Earth's Internal Structure

Earth's Internal Structure

The earth on which we live is made up of many layers. It took thousands of years to become, many actions and reactions took place. The average density of the earth is 5.5. Somewhere there are rocks on the upper structure of the earth, somewhere there is sand, somewhere there is water, and somewhere there is fertile soil. The crust and the upper part of the mantle together form the lithosphere. It is mainly composed of inelastic rocks and is found up to 100 km depth. There are mainly three layers in the internal structure of the Earth – Crust, Mantle and Core. These are also called Sil level (SiAl – silica & Aluminium), Seema level (SiMa – silica & Magnicium), Nife (NiFe – Nikil & Ferus) level respectively. We can divide these three main parts into subsections. 

1. Crust 
1. Upper Crust
2. Lower Crust
2. Mantel
1. Upper Mantel
2. Middle Mantel
3. Lower Mantel
3. Core
1. External core 
2. Inner core 

Fold - Endogenous Force on Upper Surface of the Earth

We understand this with the help of the following picture –

Mountains and It's types

A . Crust

According to the IUGG (International union of Geodesy and Geophysics), the average thickness of the earth's crust is 30 km, but according to many sources it can be up to 100 km. In continental parts it is about 40 km, while in oceanic parts it is only 5 to 10 km. In the uppermost part of the crust, a thin and discontinuous layer of stratified rocks is found about (4 km), below which there is a layer of granite-like granite rocks. Instead of granite, a layer of basalt rocks is found in the ocean basin, which occupies 0.5% of the total volume of the earth. All these together play an important role in the formation of the internal structure of the earth. The density related incompatibility between the upper crust and the lower crust is called 'Konrad's discontinuity'. Due to the abundance of Silica and Aluminum in this layer, it is also called SiAl layer. 

We can divide the earth's crust into two parts.

1. Upper Crust – From the surface of the earth to a depth of 30 km i.e. 30 km thick
2. Lower Crust – 30 km – 100 km deep i.e. 70 km thick

1. Upper Crust

In this part mainly granite rocks are found, through which the continents have been formed. The average density of this layer is 2.9. It can be up to a depth of 30 km from the surface of the earth. The speed of P waves in this layer can be up to 6.1 km/hr.

2. Lower Crust

In the lower layer, a layer of basalt rocks is found, through which the ocean surface has been formed. Its average density is 3.3. The thickness of this layer can be up to 70 km. The speed of P waves in this layer can be up to 6.9 km/hr.

Fault – Endogenous Force 

          

B . Mantel

Mantle extends from the lower layer of the crust to a depth of 2900 km, that is, it is a 2800 km thick layer. It accounts for 83% of the Earth's total volume and 68% of its mass. It has a predominance of heavy minerals like iron and magnesium. Due to which it is also called SiMa layer. IUGG has divided it into three parts on the basis of earthquake waves and due to these three parts different density relations are seen here, the details of which are given below –

1. Upper Mantel – Moho discontinuity or lower crust up to 200 km depth i.e. 100 km thick
2. Middle Mantel – 200 to 700 km deep i.e. 500 km thick
3. Lower Mantel – 700 to 2900 km deep ie 2200 km thick

1. Upper Mantel

The depth of this layer is up to 100 km from the lower crust. The density of this part is about 4.3 and the speed of P waves in this part is up to 7.8 km/h. There is a density related incompatibility between the Upper Mantle and the Lower Crust, which is called the Moho discontinuity. This discrepancy was discovered by the Russian scientist A. Mohorovicic did it.

2. Middle Mantel

This layer extends to a depth of 200 to 700 km, that is, the thickness of this layer is up to 500 km.

3. Lower Mantel

The depth of this layer ranges from 700 to 2900 km, that is, its thickness is up to 2200 km. The density of this part is up to 5.5. The speed of P waves in this part is up to 8.1 km/hr. Density related incompatibility is found between Upper Mantle and Lower Mantle, which is called Repeti discontinuity.

Lakes and Its Types - Lakes ofIndia and The World

C . Core

It is the innermost part of the Earth's internal structure and is also called the beriosphere. It plays a major role in the internal structure of the earth. It is mainly composed of nickel and iron. Hence it is also called NiFe layer. It also contains some amount of silicon. The speed of earthquake waves increases in the core. The volume of the core is 16% of the total volume of the Earth, while it is 32% of the mass. The maximum temperature of the core is 5500 degree Celsius, while the average density is 13. It is in solid or semi-liquid state or plastic state due to excessive pressure in the interior. 

We can divide it into two parts as per convenience.

1. External Core – 2900 to 5150 km ie 2250 km thick
2. Inner Core – from 5150 to 6371 km ie 1221 km thick

1. External Core

Its depth ranges from 2900 km to 5150 km, that is, the thickness of this layer is 2250 km. At the upper level of the outer core, the density is 10.0 and the speed of P waves is up to 13.6 km/hr, while the density in its lower parts is up to 12.3. There is a density related incompatibility between the lower mantle and the outer core, which is called the Gutenberg-Wishart discontinuity.

2. Inner Core

Its depth ranges from 5150 km to 6371 km, which means it is 1221 km thick. The density in the upper part of this layer is 13.3 and in the lower part the density is 13.6. The speed of P waves in this layer is 11.23 km/hr. There is a density related incompatibility between the outer core and the inner core, which is called the Lehmann discontinuity. This layer is in semi-liquid state.

Volcanoes and Its Types

The inner core also has its own core

During the search, it has been found that the inner core also has its own core, whose diameter is equal to half of the inner core. The iron crystals of the outer layer of the inner core are oriented in the north-south direction, while the iron crystals of the outer layer of the inner core of its inner core are oriented in the east-west direction. are oriented in the east-west direction. Not only its direction is oriented, but the behavior of the iron crystal is also different, that is, it can be said that the inner core of the inner core is made of different types of crystals.

Points to Remember –

• The temperature increases on going down in the ground. First it is 1 degree Celsius at 32 meters. But the rate of increase of temperature also declines with depth. It is 12 °C every 1 km for the first 100 km, then 2 °C every km up to a depth of 300 km, then 1 °C every 1 km after that.
• The reason for the increase in temperature in the earth is due to pressure and fission of radio active substances.

Exogenous Forces - Weathering andErosion