* Seafloor Spreading: The ocean crust is constantly being created at mid-ocean ridges, where magma rises from the Earth's mantle and solidifies. This process pushes older ocean crust away from the ridge, leading to a continuous cycle of creation and destruction.
* Subduction: Oceanic plates are denser than continental plates, so they are constantly being pulled beneath the continents at subduction zones. This process recycles the ocean crust back into the mantle, preventing it from becoming as old as continental rocks.
The oldest ocean crust is about 200 million years old, which is significantly younger than the oldest continental rocks, which can be over 4 billion years old.
