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.
Samal ajal kui ookeanilise keskmäestiku poolses osas saab laama uusi kihte juurde, libiseb teine serv aeglaselt kõrvaloleva laama alla ning sukeldub Maa kuuma vahevöösse.