Interior of the Earth

Interior of the Earth

1. INNER CORE (6371km to approx. 5100km)

   • Composition: mixture of iron and some nickel
   • P and S waves move through the inner core
     • Provides good evidence of a solid layer

2. LEHMANN DISCONTINUITY (5100km)

   • Boundary between materials of the same composition but in different states

3. OUTER CORE (5100km to 2900km)

   • Liquid iron nickel
   • S waves cannot pass through
     • Outer core is liquid
   • P waves slow down
     • Reduction in rigidity

4. GUTENBERG DISCONTINUITY

   • Change in material
     • From metallic iron nickel to stony silicate material
   • P wave decreases
   • S waves stop altogether

5. LOWER MANTLE

   • Solid
     • S wave can move through it
   • P waves increase in velocity
     • Increasin pressure causes the rocks to become more rigid
       • Less compressible
   • Silicate material

6. UPPER MANTLE

   • Solid silicates
     • Less dense than lower mantle
   • Main rock: Peridotite

7. CRUST

   • OCEANIC CRUST
     • Rich in iron and magnesium
     • Basalt, Dolerite, Gabbro
   • CONTINENTAL CRUST
     • Rich in aluminum and silicate
     • Granitic
     • Igneous, Metamorphic and Sedimentary rocks-deformed

8. ASTHENOSPHERE

   • Most of the mantle behaves as a solid with the ability to flow
     • Rheid
     • The temperature is high enough for about 5% of crystals in the peridotite to partially melt.
       • Plastic properties
       • Lost rigidity
         • P and S wave slow down

9. LITHOSPHERE

   • Nearer the surface, the mantle is cool enough to prevent partial melting
   • Rigid and brittle
     • Broken into plates
     • The outermost skin of the lithosphere is the oceanic or continental crust, divided from the mantle lithosphere by the Moho
   • The lithosphere cannot flow but is carried by the underlying asthenosphere