There are inner and outer shells interacting with each other.

The internal structure of the Earth

For studying internal structure The lands use the drilling of super-deep wells (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)
• 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 arise. If two plates collide with the continental crust, then collapse occurs, volcanism and the formation of mountainous regions (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.

Astronomers study space, receive information about the planets and stars, despite their great remoteness. At the same time, there are no less mysteries on the Earth itself than in the Universe. And today scientists do not know what is inside our planet. Watching how lava pours out during a volcanic eruption, one might think that the Earth is also molten inside. But it's not.

Nucleus. The central part of the globe is called the core (Fig. 83). Its radius is about 3,500 km. Scientists believe that the outer part of the nucleus is in a molten-liquid state, and the inner one is in a solid state. The temperature in it reaches +5,000 °C. From the core to the surface of the Earth, temperature and pressure gradually decrease.

Mantle. The Earth's core is covered by a mantle. Its thickness is approximately 2,900 km. The mantle, like the core, has never been seen. But it is assumed that the closer to the center of the Earth, the higher the pressure in it, and the temperature - from several hundred to -2,500 ° C. It is believed that the mantle is solid, but at the same time red-hot.

Earth's crust. Above the mantle, our planet is covered with crust. This is the top solid layer of the Earth. Compared to the core and mantle, the earth's crust is very thin. Its thickness is only 10-70 km. But this is the earthly firmament on which we walk, rivers flow, cities are built on it.

The earth's crust is formed by various substances. It is made up of minerals and rocks. Some of them you already know (granite, sand, clay, peat, etc.). Minerals and rocks differ in color, hardness, structure, melting point, solubility in water and other properties. Many of them are widely used by man, for example, as fuel, in construction, for the production of metals. material from the site

Granite

Sand

Peat

The upper layer of the earth's crust is visible in deposits on the slopes of mountains, steep river banks, and quarries (Fig. 84). And mines and boreholes, which are used to extract minerals, such as oil and gas, help to look into the depths of the crust.

Our planet has several shells, is the third from the Sun, and ranks fifth in size. We invite you to get to know our planet better, to study it in a section. To do this, we will analyze each of its layers separately.

Shells

It is known that the Earth has three shells:

• Atmosphere.
• Lithosphere.
• Hydrosphere.

Even by the name, it is easy to guess that the first is of air origin, the second is a hard shell, and the third is water.

Atmosphere

This is the gaseous shell of our planet. Its peculiarity is that it extends thousands of kilometers above ground level. Its composition is changed exclusively by man and not in better side. What is the meaning of the atmosphere? It is, as it were, our protective dome, protecting the planet from various space debris, which to a greater extent burns out in this layer.

Protects from the harmful effects of ultraviolet radiation. But, as you know, there are those that appeared exclusively as a result of human activity. Thanks to this shell, we have a comfortable temperature and humidity. A wide variety of living beings is also her merit. Let's look at the structure in layers. Let's highlight the most important and significant of them.

Troposphere

This is the bottom layer, it is the most dense. Right now you are in it. Geonomy, the science of the structure of the Earth, deals with the study of this layer. Its upper limit varies from seven to twenty kilometers, with the higher the temperature, the wider the layer. If we consider the structure of the Earth in a section at the poles and at the equator, then it will differ markedly, at the equator it is much wider.

What else is important to say about this layer? It is here that the water cycle takes place, cyclones and anticyclones are formed, wind is generated, generally speaking, all processes related to weather and climate take place. A very interesting property that applies only to the Troposphere, if you rise a hundred meters, the air temperature will drop by about one degree. Outside this shell, the law operates exactly the opposite. There is one place between the troposphere and the stratosphere where the temperature does not change - the tropopause.

Stratosphere

Since we are considering the origin and structure of the Earth, we cannot skip the layer of the stratosphere, whose name in translation means “layer” or “flooring”.

It is in this layer that they fly passenger liners and supersonic aircraft. Note that the air here is very rarefied. The temperature changes with the climb from minus fifty-six to zero, this continues until the stratopause itself.

Is there life there?

No matter how paradoxical it may sound, but in 2005 life forms were discovered in the stratosphere. This is a kind of proof of the theory of the origin of life on our planet, brought from space.

But perhaps these are mutated bacteria that have climbed to such record heights. Whatever the truth, one thing is surprising: ultraviolet does not harm bacteria in any way, although it is they who die in the first place.

