A study by the Australian National University (ANU) explores what happened during the mega-flood that the Mediterranean was subjected to five million years ago, and this helped give it its current configuration. During the process, A massive 1.5 kilometer high waterfall was produced in the region of present-day Sicily, which helped fill the entire eastern half of the Mediterranean basin with water.
The event, called the Zanclean megacele, was the largest flood known to science. He transformed the Mediterranean basin from a barren saltwater pool into the bustling marine ecosystem we know today. ANU study, published nature geologyIt sheds light on how this transformation took place.
It is possible to come across sea shells in the Troodos Mountains, which are the widest mountain ranges of the island today. This is because the Mediterranean has a turbulent history of tectonic activity, sinking and rising islands, and floods.
Udara Amarathunga, lead author and ANU PhD researcher in paleoenvironments, said that the Zanclean flood It was one of the most abrupt global environmental changes since the mass extinction that wiped out the dinosaurs.. The researcher considers this to be the “Mediterranean renaissance”.
Gibraltar ‘gate’ closing
“The Megasel triggered the end of the Messinian Salinity Crisis (MSC). Mediterranean basin partially dried up as Atlantic-Mediterranean passage closes [Gibraltar]leaving large salt deposits and killing most life forms”, explains in Cosmos magazine.
Amarathunga added that the MSC began six million years ago when the European and African continental plates pushed toward each other, separating the Mediterranean from the Atlantic at the point where Gibraltar is today.
Amarathunga says this “gate” is not completely closed and allows little access to the Mediterranean. But It closed completely 5.6 million years ago, and this is the peak of the salinity crisis.”
While scientists aren’t sure of the exact extent of the Mediterranean’s drying up, Amarathunga says they think the level of the Mediterranean dropped 1-2 kilometers, forming two different basins: the eastern and western basin, separated by what is now Sicily.
A giant waterfall 1.5 kilometers high
But how did the Mediterranean cease to be an uninhabitable saltwater lake?
Slowly but surely, Amarathunga explains, Erosion in Gibraltar caused small amounts of water to seep from the Atlantic into the Mediterranean. The megacele hypothesis was first developed in 2009 by Spanish scientist Daniel García-Castellanos, and after this initial slow flow, The “dam wall” would have been breached, causing large volumes of water to enter the Mediterranean.
This would have created a massive waterfall 1.5 kilometers high at the height of Sicily and flooded the other half of the basin.
The energy produced by the great movement of water in a single day at the peak of the flood would be equivalent to 500 times the energy produced by Niagara Falls in an entire year. The Mediterranean Sea is predicted to rise more than 10 meters per day at the peak of the flood.
The rest of the world’s seas suddenly dropped nine meters.
“It would have been the most sudden flood in recorded history,” says Amarathunga. The magnitude of this phenomenon is that “as the Mediterranean fills andGlobal sea level has dropped by nearly nine meters”.
Immediately after the eastern Mediterranean flood surface is an “organic rich layer” that shows low oxygen levels in the water as oxygen leads to oxidation of this organic matter. This layer is not seen in the western basin. Thus, these anoxic dead zones in the Eastern Mediterranean indicate that the eastern basin was oxygen-free after the flood.
The mega-overflow and deposition of organic matter-rich layers took place in stages.
The western basin of the Mediterranean fills first. Later, when the land barrier that existed at the summit of Sicily is overcome, a huge waterfall forms in the east. But this waterfall, as Amarathunga’s work shows, must have carried large quantities of salt into the eastern basin.
“Our interpretation is that, towards the end of the flood both basins mix. However, due to the energy of the storm water, all the salt is transferred from this waterfall to the eastern basin,” says Amarathunga. “This salt now needs to be transported across the Atlantic. We used another model to estimate how long it would take to get the salt into the Atlantic.”
“Our study shows that It took another 26,000 years to remove all of the excess salt. and it restores the Mediterranean Sea to the appearance of a normal sea basin,” he adds.
This long transition period was hitherto unknown to scientists. However, the megacele hypothesis is subject to some controversy. Some scientists suggest that the Mediterranean never dried out on a large scale. But This new ANU study provides evidence that strengthens the mega-flood hypothesis.
Amarathunga said such a large and rapid transformation is rare and the Zanclean flood is a unique example of how quickly entire ecosystems can change.
Reference work: https://www.nature.com/articles/s41561-022-00998-z
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