Narrator: Listen to part of a lecture in a geology class.
Professor: As we've discussed, Earth's crust is made up of large plates that rest on a mantle of molten rock.
These plates...uh...now these tectonic plates support the continents and oceans.
Over time, the tectonic plates move and shift, which moves the continents and the ocean floors too.
Once it was understood how these plates move, it was possible to determine past movements of Earth's continents and how these slow movements have reshaped Earth's features at different times.
OK. Well, as studying the movements of the plates can tell us about the location of the continents in the past, it can conceivably tell us about their location in the future too, right?
So, in recent years, some geologists have used plate tectonic theory to make what they call geopredictions.
Geopredictions are guesses about what Earth's surface might look like millions of years from now.
So, we know how certain continents are currently moving.
For example, the continents of Africa has been creeping north toward Europe.
And Australia has been making its way north too, toward Asia.
Does anyone know what's happening to the Americas?
I...I think we've talked about that before. Lisa?
Student: They are moving westward, away from Europe and Africa. Right?
Professor: Right. And what makes us think that?
Student: The Atlantic Ocean floor is spreading and getting wider, so there is more ocean between the Americas and Europe and Africa.
Professor: OK. And why is it spreading?
Student: Well, the sea floor is split.
There is a ridge, a mountain range that runs north and south there.
And the rock material flows up from Earth's interior here, at the split, which forces the two sides of the ocean floor to spread apart, to make room for the new rock material.
Professor: Good. And that means, over the short term...uh... and by short term I mean 50 million years, that's a blink of the eye in geological time.
Um...over the short term, we can predict that the Americas will continue to move westward, farther away from Europe, while Africa and Australia will continue to move northward.
But what about over the long term? Say 250 million years or more.