Forget the mythical lost continent of Atlantis. Geologists have reconstructed, time slice by time slice, a near history of a landmass that lies underwater, not under an ocean somewhere, but largely below southern Europe.
The researchers’ analysis represents “a huge amount of Work,” says Laurent Jolivet, a geologist at Sorbonne University in Paris who wasn’t involved in the new study. Although the tectonic history of the landmass has been known for a few decades, he says, “The amount of detail in the team’s systematic time-lapse reconstruction is unprecedented.”
The only visible remnants of the continent–called Greater Adria–are limestones and other stones found in the mountain ranges of Europe. Scientists believe these stones started as sediments and were scraped the surface of the landmass off and lifted through the collision of tectonic plates. Yet the landmass’ size, shape, and history — a lot of which lay beneath shallow seas for centuries –have been tough to reconstruct.
For starters, Greater Adria had a violent, complex History, notes a geologist at Utrecht University in the Netherlands, Douwe van Hinsbergen. It became a separate entity when it jumped from the southern supercontinent of Gondwana (which comprised what is now Africa, South America, Australia, Antarctica, the Indian subcontinent, and the Arabian Peninsula) about 240 million years ago and began to move northward, scientists think. About 140 million years ago, it was a landmass submerged in a tropical sea, where sediments accumulated and gradually turned into stone. Then, with what is now Europe between 100 million and 120 million years ago, as it collided, it shattered into pieces and has been pushed beneath that continent. Only a portion of the stones of Greater Adria remained on the surface for geologists of Earth to discover.
Another complication is that the stones of Greater Adria are dispersed across over 30 countries, to Iran in a swath from Spain. Therefore, data have been scattered and are difficult to gather like the stones themselves, van Hinsbergen states. And finally, he notes, until the past decade or geologists haven’t had the software required to perform such reconstructions. “The Mediterranean region is quite simply a geological mess,” he says. “Everything is curved, broken, and piled”
In the study, his colleagues and van Hinsbergen spent More than 10 years collecting information thought to be from the management of any magnetic fields, as well as Greater Adria. That let the researchers identify not only when, but where, the rocks were formed.
Rather than moving north without a change in its Orientation, Greater Adria spun counterclockwise as it scraped other tectonic plates that are beyond and jostled, van Hinsbergen’s team reports this week in Gondwana Research. Even though the collision happened at speeds of no more than 3 to 4 centimeters each year, the shattered the bit of crust and delivered most of it deep inside Earth’s mantle, van Hinsbergen says.
The analysis is not the proof for Greater Adria lost continent. Other researchers who use waves to create computerized tomography–like images of structures deep inside Earth have Made an “atlas of the underworld”–a graveyard of slabs of crust that have Sunk into the mantle. This research shows that portions of Greater Adria Lie up to 1500 kilometers below our planet’s surface.
For Further Study: Adriatic Plate