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(Original article at Nature.com)

"Imagine you suddenly discovered part of your umbilical cord was still attached. Scientists just did that for the planet Earth. What's been found is a clear sign that beneath the crust in northern Canada there is a chunk of pristine, undisturbed rock from the time when Earth was nothing but molten rock.

The evidence comes in the form of lava rocks that, themselves, are a mere 60 million years old. But these rocks contain an early Earth mixture of helium, lead and neodymium isotopes which suggest the mantle rock beneath the crust that yielded them is a virgin pocket of Earth's original material.

That pocket had survived for 4.5 billion years under Baffin Island without being mixed by plate tectonics or erupted onto the surface.

"I was surprised that any of the (original) mantle survived," said geoscientist Matthew Jackson of Boston University. He is the lead author on a paper announcing the discovery in this week's issue of the journal Nature. "Finding a piece of the original mantle has been a holy grail. The original Earth was a big ball of magma. That's our (planet's) original composition.""


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