[jamiek88]

Yeah subduction is the missing key that took a while for us to understand. Ocean crust is young.

In fact most earthly rock is relatively young.

Plate tectonics was such a clever idea. So obvious now, I mean just look at a map of the world of course continents were once one, you can see where they join, like a jigsaw puzzle.

It astonished early western explorers finding seashells on mountains!

[DavHeheCuddly]

or maybe all the continents were once one because it was just the full surface of an expanding planet