According to this theory large amount of material mass join together form earth. Large amount of heat was generated during fusion. As earth cool down, heavier material sank to center and lighter one toward top. The upper part is called crust and inner part is called as core.
Due to high temperature and pressure difference between crust and core it results in convention current (like flow of water molecule when heated up). These current result in circulation of earth mass from crust to core and vice versa. Hot molten lava comes out and cold rock mass goes into earth. This flow of material cause crust and some part of mantle to slide on outer core. This sliding of earth mass take place in difference part of earth called tectonic plate.
Earth surface has seven tectonic plate. These plate move in different direction and different speed, which result in rising and sinking of continent (formation of mountain and valleys).
Major tectonic plates on earth surface are :
- Eurasian plate
- North American plate
- Indo Australian plate
- Pacific plate
- South American plate
- African plate
- Antarctic plate