Interior of the Earth


                         The interior of the Earth has long been shrouded in mystery. The landforms that we see around us directly or indirectly are controlled by the components of the interior of the earth. The sources of the earths interior can be classified into Direct and Indirect sources.


Direct Sources :  

          The sources from which we can directly know about the interior of the earth are Direct sources. Mainly  
  1. Volcanic Eruptions
  2. Mines and drilling projects 

Indirect Sources : 

   The sources include :
    
  1. Temperature, Pressure, Denisty
  2. Gravitation 
  3. Seismic activity studies
  4. Magnetic field 
  5. Meteors that reach the earth as the material
    These sources provide information indirectly and these are interferances based on various studies.

Based on the above studies the earth interior has been classified into :



     

  1. Crust
  2. Mantle
  3. Core         
    based on varying properties of material present at different depths.


CRUST 
  • It is the  outermost part of the earth
  • It is brittle in nature.
  • The thickness varies from continental crust (thicker) and oceanic crust(thinner)
  • It mainy consists of Silica and Aluminium(sial).
  • The mean density of material in continental crust is 2.7 g/cm^3 and in oceanic crust is 3 g/cm^3
  • Mohrovicc discontinuity line separtes the crust and the upper mantel   .
  • The crust and the upper most part of the mantle are called as lithosphere.

MANTLE  :

  • The portion of the earths's interior beyond the crust is called the mantle
  • It extends upto 2900 km depth.
  • Again it is divided into 1) Upper Mantle 2) Lower Mantle
  • The upper portion of the mantle is called Asthenosphere. 
  • Asthenosphere is the chief source of magma that find its way to the surface during volcanic eruptions.
  • Repti Discontinuity which seperates the upper and lower mantle.
  •  The lower mantle is  hotter than the    upper mantle , as a result of intense pressure at this depth.
  • Mainly made of mafic , ma for  magnesium and fic for  ferric that is iron   .      

Mantle occupies 83% of the earth's interior. It is very important in landform formation.As it provides the endogenic forces. The main driving force of plates is  mantel because of convectional currents produced due to radioactivity.


CORE :  

    The heavier metals sink down and form the core. It is again two types:
   1) Outer Core  2) Inner Core
    Outer core is liquid and Inner core is solid. This is because the overlying layers caused intense pressure on the material in the inner core. 
  1.  The core is about 3500 Km in radius and very hot.
  2. The core is made up of very heavy material mostly constituted by Nickel and Iron.
  3. Gutenberg Discontinuity lies between lower mantel and upper core.
  4. Lehman Discontinuity lies between the outer core and the inner core.