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A bathymetric map of the Atlantic Ocean.

The continents may become a single landmass—or "supercontinent"—and the ocean would close.

Map courtesy Reto Stöckli, NASA Earth Observatory

Ker Than

for National Geographic

Published June 19, 2013

A newly discovered crack in the Earth's crust could pull North America and Europe together and cause the Atlantic Ocean to vanish in about 220 million years, scientists say.

A new map of the seafloor off the coast of Iberia—the region of Europe that includes Portugal and Spain—has revealed what could be the birth of a new subduction zone.

Subduction zones happen when tectonic plates—the large rock slabs that make up the Earth's crust—crash into one another. The edge of the heavier plate slides, or subducts, below the lighter plate. It then melts back into the Earth's mantle—the layer just below the crust.

The discovery of this new subduction zone, published on June 6 in the journal Geology, could signal the start of an extended cycle that fuses continents together into a single landmass—or "supercontinent"—and closes our oceans.

This breakup and reformation of supercontinents has happened at least three times during Earth's approximately four-billion-year history.

In the far future, Earth's continents could "look very much like the Pangea," said study first author João Duarte, referring to a supercontinent that existed about 200 million years ago.

So what's new? The newly discovered subduction zone is located in the Atlantic Ocean about 120 miles (200 kilometers) off the southwest coast of Portugal. It is made up of six distinct segments that together span a distance of about 186 miles (300 kilometers).

The subduction zone is actually a newly formed crack in the Eurasian plate—one of about a dozen tectonic plates that make up the Earth's crust. The Eurasian plate contains all of Europe and most of Asia.

"In this case, the Eurasia plate is breaking in two," said Duarte, a geoscientist at the University of Monash in Australia.

Why is it important? Scientists have long suspected that a new subduction zone was forming near the western margin of the Eurasian plate, off the coast of Portugal.

Part of the reason is that the region has been the site of significant earthquake activity, including an 8.7-magnitude quake in 1755 that devastated Lisbon.

Over the past 20 years, several scientific teams from different countries have launched research cruises to map the seafloor around the region to look for proof that a new subduction zone was forming.

As part of his research project while at the University of Lisbon, Duarte gathered together the data from all of the different mapping projects and combined them to create a new tectonic map of the seafloor off the coast of Portugal.

The updated map provided the first conclusive proof that the ocean floor off the coast of Iberia is indeed beginning to fracture, and that a new subduction zone is starting to form.

"It is not a fully developed subduction, but an embryonic one," Duarte said.

What does this mean? The evidence collected by Duarte's team indicate that the Eurasia plate could eventually split into separate oceanic and continental sections.

If this happens, the oceanic section—which is made of denser rock—will dive beneath the continental section. This will cause the Atlantic Ocean to shrink and pull North America and Iberia closer together.

Other studies have indicated that geologic activity in the region could also pull Africa and Iberia together, causing the Mediterranean Sea to vanish.

"Eventually North America and Iberia will be together again, and the collision will give origin to new mountain chains like the Himalaya," Duarte said.

What's next? Scientists will continue to study the nascent subduction zone because it could help answer a long-lasting mystery: How do oceans—especially ones like the Atlantic that have "passive" margins that are free of fractures—start to close?

"For the first time we are seeing a [passive] Atlantic margin turn into a Pacific one," for which subduction zones are common, Duarte said.

His team plans to continue collecting data about the crust and seafloor in the region to further investigate the subduction zone. They are also developing computer and physical models of the subduction process and plate motions.

"Understanding these processes will certainly provide new insights on how subduction zones may have initiated in the past and how oceans start to close," Duarte said in a statement.

18 comments
Li T Kong
Li T Kong

Would the closing in of the Atlantic ocean, Mediterranean Sea, etc lead to more massive Pacific, Indian and Southern oceans?

