Definition of the lithosphere is a diagram of the internal structure of the earth. Schemes of the internal structure of the earth

The Earth, like many other planets, has a layered internal structure. Our planet consists of three main layers. The inner layer is the core, the outer is the earth's crust, and between them is the mantle.

The core is the central part of the Earth and is located at a depth of 3000-6000 km. The radius of the core is 3500 km. According to scientists, the core consists of two parts: the outer - probably liquid, and the inner - solid. The core temperature is about 5000 degrees. Modern ideas about the core of our planet were obtained through long-term research and analysis of the data obtained. Thus, it has been proven that in the planet’s core the iron content reaches 35%, which determines its characteristic seismic properties. The outer part of the core is represented by rotating flows of nickel and iron, which conduct electric current well. The origin of the Earth's magnetic field is connected precisely with this part of the core, since the global magnetic field is created by electric currents flowing in the liquid substance of the outer core. Due to the very high temperature, the outer core has a significant influence on the areas of the mantle in contact with it. In some places, enormous heat and mass flows arise directed towards the Earth's surface. The inner core of the Earth is solid and also has a high temperature. Scientists believe that this state of the inner part of the core is ensured by very high pressure in the center of the Earth, reaching 3 million atmospheres. As the distance from the Earth's surface increases, the compression of substances increases, many of which pass into the metallic state.

The intermediate layer - the mantle - covers the core. The mantle occupies about 80% of the volume of our planet, it is the largest part of the Earth. The mantle is located upward from the core, but does not reach the Earth's surface; from the outside it is in contact with the earth's crust. Basically, the mantle material is in a solid state, except for the upper viscous layer approximately 80 km thick. This is the asthenosphere, translated from Greek as “weak ball”. According to scientists, the mantle material is constantly moving. As the distance from the earth's crust increases towards the core, the mantle material transitions to a more dense state.

On the outside, the mantle is covered by the earth's crust - a strong outer shell. Its thickness varies from several kilometers under the oceans to several tens of kilometers in mountain ranges. The earth's crust accounts for only 0.5% of the total mass of our planet. The composition of the bark includes oxides of silicon, iron, aluminum, and alkali metals. The continental crust is divided into three layers: sedimentary, granite and basalt. The oceanic crust consists of sedimentary and basaltic layers.

The Earth's lithosphere is formed by the earth's crust together with the upper layer of the mantle. The lithosphere is composed of tectonic lithospheric plates, which seem to “slide” along the asthenosphere at a speed of 20 to 75 mm per year. The lithospheric plates moving relative to each other are different in size, and the kinematics of movement is determined by plate tectonics.

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The internal structure of the Earth is one of the most interesting and little-studied topics of modern scientists. Today, we have tens of times more information about space than about what is happening in the very heart of our planet. Human penetration into the earth’s crust is as scanty as a mosquito’s sting can penetrate human skin. The thing is that the top layer of the entire globe is the earth’s crust, which is quite dense in composition. And to drill a well in it, having the most modern equipment, you need to spend several months, and its depth will be only a few kilometers.

What are a few kilometers compared to several thousand? Seismology plays a major role in the study of the inner layers of the Earth. Ideally, this is a science that studies earthquakes. But it was thanks to seismic methods (natural earthquakes or artificial explosions) that it was possible to find out that the entire interior of the planet is conventionally divided into three parts - the earth’s crust, viscous mantle and core.

Earth's crust

The Earth's crust is the solid shell of the Earth and is the upper part of the lithosphere. Most of it is located under the World Ocean and from here the crust is divided into oceanic (occupies 21%) and continental (79%). If we take the total mass of the planet as 100%, then the crust accounts for only 0.47%. The earth's crust is characterized by constant horizontal and vertical movements, which leads to the formation of various forms of relief. The division of the crust into continental and oceanic is justified by its different structure.

