Structure of the Earth

 The earth's interior is divided into three layers: crust, mantle, and core. The crust is the earth's outermost layer, and the core is the earth's innermost layer, located at a depth of 2900 kilometers. This article provides a brief overview of the earth's three interior layers.


The core is the source of the Earth's internal heat. This is due to the presence of radioactive materials, which emit heat as they degrade into more stable materials. The core is located at the center of the Earth. It has two layers -
  • Inner core
  • Outer core

Inner Core - The inner core can reach temperatures of up to 4000°C, while the outer core can reach temperatures of up to 3600°C. The Lehmann Discontinuity is a liquid-solid boundary that exists between these two layers. This is the most intense part of the core. It's as hot as the Sun's surface!

The inner core is approximately 1216 km thick. It's made of solid iron and nickel. These heavy metals would have sunk to the centre of the young Earth. The liquid outer core rotates around the solid inner core.

Outer Core - The outer core is approximately 2270 km thick. It's made of liquid iron and nickel. Because it is under less pressure than the inner core, it is liquid. This layer is also electrically conductive. This produces the electrical currents that make up the Earth's magnetic field.


The mantle is located above the core. The mantle is composed of two layers of hot, dense, semi-solid rock. The mantle, like the core, has two layers - 

  • Lower Mantles
  • Upper Mantles

These are approximately 2885 km thick. This layer is so massive that it accounts for approximately 84% of the total volume of the Earth! The mantle's temperature is lower than the core's. It only gets to about 3000°C. The material becomes less dense as you move from the lower to upper mantle.

A transition zone exists between the lower and upper mantles. It is located 400-660 kilometers beneath the Earth's surface.

The upper mantle is located above the transition zone. This zone extends from 400 km below the Earth's surface to the crust layer. The asthenosphere is the uppermost part of the upper mantle. The asthenosphere is composed of fluid, soft rock.


The crust is our planet's solid, rigid outer layer. The crust is not a continuous layer of rocks, but consists of large masses called plates, which are free to drift slowly on top of the asthenosphere. It ranges in thickness from 5 to 80 km. The lithosphere is made up of the upper asthenosphere and the crust. 

The ocean floor contains the thinnest parts of the crust. It contributes to the formation of the oceanic crust. This section of the crust may be as thin as 5 km.
The continents contain the thickest parts of the Earth's crust. It contributes to the formation of the continental crust. This layer of the crust can be up to 80 kilometers thick.

The crust closest to the mantle has a temperature of about 500°C. The temperature of the crust near the Earth's surface is roughly the same as the temperature of the air.

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