NCERT Notes: Structure Of The Earth [Geography Notes For UPSC]

NCERT notes on important topics for the IAS aspirants. These notes will also be useful for other competitive exams like banking PO, SSC, state civil services exams and so on. This article talks about the structure of Earth- The Crust, Mantle, and Core.

 

Structure of the Earth

Earth_internal_structure

  • The Crust
  • The Mantle
  • The Core

The Crust
  • The crust is the outermost solid part of the earth.
  • It is fragile 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 continental crust is thicker in the areas of major mountain systems.
  • The crust made up of heavier rocks having a density of 3 g/cm3.
  • The kind of rock seen in the oceanic crust is basalt.
  • The mean density of material in the oceanic crust is 2.7 g/cm3.

The Mantle
  • The portion of the interior beyond the crust is called the mantle.
  • It is in a solid state.
  • It has a density higher than the crust portion.
  • The thickness ranges from 10-200 km.
  • The mantle extends from Moho’s discontinuity to a depth of 2,900 km.
  • The asthenosphere is the upper portion of Mantle.
  • It is the chief source of magma that finds its way to the surface during volcanic eruptions.
  • The crust and the uppermost part of the mantle are called lithosphere.

The Core
  • The core-mantle boundary is positioned at the depth of 2,900 km.
  • The inner core is in the solid state whereas the outer core is in the liquid state.
  • The core is made up of very heavy material mostly constituted by nickel and iron. Hence it is also called the “nife” layer.

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