Structure Of The Earth

The structure of the earth in the overt appearance, the earth is a nearly spherical ball with a polar radius of 6357 kilometres and equator radius 6378 kilometres. Internally the earth comprises of three major layers.

It’s mass is 5.97 * 10²⁴ kilogram and average density is 5.5 grams per cm³. This is nearly twice the denser of typical rocks, so there is a much denser material somewhere inside and the earth must have a definite internal structure these structures are investigated using shock waves from earthquakes for large explosions.

• The Crust of the Earth

The outermost layer of the earth is called the crust. It is made of light rocks rich in silica and aluminium having a low density of about 3 gram per centimetre cube, the thickness of the crust changes from place to place. It is maximum under the continents (35 kilometre) and minimum under the oceans(5 kilometre).Three quarters of the earth crust is covered with water, over the earth's crust is the layer of atmosphere and right from the day of formation of earth, it's crust has been constantly broken and then reorganised to form new continents and oceans.

• The Mantle of the Earth.

The central region between the crust of earth and core of the earth is called mantle, the mantle of the earth extends to a depth of about 2900 km below the crust. It consists of rocks which are made up largely of iron silicate and magnesium silicate. The pressure inside the mantle increases with depth, under extreme pressure and temperature, some of the rocks near the bottom of the mantle tend to flow like a coal-tar, the density of the mantle increases slowly as we go downwards, it increases from about 4 gram per centimetre cube to 6 gram per centimetre cube.

• The Core of the Earth.

The innermost part of the earth is called its core, the core of earth has a radius of about 3400 cm and it's extremely hot. The core of the earth is made up of mainly iron and some nickel. The core of earth consists of two parts inner core & outer core.

The core of the earth consists of an inner solid sphere of highly compressed iron surrounded by an outer shell of molten iron, the temperature at the centre of the earth is about 4000° C and the pressure is extremely high being about 3.7 million atmosphere, it's the cause of extremely high pressure that the iron in the inner core can remain in solid-state. Since the pressure is comparatively lower in the outer core, therefore the iron metal remains in the molten state in the outer part of the core of the earth does about 1600 kilometre of the outer core behaves like a liquid, since the core of the earth is very hot but the surface of the earth is colder, so heat flows outward from the hot interior to the surface of the earth. The flow of heat through the outer core of molten iron convection currents which produces a magnetic field around the earth.