New oceanic crust is created at rift zones. Where is the old crust destroyed?

1. Earth is not growing, so crust made in one place must be lost in another. 2. At a subduction zone one plate is forced down beneath another into the mantle. 3. The plate melts at depth and its material rejoins the mantle flow. 4. Mid-ocean ridges are rift zones, so they make new crust rather than destroy it. _Source: OpenStax Astronomy (CC BY 4.0), section 8.2 Earth’s Crust_