The oldest continental crustal rocks on Earth are between 3.7 to 4.28 billion years old.

This has nothing to do with the oceans themselves, but depends on the different densities of oceanic and continental rocks.

For the Earth, oceanic rocks have a higher density than continental rocks.

Some ancient, forgotten god had amused himself (or, perhaps, herself) removing great bites of continental rock.

Other volcanos occur near the edges of some continents, where oceanic crust is being "subducted" underneath continental rock.

Fold mountains occur when two plates collide: the continental rocks then crumple together and the surface rises.

Prior to 1984 there was little suspicion that continental rocks could reach such high pressures.

Specifically, they did not see how continental rock could plow through the much denser rock that makes up oceanic crust.

It therefore looked apparent that a layer of basalt (sial) underlies the continental rocks.

The continental rock buckles up to form a mountain range.