The continental part is much thicker than the oceanic part, and its border does not coincide with the coastline of the World Ocean. From a geographical point of view, it is believed that coastal zones, shallow seas, bays with a depth of up to 200 meters are a continuation of the continental part. After all, as studies show, the presence of small water bodies in a given territory is not a constant phenomenon. The oceanic part of the crust begins where the water depth reaches 4 kilometers.

The continental crust is formed by three layers:

• Sedimentary - its thickness in some places reaches up to 15 km. The layer got its name because it consists of sediments of various types, which accumulated layer by layer over millions of years. The study of this layer allows scientists to observe various geological processes and trace the stages of rise and fall of the crust.
• The granite layer got its name as a result of the same speed of seismic waves in it and in the granite itself. It consists of rocks of crystalline origin, which were formed as a result of the rise of magma from the depths of the Earth.
• The basalt layer also got its name due to the speed of seismic waves in it. The lower boundary of this layer can reach 70 km in depth and, accordingly, no one knows its exact composition. According to some assumptions, it consists of basalts, according to others - from metamorphic rocks with a high degree of metamorphism.

The oceanic part of the earth's crust differs in composition from the continental one, although in its structure it also has three layers. The sedimentary layer in the oceanic part reaches only 1 km in width. The granite layer is missing, and in its place there is a little-studied part, which is most often referred to as the second or intermediate layer. Well, the third is a basalt layer, which in its structure is similar to the continental one. It should be noted that the thickness of the oceanic crust is only 3-7 km, which is much less than that of the continental crust.

Mantle

The part of the Earth that is located under the earth's crust is called the mantle. This is the most voluminous part, accounting for 67% of its mass. The upper boundary of the mantle is at a depth of 30 km, and the lower boundary is 2900 km from the surface. The gap between the crust and the mantle is called the Mohorovicic zone. In turn, the mantle itself is divided into several spheres: the upper (depth up to 900 km) and the lower mantle. The processes that occur in the mantle significantly affect the Earth's surface and the crust itself. It is thanks to the viscous composition of the mantle that the movement of lithospheric plates, volcanic eruptions, earthquakes and the formation of various ore deposits occurs.

According to one opinion, scientists believe that the mantle consists of elements that were in a solid state during the formation of the planet. Iron and magnesium combined with silicon dioxide to form silicates. Magnesium silicates are found in the upper part of the mantle, and the amount of iron silicates increases with depth. In the lower part of the mantle they decompose into oxides. With increasing depth there is a significant increase in temperature and pressure. The study of the mantle has long been of great interest among scientists all over the planet. A study of the rocks that scientists believe make up the upper and lower mantle led them to the conclusion that there is a significant amount of silicon in the lower part. And the upper layer is characterized by water reserves that seep there through the earth’s crust, and are also capable of rising back.

Core of the globe

In the very center of our planet there is a core, which occupies 31.5% of the total mass of the Earth. Just like the rest of the internal components of the planet, the core consists of several parts - the outer and inner core. According to the studies, it was found that the composition of the core is dominated by an iron-nickel alloy. The outer part of the core has a radius of about 2200 km, and its composition is more liquid. The inner part is smaller, has a radius of 1300 km and is more dense. Our planet has a magnetic field, the creation of which is directly influenced by the internal structures of the Earth.

This suggests that the core must be an electrical conductor. The average density of the substance that is part of the core is 11 t/m3. Only metal can have such density. No scientist can figure out the exact composition of the core, since it is simply unrealistic to obtain samples from the center of the Earth. And all the information that is available is just guesses and assumptions.

Analyzing all of the above, we can conclude that the internal structure of the Earth is very complex. On the one hand, everything is simple - crust, mantle, core. But on the other hand, we cannot look inside to be 100% sure of what is happening there. It has been proven that the planet was formed from the accumulation of various pieces of meteorites, asteroids, comets, dust and dirt. All these particles formed the Earth in no particular order. And this means that initially in all spheres there were pieces of the same composition. In order for geographic shells to form, for the separation of the inner layers of the globe to occur, gigantic processes had to occur.

