Scientists have discovered evidence of a vast reservoir of water hiding up to 400 miles beneath the surface.
The discovery could transform our understanding of how the planet was formed, suggesting that Earth's water may have come from within, rather than from collisions with large, icy comets.
The water is trapped in a blue mineral called ringwoodite that sits in the mantle, a hot, rocky layer between the Earth's crust and outer core. That means the water is not the familiar liquid, vapor or ice, but a fourth, mineral form. We
reported earlier this year on a rare diamond containing a microscopic piece of ringwoodite that bolstered evidence for the vast wet zone.
"If just 1 percent of the weight of mantle rock located in the transition zone was water it would be equivalent to nearly three times the amount of water in our oceans," Geophysicist Steve Jacobsen from Northwestern University, said.