Evidence That the Continenents Will Once Join Together Again
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October vi, 2000 -- The World is going to be a very dissimilar identify 250 million years from at present.
Africa is going to smash into Europe equally Australia migrates north to merge with Asia. Meanwhile the Atlantic Ocean will probably widen for a spell before it reverses course and later disappears.
Two hundred and l 1000000 years ago the landmasses of Earth were amassed into 1 supercontinent dubbed Pangea. Every bit Yogi Berra might say, it looks like "deja vu all again" as the present-day continents slowly converge during the adjacent 250 million years to form another mega-continent: Pangea Ultima.
Above: A map of the world as it might appear 250 million years from now. Detect the clumping of nigh of the world's landmass into one super-continent, "Pangea Ultima," with an inland sea -- all that's left of the once-mighty Atlantic Bounding main. Image courtesy of Dr. Christopher Scotese.
The surface of the Earth is broken into big pieces that are slowly shifting -- a gradual procedure 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 time to come.
"We don't actually know the futurity, obviously," Scotese said. "All we can practice is brand predictions of how plate motions volition go along, what new things might happen, and where information technology will all end up." Amidst those predictions: Africa is likely to continue its northern migration, pinching the Mediterranean closed and driving up a Himalayan-calibration mountain range in southern Europe.
What's it similar to see two continents collide? Simply look at the Mediterranean region today.
Africa has been slowly colliding with Europe for millions of years, Scotese said. "Italy, Hellenic republic and near everything in the Mediterranean is office of (the African plate), and it has been colliding with Europe for the last forty one thousand thousand 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 50 million years from at present. Africa has collided with Europe, closing off the Mediterranean Sea. The Atlantic has widened, and Australia has migrated north. Prototype courtesy of Dr. Christopher Scotese.
"The Mediterranean is the remnant of a much larger body of water that has closed over the terminal 100 one thousand thousand years, and it volition continue to close," he said. "More and more than of the plate is going to get crumpled and go pushed college and higher up, like the Himalayas."
Commonwealth of australia is likewise likely 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 Commonwealth of australia gets defenseless, and then Australia rotates and collides confronting Kalimantan and s China -- sort of similar Republic of india collided 50 meg years ago -- and gets added to Asia."
Meanwhile, the Americas volition exist moving further away from Africa and Europe as the Atlantic Bounding main steadily grows. The Atlantic body of water floor is split from north to due south by an underwater mountain ridge where new stone material flows upwards from Earth's interior. The 2 halves of the sea flooring 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 niggling fleck slower," Scotese said. Still, over millions of years that minute movement volition bulldoze the continents apart.
Left: NASA's LAGEOS Two satellite measures tiny shifts in continental positions from World orbit. [more data]
That part of the prediction is fairly certain, because information technology is but the continuation of existing motions. Across about 50 meg years into the future, prediction becomes more than hard.
"The difficult role is the uncertainty in (new behaviors)," Scotese said.
"It's like if you're traveling on the highway, you can predict where y'all'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 attempt to understand what causes those changes. That's where we have to brand some guesses about the far futurity -- 150 to 250 million years from now."
In the case of the widening Atlantic, geologists think that a "subduction zone" will eventually grade on either the due east or west edges of the bounding main. At a subduction zone, the ocean flooring dives under the edge of a continent and down into the interior of the Globe.
"The subduction zone turns out to be the most important office of the arrangement if you want to understand what causes the plates to move," Scotese said.
Like cold air drifting down from an open attic in wintertime, the common cold, dense seabed at the ocean'south edges sometimes starts sinking into the playdough-like layer beneath the chaff, called the "drape."
"As it sinks, information technology pulls the rest of the plate with information technology," like 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 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 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. "Merely that theory's all wrong."
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If a subduction zone starts on i side of the Atlantic -- Scotese thinks it will be the west side -- it will commencement to slowly drag the ocean flooring into the mantle. If this happens, the ridge where the Atlantic sea flooring spreads would somewhen be pulled into the World. The widening would stop, and the Atlantic would begin to shrink.
Tens of millions of years later, the Americas would come groovy into the merged Euro-African continent, pushing up a new ridge of Himalayan-similar mountains along the boundary. At that point, nigh of the earth's landmass would exist joined into a super-continent called "Pangea Ultima." The collision might also trap an inland ocean, Scotese said.
"Information technology's all pretty much fantasy to start with. But it's a fun exercise to call up about what might happen," he said. "And you tin can only do it if you have a really articulate thought of why things happen in the start place."
For now information technology appears that in 250 million years, the Earth's continents will be merged again into one giant landmass...just as they were 250 1000000 years before now. From Pangea, to present,
to Pangea Ultima!
Spider web Links
PALEOMAP -- Web site for the project that produced the predictions of the future positions of World's continents. The site also has reconstructions of the past positions of the continents, equally well as estimates of past climate.
Information on Plate Tectonics -- By the U.S. Geological Survey
On the Move -- Continental Drift and Plate Tectonics --Learn more about NASA's Role in Investigating Continental Drift
Dr. Christopher Scotese -- Information about the scientist from the University of Texas at Arlington Spider web site.
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Source: https://science.nasa.gov/science-news/science-at-nasa/2000/ast06oct_1/
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