Analyzing the dynamics of the development of the earth's crust, we are once again convinced that these processes do not fade away even now. For billions of years, the movement of lithospheric plates occurs, the formation of huge depressions, the outpouring of lava, and the formation of mountains. Then it all gets destroyed and rebuilt. All this is possible only in the presence of enormous energy and matter, which do not cease to be released from the bowels of the Earth. Finding out the causes of all these processes and unraveling their relationship with each other is the main task of scientists, which will take many more decades to unravel.

Studying the internal structure of planets, including our Earth, is an extremely difficult task. We cannot physically “drill” into the earth’s crust right down to the core of the planet, so all the knowledge we have acquired at the moment is knowledge obtained “by touch,” and in the most literal way.

How seismic exploration works using the example of oil field exploration. We “call” the earth 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 speed of propagation seismic waves in the depths of the planet.

It is known that the speed of longitudinal seismic waves increases in denser media and, on the contrary, decreases in loose soils. Accordingly, knowing the parameters of different types of rock and having calculated data on pressure, etc., “listening” to the response received, you 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. Natural sources of vibrations are earthquakes, the waves of which carry the necessary information about the density of the rocks through which they penetrate.

The arsenal of artificial sources of vibrations 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 pulses, seismic vibrators, etc.

Conducting blasting operations and studying seismic wave velocities seismic survey- one of the most important branches of modern geophysics.

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

Earth's crust

The first jump, in which speeds increase from 6.7 to 8.1 km/s, according to geologists, is recorded base 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 between the earth's crust and the underlying shell, the mantle, is called "Mohorovicic surfaces", named after the Yugoslav scientist A. Mohorovicic who first established it.

Mantle

Mantle lies at depths of up to 2,900 km and is divided into two parts: upper and lower. The boundary between the upper and lower mantle is also recorded by a jump in the speed of propagation 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 essentially do not change. This layer is named waveguide. Its thickness is usually 200-300 km.

The part of the upper mantle and crust that lies above the waveguide is called lithosphere, and the layer of reduced velocities itself - asthenosphere.

Thus, the lithosphere is a rigid, solid shell underlain by a plastic asthenosphere. It is assumed that processes occur in the asthenosphere that cause 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 speed of propagation of longitudinal waves from 13.9 to 7.6 km/s. At this level lies the boundary between the mantle and Earth's core, deeper than which transverse seismic waves no longer propagate.

The radius of the core reaches 3500 km, its volume: 16% of the volume of the planet, 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 values ​​of the velocities of longitudinal waves; in the inner part (with a radius of 1200 km) the velocities of seismic waves 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 could be iron. Most likely, iron is an integral part of the core, since a core of pure iron or iron-nickel composition should have a density 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 different shells of the Earth and other terrestrial planets according to physical parameters finds quite clear geochemical confirmation based on the theory of heterogeneous accretion, according to which the composition of the cores of planets and their outer shells is, for the most part, initially different and depends on the earliest stage of their development.

As a result of this process, the heaviest ones were concentrated in the core ( iron-nickel) components, and in the outer shells - lighter silicate ( chondritic), enriched in the upper mantle with volatile substances 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 substance: " mainland" - feldspathic and " oceanic" - basalt.

Continental crust of the Earth

The continental (continental) crust of the Earth is composed of granites or rocks similar to them in composition, 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, although of a slightly different composition than in granites.

The oldest (4.0-4.5 billion years) surfaces of the planets are composed of these rocks.

Oceanic (basaltic) crust of the Earth

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

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

The Earth's satellite, the Moon, also has a shell structure that generally replicates that of the Earth, although it has a striking difference in composition.

