seismologist Gutenberg and is often referred to as Gutenberg border, although this name is not official.

Sharp changes in the speed and nature of the passage of waves are recorded at depths of 670 km and 5150 km. Border 670 km divides the mantle into upper mantle (33-670 km) and lower mantle (670-2900 km). Border 5150 km divides the core into an external liquid (2900-5150 km) and an internal solid (5150-6371 km).

Significant changes are also noted in the seismic section 410 km dividing the upper mantle into two layers.

The obtained data on global seismic boundaries provide a basis for considering a modern seismic model of the deep structure of the Earth.

The outer shell of the solid earth is Earth's crust bounded by the Mohorovichic boundary. This is a relatively thin shell, the thickness of which ranges from 4-5 km under the oceans to 75-80 km under continental mountain structures. The upper crust is distinctly distinguished in the composition of the sedimentary layer, consisting of non-metamorphosed sedimentary rocks, among which volcanics may be present, and underlying it consolidated, or crystalline,bark, formed by metamorphosed and igneous intrusive rocks. There are two main types of the earth's crust - continental and oceanic, fundamentally different in structure, composition, origin and age.

continental crust lies under the continents and their underwater margins, has a thickness of 35-45 km to 55-80 km, 3 layers are distinguished in its section. The upper layer, as a rule, is composed of sedimentary rocks, including a small amount of weakly metamorphosed and igneous rocks. This layer is called sedimentary. Geophysically, it is characterized by a low P-wave velocity in the range of 2-5 km/s. The average thickness of the sedimentary layer is about 2.5 km.
Below is the upper crust (granite-gneiss or "granite" layer), composed of igneous and metamorphic rocks rich in silica (on average, corresponding in chemical composition to granodiorite). The velocity of P-waves in this layer is 5.9-6.5 km/s. At the base of the upper crust, the Konrad seismic section is distinguished, reflecting an increase in the velocity of seismic waves during the transition to the lower crust. But this section is not fixed everywhere: in the continental crust, a gradual increase in wave velocities with depth is often recorded.
The lower crust (granulite-mafic layer) is distinguished by a higher wave speed (6.7-7.5 km/s for P-waves), which is due to a change in the rock composition during the transition from the upper mantle. According to the most accepted model, its composition corresponds to granulite.

Rocks of various geological ages take part in the formation of the continental crust, up to the most ancient ones, about 4 billion years old.

oceanic crust has a relatively small thickness, an average of 6-7 km. In its most general form, two layers can be distinguished in its section. The upper layer is sedimentary, characterized by low thickness (about 0.4 km on average) and low P-wave speed (1.6-2.5 km/s). The lower layer - "basalt" - is composed of basic igneous rocks (above - basalts, below - basic and ultrabasic intrusive rocks). The velocity of longitudinal waves in the "basalt" layer increases from 3.4-6.2 km/s in basalts to 7-7.7 km/s in the lowest horizons of the crust.

The oldest rocks of modern oceanic crust are about 160 million years old.

Mantle It is the largest inner shell of the Earth in terms of volume and mass, bounded from above by the Moho boundary, from below by the Gutenberg boundary. In its composition, the upper mantle and lower mantle are distinguished, separated by a boundary of 670 km.

The upper mania is divided into two layers according to geophysical features. Upper layer - subcrustal mantle- extends from the Moho boundary to depths of 50-80 km under the oceans and 200-300 km under the continents and is characterized by a smooth increase in the speed of both longitudinal and transverse seismic waves, which is explained by the compaction of rocks due to the lithostatic pressure of the overlying strata. Below the subcrustal mantle to the global interface of 410 km there is a layer of low velocities. As follows from the name of the layer, the seismic wave velocities in it are lower than in the subcrustal mantle. Moreover, in some areas, lenses are detected that do not transmit S-waves at all, which gives reason to state that the mantle substance in these areas is in a partially molten state. This layer is called the asthenosphere ( from the Greek "asthenes" - weak and "sphair" - sphere); the term was introduced in 1914 by the American geologist J. Burrell, often referred to in English literature as LVZ - Low Velocity Zone. In this way, asthenosphere- this is a layer in the upper mantle (located at a depth of about 100 km under the oceans and about 200 km or more under the continents), identified on the basis of a decrease in the speed of passage of seismic waves and having a reduced strength and toughness. The surface of the asthenosphere is well established by a sharp decrease in resistivity (to values ​​of about 100 Ohm . m).