John J Wiggins
John J Wiggins

This article practically supports one of the theorized future supercontinents, in this case it supports Pangea Ultima which is supposed to form around 200 million years in the future, and North America will collide with Africa and Europe. Austraila will merge with Southeast Asia. and Antartica will collide with South America. Of course there's alsdo another theorized Super Continent called Amasia, where North and South America will coillide with eastern Asia as will Australia. 

H S
H S

Strange that the still-quite-active Mid-Atlantic Ridge, the massive divergent boundary running down the length of the Atlantic, seems to be totally ignored in these calculations. If anything, this would seem to be a furrow on one side of the Atlantic as the North American and Eurasian plates drift apart. It shouldn't have any bearing on the North American plate itself, as it does not seem to border it. Can't access the article to see exactly what was supposedly demonstrated and if there were any explanations for the MAR, but these conclusions seem fishy at best.

emily james
emily james

It is better we plan a natural Eco-friendly environment by planting more and more trees near our surroundings to avoid such things happening as our future  lifestyle totally depend as what we provide them.

A Better Future is necessary and it all depends on every human contribution. 

SAVE THIS BEAUTIFUL PLANET BY PLANTING ATLEAST ONE TREE IN YOUR SURROUNDINGS.



Sabz Aliy
Sabz Aliy

i will not live long enough to see it happening. :( . i wish i could. . 

Todd Brown
Todd Brown

OK so this news is that a new subduction zone is forming, but for the past 40 years I've been told that Europe and North America were separating at the rate of 1 inch a year.  Has this process slowed or stopped, the distance can't be both widening and shrinking at the same time.

Serge Redchuk
Serge Redchuk

Interesting but nothing surprising. Such changes are normal for such periods.

Miguel Rodriguez
Miguel Rodriguez

Very interesting article. And actually is good news: I always wanted to go to Europe. I only have to be patient and plate tectonics will do the rest.

Roger Dorn
Roger Dorn

@H S

 I don't really buy into the whole Atlantic closure hypotesis, but mid-ocean ridges do subduct under continents just like any other oceanic crust. In fact the ancient mid-Pacific ridge is still in the end stages of subducting under North America off the coast of the Pacific Northwest and Central America (the Juan de la Fuca plate and the Cocos plate are remnants of the Farallion plate that has been slowly submerged under North America for the last several hundred million years. They are still spreading at the same time too.)

H S
H S

@emily james Really don't see how planting trees and plate tectonics are related...

Lavan S
Lavan S

@emily james Tell that to nations of war, looking to control resources...who the heck wants to share borders, when oceans run dry and lands be newly created.

Ker Than
Ker Than

@Luis Soares Interesting question! I wish I thought to ask the scientists that. I do know that it's not uncommon for islands and "microcontinents" to become merged with larger continents. So that could happen here – the Azores might cease to exist when the Atlantic closes, but it could become part of whatever supercontinent is formed.

Ker Than
Ker Than

@Todd Brown Good question, and one that I don't know the answer to. The theory expressed in this article is based on a new tectonic map of the seafloor off of Iberia, so it could be that it's changing ideas about how the continents will move over time. But I'd have to ask the scientists to know for sure.

Hendrik Smith
Hendrik Smith

@Todd BrownThe Mid-Atlantic ridge is still active.More than likely the direction that North America moves in will be determined by the difference in the spreading rate of the Northern part of the Mid-Atlantic ridge and the rate of subduction, once it has been initiated. Just because you are forming a new subduction zone does not mean the spreading and upwelling at the Mid-Atlantic ridge will stop. Europe will maybe move closer to the Mid-Atlantic ridge, but North America will continue to move away from it.

Buzaeanu Alexandru
Buzaeanu Alexandru

@Todd Brown Actually, North America will be approaching Europe, while South America will continue to move to the west because of the Atlantic rift. At least that's what I think.

Ker Than
Ker Than

@Miguel Rodriguez That's true – you'll save bundles on Transatlantic flights if you can just wait a few tens of millions of years.

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