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

Method for measuring heat flow to study 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 up 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 depth from the Earth's surface averages about 15° C per 1 km. This means that at the boundary of the lithosphere and asthenosphere, located at approximately a depth of 100 km, the temperature should be close to 1500 ° C. It has been established that at this temperature the melting of basalts occurs. This means that the asthenospheric shell can serve as a source of magma of basaltic composition.

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

It has been established that heat release 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, magnetism, phase state. Therefore, the thermal state can be used to 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 Earth's internal temperature can be studied indirectly through heat flow measurements.

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

Measurements have shown that the average heat flow on continents and 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 flows is more intense - convection.

Convection is a process in which heated fluid expands, becoming lighter, and rises, while cooler layers sink. Since mantle matter is closer in its state to a solid body, convection in it occurs under special conditions, at low flow rates of the material.

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. The heat then resulted from radioactive decay. Under the influence of heat, a layered structure of the Earth and the terrestrial planets arose.

Radioactive heat is still being released in the Earth. There is a hypothesis according to which, at the border of the Earth’s molten core, the processes of splitting matter continue to this day with the release of a huge amount of thermal energy, heating the mantle.

The interior of the Earth is very mysterious and practically inaccessible. Unfortunately, there is no such apparatus yet with which one can penetrate and study the internal structure of the Earth. Researchers have found that at the moment the deepest mine in the world has a depth of 4 km, and the deepest well is located on the Kola Peninsula and is 12 km.

However, certain knowledge about the depths of our planet has been established. Scientists studied its internal structure using the seismic method. The basis of this method is the measurement of vibrations during an earthquake or artificial explosions produced in the bowels of the Earth. Substances with different densities and compositions passed vibrations through them at a certain speed. This made it possible to measure this speed using special instruments and analyze the results obtained.

Scientists' opinion

Researchers have found that our planet has several shells: the earth's crust, mantle and core. Scientists believe that approximately 4.6 billion years ago the stratification of the Earth's interior began and continues to stratify to this day. In their opinion, all heavy substances descend to the center of the Earth, joining the planet's core, and lighter substances rise up and become the earth's crust. When the internal stratification ends, our planet will turn cold and dead.

Earth's crust

It is the thinnest shell of the planet. Its share is 1% of the total mass of the Earth. People live on the surface of the earth's crust and extract from it everything they need for survival. In the earth's crust, in many places, there are mines and wells. Its composition and structure are studied using samples collected from the surface.

Mantle

It is the most extensive shell of the earth. Its volume and mass make up 70 - 80% of the entire planet. The mantle consists of solid matter, but less dense than the core material. The deeper the mantle is, the greater its temperature and pressure become. The mantle has a partially molten layer. With the help of this layer, solids move to the earth's core.

Core

Is the center of the earth. It has a very high temperature (3000 - 4000 o C) and pressure. The core consists of the densest and heaviest substances. It makes up approximately 30% of the total mass. The solid part of the core floats in its liquid layer, thereby creating the earth's magnetic field. It is a protector of life on the planet, protecting it from cosmic rays.

Popular science film about the formation of our world

Shell structure of the Earth. Physical state (density, pressure, temperature), chemical composition, movement of seismic waves in the interior of the Earth. Terrestrial magnetism. Sources of internal energy of the planet. Age of the Earth. Geochronology.

The Earth, like other planets, has a shell structure. When seismic waves (longitudinal and transverse) pass through the body of the Earth, their velocities at some deep levels change noticeably (and abruptly), which indicates a change in the properties of the medium passed by the waves. Modern ideas about the distribution of density and pressure inside the Earth are given in the table.

Changes in density and pressure with depth inside the Earth

(S.V. Kalesnik, 1955)

The table shows that in the center of the Earth the density reaches 17.2 g/cm 3 and that it changes with a particularly sharp jump (from 5.7 to 9.4) at a depth of 2900 km, and then at a depth of 5 thousand km. The first jump makes it possible to isolate a dense core, and the second - to subdivide this core into outer (2900-5000 km) and inner (from 5 thousand km to the center) parts.