The presence of a plastic asthenospheric layer, which differs in mechanical properties from the solid overlying layers, gives grounds for isolating lithosphere- the solid shell of the Earth, including the earth's crust and subcrustal mantle, located above the asthenosphere. The thickness of the lithosphere is from 50 to 300 km. It should be noted that the lithosphere is not a monolithic stone shell of the planet, but is divided into separate plates constantly moving along the plastic asthenosphere. The foci of earthquakes and modern volcanism are confined to the boundaries of lithospheric plates.

Deeper than 410 km in the upper mantle, both P- and S-waves propagate everywhere, and their speed increases relatively monotonously with depth.

AT lower mantle, separated by a sharp global boundary of 670 km, the speed of P- and S-waves increases monotonically, without abrupt changes, up to 13.6 and 7.3 km/s, respectively, up to the Gutenberg section.

In the outer core, the speed of P-waves sharply decreases to 8 km/s, while S-waves completely disappear. The disappearance of transverse waves suggests that the outer core of the Earth is in a liquid state. Below the 5150 km section, there is an inner core in which the speed of P-waves increases, and S-waves begin to propagate again, which indicates its solid state.

The fundamental conclusion from the velocity model of the Earth described above is that our planet consists of a series of concentric shells representing a ferruginous core, a silicate mantle, and an aluminosilicate crust.

Geophysical characteristics of the Earth

Distribution of mass between the inner geospheres

The bulk of the Earth's mass (about 68%) falls on its relatively light, but large mantle, with about 50% falling on the lower mantle and about 18% on the upper. The remaining 32% of the total mass of the Earth falls mainly on the core, and its liquid outer part (29% of the total mass of the Earth) is much heavier than the inner solid part (about 2%). Only less than 1% of the total mass of the planet remains on the crust.

Density

The density of the shells naturally increases towards the center of the Earth (see fig.). The average density of the bark is 2.67 g/cm 3 ; at the Moho border, it increases abruptly from 2.9-3.0 to 3.1-3.5 g/cm3. In the mantle, the density gradually increases due to the compression of the silicate substance and phase transitions (restructuring of the crystalline structure of the substance in the course of "adaptation" to the increasing pressure) from 3.3 g/cm 3 in the subcrustal part to 5.5 g/cm 3 in the lower mantle . At the Gutenberg boundary (2900 km), the density almost doubles abruptly, up to 10 g/cm 3 in the outer core. Another jump in density - from 11.4 to 13.8 g / cm 3 - occurs at the border of the inner and outer core (5150 km). These two sharp density jumps have a different nature: at the mantle/core boundary, a change in the chemical composition of matter occurs (transition from a silicate mantle to an iron core), and a jump at the boundary of 5150 km is associated with a change in the state of aggregation (transition from a liquid outer core to a solid inner core) . In the center of the Earth, the density of matter reaches 14.3 g/cm 3 .

Pressure

The pressure in the Earth's interior is calculated based on its density model. The increase in pressure as you move away from the surface is due to several reasons:

compression due to the weight of the overlying shells (lithostatic pressure);

phase transitions in chemically homogeneous shells (in particular, in the mantle);

the difference in the chemical composition of the shells (crust and mantle, mantle and core).

At the foot of the continental crust, the pressure is about 1 GPa (more precisely, 0.9 * 10 9 Pa). In the Earth's mantle, the pressure gradually increases, reaching 135 GPa at the Gutenberg boundary. In the outer core, the pressure growth gradient increases, while in the inner core, on the contrary, it decreases. The calculated values ​​of pressure at the boundary between the inner and outer cores and near the center of the Earth are 340 and 360 GPa, respectively.

Temperature. Sources of thermal energy

The geological processes occurring on the surface and in the bowels of the planet are primarily due to thermal energy. Energy sources are divided into two groups: endogenous (or internal sources), associated with the generation of heat in the bowels of the planet, and exogenous (or external in relation to the planet). The intensity of the flow of thermal energy from the depths to the surface is reflected in the magnitude of the geothermal gradient. geothermal gradient is the temperature increment with depth, expressed in 0 C/km. The "inverse" characteristic is geothermal stage- depth in meters, upon immersion to which the temperature will increase by 1 0 С. areas with a calm tectonic regime. With depth, the value of the geothermal gradient decreases significantly, amounting to an average of about 10 0 С/km in the lithosphere, and less than 1 0 С/km in the mantle. The reason for this lies in the distribution of thermal energy sources and the nature of heat transfer.

