Its northern Canada, its cold, its remote, its where a pristine undisturbed rock has been found from the time when Earth was just a molten baby planet. The ancient rock was found in a pocket of 60 million year old lava rock on Baffin Island. The pocket is approximately 4.5 billion years old and has managed to survive plate tectonics, a process which 'recycles' rocks and is why we don't see very old rocks today. The new find is composed of a mixture of helium, lead, and neodymium isotopes, specifically, a large amount of the isotopes helium-3 relative to helium-4 and a very old lead-isotope signature which suggest the mantle rock beneath the crust that yielded them is of the Earth's original material. Some researchers suggest that as much as 10% of the early mantle may yet exist, but this is still a remarkable find.
Read more here:
http://news.discovery.com/earth/oldest-earth-rock-lava.html
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