Washington, July 7 : Scientists have come up with a plausible explanation for the splitting up of the supercontinent Pangea, attributing the break-up to a mechanism which caused the massive land mass to eat itself to pieces.
According to a report in New Scientist, convection in the Earth's mantle shifts the floating continental plates around, eventually driving them together into supercontinents every few hundred million years.
Though it is known that supercontinents eventually break up again, it's not clear how they do this.
Now, Gabriel Gutierrez-Alonso of the University of Salamanca in Spain and colleagues have explained the most recent break up which split Pangaea into today's continents.
They have proposed a mechanism called "self-subduction", which would explain several geological mysteries better than prior theories.
In standard subduction, one tectonic plate slips under another.
The situation could have been slightly different 300 million years ago because Pangaea was shaped like a pie with one piece missing. This area was occupied by an ocean called Paleo-Tethys.
The new theory has it that, as Pangaea's southern coast moved northward, the ocean began to close up.
Eventually, the continent's southern continental shelf was subducted beneath the northern coast.
"It's like a cat trying to bite its own tail," said Fernando Corfu, a geologist at the University of Oslo, and one of Gutierrez-Alonso's collaborators.
The theory predicts that the land in Pangaea's centre would have compressed, explaining the Iberian-Armorican Arc, a twisted mountain range that is known to have stretched from modern-day Turkey up to the UK and then down to Spain.
Meanwhile, the rest of the pie would have stretched to breaking point, allowing surrounding oceanic plates to move into the gaps.
This explains why a number of ancient rifts, including ones that can be visited today in Norway and Madagascar, were once arranged radially like the spokes of a bicycle.