Sources of endogenous energy are the following.
1. Energy of deep gravitational differentiation, i.e. heat release during the redistribution of matter in density during its chemical and phase transformations. The main factor in such transformations is pressure. The core-mantle boundary is considered as the main level of this energy release.
2. Radiogenic heat produced by the decay of radioactive isotopes. According to some calculations, this source determines about 25% of the heat flux radiated by the Earth. However, it should be taken into account that elevated contents of the main long-lived radioactive isotopes - uranium, thorium and potassium are observed only in the upper part of the continental crust (isotope enrichment zone). For example, the concentration of uranium in granites reaches 3.5 10 -4%, in sedimentary rocks - 3.2 10 -4%, while in the oceanic crust it is negligible: about 1.66 10 -7%. Thus, radiogenic heat is an additional source of heat in the upper part of the continental crust, which determines the high value of the geothermal gradient in this region of the planet.
3. Residual heat, preserved in the depths since the formation of the planet.
4. Solid tides, due to the attraction of the moon. The transition of kinetic tidal energy into heat occurs due to internal friction in the rock masses. The share of this source in the total heat balance is small - about 1-2%.

In the lithosphere, the conductive (molecular) mechanism of heat transfer predominates; in the sublithospheric mantle of the Earth, a transition occurs to a predominantly convective mechanism of heat transfer.

Calculations of temperatures in the bowels of the planet give the following values: in the lithosphere at a depth of about 100 km, the temperature is about 1300 0 C, at a depth of 410 km - 1500 0 C, at a depth of 670 km - 1800 0C, at the border of the core and mantle - 2500 0 C, at a depth of 5150 km - 3300 0 С, in the center of the Earth - 3400 0 С. In this case, only the main (and most probable for deep zones) source of heat, the energy of deep gravitational differentiation, was taken into account.

Endogenous heat determines the course of global geodynamic processes. including the movement of lithospheric plates

On the surface of the planet, the most important role is played by exogenous source heat is solar radiation. Below the surface, the effect of solar heat is sharply reduced. Already at a shallow depth (up to 20-30 m) there is a zone of constant temperatures - a region of depths where the temperature remains constant and is equal to the average annual temperature of the region. Below the belt of constant temperatures, heat is associated with endogenous sources.

Earth magnetism

The earth is a giant magnet with a magnetic force field and magnetic poles that are close to geographic, but do not coincide with them. Therefore, in the readings of the magnetic needle of the compass, magnetic declination and magnetic inclination are distinguished.

Magnetic declination- this is the angle between the direction of the magnetic needle of the compass and the geographic meridian at a given point. This angle will be the largest at the poles (up to 90 0) and the smallest at the equator (7-8 0).

Magnetic inclination- the angle formed by the inclination of the magnetic needle to the horizon. When approaching the magnetic pole, the compass needle will take a vertical position.

It is assumed that the occurrence of a magnetic field is due to systems of electric currents that arise during the rotation of the Earth, in connection with convective movements in the liquid outer core. The total magnetic field is the sum of the values ​​of the main field of the Earth and the field due to ferromagnetic minerals in the rocks of the earth's crust. Magnetic properties are characteristic of minerals - ferromagnets, such as magnetite (FeFe 2 O 4), hematite (Fe 2 O 3), ilmenite (FeTiO 2), pyrrhotite (Fe 1-2 S), etc., which are minerals and are established by magnetic anomalies. These minerals are characterized by the phenomenon of remanent magnetization, which inherits the orientation of the Earth's magnetic field that existed at the time of the formation of these minerals. The reconstruction of the location of the Earth's magnetic poles in different geological epochs indicates that the magnetic field periodically experienced inversion- a change in which the magnetic poles are reversed. The process of changing the magnetic sign of the geomagnetic field lasts from several hundred to several thousand years and begins with an intensive decrease in the intensity of the main magnetic field of the Earth to almost zero, then the reverse polarity is established, and after a while a rapid restoration of intensity follows, but of the opposite sign. The North Pole took the place of the South Pole and, vice versa, with an approximate frequency of 5 times in 1 million years. The current orientation of the magnetic field was established about 800 thousand years ago.

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

Nucleus

Nucleus(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. it 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.

Earth structure

From Wikipedia, the free encyclopedia

Earth in the section from the core to the exosphere. The left picture is not to scale.

