How Long Would It Take for the Pangea to Form Again
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October 6, 2000 -- The Earth is going to be a very unlike identify 250 meg years from at present.
Africa is going to smash into Europe as Australia migrates north to merge with Asia. Meanwhile the Atlantic Bounding main will probably widen for a spell earlier information technology reverses course and later disappears.
Two hundred and fifty 1000000 years ago the landmasses of Earth were clustered into one supercontinent dubbed Pangea. Equally Yogi Berra might say, it looks like "deja vu all over over again" equally the present-day continents slowly converge during the next 250 million years to grade some other mega-continent: Pangea Ultima.
Higher up: A map of the world as it might announced 250 million years from now. Discover the clumping of about of the world's landmass into i super-continent, "Pangea Ultima," with an inland sea -- all that's left of the once-mighty Atlantic Ocean. Image courtesy of Dr. Christopher Scotese.
The surface of the Earth is broken into big pieces that are slowly shifting -- a gradual process called "plate tectonics." Using geological clues to puzzle out past migrations of the continents, Dr. Christopher Scotese, a geologist at the University of Texas at Arlington, has made an educated "guesstimate" of how the continents are going to move hundreds of millions of years into the hereafter.
"We don't really know the hereafter, obviously," Scotese said. "All we tin can practice is make predictions of how plate motions volition go on, what new things might happen, and where it will all end up." Among those predictions: Africa is likely to continue its northern migration, pinching the Mediterranean airtight and driving up a Himalayan-scale mountain range in southern Europe.
What'south 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 final xl million 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 Globe 50 meg years from now. Africa has collided with Europe, closing off the Mediterranean Sea. The Atlantic has widened, and Australia has migrated north. Epitome courtesy of Dr. Christopher Scotese.
"The Mediterranean is the remnant of a much larger ocean that has airtight over the last 100 one thousand thousand years, and information technology will continue to close," he said. "More than and more than of the plate is going to get crumpled and get pushed higher and college up, similar the Himalayas."
Australia is also likely to merge with the Eurasian continent.
"Australia is moving north, and is already colliding with the southern islands of Southeast Asia," he continued. "If we projection that move, the left shoulder of Australia gets caught, so Commonwealth of australia rotates and collides confronting Borneo and south China -- sort of like Republic of india collided l million years ago -- and gets added to Asia."
Meanwhile, the Americas volition be moving further away from Africa and Europe every bit the Atlantic Bounding main steadily grows. The Atlantic sea floor is separate from n to south by an underwater mountain ridge where new rock material flows up from Earth'due south interior. The two halves of the sea floor slowly spread apart as the ridge is filled with the new textile, causing the Atlantic to widen.
"It's well-nigh as fast every bit your fingernails abound. Mayhap a little scrap slower," Scotese said. Withal, over millions of years that minute motility volition drive the continents apart.
Left: NASA's LAGEOS Two satellite measures tiny shifts in continental positions from Globe orbit. [more than information]
That part of the prediction is fairly certain, because it is just the continuation of existing motions. Beyond most 50 million years into the futurity, prediction becomes more difficult.
"The difficult part is the doubt in (new behaviors)," Scotese said.
"It's similar if you're traveling on the highway, yous tin predict where yous're going to exist in an 60 minutes, but if in that location'due south an accident or you have to get out, yous're going to modify direction. And we have to try to understand what causes those changes. That'south where we have to brand some guesses well-nigh the far time to come -- 150 to 250 million years from now."
In the case of the widening Atlantic, geologists recollect that a "subduction zone" will somewhen form on either the east or west edges of the ocean. At a subduction zone, the ocean floor dives nether the edge of a continent and downwardly into the interior of the Earth.
"The subduction zone turns out to be the most of import part of the system if you want to sympathise what causes the plates to motility," Scotese said.
Like cold air drifting down from an open cranium in winter, the cold, dense seabed at the ocean's edges sometimes starts sinking into the playdough-similar layer beneath the crust, called the "pall."
"As information technology sinks, it pulls the remainder of the plate with information technology," similar a tablecloth sliding off a table. This accounts for most of the force that moves the plates effectually, Scotese said.
This "slab pull" theory for the machinery driving the movement of the plates stands in opposition to the older "river raft" theory.
"For a long fourth dimension, geologists had this model that there were 'conveyer belts' of drape convection, and the continents were riding passively on these conveyer belts, sort of like a raft on a river," Scotese said. "But that theory's all wrong."
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If a subduction zone starts on one side of the Atlantic -- Scotese thinks information technology volition be the west side -- it will beginning to slowly drag the bounding main floor into the drapery. If this happens, the ridge where the Atlantic sea floor spreads would eventually be pulled into the Earth. The widening would stop, and the Atlantic would begin to shrink.
Tens of millions of years later, the Americas would come cracking into the merged Euro-African continent, pushing upward a new ridge of Himalayan-similar mountains along the boundary. At that point, most of the world'due south landmass would exist joined into a super-continent called "Pangea Ultima." The collision might besides trap an inland sea, Scotese said.
"Information technology's all pretty much fantasy to first with. But information technology's a fun exercise to retrieve near what might happen," he said. "And you can simply exercise information technology if you take a actually clear idea of why things happen in the first place."
For now it appears that in 250 one thousand thousand years, the Globe'south continents will exist merged again into ane giant landmass...just as they were 250 million years before now. From Pangea, to present,
to Pangea Ultima!
Web Links
PALEOMAP -- Spider web site for the project that produced the predictions of the future positions of Earth's continents. The site also has reconstructions of the past positions of the continents, too equally estimates of past climate.
Information on Plate Tectonics -- By the U.Southward. Geological Survey
On the Move -- Continental Migrate and Plate Tectonics --Learn more about NASA's Role in Investigating Continental Drift
Dr. Christopher Scotese -- Information about the scientist from the Academy 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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