A massive underground ocean has been discovered deep in Earth’s mantle.
Where does Earth’s water come from? How have the oceans stayed the same size for millions of years?
The popular prevailing theory among scientists has been comets delivering water as they bombarded during the chaotic days of the early solar system. A study published in 2009 claims to have evidence of comets full of water ice bombarding Earth and the Moon.
That theory will now be called into question with this stunning discovery of the underground ocean.
A team of scientists from Northwestern University in Illinois recently discovered an enormous reservoir of water with 3x the volume as all of Earth’s oceans combined.
The water was discovered around 450 miles deep in the mantle, where it is trapped inside a porous blue rock called ringwoodite. The ringwoodite has a special crystal structure that easily attracts hydrogen and allows it to trap water deep in the mantle. The mantle, 84% of Earth’s total volume, is an 1,800-mile-thick band of mostly solid, hot rock located between the thin crust and super-hot core.
As the rock moves up from the lower mantle and reaches the transition zone to the upper mantle the temperature and pressure decreases and the rock begins to sweat water along the grain boundaries.
Steven Jacobsen of Northwestern University says, “It’s good evidence the Earth’s water came from within.”
Earthquakes create seismic waves that cause the Earth to “ring like a bell” for days afterword, according to Jacobsen. Jacobsen’s team studied the seismic waves from 500 earthquakes using 2000 seismometers. As they measured the speed of the waves at different depths they could determine the type of rock the waves were traveling through. The massive water deposit was discovered when the waves hit the soggy rock and slowed down.
The discovery was made under the United States and the next step is to find out if the ringwoodite wraps the planet.
This new discovery gives increased weight to an alternative theory, published in Chemical Communications, that claims Earth’s water was bound up in the dust grains that eventually formed Earth. The study authors claim our oceans gradually oozed out of the interior of the young Earth.
It is likely Earth’s water is a result of both methods as there is substantial evidence for both theories.