The event that refilled the Mediterranean basin 5m years ago is thought to have been the largest flood in Earth’s history, with water surging through the present-day strait of Gibraltar 1,000 times faster than the Amazon River, filling the basin in just a couple of years. Now jumbled rock deposits on the top of hills in south-east Sicily provide the first land-based evidence for this flood.
The megaflood theory emerged in 2009, when scientists discovered a massive eroded channel at the bottom of the strait of Gibraltar. Subsequent research has revealed scours on the sea floor, showing how the water forced its way through the shallow gap between Sicily and mainland Africa, to fill the eastern Mediterranean Sea.
Giovanni Barreca from the University of Catania in Italy, who grew up in Sicily, had long wondered if the unusual lozenge-shaped hills in south-eastern Sicily, which all align in the same direction, had been shaped by the megaflood. Together with fellow researchers, analysis of the jumbled rock deposits on these hills has confirmed Barreca’s hunch.
The findings, published in Scientific Reports, show that the boulders on top of these hills were washed up from far deeper layers, with a computer simulation suggesting the hills were carved out by water 40 metres (130ft) deep and travelling at 115km/h (70mph).
