Layers of Earth Illustrated with Suitable Diagrams

There are basically three layers of earth, namely; crust, mantle and core. These are explained further below:

(a) Crust

The crust is the uppermost layer of the earth. It is the thinnest among the three layers, forming just 1% of the earth’s volume. The crust is made up of two layers. The upper layer forms continents. It consists of the minerals silica and aluminum, therefore is called Sial.
The lower crust is the continuous layer of denser rocks forming the floor of the oceans. It is made of minerals silica and magnesium and is therefore called Sima.
The crust varies thickness from around 5-7 km under the under oceans and 35-70 km under the continents.

(b) Mantle

It lies just under the earth. It is about 2900 km thick. The upper mantle is a thin-stiff layer of the earth. It consists of silica, iron and magnesium. The upper crust extends around from the bottom of the crust to 300 km.
The lower mantle extends from 300 km to 2900 km. It is the zone of mixed minerals such as iron, magnesium, aluminum and silicon. The average temperature here is about 3000OC. The lower mantle is semi-solid, and materials here can move slowly in a plastic manner.
The molten material in the lower mantle is called magma, which flows out as lava out of a volcanic eruption. The lower mantle is called mesosphere.

(c) Core

The innermost layer of the earth is the core. The radius of the core is about 3500 km. The core is divided into the upper core and the inner core.
The outer core is 2300 km thick and the inner core is about 1200 km. The upper core is so hot that it is molten {liquid ore}; the inner core, though hotter, is under such extreme pressure that it remains solid {solid ore}. The temperature in the core is hotter than that on the sun’s surface. The intense heat from the inner core causes materials in the outer core and inner mantle to move around.
The dominant minerals here are nickel and iron. This layer is known as Nife.
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