Different between three layers of earth

Our earth is made up of several concentric layers with one inside another. These layers are three in number-crust, mantle and core.

1. Crust:
   It is the uppermost layer over the earth's surface. It is the thinnest of all the layers. It is about 35 km on the continental masses and only 5 km on the ocean floors.
   The continental masses are made up of silica and alumina. It is thus called sima (si-silica and al-alumina). The oceanic crust mainly consists of silica and magnesium. It is thus called sima (si-silica and ma-magnesium).
   
2. Mantle:
   It is just beneath the crust. It extends up to a depth of 2900 km below the crust.
3. Core:
   It is the innermost layer. Its radius is about 3500 km. It is mainly made up of nickel and iron and is known as nife (ni-nickel and fe-ferrous, i.e., iron). The central core has very high temperature and pressure.