A basin of water three times the size of all the oceans has been found deep under the Earth’s surface. The discovery may enlighten where Earth’s seas came from, and loan some concrete evidence to the hollow earth theory.
The water is concealed inside a blue rock called “Ringwoodite” that lies 700 kilometres under the earths’ surface in the mantle, the layer of hot rock in the middle of Earth’s surface and its core. The gigantic size of the basin throws new light on the source of Earth’s water. Many geologists think water reached in comets as they struck the planet, but the new finding aids an different idea that the oceans slowly oozed out of the inside of the early Earth.
“It’s good evidence the Earth’s water came from within,” says Steven Jacobsen of Northwestern University in Evanston, Illinois. The concealed water could also act as a buffer for the oceans on the surface, clarifying why they have remained the same volume for millions of years.
Jacobsen and associates used 2000 seismometers to examine the seismic waves produced by more than 500 earthquakes. These waves move all the way through Earth’s interior, including the core, and can be sensed at the surface. “They make the Earth ring like a bell for days afterwards,” says Jacobsen.
By calculating the speed of the waves at various depths, the team could figure out which kinds of rocks the waves were passing through. The water layer exposed itself as the waves slowed down, as it takes them longer to get pass soggy rock than dry rock.
Jacobsen found out in advance what would take place to the waves if water-containing ringwoodite was present. He raised ringwoodite in his lab, and exposed samples of it to huge pressures and temperatures corresponding those at 700 kilometres down.
Sure enough, they discovered marks of wet ringwoodite in the transition zone 700 kilometres down, which splits the upper and lower regions of the mantle. At that distance, the pressures and temperatures are just right to crush the water out of the ringwoodite. “It’s rock with water along the boundaries between the grains, almost as if they’re sweating,” says Jacobsen.
Jacobsen’s discovery agrees with a fresh study by Graham Pearson of the University of Alberta in Edmonton, Canada. Pearson examined a diamond from the transition zone that had been carried to the surface in a volcano, and found that it had water-bearing ringwoodite, the first strong proof that there was loads of water in the transition zone (Nature, doi.org/s6h).
“Since our initial report of hydrous ringwoodite, we've found another ringwoodite crystal, also containing water, so the evidence is now very strong,” says Pearson.
So far, Jacobsen only has proof that the watery rock sits underneath the US. He now desires to find out if it wraps about the entire planet.
“We should be grateful for this deep reservoir,” says Jacobsen. “If it wasn't there, it would be on the surface of the Earth, and mountain tops would be the only land poking out.”
This post was written by Usman Abrar. To contact the writer write to firstname.lastname@example.org. Follow on Facebook