www.nature.com/news/2005/050718/full/050718-13.html
Nature (source pictures: punchstock/getty) "There occurred violent earthquakes and floods. the island of Atlantis disappeared in the depths o f the sea." This account, written by Plato more than 2,300 years ago, set scientists on the trail of the lost city of Atlantis. And if so, where was it located, and when did it disappear? In a recent paper in Geology, Marc-Andre Gutscher of the European Institu te for Marine Studies in Plouzan gives details of one candidate for the lost city: the submerged island of Spartel, west of the Straits of Gibr altar. The top of this isle lies some 60 metres beneath the surface in the Gulf of Cadiz, having plunged beneath the waves at the end of the most recent ice age as melting glaciers caused the sea level to rise. Geological evidence has shown that a large earthquake and a tsunami hit t his island some 12,000 years ago, at roughly the location and time indic ated in Plato's writings. Gutscher has surveyed this island in detail, using sound waves reflected off the sea floor to map its contours^ 1 His results bring mixed new s to Atlantis hunters. Ups and downs At first, his conclusions seemed disappointing. At the time identified by Plato for the city's loss, the sea level would have been fairly high on the island's banks. With the information we have from the ancient text, it may never be foun d, if indeed it ever existed. Floyd McCoy, geologist University of Hawaii, Kaneohe According to sea-level measurements alone, Gutscher estimates the island "would have been reduced to wave-swept rocky islets" and would have been less than 500 metres in diameter, making it impossibly small for a soph isticated city. Gutscher says the island might have sunk fur ther since those times from seismic activity. Layers of turbidite, the sand and mud shaken up by underwater avalanches, suggest that eight earthquakes have happened in the area since Atlantis sank. Each earthquake could have resulted in a drop of the sea floor by several metres. So 12,000 years ago, Spartel might have been 40 metres higher than expect ed, and could have measured five by two kilometres. "This is an interesting contribution to the discussion," says Jacques Col lina-Girard, a geologist at the University of the Mediterranean in Aix-e n-Provence, who suggested Spartel as a candidate for Atlantis a few year s ago. Simple folk "This does not mean the island was inhabited," Gutscher cautions. At a co nference of Atlantis researchers in Greece this month, he became convinc ed that the sophisticated city described by some could not have existed this long ago. "If inhabited, it would have probably been simple fisherm en and not a Bronze Age culture as described by Plato," he says. The Bronze Age is usually described as beginning just 5,000 years ago. Gu tscher adds that his sound reflection data revealed no unusual geometric structures that could suggest an extinct civilization. He says that the Egyptians who told Plato the Atlantis story may have use d a different definition of 'years', meaning the destruction of Atlantis happened more recently than thought. Candidate city The conference in Greece came to no firm conclusions about the city's exi stence. But researchers managed to agree on 24 criteria that a geographi cal area must satisfy in order to qualify as a site where Atlantis could have existed. The place must have accommodated such oddities as hot spr ings, northerly winds, elephants, enough people for an army of 10,000 ch ariots, and a ritual of bull sacrifice.
At present there are half a dozen candidates for Atlantis's location, eac h one with its own shortcomings. Some say that settling on a final answe r may prove impossible. "The geophysics is well done, the geology excellent," says geologist Floy d McCoy of the University of Hawaii, Kaneohe, of Gutscher's study. "But most of Plato's description of Atlantis is so ambiguous and open to inte rpretation. With the information we have from the ancient text, it may n ever be found, if indeed it ever existed."
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