* Plate Tectonics: Oceanic crust is constantly being created at mid-ocean ridges, where magma rises from the Earth's mantle and cools to form new crust. This process is called seafloor spreading.
* Subduction: As new crust forms, older oceanic crust moves away from the ridge and eventually gets pulled back down into the mantle at subduction zones.
* Age Limits: The oldest oceanic crust found on Earth is about 200 million years old. This is significantly younger than the oldest rocks found on continents, which can be billions of years old.
So, while the Earth itself is about 4.5 billion years old, the oldest rocks in oceanic crust are only about 200 million years old.
