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Scientists have discovered new evidence that the Earth's interior has cooled considerably over the last three billion years, a finding they claim leads to fresh questions about whether plate tectonic movement is only a relatively recent phenomenon.
An international team, led by the Australian National University, used synchrotron technology to study the chemical composition of komatiites -- ancient volcanic rocks thrown up from the planet's mantle -- to come to the conclusion.

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nefall_tmo_2008286.jpg

There is a spectacular image of the Northeastern United States on NASA's Earth Observatory Website. It stretches from Nova Scotia to Buffalo, and south to Virginia Beach, all bathed on sunshine under clear skies. You can see autumn colours spilling down out of the mountains, and creeping southward.

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Ancient lava flows are guiding a better understanding of what generates and controls the Earth's magnetic field - and what may drive it to occasionally reverse direction.

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This image shows a portion of the oldest-known rocks on Earth, dating from 4.28 billion years ago and found on the eastern shore of Canada's Hudson Bay.
Credit Xinhua

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Quebec bedrock may be Earth's oldest
By measuring tiny variations in the chemical composition of the Nuvvuagittuq greenstone from Hudson's Bay, researchers Jonathan O'Neil of McGill University in Montreal and Richard Carlson of the Carnegie Institution of Washington were able to date various rock samples to between 3.8 billion and 4.28 billion years ago.

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Oldest bedrock found in Canada
A traveller walking along the eastern bank of Hudson Bay in northern Quebec can stand on the oldest bedrock known on Earth.
This ancient section of the planet's crust may be as much as 4.28 billion years old, researchers report in Friday's edition of the journal Science.
While the age of the Earth itself is estimated at 4.6 billion years, most of the original surface has been crushed and recycled through tectonics, the movement of giant plates across the planet's surface.

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Chemical equator
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Scientists have discovered a "chemical Equator" that divides the polluted air of the Northern Hemisphere from the largely uncontaminated atmosphere of the Southern Hemisphere.
Researchers from Britain's University of York found evidence for an atmospheric chemical line about 50 kilometers (30 miles) wide in cloudless skies in the Western Pacific, with levels of carbon monoxide four times higher on the northern side.

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New University of Queensland (UQ) volcano research is helping to unlock the mystery surrounding one of the world's most important tectonic events.
The study, which forms part of an ongoing research team effort in the University's Argon Geochronology in Earth Sciences (UQ-AGES), has found a major collision between the Australia plate and Earth's largest oceanic plateau, the Ontong Java Plateau, in the South Pacific, happened about 26 million years ago.

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Tiny minerals found inside diamonds have provided us with a rare glimpse of the Earths deepest secrets. This exciting new research by a team of scientists, led by the University of Bristol, is reported today (30 July) in Nature.
The Earths crust that underlies our oceans is constantly being made at mid-oceanic ridges which run down the centre of our oceans. There, magma derived from the mantle (the layer beneath the crust) is injected between diverging tectonic plates, pushing them apart. On the far side of each plate, old oceanic crust is eventually recycled by returning it to the mantle at subduction zones, huge trenches that dive deep beneath the continents.

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Earth's atmosphere in stunning sunrise from space
With its graphic horizontal splashes of vibrant colour, one might think this was a piece of modern art.
In fact, this dramatic image shows the sun rising over central Asia from space.

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