About 5 million years ago Tens of millions of cubic meters per second of ocean water rapidly poured into the Mediterranean Seagoing to fill what for 500,000 years had become an almost completely dry basin. This event, called “Zancleana flood”, It was The largest flood ever on earth and allowed the Mediterranean to return to being a sea, after the catastrophic geological event known as the Salininity crisis of the Messinian, who had caused the Closing of the Strait of Gibraltar By isolating the pelvis and making it evaporate the water. The modalities of this “mega-aluvione” have been the subject of debate for decades among scientists. Now, thanks also to a recent study, it was determined that it was the rapid collapse of the Item created in correspondence with the Strait of Gibraltar to allow the Zancleana flood.
From the Salinity crisis of the Messinian to the Zancleana flood
About 5.5 million years agothe Mediterranean Sea had a completely different appearance than the current one: it was one Wide expanse of salt depositsalmost completely devoid of water. To determine the drying of the Mediterranean had been a event that lasted almost 700,000 yearsthe so -called “Messinian salinity crisis “. At the basis of this phenomenon there were the movements of the terrestrial lithosphere, which determined the lifting of the area of the Strait of Gibraltarinterrupting the influx of water from the Atlantic Ocean. The Mediterranean Sea thus became a isolated basinin which the intense evaporation caused the deposit on the bottom of large quantities of salts. The area therefore had to appear as one Great salty desert expansewith a few hypersaline water basins, in which most marine species could not survive, extinguishing themselves. If the Mediterranean returned to take on the appearance of a sea it was thanks to aflood of enormous proportionsthe “Zancleana flood”, About 5 million years ago.
How the Zancleana flood in the Mediterranean took place
For a long time, scientists divided between those who supported a slow filling of the pelvis (lasting about 10,000 years) and those who instead believed that the filling had even occurred over a few years. Recent studies have proven that this mega-highlighted occurred over a few years (from 2 to 16) due to the collapse of the Isto of Gibraltar that for hundreds of thousands of years he had isolated the Mediterranean. The reliefs that made up this barrier sinked to allow the water of the Atlantic Ocean to overflow towards the Mediterranean basin. It is estimated that they fled Between 65 and 100 million cubic meters per second of water and that the sea level increased by about 10 m per day: these impressive values would make it the most impressive flood ever on our planet. From the western Mediterranean the water flowed east reaching Sicily and then, after having overcome the Scarpata of Malta, it also poured into the eastern part of the pelvis, until it reached the level of the Atlantic Ocean.
The traces of the Zancleana flood in Sicily
The traces of the enormous flow of water were found in Sicilybetween the provinces of Syracuse and Ragusa, in the southernmost part of the Ibleo plateau (between Noto, Portopalo, Rosolini and Pozzallo) and in the submerged areas of the Gulf of Noto. Here have been identified beyond 300 hills with a narrow and elongated shape, arranged in a Northeast-Sudovest direction e separated by deep furrows. These furrows have been dug in the rocks with a committed water flow and therefore indicate its direction. Erosion has produced enormous quantities of debris that today find themselves on the hills. Another testimony is the Canyon of Notoa deep underwater valley in the eastern Mediterranean, result of the excavation on the seabed by water and debris. The catastrophic floods like this are at the center of a growing interest because in the future due to climate change Similar phenomena may occur, linked to the fusion of enormous quantities of ice.
