The megaflood that refilled the Mediterranean Sea 5 million years ago was so huge and fast that it shaped the landscape of what is now Sicily
By Michael Le Page
21 January 2025
A ridge in south-east Sicily that was eroded by the megaflood
Kevin Sciberras and Neil Petroni
Jumbled deposits of rock found on the top of hills in south-east Sicily were left by the megaflood that refilled the Mediterranean sea 5 million years – the largest known flooding event in Earth’s history.
The rock deposits and eroded hills in this part of Sicily, a region of Italy, are the first land-based evidence found for the megaflood, says Paul Carling at the University of Southampton in the UK. “You can actually walk around and see it,” says Carling.
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Around 6 million years ago, during the so-called Messinian salinity crisis, the Mediterranean Sea was cut off from the Atlantic Ocean and began to dry out. Vast deposits of salt formed at this time and the sea level may have dropped by a kilometre or more.
Water once again started flowing through the Strait of Gibraltar into the Mediterranean around 5.3 million years ago. Researchers initially thought an enormous waterfall near Gibraltar refilled it over a period of tens of thousands of years.
But in 2009, the discovery of a massive eroded channel on the bottom of the strait pointed to a much more abrupt megaflood. The evidence for this has been growing ever since.