Earth has a spherical shape in the first rough approximation (the actual radius of the Earth is 6357-6378 km) and consists of several shells. These layers can be defined either chemical or their rheological properties. Located in the center core of the earth with a radius of about 1250 km, which mainly consists of iron and nickel. Next comes liquid part of the earth's core(consisting mainly of iron) with a thickness of about 2200 km. Then 2900 km viscous mantle, consisting of silicates and oxides, and on top is quite thin, hard Earth's crust. It also consists of silicates and oxides, but is enriched in elements not found in mantle rocks. Scientific understanding of the internal structure of the Earth is based on observations topography and bathymetry, observations rocks in outcrops, samples raised to the surface from great depths as a result of volcanic activity, analysis seismic waves that pass through the earth, dimension gravity regions of the Earth, and experiments with crystalline solid bodies at pressures and temperatures characteristic of the deep interior of the Earth.

1 Assumptions

2 Structure

• 2.1 Core

  2.2 Robe

  2.3 Kora

3 Historical development of alternative concepts

6 Further reading

Assumptions

The force, gravity of the Earth can be used to calculate its mass, as well as to estimate the volume of the planet, and its average density. Astronomers can also calculate the mass of the Earth from its orbit and influence on nearby planetary bodies. Observations of rocks, water bodies and the atmosphere allow us to estimate the mass, volume and density of rocks at a certain depth, so that the rest of the mass must be in deeper layers.

Structure

The structure of the Earth can be classified according to two principles: mechanical properties such as rheology, or chemical properties. Mechanically, it can be divided into lithosphere , asthenosphere , mesosphere, outer core and inner core. Chemically, the Earth can be divided into the earth's crust, top mantle, lower mantle, outer nucleus and inner core.

Schematic representation of the internal structure of the Earth. 1. continental crust - 2. oceanic crust - 3. upper mantle - 4. lower mantle - 5. Outer core - 6. Inner core - A: Mohorovichic surface-B: Gutenberg Gap-C: Lehmann-Bullen gap

The geological layers of the Earth are at the following depths below the surface: :

Depth		Layer
Kilometers	Miles
		Lithosphere (locally varies from 5 to 200 km)
		Kora (locally ranges from 5 to 70 km)
		Upper part of the mantle
		asthenosphere
		Upper mesosphere (upper mantle)
		Lower mesosphere (lower mantle)
		outer core
		inner core

The layers of the Earth were determined indirectly by measuring the propagation time of refracted and reflected seismic waves created by earthquakes. The core does not transmit transverse waves, and the speed of wave propagation differs in different layers. Changes in the speed of seismic waves between different layers cause them to refract due to Snell's law.

Nucleus

Main article: Earth's core

Average Earth Density 5515 kg/m 3 . Since the average density of the surface material is only about 3000 kg/m 3 , we must conclude that dense materials exist in the Earth's core. Another piece of evidence for the high density of the core comes from the study of seismology.

Seismic measurements show that the core is divided into two parts, a solid inner core with a radius of ~1220 km [2] and a liquid outer core with a radius of ~3400 km .

Mantle

Main article: Mantle of the Earth

The Earth's mantle extends to a depth of 2890 km, making it the thickest layer of the Earth. The pressure in the lower mantle is ~140 GPa (1.4 M atm). The mantle is composed of silicate rocks rich in iron and magnesium in relation to the overlying crust. High temperatures in the mantle make the silicate material plastic enough to allow for convection of matter in the mantle to come to the surface through faults in the tectonic plates. The melting and viscosity of matter depend on pressure and chemical changes in the mantle. The viscosity of the mantle ranges from 1021 to 1024 Pa s, depending on the depth. For comparison, the viscosity of water is about 10 −3 Pa s, a sand 10 7 Pa s.

Bark

Main article: Earth's crust

The crust ranges from 5 to 70 km deep from the surface. The thinnest parts of the oceanic crust that underlie the ocean basins (5-10 km) and consist of dense ( mafic (English )) iron-magnesium silicate rock, such as basalt.

Historical development of alternative concepts

Main article: hollow earth

Hypothesis illustration Halley.

In 1692 Edmund Halley(in an article printed in the Philosophical Transactions of the Royal Society in London), put forward the idea of ​​the Earth consisting of a hollow body about 500 miles thick, with two inner concentric shells around an inner core corresponding to the diameter of the planets Venus, Mars and Mercury, respectively .

