Paris: A hundred and fifty years ago, in "Journey to the Centre of the Earth", French science-fiction forerunner Jules Verne pictured a vast sea that lay deep under our planet`s surface.
Today, that strange and haunting image has found an unexpected echo in a scientific paper.
Writing in the journal Nature, scientists today said they had found an elusive mineral pointing to the existence of a vast reservoir deep in Earth`s mantle, 400-600 kilometres beneath our feet.
It may hold as much water as all the planet`s oceans combined, they believe.
The evidence comes from a water-loving mineral called ringwoodite that came from the so-called transition zone sandwiched between the upper and lower layers of Earth`s mantle, they said.
Analysis shows that a whopping 1.5 per cent of the rock comprises molecules of water.
The find backs once-contested theories that the transition zone, or at least significant parts of it, is water-rich, the investigators said.
"This sample really provides extremely strong confirmation that there are local wet spots deep in the Earth in this area," said Graham Pearson of Canada`s University of Alberta, who led the research.
"That particular zone in the Earth, the transition zone, might have as much water as all the world`s oceans put together."
Ringwoodite is named after Australian geologist Ted Ringwood, who theorised that a special mineral was bound to be created in the transition zone because of the ultra-high pressures and temperatures there.
A piece of this mineral has been a long-sought goal. It would resolve a long-running debate about whether the poorly-understood transition zone is bone-dry or water-rich.
But, until now, ringwoodite has only ever been found in meteorites. Geologists had simply been unable to delve deep enough to find any sample on Earth.