Internal Structure of The Earth

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Earth's Crust

» The outermost solid cover or shell of the earth is known as the earth's crust.
» The thickness of the crust is about 30 km.
» It is thicker in the region of the continents and thinner in the region of the ocean floors.
» The density of the rocks in the earth's crust ranges from 2.7 to 3 g/c.c (grams per cubic centimeter).
» The upper part of the crust consists of silica and aluminium in greater proportions. That is why, it is called 'Sial'.
» Whereas the lower part of the crust is called 'Sima' because the proportion of silica and magnesium is higher in this part.


» This layer lies below the crust.
» Its thickness is about 2900 km and the density of substances in the mantle ranges from 3.0 to 4.7.


» The earth's core lies below the mantle. Its thickness may be about 3,471 km. Its radius is 6,371 km., according to IUGG.
» It is divided into two parts-the outer core and the inner core. The outer core is probably in a liquid state and the inner core in a solid state.
» The core mainly consists of iron with some amount of nickel and sulphur (NIFE).
» After the mantle, the earth's density goes on increasing rapidly towards its centre and finally is more than 13.
» The temperature of the central part of the earth may be about 5000°C.
» The study of the earth's interior helps us to understand the original rocks in the earth's crust and their later transformation.

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