Chapter 8 The Inert Matter of the Earth

§ 8.1. The shape and structure of the Earth

earth shape

The Earth is the arena in which civilizations arise, develop and perish, and a single modern society is being formed. Our future largely depends on how well we understand the structure of our planet. However, we know no more about it (and often much less) than about distant stars. Let's start with ideas about the shape of the Earth. Currently, no one denies the claim that our planet is "round". Indeed, in the first approximation, the shape of the Earth is defined as spherical. This idea originated in ancient Greece. And only in the XVII-XVIII centuries. it began to be clarified. It was found that the Earth is flattened along the axis of rotation (the difference between the axes is about 21 km). It is assumed that the Earth was formed under the influence of the combined action of gravity and centrifugal forces. The resultant of these forces - the force of gravity - is expressed in the acceleration that each body acquires at the surface of the Earth. Already I. Newton theoretically substantiated the position according to which the Earth should be compressed in the direction of the axis of rotation and take the form of an ellipsoid, which was subsequently confirmed empirically. Later it was discovered that the Earth is compressed not only at the poles, but also to a small extent along the equator. The largest and smallest radii of the equator differ by 213 m, i.e. The earth is a triaxial ellipsoid. But the idea of ​​the Earth as an ellipsoid is also correct only in the first approximation. The real surface of the Earth is even more complex. Closest to the modern figure of the Earth geoid - an imaginary level surface, in relation to which the vector of gravity is directed perpendicularly everywhere. In the area of ​​the oceans, the geoid coincides with the surface of the water, which is at rest. The discrepancy between the geoid and the ellipsoid in some places reaches ±(100-150) m, which is explained by the uneven distribution of masses of different densities in the Earth's body, which affects the change in gravity, and hence the shape of the geoid. At present, to create the geodetic basis for maps and other purposes in Russia, the Krasovsky ellipsoid is used with the following main parameters: equatorial radius 6378.245 km; polar radius 6356.863 km; polar compression 1/298.25; the surface area of ​​the Earth is about 510 million km2, its volume is 1.083 1012 km3. The mass of the Earth is 5.976 1027 g.

The internal structure of the Earth

It should be noted that only the uppermost (to depths of 15-20 km) horizons of the earth's crust, which are exposed to the surface or uncovered by mines, mines and boreholes, are available for direct observation. Judgments about the composition and physical state of deeper shells are based on the data of geophysical methods, i.e. are speculative. Of these methods, the seismic method is of particular importance, based on recording the propagation velocity in the Earth's body of waves caused by earthquakes or artificial explosions. In earthquake sources, so-called longitudinal seismic waves arise, which are considered as a reaction of the medium to a change in volume, and transverse waves are the reaction of the medium to a change in shape, which propagate only in solids. Based on geophysical observations, it has been established that the Earth is heterogeneous and differentiated along the radius. Currently, there are several models of the structure of the Earth. Most researchers accept a model according to which three main shells of the Earth are distinguished, separated by clearly defined seismic interfaces, where seismic wave velocities change dramatically (Fig. 8.1):

the earth's crust is the hard upper shell of the earth. Its thickness varies from 5-10 km under the oceans to 30-40 km in the plains and reaches 50-75 km in mountainous areas (maximum values ​​are found under the Andes and the Himalayas);

the Earth's mantle extends below the earth's crust to a depth of 2900 km from the surface and is divided into two parts: the upper mantle - to a depth of 900-1000 km and the lower mantle - from 900-1000 to 2900 km;

3) the core of the Earth, where the outer core is isolated - up to a depth of about 5120 km and the inner core - below 5120 km. Earth's crust it is separated from the mantle in most cases by a rather sharp seismic boundary - the Mohorovichic surface (abbreviated as Μ οho, or M). The seismic method in the upper mantle revealed a layer of relatively less dense, as it were, “softened” rocks - the asthenosphere. In this layer, a decrease in the speed of seismic waves, especially transverse ones, and an increase in electrical conductivity are observed, which indicates a less viscous, more plastic state of matter - on 2-3 orders of magnitude lower than in the overlying and underlying layers of the mantle. It is assumed that these properties are associated with partial melting of the mantle matter (1-10%) as a result of a faster increase in temperature than pressure with increasing depth. The viscosity of the asthenosphere changes significantly both in the vertical and horizontal directions, and its thickness also changes. The asthenosphere is located at different depths: under the continents - from 80-120 to 200-250 km, under the oceans - from 50-70 to 300-400 km. It is most clearly expressed and elevated, in some places to depths of 20-25 km or less, under the most mobile zones of the earth's crust and, on the contrary, is weakly expressed and lowered under the calmest parts of the continents (platform shields). The asthenosphere plays an important role in deep geological processes. The solid suprasthenospheric layer of the mantle, together with the earth's crust, is called the lithosphere.

