B.5. Structure Of The Earth
The earth is made up of the following layers-
Layer |
Thickness and density |
Other features |
The Crust 1. Â Oceanic crust 2. Â Continental Crust |
5 Km. and 2.7g/cm3 30 Km and 3 g/cm3 |
Outermost solid part or the earth. The oceanic crust is thinner as compared to the continental layer. The oceanic crust is basaltic rock. |
The Mantle |
2900 km. and 3.4g/cm3 |
The upper portion of the mantle is called the asthenosphere and extends up to 400 km. The Crust and uppermost part of the Mantle are called the lithosphere(from 10 km to 200 km). |
The Core |
6300 km and 13g/cm3 |
The earthquake wave velocities helped in understanding the existence of the core of the earth. The core is made up of very heavy material mostly composed of nickel and iron. |