Answer:
The hypothesis that the lithosphere is isolated into structural plates that move gradually over the asthenosphere. Lithospheric plates are districts of Earth's outside layer and upper mantle that are broken into plates that move over a more profound plasticine mantle.
Earth's outside layer is broken into 13 noteworthy and around 20 all out lithospheric plates. The speed a structural plate moves for each year is best estimated in centimeters every year.