External	Atmosphere Hydrosphere Biosphere
Internal	1) Bark (continental crust · oceanic crust ): Sedimentary layer Upper bark Conrad border lower bark Lithosphere (Lithospheric plates ) Mohorovichic surface 2) Mantle : Upper mantle (asthenosphere) Seismic section 660 km lower mantle Gutenberg border 3) Nucleus : outer core inner core

Basic characteristics of the Earth

The average density of the Earth, according to gravimetric data, is 5.5 g/cm. The density of the rocks that make up the earth's crust ranges from 2.4 to 3.0 g/cm. Comparison of these values ​​with the average density of the Earth leads to the assumption that with depth an increase in density in the mantle and core of the Earth should be observed. It is believed that in the above asthenospheric part of the mantle below the Moho boundary, the rocks are much denser. When moving from the mantle to the core, the density jumps up to 9.7-10.0 g/cm3, then it rises and in the inner core it is 12.5-13.0 g/cm3. It is calculated that the acceleration due to gravity varies from 9.82 m/s2 at the surface to a maximum value of 10.37 m/s2 at the base of the lower mantle (2900 km). In the core, the acceleration of gravity falls rapidly, reaching 4.52 m/s2 at a depth of about 5000 km, then falling to 1.26 m/s2 at a depth of 6000 km, and in the center to zero. It is known that the Earth is like a giant magnet with a force field around. In the modern era, the Earth's magnetic poles are located near the geographic poles, but do not coincide with them. At present, the origin of the Earth's main magnetic field is most often explained using the Frenkel-Elsasser dynamotheorical concept, according to which this field arises as a result of the action of a system of electric currents caused by complex convective movements in the liquid outer core during the rotation of the Earth. The general background of the magnetic field is superimposed by the influence of rocks that contain ferromagnetic minerals occurring in the upper part of the earth's crust, as a result of which magnetic anomalies are formed on the surface of the earth. The residual magnetization of rocks containing ferromagnetic minerals is oriented like the Earth's magnetic field that existed during their formation. Studies of this magnetization have shown that the Earth's magnetic field has repeatedly experienced inversions in the course of geological history: the north pole became south, and the south pole became north. The scale of magnetic inversions is used to compare rock strata and determine their age. To understand the processes occurring in the depths of the Earth, the issue of the thermal field of the planet turned out to be important. Currently, there are two sources of heat of the Earth - the Sun and the bowels of the Earth. Heating by the Sun extends to a depth not exceeding 28-30 m. At a certain depth from the surface there is a belt of constant temperature equal to the average annual temperature of the area. Thus, in Moscow, at a depth of 20 m, a constant temperature of +4.2 °C is observed, and in Paris, +11.83 °C at a depth of 28 m. Below the belt of constant temperature, observations in mines, mines, boreholes have established an increase in temperature with depth, which is due to the heat flow coming from the bowels of the Earth. The average value of the internal heat flux for the Earth is about 1.4-1.5 μcal/cm2 per second. It has been established that the heat flow depends on the degree of mobility of the crust and the intensity of endogenous (internal) processes. Within the calm regions of the continents, its value is somewhat less than the average. Significant fluctuations in the heat flow are characteristic of mountains; on most of the ocean floor, the heat flow is almost the same as on the continental plains, but within the so-called rift valleys of the mid-ocean ridges, it sometimes increases by 5-7 times. High values ​​of the heat flux are noted in the inner regions of the Red Sea. The sources of the internal thermal energy of the Earth are still insufficiently studied. But the main ones are: 1) the decay of radioactive elements (uranium, thorium, potassium, etc.); 2) gravitational differentiation with redistribution of material in terms of density in the mantle and core, accompanied by the release of heat. Observations in mines, mines and boreholes indicate an increase in temperature with depth. To characterize it, a geothermal gradient is introduced - an increase in temperature in degrees Celsius per unit of depth. Its meanings are different in different parts of the world. Approximately 30 °C per 1 km is considered to be average, and the extreme values ​​of the range differ by more than 25 times, which is explained by different endogenous activity of the earth's crust and different thermal conductivity of rocks. The largest geothermal gradient, equal to 150 °С per 1 km, was noted in the state of Oregon (USA), and the smallest (6 °С per 1 km) - in South Africa. In the Kola well, at a depth of 11 km, a temperature of about 200 °C was recorded. The highest values ​​of the gradient are associated with the mobile zones of the oceans and continents, while the lowest values ​​are associated with the most stable and ancient sections of the continental crust. The change in temperature with depth is determined very approximately from indirect data. For the Earth's crust, temperature calculations are based mainly on data on heat flow, thermal conductivity of rocks, and lava temperature, but such data are not available for large depths, and the composition of the mantle and core is not exactly known. It is assumed that below the asthenosphere the temperature rises naturally with a significant decrease in the geothermal gradient. Based on the idea that the core consists mainly of iron, calculations were made of its melting at various boundaries, taking into account the pressure existing there. It was found that at the boundary between the lower mantle and the core, the melting point of iron should be 3700 °C, and at the boundary between the outer and inner core - 4300 °C. From this it is concluded that, from a physical point of view, the temperature in the core is 4000-5000 °C. For comparison, we can point out that on the surface of the Sun the temperature is slightly less than 6000 °C. Let us touch upon the question of the state of aggregation of the matter of the Earth. It is believed that the substance of the lithosphere is in a solid crystalline state, since the temperature at existing pressures here does not reach the melting point. However, in some places and inside the earth's crust, seismologists note the presence of separate low-velocity lenses resembling the asthenospheric layer. According to seismic data, the substance of the Earth's mantle, through which both longitudinal and transverse seismic waves pass, is in an effectively solid state. At the same time, the substance of the lower mantle is probably in a crystalline state, since the pressure existing in them prevents melting. Only in the asthenosphere, where seismic wave velocities are lowered, does the temperature approach the melting point. It is assumed that the substance in the asthenospheric layer can be in an amorphous glassy state, and some (less than 10%) even in a molten state. Geophysical data, as well as magma chambers arising at different levels of the asthenospheric layer, indicate the heterogeneity and stratification of the asthenosphere. As for the state of matter in the Earth's core, most researchers believe that the matter of the outer core is in a liquid state, and the inner core is in a solid state, since the transition from the mantle to the core is accompanied by a sharp decrease in the velocity of longitudinal seismic waves, and transverse waves propagating only in solid medium, it does not include.

