Long Lost Continent Found Indian Ocean
Now, researchers have identified a lost micro-continent beneath the floor of the Indian Ocean. And they say there could be many more.......abc.net.au
Ashley Hall reports.
ASHLEY HALL: The researchers found the answer to this mystery locked deep in the sand on the island of Mauritius in the western Indian Ocean. They were surprised to find ancient zircon minerals hundreds of millions of years older than expected.
RICHARD ARCULUS: Zircon is a mineral made of zirconium and silica and it's a very tough individual. Once you've made it it's very hard to get rid of.
ASHLEY HALL: Richard Arculus is a professor of geology at the Research School of Earth Sciences at the Australian National University. And he's been reviewing the study published this week in the journal Nature Geoscience.
RICHARD ARCULUS: It's formed particularly in granites, which is the rock type that defines the continental crust.
ASHLEY HALL: The researchers believe the tiny zircon fragments were brought to the surface by volcanic activity from an ancient piece of continental crust buried beneath the ocean.
RICHARD ARCULUS: Mauritius itself is located over on a bank which stretches from Mauritius itself, through what's called the Mascarene Plateau, up towards the Seychelles. Now the Seychelles are an isolated group of islands between Madagascar and India, and we've known for a while that that's likely to be a micro-continent left behind as India has ruptured away from Madagascar.
ASHLEY HALL: Thousands of millions of years ago, all of the earth's land masses were united in one massive continent, with India sitting next to Madagascar. Gradually each of the continental plates began to drift apart.
The lead researcher Trond Torsvik of the University of Oslo is fascinated with what's been left behind
TROND TORSVIK: At the moment the Seychelles is a piece of granite or continental crust which is sitting practically in the middle of the Indian Ocean but once upon a time it was sitting north of Madagascar. And what we're saying is that maybe this was much bigger and there are many of these continental fragments which are spread around in the Indian Ocean.
ASHLEY HALL: For generations, humans have told stories about continents and civilisations that have been lost, buried by the sea.
Professor Arculus says that's not the same as the continental fragments identified by the team of researchers.
RICHARD ARCULUS: It's a leap too far because the lost continents in human mythology would be things that, say in the last 200,000 years, that we might have known about, since human beings have been around.
So anything that's disappeared below the waves within historic memory, you might say, 'yeah, there's evidence for something that's been drowned'. But this wouldn't have been at the surface for millions of years. It's been submerged, probably with the separation of India from Madagascar it's been submerged for a long time.
ASHLEY HALL: Nonetheless, the location of the fragments is important. He says there could be profits available to the communities living above them.
RICHARD ARCULUS: Under the law of the sea, if you can demonstrate you have a piece of continental crust, on which you can put your flag, you can immediately claim 200 nautical miles around it. And that's yours under the law of the sea to do what you like with economically. So there's some degree of economic significance to something that might be purely scientific in terms of its discovery.
MARK COLVIN: Richard Arculus, a professor of geology at the Australian National University, ending Ashley Hall's report.
And if the idea sounds familiar, it may well be. The Lord Howe Island Rise to the east of the Australian mainland is believed to be a similar continental fragment.