Dependence of the speed of longitudinal and transverse waves on depth

Thus, there are essentially two sharp changes in velocities: at a depth of 60 km and at a depth of 2900 km. In other words, the earth's crust and inner core are clearly separated. In the intermediate belt between them, as well as inside the core, there is only a change in the rate of increase in speeds. It can also be seen that the Earth is in a solid state down to a depth of 2900 km, because Transverse elastic waves (shear waves) pass freely through this thickness, which are the only ones that can arise and propagate in a solid medium. The passage of transverse waves through the core was not observed, and this gave reason to consider it liquid. However, the latest calculations show that the shear modulus in the core is small, but still not equal to zero (as is typical for a liquid) and, therefore, the Earth's core is closer to a solid state than a liquid state. Of course, in this case, the concepts of “solid” and “liquid” cannot be identified with similar concepts applied to the aggregate states of matter on the ground surface: high temperatures and enormous pressures prevail inside the Earth.

Thus, the internal structure of the Earth is divided into the crust, mantle and core.

Earth's crust - the first shell of the Earth’s solid body, has a thickness of 30-40 km. By volume it is 1.2% of the volume of the Earth, by mass - 0.4%, the average density is 2.7 g / cm 3. Consists mainly of granites; sedimentary rocks are of subordinate importance in it. The granite shell, in which silicon and aluminum play a huge role, is called “sialic” (“sial”). The earth's crust is separated from the mantle by a seismic section called Moho border, from the name of the Serbian geophysicist A. Mohorovicic (1857-1936), who discovered this “seismic section”. This boundary is clear and is observed in all places on Earth at depths from 5 to 90 km. The Moho section is not simply a boundary between rocks of different types, but represents a plane of phase transition between eclogites and gabbros of the mantle and basalts of the earth's crust. During the transition from the mantle to the crust, the pressure drops so much that gabbro turns into basalts (silicon, aluminum + magnesium - “sima” - silicon + magnesium). The transition is accompanied by an increase in volume by 15% and, accordingly, a decrease in density. The Moho surface is considered the lower boundary of the earth's crust. An important feature of this surface is that in general terms it is like a mirror image of the topography of the earth's surface: under the oceans it is higher, under the continental plains it is lower, under the highest mountains it sinks lowest (these are the so-called roots of the mountains).

There are four types of the earth's crust; they correspond to the four largest forms of the Earth's surface. The first type is called mainland, its thickness is 30-40 km; under young mountains it increases to 80 km. This type of earth's crust corresponds in relief to continental protrusions (the underwater margin of the continent is included). The most common division is into three layers: sedimentary, granite and basalt. Sedimentary layer, up to 15-20 km thick, complex layered sediments(clays and shales predominate, sandy, carbonate and volcanic rocks are widely represented). granite layer(thickness 10-15 km) consists of metamorphic and igneous acidic rocks with a silica content of over 65%, similar in properties to granite; the most common are gneisses, granodiorites and diorites, granites, crystalline schists). The lower layer, the densest, 15-35 km thick, is called basalt for its resemblance to basalts. The average density of the continental crust is 2.7 g/cm3. Between the granite and basalt layers lies the Conrad boundary, named after the Austrian geophysicist who discovered it. The names of the layers - granite and basalt - are arbitrary; they are given according to the speed of passage of seismic waves. The modern name of the layers is somewhat different (E.V. Khain, M.G. Lomize): the second layer is called granite-metamorphic, because There are almost no granites in it; it is composed of gneisses and crystalline schists. The third layer is granulite-basite; it is formed by highly metamorphosed rocks.

Second type of earth's crust – transitional, or geosynclinal – corresponds to transition zones (geosynclines). Transition zones are located off the eastern shores of the Eurasian continent, off the eastern and western shores of North and South America. They have the following classical structure: a marginal sea basin, island arcs and a deep-sea trench. Under the basins of the seas and deep-sea trenches there is no granite layer; the earth's crust consists of a sedimentary layer of increased thickness and basalt. The granite layer appears only in island arcs. The average thickness of the geosynclinal type of the earth's crust is 15-30 km.