Ozone layer and mesosphere

Studying the structure of the Earth in a section, we can notice the well-known ozone layer. As mentioned earlier, it is he who is our shield from ultraviolet radiation. Let's see where he came from. Oddly enough, but it was created by the inhabitants of the planet themselves. We know that plants produce the oxygen we need to breathe. It rises through the atmosphere, when it meets ultraviolet radiation, it reacts, as a result, ozone is obtained from oxygen. One thing is surprising: ultraviolet is involved in the production of ozone and protects the inhabitants of planet Earth from it. In addition, as a result of the reaction, the atmosphere around is heated. It is also very important to know that the ozone layer borders on the mesosphere, there is no life outside it and cannot be.

As for the next layer, it is less studied, since only rockets or aircraft with rocket engines. The temperature here reaches minus one hundred and forty degrees Celsius. When studying the structure of the Earth in a section, this layer is the most interesting for children, because it is thanks to it that we see phenomena such as starfall. An interesting fact is that up to a hundred tons of cosmic dust falls on Earth every day, but it is so small and light that it can take up to a month to settle.

There is an opinion that this dust can cause rain, like emissions after nuclear explosion or volcanic ash.

Thermosphere

We will find it at an altitude of eighty-five to eight hundred kilometers. Distinctive feature- high temperature, nevertheless the air is very rarefied, this is what a person uses when launching satellites. Air molecules are simply not enough to heat the physical body.

The thermosphere is the source of the northern lights. Very important: one hundred kilometers is the official boundary of the atmosphere, although there are no obvious signs. Flying beyond this line is not impossible, but very difficult.

Exosphere

Considering in a section, we will see this shell as the last external one. It is located at an altitude of more than eight hundred kilometers above the ground. This layer is characterized by the fact that atoms can easily and freely fly into the expanses open space. It is believed that the atmosphere of our planet ends with this layer, the height from is about two to three thousand kilometers. Recently, the following has been discovered: particles that have escaped from the exosphere form a dome, which is located at an altitude of about twenty thousand kilometers.

Lithosphere

This is the solid shell of the Earth, has a thickness of five to ninety kilometers. Like the atmosphere, it is created by substances released from upper mantle. It is worth paying attention to the fact that its formation continues to this day, mainly it occurs at the bottom of the ocean. The basis of the lithosphere is the crystals formed after the cooling of the magma.

Hydrosphere

it water shell our earth, it is worth noting that water covers more than seventy percent of the entire planet. All water on Earth is usually divided into:

• World Ocean.
• surface waters.
• The groundwater.

In total, there are more than 1300 million cubic kilometers of water on planet Earth.

Earth's crust

So what is the structure of the earth? It has three components: atmosphere, lithosphere and hydrosphere. Let's take a look at what the Earth's crust looks like. The internal structure of the Earth is represented by the following layers:

• Bark.
• Geosphere.
• Nucleus.

In addition, the Earth has gravitational, magnetic and electric fields. Geospheres can be called: core, mantle, lithosphere, hydrosphere, atmosphere and magnetosphere. They differ in the density of the substances that make them up.

Nucleus

Note that the denser the constituent substance, the closer to the center of the planet it is. That is, it can be argued that the densest matter of our planet is the core. As you know, it consists of two parts:

• Internal (solid).
• External (liquid).

If we take the entire core, then the radius will be approximately three and a half thousand kilometers. The inside is solid because there more pressure. The temperature reaches four thousand degrees Celsius. The composition of the inner core is a mystery to mankind, but there is an assumption that it consists of pure nickel iron, but its liquid part (outer) consists of iron with impurities of nickel and sulfur. It is the liquid part of the nucleus that explains to us the presence of a magnetic field.

Mantle

Like the core, it consists of two parts:

• Lower mantle.
• Upper mantle.

The mantle material can be studied thanks to powerful tectonic uplifts. It can be argued that it is in a crystalline state. The temperature reaches two and a half thousand degrees Celsius, but why does it not melt? Thanks to the strong pressure.

AT liquid state only the asthenosphere is located, while the lithosphere floats in this layer. It has an amazing feature: with short loads it is solid, and with long loads it is plastic.

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

Chemical composition Earth(Fig. 1) is similar to the composition of other planets terrestrial group like 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 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 common namelithosphere(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. (Characteristic physical properties various minerals you will find in Appendix 2.) The composition of the minerals of the Earth 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, since they can learn about 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

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 diving on great depths under pressure and high temperatures undergo significant changes, becoming 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.

Power and vertical structure 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 fluctuations temperature. Its average thickness is about 30 m.

Below is an even thinner layer, feature which is 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 is mainly due to the decay radioactive elements, which are part of 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.