Question

All rock on the ocean floor is less than 180 million years old because?

Answer 1

Because the oldest parts reach the continental crust and then the ocean floor sinks beneath the continental crust, into the mantle.

Answer 2

The Continental rocks are older than the other than the rocks that are present in the ocean floor. But the ocean floor is approximately 180 million years old.

The oceanic crust was ultimately destroyed in the subduction zones so it was recycled.

The oceanic crust was formed approximately 4 million years ago when the earth was formed. But the ocean floor older than 200 million years old was destroyed by the activity of tectonic plates.