Worldwide, plates move at an average of about one inch [3 cm] per year. According to the plate tectonic theory, as the plates diverge along the ridge system, they allow hot rock from the mantle, the region below the crust, to rise.
Saskaņā ar plātņu tektonikas teoriju, plātnēm atvirzoties no grēdu sistēmas uz abām pusēm, karstā iežu masa no mantijas, zemeslodes daļas zem garozas, paceļas uz augšu.