Sand from Mauritian beaches reveals rock from ancient landmass.
24 February 2013
The drowned remnants of an ancient microcontinent may lie scattered beneath the waters between Madagascar and India, a new study suggests.
Evidence for the long-lost land comes from Mauritius, a volcanic island about 900 kilometres east of Madagascar. The oldest basalts on the island date to about 8.9 million years ago, says Bjørn Jamtveit, a geologist at the University of Oslo. Yet grain-by-grain analyses of beach sand that Jamtveit and his colleagues collected at two sites on the Mauritian coast revealed around 20 zircons — tiny crystals of zirconium silicate that are exceedingly resistant to erosion or chemical change — that were far older.
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