A reservoir of water three times the volume of all the
oceans has been discovered deep beneath the Earth’s surface. The finding may
explain where Earth’s seas came from, and lend some interesting evidence to the
Hollow Earth Theory.
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. Many geologists think water arrived in comets as they struck the planet,
but the new discovery supports an alternative idea that the oceans graduallyoozed out of the interior 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
hidden water could also act as a buffer for the oceans on the surface,
explaining why they have stayed the same size for millions of years.
Jacobsen’s team used 2000 seismometers to study the seismic
waves generated by more than 500 earthquakes. These waves move throughout
Earth’s interior, including the core, and can be detected at the surface. “They
make the Earth ring like a bell for days afterwards,” says Jacobsen.
By measuring the speed of the waves at different depths, the
team could figure out which types of rocks the waves were passing through. The
water layer revealed itself because the waves slowed down, as it takes them
longer to get through soggy rock than dry rock.
Jacobsen worked out in advance what would happen to the
waves if water-containing ringwoodite was present. He grew ringwoodite in his
lab, and exposed samples of it to massive pressures and temperatures matching
those at 700 kilometres down.
Sure enough, they found signs of wet ringwoodite in the
transition zone 700 kilometres down, which divides the upper and lower regions
of the mantle. At that depth, the pressures and temperatures are just right to
squeeze 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 finding supports a recent study by Graham Pearson
of the University of Alberta in Edmonton, Canada. Pearson studied a diamond
from the transition zone that had been carried to the surface in a volcano, and
found that it contained water-bearing ringwoodite, the first strong evidence
that there was lots 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 evidence that the watery rock sits
beneath the US. He now wants to find out if it wraps around 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.”
Via :
Thespiritscience.net