The earth's interior structure geography for ssc

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The earth's interior has three different layers
(i) the crust
(ii) mantle
(iii) the core.

The Crust
It is the outermost solid part of the earth. All of the Earth's landforms (mountains, plains, and plateaus) are contained within it, along with the oceans, seas, lakes and rivers. .
It comprises about 0.5% of the earth’s body.It is brittle in nature. The thickness of the crust varies under the oceanic and continental areas. Oceanic crust is thinner as compared to the continental crust.
The mean thickness of oceanic crust is 5 km whereas that of the continental is around 30 km.
The continental crust is thicker in the areas of major mountain systems. It is as much as 70 km thick in the Himalayan region.


Exam focus remember it:-
• core is made up of two layers: upper lighter layer (density=2.7 g/cc) called the sial (silica + aluminium) and a lower denser layer (density=3.0 g/cc) called sima (silica + magnesium).


The Mantle
The portion of the interior beyond the crust is called the mantle depth of 2,900 km.
It is the thick, dense rocky matter that surrounds the core .
mantle covers the majority of the Earth's volume. This is basically composed of silicate rock rich in iron and magnesium.
The upper portion of the mantle is called asthenosphere.
The word astheno means weak. It is considered to be extending upto 400 km. It is the main source of magma that finds its way to the surface during volcanic eruptions.
The lower mantle extends beyond the asthenosphere.
It is in solid state. Mental has a density higher than the crust’s density (3.4 g/cm3).
The crust and the uppermost part of the mantle are called lithosphere.

• The mantle consists predominantly of solid rocks made up of silicates of magnesium and iron and displaying plastic properties.
• This layer is separated from the crust by Mohorovicic Discontinuity. The outer and the inner mantle are separated by another discontinuity named Repetti discontinuity.

The Core
It is below mental .
The core is made up of very heavy material mostly constituted by nickel and iron.
It is sometimes referred to as the nife layer.

The core is earth's source of internal heat because it contains radioactive materials which release heat as they break down into more stable substances.
The core is divided into two different parts.
The outer core and inner core . the outer core is a liquid because the temperatures there are adequate to melt the iron-nickel alloy.
However, the inner core is a solid even though its temperature is higher than the outer core. Because Here, tremendous pressure, produced by the weight of the overlying rocks is strong enough to crowd the atoms tightly together and prevents changing it to the liquid state
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earth structure, the earth

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