Plate tectonics is a scientific premise describing the large-scale motion of seven larger plates and the motion of a more significant number of smaller plates of the earth's lithosphere. Tectonic plates are made of oceanic lithosphere and thicker continental lithosphere and their own kind of crust tops each. The plates can move because the earth's lithosphere has greater mechanical strength than the underlying atmosphere.
Plate movement or shifting is believed to be driven by a combination of the motion of the seafloor away from spreading ridges. These movements are due to variations in topography and density changes in the crust. The critical principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates, which ride on the asthenosphere.
Convection currents cause by the unequal distribution of heat within the earth s core which causes the plates to move
2. mantle- second layer, made of dense rocks
3. outer core- third layer, made of metal
4. inner core- inner part of earth, made of dense ball of iron and nickle