By Gemma Tarlach
Researchers who want to study the nature of Earth’s original crust find themselves between a rock and a hard place: Our planet’s top layer is constantly wearing down in one spot and building up in another, continents colliding or slip-sliding past each other in the great mosh pit of plate tectonics. You might have figured none of the early crust was even still around. New research shows you would have figured wrong.
Today in Science, researchers announced they’d found bits of Earth’s original crust still in place, in northern Quebec, Canada. The team believes the rocks are more than 4.2 billion years old — that’s just a couple hundred million years shy of Earth’s birth some 4.5 billion years ago. And really, what’s a couple hundred million years between friends?
Previously, researchers had turned up fragments of rock that were roughly 4 billion years old. There are also a few teensy grains of zircon from Jack Hills, Australia, dated to about 4.4 billion years old. Controversy about the accuracy of the dates for all of these old-timers abounds, however, because a number of factors can make it difficult to determine just how old the material is.
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