The structure of our planet is not homogeneous. One consists of several levels, including solid and liquid shells. What are the layers of the Earth called? How many of them? How do they differ from each other? Let's figure it out.
Among the planets of the terrestrial group (Mars, Venus,Mercury) Earth has the largest mass, diameter and density. It was formed about 4.5 billion years ago. According to one version, our planet, like others, was formed from small particles that appeared after the Big Bang.
The debris, dust and gas began to unite underthe action of gravity and acquired a spherical shape. The proto-earth was very hot and melted the minerals and metals that came into it. More dense substances were sent down to the center of the planet, less dense ones went up.
So the first layers of the Earth appeared - the core and the mantle. Along with them arose a magnetic field. Above, the mantle gradually cooled and covered with a film, which later became bark. On this the processes of formation of the planet did not end, in principle, they continue even now.
Gases and seething mantle constantlybroke out through splits in the bark. Their weathering formed the primary atmosphere. Then along with hydrogen and helium there was a lot of carbon dioxide in it. Water, according to one version, appeared later from the condensation of ice, which asteroids and comets brought.
The layers of the Earth are represented by the core, mantle and bark. All of them differ in their properties. In the center of the planet is the core. It is studied less than other shells, and all the 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 is located 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 consist of iron and nickel. It is assumed that the core can contain sulfur, silicon, hydrogen, carbon, phosphorus.
Its inner layer is in the solid statebecause of the enormous pressure. The size of its radius is equal to 70% of the radius of the moon, it is approximately 1200 kilometers. The outer core is in the liquid state. It consists not only of iron, but also of sulfur and oxygen.
The temperature of the outer core varies from 4 to 6 thousand degrees. Its fluid constantly moves and thus affects the Earth's magnetic field.
The mantle envelops the core and represents the middlelevel in the structure of the planet. It is not available for direct investigation and is studied by geophysical and geochemical methods. It occupies about 83% of the planet's volume. Under the surface of the oceans, its upper boundary passes at a depth of several kilometers, under the continents these figures increase to 70 kilometers.
It is divided into upper and lower parts, betweenwhich passes the Golitsin layer. Like the lower layers of the Earth, the mantle has a high temperature - from 900 to 4000 degrees. According to its consistency, it is viscous, while its density is vortexed 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 contained in the earth's crust. Under the influence of strong temperatures in the lower level of the mantle, many minerals decompose into oxides.
Above the mantle is the surfaceMohorovicic, denoting the boundary between shells of different chemical composition. In this part, the velocity of seismic waves increases sharply. The upper layer of the Earth is represented by bark.
The outer part of the shell is in contact withhydrosphere and the atmosphere of the planet. Under the oceans, it is much thinner than on land. Approximately 3/4 of it is covered by 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.
The oceanic crust is relatively young. Most of it is represented by basalt rocks. The thickness of the layer in different parts of the ocean is from 5 to 12 kilometers.
The continental crust consists of three layers. Below are the 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.
One of the geographic areas of ourthe planet is the lithosphere. It unites such layers of the Earth as the upper mantle and bark. It is also defined as the solid shell of the planet. Its thickness is from 30 kilometers on the plains to 70 kilometers in the mountains.
The lithosphere is divided into stable platforms andmobile folded areas in which areas are located mountains and volcanoes. The upper layer of the solid shell formed magma streams that broke through the earth's crust from the mantle. Due to this, the lithosphere consists of crystalline rocks.
It is subject to external processes of the Earth, for exampleweathering. Processes in the mantle do not subside and are manifested by volcanic and seismic activity, movement of lithospheric plates, mountain building. This, in turn, also affects the structure of the lithosphere.