Continents in Collision

Meanwhile, the Americas will be moving further away from Africa and Europe as the Atlantic Ocean steadily grows. The Atlantic sea floor is split from north to south by an underwater mountain ridge where new rock material flows up from Earth's interior. The two halves of the sea floor slowly spread apart as the ridge is filled with the new material, causing the Atlantic to widen.

"It's about as fast as your fingernails grow. Maybe a little bit slower," Scotese said. Still, over millions of years that minute movement will drive the continents apart.

Image courtesy of Dr. Christopher Scotese.

A map of the world as it might appear 250 million years from now. Notice the clumping of most of the world's landmass into one super-continent, "Pangaea Ultima," with an inland sea -- all that's left of the once-mighty Atlantic Ocean.

That part of the prediction is fairly certain, because it is just the continuation of existing motions. Beyond about 50 million years into the future, prediction becomes more difficult.

"The difficult part is the uncertainty in (new behaviours)," Scotese said.

"It's like if you're travelling on the highway, you can predict where you're going to be in an hour, but if there's an accident or you have to exit, you're going to change direction. And we have to try to understand what causes those changes. That's where we have to make some guesses about the far future -- 150 to 250 million years from now."

In the case of the widening Atlantic, geologists think that a "subduction zone" will eventually form on either the east or west edges of the ocean. At a subduction zone, the ocean floor dives under the edge of a continent and down into the interior of the Earth.