Hello, PhysicsForums! I've been discussing what little I know of plate tectonics with someone and the other party has suggested that convection cells within the mantle (assuming convection really occurs at all) should eventually move such that they no longer push more matter up through oceanic-ridges. Given this assumption, said ridges should eventually become inactive and perhaps new ridges should form in other places. So, have there been any studies into whether convection cells themselves eventually migrate? Thanks.