Continental Crust
- In terms of structure, composition, density and thickness, the continental crust differs from the oceanic crust.
- It is composed of granitic and andesitic rocks.
- The continental crust is rich in Feldspar mineral.
- Moreover, the density of the continental crust is about 2.6gm/cm3.
- The average thickness is about 40km.
- However, under the mountainous regions, the thickness reaches up to 100 Km.
Oceanic Crust
- The oceanic crust is made up of the Basalt.
- It is rich in ferro-magnesia.
- Its density is about 3 gm/cm3.
- The Conrad discontinuity divides the continental crust and the oceanic crust.
Upper most Mantle
- It comprises of Peridotite and Gabbro and Plagioclase minerals.
- The average density of the upper mantle is about 4.5 gm/cm3.
- The average temperature of this layer is about 1100 C ⁰.
- The Repetti Discontinuity separates the upper mantle from the lower mantle.
- Due to Repetti discontinuity, there is a sharp increase in the velocity of the seismic waves.
- The upper mantle is heterogeneous in terms of density and composition.
- The thickness of the uppermost part of this stratum is about 80-100 km.
- The uppermost part of the upper mantle is as rigid as the crust.
- Both crust and upper mantle constitute the Lithosphere.
Lower Mantle
- The lower mantle extends at a depth of 670 km to 2900km.
- The average density of this region is about 6.5gm/cm3.
- It is composed of Olivine, Plagioclase and Orthoclase minerals.
- Guttenberg Discontinuity separates the lower mantle and the upper core of the earth.
Outer Molten Core
- It extends between 2900 km to 5150 km.
- The density of the outer core is about 10gm/cm3.
- It mainly consists of Iron and Nickle (about 85%).
- The outer core is always in the molten state.
- Lehman Discontinuity separates the outer core and the inner-core.
Inner Solid Core
- The inner-core extends between 5150 km to 6371 km.
- The average density of the inner core is about 13gm/cm3.
- Despite the high temperature, the inner-core is always in the solid-state due to very high pressure prevailing in this region.
- The temperature of the inner core is about 6000 C⁰.
GAME OVER