Uncovering The Interior Structure Of The Earth

The third planet from the sun. Fifth largest planet and the only planet that hosts life. There are so many such facts that we know about the earth as a planet and life on it. But very few facts are known when it comes to the insides of the earth. Therefore, let’s find out how much we know about the insides of the earth through this article. In this article, we will uncover the interior structure of the earth and know some interesting facts. 

What did Sir Issac say?

  • About 3 centuries ago, Sir Issac Newton’s observation gave a significant direction to the studies of the interior of the earth that remains unchallenged till today.
  • Sir Newton concluded that the earth’s interior is composed of much denser material.
  • He could conclude that based on his calculations of the average density of the earth and the surface rocks in which he found that the earth’s density is twice the density of the surface rocks.

How do we know what we all know?

Currently, our understanding of the Interior Structure of the Earth comes in 3 ways. Let’s find out about these ways from the points below – 

  • Firstly, from the observations of the path and features of the seismic waves.
  • Secondly, the laboratory studies of the surface mineral and rocks under high pressure and temperature.
  • The third way is through the geological observation of surface rocks, studies conducted on earth’s motions in the solar system, its gravity, magnetic fields, and the flow of heat.

What is found inside the earth?

Our planet is made of 3 shells, the thin crust, mantle and core. The crust only makes up 1% of the total, while the mantle covers 84% and the core occupies 15%. 


  • Being the outermost shell and the one easily accessible, the crust has been studied the most. 
  • Inside the crust, scientists have observed various complex patterns, formed when Rocks are redistributed and deposited in layers. 
  • The reasons behind these layers are lava eruption, erosion, consolidation of rock particles, solidification and recrystallization of porous rock.
  • The crust is much thinner under the oceans than under the continents.
  • The tectonic plates that include the crust and part of the upper mantle can collide and can produce mountains. 
  • Between the crust and mantle there lies a boundary named the Mohorovicic discontinuity or Moho after the Croatian scientist Andrija Mohorovicic
  • No one has ever seen this boundary, but. drilling holes to penetrate the Moho have been proposed, but the penetration is not likely very soon.


  • The mantle can be studied by dividing it into three zones, a low-velocity earthquake wave zone, transition zone and lower mantle.
  • The low-velocity zone can be identified as the region between 100 and 200 km below the Earth’s surface where there is a lower velocity of seismic waves and where it is presumed that the tectonic plates ride. 
  • Here the temperature of the rock is near the melting point and from where the molten rock erupted by some volcanoes originates.
  • The transition zone has variations from less dense to more dense minerals.
  • Lastly, the lower mantle which lies below the transition zone is made up of simple iron and magnesium silicate minerals which change to denser forms as we go deeper.


  • Core was identified by R.D. Oldham Core in 1906. It was the first internal structure to be identified.
  • The outer core is suspected to be liquid and the inner core is considered to be solid.
  • This region is presumed to be composed mainly of iron, with about 10% alloy of either oxygen, sulfur or nickel, or their combination.
  • As we go deeper from the mantle to the core there is an increase in density and a decrease in seismic waves.

We hope we could value your time and provide you with adequate knowledge about the interior structure of the earth. For more such informative and interesting content stay connected.

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