2014-06-16. The Earth’s Hidden Ocean.

posted Jun 21, 2014, 8:28 PM by Alan Gould
For GSS Energy Flow chapter 3. Excerpt: An analysis of seismic waves passing through the deep earth appears to confirm what laboratory experiments have suggested was possible: that an ocean of water is tied up in the mantle, 400 miles below the surface. Any voyager to the center of the earth could leave the wet suit behind, however. The water is not liquid, but rather bound in minerals that exist at the extreme pressures found at such depths. ...“It’s a new view of the structure of this part of the earth,” said Brandon Schmandt, a geophysicist at the University of New Mexico and an author of a recent paper in the journal Science describing the research. The work also adds credence to the idea that the earth’s water accumulated in the interior during the planet’s formation, rather than arriving later through the bombardment of icy comets. In this view, water bound up in minerals in the mantle, the 1,800-mile-thick layer between the thin crust and the hot metallic core, degassed over time and reached the surface. The scientists studied a part of the mantle called the transition zone, from about 300 to 440 miles deep. The ability of this zone to contain water — and apparently to retain a lot of it — “may have something to do with stabilizing or buffering the size of the oceans,” said Steven D. Jacobsen, a mineralogist at Northwestern University and another author of the paper. “It may be fortunate that the earth’s interior can act like a sponge.” ...it’s not as if there are huge chambers of magma hundreds of miles below the surface, Dr. Jacobsen said. The melting occurs on the boundaries of the mineral grains. “You end up having a mushy rock,” he said. http://www.nytimes.com/2014/06/17/science/the-earths-hidden-ocean.html. By Henry Fountain.