Third type - oceanic the earth's crust corresponds to the ocean floor, the thickness of the crust is 5-10 km. It has a two-layer structure: the first layer is sedimentary, formed by clayey-siliceous-carbonate rocks; the second layer consists of holocrystalline igneous rocks of basic composition (gabbro). Between the sedimentary and basaltic layers there is an intermediate layer consisting of basaltic lavas with interlayers of sedimentary rocks. Therefore, they sometimes talk about the three-layer structure of the oceanic crust.

Fourth type - riftogenic the earth's crust, it is characteristic of mid-ocean ridges, its thickness is 1.5-2 km. At mid-ocean ridges, mantle rocks come close to the surface. The thickness of the sedimentary layer is 1-2 km, the basalt layer in the rift valleys pinches out.

There are the concepts of “earth’s crust” and “lithosphere”. Lithosphere– the rocky shell of the Earth, formed by the earth’s crust and part of the upper mantle. Its thickness is 150-200 km, limited by the asthenosphere. Only the upper part of the lithosphere is called the earth's crust.

Mantle by volume it is 83% of the Earth's volume and 68% of its mass. The density of the substance increases to 5.7 g/cm3. At the boundary with the core, the temperature increases to 3800 0 C, the pressure - to 1.4 x 10 11 Pa. The upper mantle is distinguished to a depth of 900 km and the lower mantle to a depth of 2900 km. In the upper mantle at a depth of 150-200 km there is an asthenospheric layer. Asthenosphere(Greek asthenes - weak) - a layer of reduced hardness and strength in the upper mantle of the Earth. The asthenosphere is the main source of magma, where volcanic feeding centers are located and lithospheric plates move.

Core occupies 16% of the volume and 31% of the mass of the planet. The temperature in it reaches 5000 0 C, pressure – 37 x 10 11 Pa, density – 16 g/cm 3. The core is divided into an outer one, up to a depth of 5100 km, and an inner one. The outer core is molten and consists of iron or metallized silicates, the inner core is solid, iron-nickel.

The mass of a celestial body depends on the density of matter; mass determines the size of the Earth and the force of gravity. Our planet has sufficient size and gravity; it retains the hydrosphere and atmosphere. Metallization of matter occurs in the Earth's core, causing the formation of electric currents and the magnetosphere.

There are various fields around the Earth, the most significant influence on GO is gravitational and magnetic.

Gravity field on Earth it is the gravity field. Gravity is the resultant force between the force of attraction and the centrifugal force that occurs when the Earth rotates. Centrifugal force reaches its maximum at the equator, but even here it is small and amounts to 1/288 of the force of gravity. The force of gravity on earth mainly depends on the force of attraction, which is influenced by the distribution of masses inside the Earth and on the surface. The force of gravity acts everywhere on earth and is directed plumb to the surface of the geoid. The strength of the gravitational field decreases uniformly from the poles to the equator (at the equator the centrifugal force is greater), from the surface upward (at an altitude of 36,000 km it is zero) and from the surface downward (at the center of the Earth the gravity force is zero).

Normal gravitational field The shape of the Earth is what the Earth would have if it had the shape of an ellipsoid with a uniform distribution of masses. The real field strength at a specific point differs from normal, and a gravitational field anomaly occurs. Anomalies can be positive and negative: mountain ranges create additional mass and should cause positive anomalies, ocean trenches, on the contrary, negative ones. But in fact, the earth's crust is in isostatic equilibrium.

