* Subduction: At convergent plate boundaries, where two tectonic plates collide, one plate (usually the denser oceanic plate) dives beneath the other. This process is called subduction.
* Melting and Recycling: As the subducted plate descends, it is heated by the Earth's mantle. This heat causes the rock to melt, and the melted material rises to the surface, eventually erupting as volcanoes or forming new crust.
* Destruction and Transformation: The old crust that gets subducted is destroyed, but its material is not lost. It is melted and recycled back into the Earth's mantle, where it can contribute to the formation of new crust.
In short, the old crust is destroyed and recycled into the Earth's mantle, where it can contribute to the formation of new crust.
Here's a simplified analogy: Imagine a giant conveyor belt. New crust is being created at one end, and the old crust is being pulled under at the other end. The material on the conveyor belt is constantly being moved and recycled, with new material being added and old material being removed.