The upper layer of the Earth, which gives life to the inhabitants of the planet, is just a thin shell covering many kilometers of inner layers. Little more is known about the hidden structure of the planet than about outer space. The deepest Kola well, drilled into the earth's crust to study its layers, has a depth of 11 thousand meters, but this is only four hundredth of the distance to the center of the globe. Only seismic analysis can get an idea of ​​the processes taking place inside and create a model of the Earth's structure.

Inner and outer layers of the Earth

The structure of the planet Earth is heterogeneous layers of inner and outer shells, which differ in composition and role, but are closely related to each other. The following concentric zones are located inside the globe:

• The core - with a radius of 3500 km.
• Mantle - approximately 2900 km.
• The earth's crust is an average of 50 km.

The outer layers of the earth make up a gaseous shell, which is called the atmosphere.

Center of the planet

The central geosphere of the Earth is its core. If we raise the question of which layer of the Earth is practically the least studied, then the answer will be - the core. It is not possible to obtain exact data on its composition, structure and temperature. All information that is published in scientific papers has been obtained by geophysical, geochemical methods and mathematical calculations and is presented to the general public with the reservation “presumably”. As the results of the analysis of seismic waves show, the earth's core consists of two parts: internal and external. The inner core is the most unexplored part of the Earth, since seismic waves do not reach its limits. The outer core is a mass of hot iron and nickel, with a temperature of about 5 thousand degrees, which is constantly in motion and is a conductor of electricity. It is with these properties that the origin of the Earth's magnetic field is associated. The composition of the inner core, according to scientists, is more diverse and is supplemented by even lighter elements - sulfur, silicon, and possibly oxygen.

Mantle

The geosphere of the planet, which connects the central and upper layers of the Earth, is called the mantle. It is this layer that makes up about 70% of the mass of the globe. The lower part of the magma is the shell of the core, its outer boundary. Seismic analysis shows here a sharp jump in the density and velocity of compressional waves, which indicates a material change in the composition of the rock. The composition of the magma is a mixture of heavy metals, dominated by magnesium and iron. The upper part of the layer, or asthenosphere, is a mobile, plastic, soft mass with a high temperature. It is this substance that breaks through the earth's crust and splashes to the surface in the process of volcanic eruptions.

