What is the structure of the Earth? The structure of the Earth is made up of different layers and these layers are made up of different major components. Now the question arises: What is the structure of the Earth?
The earth’s structure consists of the crust, the mantle and the core. The boundaries between these layers were discovered by seismograph. Seismograph is a instrument which helps us to record the seismic waves which were generated during the occurrence of earthquakes.
Structure of the Earth
All the major components like the crust, the mantle, and the core have a unique chemical composition and the unique physical state which can impact life on earth’s surface. Now we will understand in brief about the different layers of the earth.
Layers of the Earth
The Crust
Crust is the outermost layer of the Earth. Crust is made up of solid rocks mainly of basalt and granite. The thickness of the crust ranges between 30 km and 100 km. On the basis of the change in the velocity of the seismic waves crust is further divided into two components.
(A) Upper Crust (B) Lower Crust
The average density of the upper crust and lower crust is 2.8 and 3.0 respectively.
The Mantle
It represents the second zone of the interior of the earth and extends from 30 km to 2900 km depth.
- The space between the lower crust and the upper mantle is separated by the term Moho – Discontinuity.
- Mantle is also divided into sub components named as Upper Mantle and Lower Mantle.
- Upper mantle which ranges between 200 km to 700 km in depth. and lower mantle which ranges between 700 km to 2900 km in depth.
- Mantle is made up of silicate minerals.
The Core
It is the deepest and most inaccessible zone of the interior of the earth. It extends from the lower boundary of the mantle at the depth of 2900 km to the center of the earth. The Core is further divided into two subparts :-
- Outer core
- Inner Core
Outer Core remains liquid as there is not enough pressure to keep it solid. And inner core at the same time remains solid because the amount of pressure is sufficient in the zone to convert it into a solid state.
Layering System of Earth according to E. Suess
E. Suess has identified three different layers of the earth on the basis of chemical composition :-
- SIAL – This layer is located just below the outer sedimentary block. The layer is made up of silica and aluminum (SIAL = SI + AL). average density of sial is 2.9 whereas the thickness of this layer ranges between 50 to 300 km.
- SIMA – This layer is located below the sial layer and is composed of basalt. Average density of this layer is between 2.9 to 4.7 whereas the thickness varies from 1000 km to 2000 km.
- NIFE – This layer is located just below the sima layer and is made up of nickel (NI) and fermium (Fe). The diameter of this zone is 6880 km.
