If Continents Moved Again Where Are They Likely to Move
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October vi, 2000 -- The World is going to be a very different place 250 one thousand thousand years from now.
Africa is going to smash into Europe as Australia migrates north to merge with Asia. Meanwhile the Atlantic Ocean will probably widen for a spell earlier it reverses course and afterward disappears.
Two hundred and fifty 1000000 years ago the landmasses of Earth were clustered into one supercontinent dubbed Pangea. As Yogi Berra might say, it looks like "deja vu all over again" as the present-mean solar day continents slowly converge during the side by side 250 meg years to course another mega-continent: Pangea Ultima.
To a higher place: A map of the world every bit it might announced 250 million years from now. Notice the clumping of about of the world's landmass into 1 super-continent, "Pangea Ultima," with an inland sea -- all that'due south left of the once-mighty Atlantic Ocean. Image courtesy of Dr. Christopher Scotese.
The surface of the Earth is cleaved into big pieces that are slowly shifting -- a gradual process chosen "plate tectonics." Using geological clues to puzzle out past migrations of the continents, Dr. Christopher Scotese, a geologist at the Academy of Texas at Arlington, has made an educated "guesstimate" of how the continents are going to move hundreds of millions of years into the future.
"We don't actually know the hereafter, plain," Scotese said. "All nosotros can practice is make predictions of how plate motions will keep, what new things might happen, and where it will all terminate up." Among those predictions: Africa is likely to proceed its northern migration, pinching the Mediterranean closed and driving up a Himalayan-scale mountain range in southern Europe.
What's it like to run into two continents collide? Only look at the Mediterranean region today.
Africa has been slowly colliding with Europe for millions of years, Scotese said. "Italia, Greece and almost everything in the Mediterranean is role of (the African plate), and it has been colliding with Europe for the concluding twoscore 1000000 years."
That collision has pushed up the Alps and the Pyrenees mountains, and is responsible for earthquakes that occasionally strike Greece and Turkey, Scotese noted.
Above: The possible appearance of the Earth l million years from now. Africa has collided with Europe, closing off the Mediterranean Sea. The Atlantic has widened, and Australia has migrated north. Paradigm courtesy of Dr. Christopher Scotese.
"The Mediterranean is the remnant of a much larger ocean that has closed over the last 100 million years, and it will continue to shut," he said. "More than and more of the plate is going to become crumpled and get pushed higher and higher up, like the Himalayas."
Australia is also probable to merge with the Eurasian continent.
"Commonwealth of australia is moving north, and is already colliding with the southern islands of Southeast Asia," he continued. "If we project that motion, the left shoulder of Australia gets caught, then Australia rotates and collides against Borneo and south China -- sort of like Bharat collided 50 one thousand thousand years ago -- and gets added to Asia."
Meanwhile, the Americas will exist moving further away from Africa and Europe as the Atlantic Ocean steadily grows. The Atlantic sea flooring is carve up from north to south by an underwater mountain ridge where new rock material flows upward from Earth'due south 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 equally your fingernails grow. Perchance a little bit slower," Scotese said. Still, over millions of years that minute movement will drive the continents apart.
Left: NASA's LAGEOS Two satellite measures tiny shifts in continental positions from Globe orbit. [more information]
That part of the prediction is fairly sure, because it is just the continuation of existing motions. Beyond about 50 million years into the future, prediction becomes more hard.
"The difficult part is the doubtfulness in (new behaviors)," Scotese said.
"It's like if you're traveling on the highway, you tin predict where you're going to be in an hour, just if there's an blow or you take to exit, you lot're going to change direction. And we have to endeavour to understand what causes those changes. That'southward where we have to make some guesses about the far future -- 150 to 250 meg years from now."
In the case of the widening Atlantic, geologists think that a "subduction zone" will somewhen form on either the east or due west edges of the sea. At a subduction zone, the ocean floor dives under the edge of a continent and downwards into the interior of the Earth.
"The subduction zone turns out to be the near important role of the organisation if you want to understand what causes the plates to move," Scotese said.
Like common cold air drifting down from an open attic in winter, the cold, dense seabed at the ocean'south edges sometimes starts sinking into the playdough-like layer below the crust, called the "mantle."
"Every bit it sinks, it pulls the residuum of the plate with it," similar a tablecloth sliding off a tabular array. This accounts for most of the force that moves the plates effectually, Scotese said.
This "slab pull" theory for the mechanism driving the motion of the plates stands in opposition to the older "river raft" theory.
"For a long time, geologists had this model that at that place were 'conveyer belts' of mantle convection, and the continents were riding passively on these conveyer belts, sort of similar a raft on a river," Scotese said. "Only that theory's all incorrect."
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If a subduction zone starts on one side of the Atlantic -- Scotese thinks it will be the due west side -- it will start to slowly drag the sea flooring into the mantle. If this happens, the ridge where the Atlantic sea floor spreads would eventually be pulled into the Earth. The widening would cease, and the Atlantic would begin to shrink.
Tens of millions of years later, the Americas would come smashing into the merged Euro-African continent, pushing upwardly a new ridge of Himalayan-like mountains forth the boundary. At that point, most of the world'due south landmass would be joined into a super-continent chosen "Pangea Ultima." The collision might also trap an inland bounding main, Scotese said.
"It'southward all pretty much fantasy to start with. But it'southward a fun exercise to think nearly what might happen," he said. "And you tin can only practice it if you have a really clear thought of why things happen in the first identify."
For now information technology appears that in 250 million years, the Earth'southward continents will be merged again into i giant landmass...just equally they were 250 meg years before now. From Pangea, to present,
to Pangea Ultima!
Web Links
PALEOMAP -- Web site for the project that produced the predictions of the future positions of Earth'southward continents. The site also has reconstructions of the past positions of the continents, too every bit estimates of past climate.
Information on Plate Tectonics -- By the U.S. Geological Survey
On the Move -- Continental Drift and Plate Tectonics --Larn more virtually NASA'southward Role in Investigating Continental Drift
Dr. Christopher Scotese -- Data most the scientist from the University of Texas at Arlington Web site.
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Source: https://science.nasa.gov/science-news/science-at-nasa/2000/ast06oct_1/
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