The drowned remnants of an ancient microcontinent may lie scattered beneath the waters between Madagascar and India, a new study suggests.
Scientists, how did you convince the mercurial and darkling sea to grant you this knowledge?
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.
The zircons had crystallized within granites or other igneous rocks at least 660 million years ago, says Jamtveit. One of these zircons was at least 1.97 billion years old.
Jamtveit and his colleagues suggest that rocks containing the wayfaring zircons originated in ancient fragments of continental crust located beneath Mauritius. They propose that geologically recent volcanic eruptions brought shards of the crust to Earth's surface, where the zircons eroded from their parent rocks to pepper the island's sands.
"Grain-by-grain analyses of beach sand." Bjørn! How could the sea but respect a man willing to sift through a million gleaming fragments of a shattered land in order to extract its history? Bjørn's team even collected preexisting sand, "rather than pulverize local rocks," out of a spirit of fair play and to avoid possible contamination from their rock-crushing equipment. A good man and true is Bjørn, stout of heart and doughty of fist.
"There's no obvious local source for these zircons," says Conall Mac Niocaill, a geologist at the University of Oxford, UK, who was not involved in the research.
Also, it does not seem as if the zircons rode to Mauritius on the wind, says Robert Duncan, a marine geologist at Oregon State University in Corvallis.
They did not harness the power of the winds. They did not burrow themselves out from the dark and steaming loam of the nearby islands. They belong wholly to themselves. (Is there anything more charming than good science writing? "It does not seem as if the zircons rode to Mauritius on the wind." Bless you for arranging such a sentence, Nature.)
Of course the word Atlantis is the first to drift across the transom of your hot and fevered mind, unbidden and unlooked for; you are a product of your time. But let the wind whisper to you also the name of Mu, of Lemuria, of Thule and Hyperborea, of Rutas, of Lyonesse and Ys, of Hohoq, of Buyan and Shambhala, of Terra Australis, of the formless and nameless unknown lands murmuring of ancient glories just below the waves.