The structure of our planet is heterogeneous. One consists of several levels, including solid and liquid shells. What are the layers of the earth called? How many? How do they differ from each other? Let's find out.
How did the layers of the Earth form?
Among the terrestrial planets (Mars, Venus, Mercury) the Earth has the largest mass, diameter and density. It formed approximately 4.5 billion years ago. According to one version, our planet, like others, was formed from small particles that arose after the Big Bang.
Debris, dust and gas began to combine under the influence of gravity and acquired a spherical shape. The proto-Earth was very hot and melted the minerals and metals that fell on it. The denser substances were sent down to the center of the planet, the less dense went up.
So the first layers of the Earth appeared - the core and the mantle. Together with them, a magnetic field arose. From above, the mantle gradually cooled and became covered with a film, which later became the crust. The processes of the formation of the planet did not end there, in principle, they continue now.
Gases andseething substances of the mantle constantly broke out through cracks in the crust. Their weathering formed the primary atmosphere. Then, along with hydrogen and helium, it contained a lot of carbon dioxide. Water, according to one version, appeared later from the condensation of ice, which brought asteroids and comets.
Core
The layers of the Earth are represented by the core, mantle and crust. All of them differ in their properties. At the center of the planet is the core. It has been studied less than other shells, and all information about it is, although scientific, but still assumptions. The temperature inside the core reaches about 10,000 degrees, so it is not yet possible to reach it even with the best technology.
The core lies at a depth of 2900 kilometers. It is generally accepted that it has two layers - external and internal. Together they have an average radius of 3.5 thousand kilometers and are composed of iron and nickel. It is assumed that the core may contain sulfur, silicon, hydrogen, carbon, phosphorus.
Its inner layer is in a solid state due to the enormous pressure. The size of its radius is equal to 70% of the radius of the Moon, which is about 1200 kilometers. The outer core is in a liquid state. It is composed not only of iron, but also of sulfur and oxygen.
The temperature of the outer core ranges from 4 to 6 thousand degrees. Its liquid is constantly moving and thus affecting the Earth's magnetic field.
Robe
The mantle envelops the core and represents the middle level in the structure of the planet. It is not available for direct research andstudied using geophysical and geochemical methods. It occupies about 83% of the planet's volume. Under the surface of the oceans, its upper boundary runs at a depth of several kilometers, under the continents, these figures increase to 70 kilometers.
It is divided into upper and lower parts, between which there is a layer of Golitsin. Like the lower layers of the Earth, the mantle has a high temperature - from 900 to 4000 degrees. It is viscous in consistency, while its density fluctuates depending on chemical changes and pressure.
The composition of the mantle is similar to stone meteorites. It contains silicates, silicon, magnesium, aluminum, iron, potassium, calcium, as well as grospidites and carbonatites, which are not found in the earth's crust. Under the influence of high temperatures in the lower level of the mantle, many minerals decompose into oxides.
Earth's outer layer
Above the mantle is the Mohorovichic surface, marking the boundary between shells of different chemical composition. In this part, the speed of seismic waves increases sharply. The top layer of the Earth is represented by the crust.
The outer part of the shell is in contact with the hydrosphere and atmosphere of the planet. Under the oceans, it is much thinner than on land. Approximately 3/4 of it is covered with water. The structure of the crust is similar to the crust of the planets of the terrestrial group and partly of the Moon. But only on our planet it is divided into continental and oceanic.
Oceanic crust is relatively young. Most of it is represented by bas alt rocks. Layer thickness in different partsocean is 5 to 12 kilometers.
The continental crust consists of three layers. Below are granulites and other similar metamorphic rocks. Above them is a layer of granites and gneisses. The upper level is represented by sedimentary rocks. The continental crust contains 18 elements, including hydrogen, oxygen, silicon, aluminum, iron, sodium and others.
Lithosphere
One of the spheres of the geographic shell of our planet is the lithosphere. It unites such layers of the Earth as the upper mantle and crust. It is also defined as the solid shell of the planet. Its thickness ranges from 30 kilometers in the plains to 70 kilometers in the mountains.
The lithosphere is divided into stable platforms and mobile folded areas, in areas where mountains and volcanoes are located. The upper layer of the solid shell was formed by magma flows that broke through the earth's crust from the mantle. Due to this, the lithosphere consists of crystalline rocks.
It is subject to the external processes of the Earth, such as weathering. The processes in the mantle do not subside and are manifested by volcanic and seismic activity, the movement of lithospheric plates, and mountain building. This, in turn, also affects the structure of the lithosphere.
