4.4 billion years ago Earth had no mountains and was covered with water, say scientists

May 10, 2017 by  
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Tiny zircon crystals have allowed scientists at Australian National University (ANU) to paint a portrait of what Earth looked like over four billion years ago. Their scrutiny of the mineral grains – the oldest fragments of the planet we’ve ever uncovered – led them to think our world was a much different place back then. They say the planet, which was barren, had no mountains, and probably only a few islands poked up above the water blanketing the rest of the planet. Zircon crystals preserved inside sandstone rocks in the Jack Hills of Western Australia provided clues to our planet’s history – billions of years before humans ever showed up. Lead researcher Antony Burnham said the zircon samples were collected over multiple decades, and his team also drew on chemical analyses from an ANU research group two decades ago. He likened zircon grains to skin cells at a crime scene. Related: World’s largest dinosaur footprint found in Australia’s “Jurassic Park” “The history of the Earth is like a book with its first chapter ripped out with no surviving rocks from the very early period, but we’ve used these trace elements of zircon to build a profile of the world at that time,” he said in a statement. “Our research indicates there were no mountains and continental collisions during the Earth’s first 700 million years or more of existence – it was a much more quiet and dull place.” The zircon formed from melting older igneous rocks, instead of sediment melting, which is typical in continental collisions. And it appears it took a long time for the planet to change from the flat landscape into the Earth we inhabit now. “Our findings also showed that there are strong similarities with zircon from the types of rocks that predominated for the following 1.5 billion years, suggesting that it took the Earth a long time to evolve into the planet that we know today,” Burnham said. The journal Nature Geoscience published the research online yesterday. Via Australian National University Images via Stuart Hay, ANU

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4.4 billion years ago Earth had no mountains and was covered with water, say scientists

Oldest Fragment of Earth Ever Found is Confirmed to be 4.4 Billion Years Old

February 24, 2014 by  
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If you thought that diamonds were forever , they have absolutely nothing on the zircon of Jack Hills, Australia. Professor of geoscience at the University of Wisconsin , John Valley has confirmed that this bit of Earth’s crust is the oldest fragment of the planet ever found at 4.375 billion years old. Using a technique called “atom-probe tomography,” Valley and his fellow scientists dated the zircon with more accuracy than previous methods. Not only did they confirm the zircon’s spectacular age, but also solidified the theory that early Earth was cool and had temperatures low enough to sustain liquid water and a hydrosphere. Read the rest of Oldest Fragment of Earth Ever Found is Confirmed to be 4.4 Billion Years Old Permalink | Add to del.icio.us | digg Post tags: atom-probe tomography , australia , early earth , earth’s oldest fragment , geology , geoscience , jack hills , john valley , lead atoms , university of wisconsin-madison , zircon        

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Oldest Fragment of Earth Ever Found is Confirmed to be 4.4 Billion Years Old

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