During the process of subduction, the older oceanic crust is pulled by gravity down beneath the Trench and back into the Mantle.
Explanation:
The geological process of subductions consists of the convergence of the boundaries of the tectonic plates where one of them is forced to sink under the other due to the force of gravity. The regions where this geological process is frequent are known as subduction Zones and the average orate of convergence is two to eight centimeters per year.