While a plate has new layers added to it at the mid - ocean ridges, its other extremity slowly slips beneath its neighbor and descends into the hot mantle below. There it becomes assimilated into the mantle.
Kamēr vidusokeānisko grēdu rajonā plātnei pievienojas jauni slāņi, tās otra mala palēnām slīd zem blakus esošās plātnes, iegrimst karstajā mantijā un saplūst ar to.