The Plate Tectonic Theory provided an explanation about movement of the lithospheric plates. This theory evolved from the two former theories and was developed during the first decades of the 20th century. The Earth's lithospheric is divided into several plates. There are 3 types of movements - seperation of two plates (divergent), collusion of two plates (convergent) and sliding past each other (transform).
- Once the hot less dense particles cools down, they sink, and the other less particle rises. This is exactly what happens in the Earth's mantle. These forces lift and split the lithosphere at divergent plate boundaries. The hot magma flows out of the mantle and cools down to form the new ocean crust. The downward movement of the convection current occurs along a convergent boundary where the sinking force pulls the tectonic plate downward.