Isostasy (from the Greek isostasios - equal in weight) - balancing of the solid, relatively light earth's crust with a heavier upper mantle. The theory of equilibrium was put forward in 1855 by the English scientist G.B. Airy. Thanks to isostasy, an excess of mass above the theoretical equilibrium level corresponds to a shortage below. This is expressed in the fact that at a certain depth (100-150 km) in the asthenosphere layer, matter flows to those places where there is a lack of mass on the surface. Only under young mountains, where compensation has not yet fully occurred, are weak positive anomalies observed. However, the balance is constantly being disrupted: sediment is deposited in the oceans, and the ocean floor bends under its weight. On the other hand, mountains are destroyed, their height decreases, which means their mass decreases.

Gravity creates the shape of the Earth; it is one of the leading endogenous forces. Thanks to it, atmospheric precipitation falls, rivers flow, groundwater horizons are formed, and slope processes are observed. Gravity explains the maximum height of mountains; It is believed that on our Earth there cannot be mountains higher than 9 km. Gravity holds the gas and water shells of the planet together. Only the lightest molecules - hydrogen and helium - leave the planet's atmosphere. The mass pressure of matter, realized in the process of gravitational differentiation in the lower mantle, along with radioactive decay, generates thermal energy - a source of internal (endogenous) processes that rebuild the lithosphere.

The thermal regime of the surface layer of the earth's crust (on average up to 30 m) has a temperature determined by solar heat. This heliometric layer experiencing seasonal temperature fluctuations. Below is an even thinner horizon of constant temperature (about 20 m), corresponding to the average annual temperature of the observation site. Below the permanent layer, the temperature increases with depth - geothermal layer. To quantify the magnitude of this increase, two mutually related concepts. The change in temperature when going 100 m deeper into the ground is called geothermal gradient(varies from 0.1 to 0.01 0 S/m and depends on the composition of rocks, the conditions of their occurrence), and the plumb distance to which it is necessary to go deeper in order to obtain an increase in temperature by 1 0 is called geothermal stage(varies from 10 to 100 m/ 0 C).

Terrestrial magnetism - a property of the Earth that determines the existence of a magnetic field around it caused by processes occurring at the core-mantle boundary. For the first time, humanity learned that the Earth is a magnet thanks to the works of W. Gilbert.

Magnetosphere – a region of near-Earth space filled with charged particles moving in the Earth’s magnetic field. It is separated from interplanetary space by the magnetopause. This is the outer boundary of the magnetosphere.

The formation of a magnetic field is based on internal and external reasons. A constant magnetic field is formed due to electric currents arising in the outer core of the planet. Solar corpuscular flows form the Earth's alternating magnetic field. Magnetic maps provide a visual representation of the state of the Earth's magnetic field. Magnetic maps are compiled for a five-year period - the magnetic era.

The Earth would have a normal magnetic field if it were a uniformly magnetized sphere. To a first approximation, the Earth is a magnetic dipole - it is a rod whose ends have opposite magnetic poles. The places where the dipole's magnetic axis intersects with the earth's surface are called geomagnetic poles. Geomagnetic poles do not coincide with geographic ones and move slowly at a speed of 7-8 km/year. Deviations of the real magnetic field from the normal (theoretically calculated) are called magnetic anomalies. They can be global (East Siberian Oval), regional (KMA) and local, associated with the close occurrence of magnetic rocks to the surface.

The magnetic field is characterized by three quantities: magnetic declination, magnetic inclination and strength. Magnetic declination- the angle between the geographic meridian and the direction of the magnetic needle. The declination is eastern (+), if the northern end of the compass needle deviates east of the geographic one, and western (-), when the arrow deviates to the west. Magnetic inclination- the angle between the horizontal plane and the direction of the magnetic needle suspended on the horizontal axis. The inclination is positive when the north end of the arrow points down, and negative when the north end points up. The magnetic inclination varies from 0 to 90 0 . The strength of the magnetic field is characterized by tension. The magnetic field strength is low at the equator 20-28 A/m, at the pole – 48-56 A/m.

