Describe the causes of plate movement.
The causes of plate movement are described below:
(i)Thermal Convection : A. Holmes proposed that the sub-crustal convection currents invoke the mechanism of thermal convection. It acts as driving force for the movement of plates.
(ii)Movement of Currents : Hot currents rise and then cool as they reach the surface. At the same time cool currents sink down. The convectional movement moves the crustal plate.
(iii)Floating of Plates : The rigid plates of the lithosphere which floats on more mobile asthenosphere are in constant motion.
(iv)Hot Spots of Volcanic Activity : Small currents of past volcanic activity are often located far from any active plate boundary suggesting the effect of convection currents on the lithosphere. These are called the Hot Spots.
(v)Volcanic Eruptions : The source of magma in the mantle remains fixed in position while the lithospheric plate above it moves steadily. In this way volcanoes are formed over a hot spot but they become extinct. These extinct volcanic form a chain that is a record of plate motion.
