Internal Formation of the Earth
The interior of the earth is divided into three layers. Below the earth’s surface lies the solid layer covering the interior portion of the earth known as lithosphere. The lithosphere may spreads up to one hundred kilometers below the earth’s surface. Below the lithosphere is mantle zone and at last surrounding the centre of the earth is the portion called centrospheres or core (Figure…).
It is assumed that, after creation of the earth heat let off gradually from its exterior portion (e,g. the crust) and the earth crust became cool. But from the heat in the central portion could not be emitted. As a result the centrospheres and the mantle zone remain very hot.
The spherical layer of about 3500 kilometers radius from the centre of the earth is the centrospheres. There at heated nickel, iron, lead etc. metals in centrospheres. They are in solid state in the outer side and in melted state in the inner side of the centrospheres. In the middle of centrospheres and lithosphere there is mantle layer. Major portion of mantle is solid. But some portion of it is in semi-liquid or half-melted state. Scientists assume that melted lava springs out by volcanic eruption from this portion.
It is not possible to go too far below front the surface of the earth. But the scientists came to know about the interior of the earth through various forms of Investigations. When you will be in higher classes, you will know more about centrospheres and mantle layer.