Flying past the earth after it was formed we see a vast gray ocean beneath a red tinted sky punctuated by volcanoes and small land masses. As unlikely as it seems life may have gained a foothold already. That life in the oceans that gave birth to it may actually be vaporized many times by cataclysmic bombardments which have slowed by not yet stopped. Earth has begun to make up its final form, A crust; A skin so think it would be less than a sheet of paper were the size of a basketball and under that a molten solid state mantle that boils in extreme slow motion. And finally two cores, A liquid iron core pulsing out magnetic field that help shield the earth from deadly cosmic wind from our sun and A solid nickle and iron inner core.
By now, the remarkable process of plate tectonics has kicked into gear, though how and when it started we do not know. For what follows next, you might want to strap yourself . Its going to be a bumpy ride. Here’s how it might have happened, At first about 3,000 million years ago continent called Ur had the planet all to themselves, then around half billion years later Artica took shape. About another half a billion past the Artica formed, the continents roam separately until about 1.8 billion years ago Artica collided with what is now the eastern end Artica to form Nina. Then Nina Artica and Ur collided about 1 Billion to 400 Million years ago forming a super continent.
After about 300 Million years later, the 3 landmasses separated and came back together in a new configuration called Pangea. It came apart too, when it split Ur and Artica split-up too. If you’re confused, join the club, even the earth seems confused. All of this movement made a host of unlikely neighbors way back when. North America’s eastern seaboard once rub shoulders with chile. California and Australia were neighbors if not connected. And Brazil was either connected to Nigeria or very close. Run the earth time machine backwards and you can see why. But no matter how many times you run the demolition derby of the continents, A question remains. What the hell is driving that ? …. Hell apparently; The force driving the plates is the slow movement of the super hot semi solid mantle that lies below the rigid plates. Like hot soup magma boils in slow motion. Superheated magma rises towards the surface, begins to cool and then sinks back down to the bottom of the pot where it is reheated and rises again. This cycle is repeated over and over to generate what scientists call convective flow. But where is the heat keeping our earth soup performing circular gymnastics. Well most of it is left over of the spectacularly energetic collisions and gravitational crushing that created the earth to begin with. Its still trapped down there and it wants out.
There is something else in the molten depths that makes it really hot real estate; that is radio active material. The belly of the beast have plenty of uranium for radio active elements, all of which release heat as they decay. That decay have significantly slowed the rate at which the earth is cooling. So what does this mean at the surface ? Two things, Magma being burp up along the ridges, those places like Iceland where the earth is tearing itself asunder is pushing the plates back to its respective continents apart.
What goes on at the other of the plates, the collision zone may be equally important. That is the place where heavier plates dive under the lighter ones yanked downwards by gravity. They haul along their plates back into the oblivion of the mantle. That’s what we know or what we think we know, but the details of what’s going on in the deepest parts of the earth that drives the engine of plate tectonics, We may never know.