Along with Mercury, Venus and Mars, the Earth is one of the rock planets of our solar system. It is made up of several spherical layers, which are composed of different materials.
The outer layer of the Earth is the lithosphere. It consists mainly of a solid crust of silicate_rock and reaches to a depth of about 100 kilometers. Next are the mantle and the core, which together make up the greatest part of the mass of the Earth.
The lithosphere includes the upper part of the mantle. It is made up of about a dozen rigid plates, which move slowly in relation to each other. Volcanic eruptions, Earthquakes and the formation of mountains are the result of plates pushing against each other. The movements of these plates have greatly altered the topography of the Earth since it was formed.
From the original single super-continent of Pangaea 200 million years ago, where all the landmasses were still joined as one surface surrounded by oceans, the appearance of the Earth has changed into what we know it as today.
The upper mantle of the Earth is separated from the crust by the Mohorovicic discontinuity. It is separated from the lower mantle by the asthenosphere, a layer 100 kilometers thick.
The Earth's mantle is approximately 2800 kilometers thick. While the upper part consists mainly of semi-liquid material (iron and magnesium silicate), the lower part is made up of more solid silicate_rock (magnesium, iron and silicate).
The lower part of the mantle borders on the 2300-kilometer thick outer core, which consists mainly of iron and nickel. It is thought to be fluid.
The inner core, also made up of iron and nickel is, however, solid. It is about 2400 kilometers thick. Here, temperatures are over 6000┬░ Celsius. This heat has been "stored" in the core during the formation of the Earth over 4. 5 billion years ago.
From the surface of the Earth to the core, the temperature rises by approximately 30┬░ Celsius for every 1000 meters. This heat is created mainly by radioactive reactions in the interior. Convection currents in the mantle carry the heat energy from the interior to the surface. These currents are also responsible for volcanic eruptions and the tectonic_movements described above.