The thickness of the magma layer in the mantle is from 200 to 250 kilometers, the temperature is about 2000 ° C. The mantle is separated from the lower globe of the earth's crust by the Moho layer, or the Mohorovichic boundary, by a Serbian scientist who determined a sharp change in the speed of seismic waves in this part of the mantle.

hard shell

What is the name of the layer of the Earth that is the hardest? This is the lithosphere, a shell that connects the mantle and the earth's crust, it is located above the asthenosphere, and cleans the surface layer from its hot influence. The main part of the lithosphere is part of the mantle: out of the entire thickness from 79 to 250 km, the earth's crust accounts for 5-70 km, depending on the location. The lithosphere is heterogeneous, it is divided into lithospheric plates, which are in constant slow motion, sometimes diverging, sometimes approaching each other. Such fluctuations of the lithospheric plates are called tectonic movement, it is their fast tremors that cause earthquakes, cracks in the earth's crust, and magma splashing to the surface. The movement of lithospheric plates leads to the formation of troughs or hills, the frozen magma forms mountain ranges. Plates do not have permanent boundaries, they join and separate. Territories of the Earth's surface, above the faults of tectonic plates, are places of increased seismic activity, where earthquakes, volcanic eruptions occur more often than in others, and minerals are formed. At this time, 13 lithospheric plates have been recorded, the largest of them: American, African, Antarctic, Pacific, Indo-Australian and Eurasian.

Earth's crust

Compared to other layers, the earth's crust is the thinnest and most fragile layer of the entire earth's surface. The layer in which organisms live, which is the most saturated with chemicals and microelements, is only 5% of the total mass of the planet. The earth's crust on planet Earth has two varieties: continental or mainland and oceanic. The continental crust is harder, consists of three layers: basalt, granite and sedimentary. The ocean floor is made up of basalt (basic) and sedimentary layers.

• Basalt rocks- These are igneous fossils, the densest of the layers of the earth's surface.
• granite layer- absent under the oceans, on land it can approach a thickness of several tens of kilometers of granite, crystalline and other similar rocks.
• Sedimentary layer formed during the destruction of rocks. In some places it contains deposits of minerals of organic origin: coal, table salt, gas, oil, limestone, chalk, potassium salts and others.

Hydrosphere

Characterizing the layers of the Earth's surface, one cannot fail to mention the vital water shell of the planet, or the hydrosphere. The water balance on the planet is maintained by ocean waters (the main water mass), groundwater, glaciers, inland waters of rivers, lakes and other bodies of water. 97% of the entire hydrosphere falls on the salt water of the seas and oceans, and only 3% is fresh drinking water, of which the bulk is in glaciers. Scientists suggest that the amount of water on the surface will increase over time due to deep balls. Hydrospheric masses are in constant circulation, they pass from one state to another and closely interact with the lithosphere and atmosphere. The hydrosphere has a great influence on all terrestrial processes, the development and vital activity of the biosphere. It was the water shell that became the environment for the origin of life on the planet.

The soil

The thinnest fertile layer of the Earth called soil, or soil, together with the water shell, is of the greatest importance for the existence of plants, animals and humans. This ball arose on the surface as a result of erosion of rocks, under the influence of organic decomposition processes. Processing the remnants of life, millions of microorganisms have created a layer of humus - the most favorable for crops of all kinds of land plants. One of the important indicators of high soil quality is fertility. The most fertile soils are those with an equal content of sand, clay and humus, or loam. Clay, rocky and sandy soils are among the least suitable for agriculture.

Troposphere

The air shell of the Earth rotates together with the planet and is inextricably linked with all processes occurring in the earth's layers. The lower part of the atmosphere through the pores penetrates deep into the body of the earth's crust, the upper part gradually connects with space.

The layers of the Earth's atmosphere are heterogeneous in composition, density and temperature.

At a distance of 10 - 18 km from the earth's crust extends the troposphere. This part of the atmosphere is heated by the earth's crust and water, so it gets colder with height. The decrease in temperature in the troposphere occurs by about half a degree every 100 meters, and at the highest points it reaches from -55 to -70 degrees. This part of the airspace occupies the largest share - up to 80%. It is here that the weather is formed, storms, clouds gather, precipitation and winds form.

high layers

• Stratosphere- the ozone layer of the planet, which absorbs the ultraviolet radiation of the sun, preventing it from destroying all life. The air in the stratosphere is rarefied. Ozone maintains a stable temperature in this part of the atmosphere from -50 to 55 ° C. In the stratosphere, an insignificant part of moisture, therefore, clouds and precipitation are not characteristic of it, in contrast to air currents that are significant in speed.
• Mesosphere, thermosphere, ionosphere- the air layers of the Earth above the stratosphere, in which a decrease in the density and temperature of the atmosphere is observed. The layer of the ionosphere is the place where the glow of charged gas particles occurs, which is called the aurora.
• Exosphere- a sphere of dispersion of gas particles, a blurred border with space.