Download The Next Pangaea

The Next Supercontinent
Move over Pangaea, your days as Earth’s
most famous supercontinent may be coming
to an end—in about 100 million years. That’s
the theory put forth by Ross Mitchell, a
geologist at Yale University, in a new study
published in the journal Nature.
In the early 1900s Alfred Wegener famously
proposed the idea that Earth’s tectonic plates
are slowly moving around the planet. About 300 million years ago a single landmass, or
supercontinent, called Pangaea was centered on the present-day location of West Africa. As
the plates continued their slow drift, Pangaea broke apart and formed the continents and
oceans we know today.
Mitchell’s research involving the magnetic orientation in ancient rocks led him to conclude that
the continents are slowly moving northward and will eventually form a supercontinent centered
on the Arctic. According to Mitchell, this tectonic plate movement will fuse the Americas and
Eurasia, forming a new supercontinent called Amasia.
NPR
The Earth's continents are in constant motion. On at
least three occasions, they have all collided to form
one giant continent. If history is a guide, the current
continents will coalesce once again to form another
supercontinent. And a study in Nature now shows how
that could come about.
You can think of continents as giant puzzle pieces
shuffling around the Earth. When they drift apart,
mighty oceans form. When they come together,
oceans disappear. And it's all because continents sit
on moving plates of the Earth's crust.
"Continents on these plates typically move, I would say, at the rate your fingernails
grow," says Ross Mitchell, a graduate student at Yale University. That may seem slow,
but it adds up over hundreds of millions of years.
Look at an atlas and you can imagine how Africa and South America, for example, once
nestled together.
"Rewind the tape and bring all the continents back into their jigsaw arrangement, you
have this vast landmass of all the Earth's continental blocks together," Mitchell says.
Last time all the landmass clumped up, it formed a supercontinent called Pangaea. The
dinosaurs walked there. But Pangaea wasn't the first.
"There had been three, possibly a debated fourth supercontinent through the billions of
years," Mitchell says.
He has been studying that deep history by looking at tiny magnets buried in rock around
the world. Those magnets pointed north when they were locked into the rock. Sample
those magnets in layers of rock laid down over millions of years, and you can tell the
story of how those continents have moved.
And naturally, that led Mitchell to wonder what the next supercontinent will look like.
There have been two leading ideas. One is that the continents will collapse together
again at the site of the last supercontinent, centered on Africa. That would squeeze the
Atlantic Ocean shut. The other idea is that the Atlantic would keep growing and growing.
Under this scenario, "a supercontinent rifts apart, and the continents skirt around to the
opposite side of the globe, re-creating the next supercontinent, 180 degrees on the
opposite side of the globe from the previous one," Mitchell says.
That would leave us with a supercontinent in place of the Pacific Ocean.
A Supercontinent Called Amasia
But Mitchell's research for his Ph.D. thesis suggests both those ideas are wrong.
Instead, he says the continents seem to be moving north. That means the Caribbean
Sea and the Arctic Ocean will be squished shut.
"Think about closing the Caribbean Sea — you have now fused North and South
America," Mitchell says. "And then by fusing the Arctic Ocean, you would suture the
Americas with Eurasia."
http://www.npr.org/2012/02/08/146572456/amasia-the-next-supercontinent - animation on link
That would create a supercontinent called Amasia that would form at the top of the
Earth. Eventually it would slump south toward the equator. And under this scenario,
Antarctica might remain isolated at the bottom of the world.
Brendan Murphy studies supercontinents at St. Francis Xavier University in Nova
Scotia. He says the Yale team's idea is provocative, innovative and plausible.
"What they've done is they've thrown another possibility out there that, quite frankly,
many of us hadn't really thought about. And so even if the model is wrong, we will learn
a lot by testing it."
And he says the challenge isn't simply finding different ways to put together the Earth's
jigsaw puzzle continents.
"This is really important because it influences the evolution of our entire planet,
including life that lives on it," Murphy says. "For example, many people believe that
supercontinents form and stood apart their fundamental changes in climate."
Of course, the next supercontinent isn't likely to form for another 100 million years or so.
And Mitchell says the human species will probably be long gone by then, so we won't
know, "but it's certainly fun to think about."