What can our oceans tell us about Earth's structure and formation?

The ocean is not just where the land happens to be covered by water. The sea floor is geologically distinct from the continents. It is locked in a perpetual cycle of birth and destruction that shapes the ocean and controls much of the geology and geological history of the continents. Geological processes that occur beneath the waters of the sea affect not only marine life, but dry land as well.

What happened year ago