The magnetosphere has a teardrop shape. On the side facing the Sun, its radius is equal to 10 radii of the Earth; on the night side, under the influence of the “solar wind,” it increases to 100 radii. The shape is due to the influence of the solar wind, which, encountering the Earth’s magnetosphere, flows around it. Charged particles, reaching the magnetosphere, begin to move along magnetic field lines and form radiation belts. The inner radiation belt consists of protons and has a maximum concentration at an altitude of 3500 km above the equator. The outer belt is formed by electrons and extends up to 10 radii. At the magnetic poles, the height of the radiation belts decreases, and areas arise here in which charged particles invade the atmosphere, ionizing atmospheric gases and causing auroras.

The geographic significance of the magnetosphere is very great: it protects the Earth from corpuscular solar and cosmic radiation. Magnetic anomalies are associated with the search for minerals. Magnetic lines of force help tourists and ships navigate in space.

Age of the Earth. Geochronology.

The Earth arose as a cold body from an accumulation of solid particles and bodies like asteroids. Among the particles there were also radioactive ones. Once inside the Earth, they disintegrated there, releasing heat. While the size of the Earth was small, heat easily escaped into interplanetary space. But with the increase in the volume of the Earth, the production of radioactive heat began to exceed its leakage, it accumulated and heated the bowels of the planet, causing them to soften. The plastic state that opened up possibilities for gravitational differentiation of matter– floating of lighter mineral masses to the surface and gradual descent of heavier ones to the center. The intensity of differentiation faded with depth, because in the same direction, due to an increase in pressure, the viscosity of the substance increased. The earth's core was not captured by differentiation and retained its original silicate composition. But it thickened sharply due to the highest pressure, exceeding a million atmospheres.

The age of the Earth is determined using the radioactive method; it can only be applied to rocks containing radioactive elements. If we assume that all argon on Earth is a decay product of potassium-49, then the age of the Earth will be at least 4 billion years. Calculations by O.Yu. Schmidt gives an even higher figure - 7.6 billion years. IN AND. To calculate the age of the Earth, Baranov took the ratio between the modern amounts of uranium-238 and actinouranium (uranium-235) in rocks and minerals and obtained the age of uranium (the substance from which the planet later arose) of 5-7 billion years.

Thus, the age of the Earth is determined in the range of 4-6 billion years. The history of the development of the earth's surface has so far been able to be directly reconstructed in general terms only starting from those times from which the oldest rocks have been preserved, i.e. for approximately 3 - 3.5 billion years (Kalesnik S.V.).

The history of the Earth is usually divided into two eon: cryptozoic(hidden and life: no remains of skeletal fauna) and Phanerozoic(explicit and life) . Cryptose contains two eras: Archean and Proterozoic. The Phanerozoic covers the last 570 million years, it includes Paleozoic, Mesozoic and Cenozoic eras, which, in turn, are divided into periods. Often the entire period before the Phanerozoic is called Precambrian(Cambrian - the first period of the Paleozoic era).

Periods of the Paleozoic era:

Periods of the Mesozoic era:

Periods of the Cenozoic era:

Paleogene (epochs – Paleocene, Eocene, Oligocene)

Neogene (epochs – Miocene, Pliocene)

Quaternary (epochs - Pleistocene and Holocene).

Conclusions:

1. All manifestations of the internal life of the Earth are based on the transformation of thermal energy.

2. In the earth’s crust, the temperature increases with distance from the surface (geothermal gradient).

3. The heat of the Earth has its source from the decay of radioactive elements.

4. The density of the Earth’s substance increases with depth from 2.7 on the surface to 17.2 in the central parts. The pressure in the center of the Earth reaches 3 million atm. Density increases abruptly at depths of 60 and 2900 km. Hence the conclusion - the Earth consists of concentric shells that embrace each other.

5. The earth's crust is composed primarily of rocks such as granites, which are underlain by rocks such as basalts. The age of the earth is determined to be 4-6 billion years.