A reservoir of water three times the volume of all the oceans has been discovered deep beneath the Earth's surface. The finding could help explain where Earth's seas came from. The water is hidden inside a blue rock called ringwoodite that lies 700 kilometres underground in the mantle, the layer of hot rock between Earth's surface and its core. The huge size of the reservoir throws new light on the origin of Earth's water. Some geologists think water arrived in comets as they struck the planet, but the new discovery supports an alternative idea that the oceans gradually oozed out of the interior of the early Earth. Read more
Mineral hints at bright blue rocks deep in the Earth
Minerals preserved in diamond have revealed hints of the bright blue rocks that exist deep within the Earth. They also provide the first direct evidence that there may be as much water trapped in those rocks as there is in all the oceans. The diamond, from central-west Brazil, contains minerals that formed as deep as 600km down and that have significant amounts of water trapped within them. Read more