Oldest Crust of Early Earth Found

It has been thought that, due to crustal subduction, the earliest crust of the planet has long since gone and the earliest that we have on the planet is 3.6 or so billion years old.  The age of the planet has always been derived from meteorites.  The St. Severin, Juvinas and Allende chondrites all have dates that cluster around 4.5 billion years old.

Now it has been found that zircon crystals in Western Australia formed around 4.4 billion years ago.  From the Science Daily story:

Writing today (Feb. 23, 2014) in the journal Nature Geoscience, an international team of researchers led by University of Wisconsin-Madison geoscience Professor John Valley reveals data that confirm the Earth’s crust first formed at least 4.4 billion years ago, just 160 million years after the formation of our solar system. The work shows, Valley says, that the time when our planet was a fiery ball covered in a magma ocean came earlier.

“This confirms our view of how the Earth cooled and became habitable,” says Valley, a geochemist whose studies of zircons, the oldest known terrestrial materials, have helped portray how the Earth’s crust formed during the first geologic eon of the planet. “This may also help us understand how other habitable planets would form.”

Another piece of the puzzle.