One and a half miles beneath the surface of Earth in a Canadian mine, researchers have found pockets of water in rocks that have been isolated from the surface for some two billion years.
The chemistry of the water could support life, the team reports today in the journal Nature -- a tantalizing discovery that raises the possibility that life-supporting water might also lie in similar kinds of rocks deep beneath the surface of Mars.
Because the water was trapped at a time when Earth was very different than it is today, the new findings also lend insight into the evolution of the early atmosphere and the habitability of the deep Earth. Until now, the oldest known reservoirs of underground water dated back just tens of millions of years.
"For the first time, we found that waters of this age can be preserved on our planet," said Barbara Sherwood Lollar, an isotope geochemist at the University of Toronto. "Really, it's a whole new world, a whole new hydrosphere on our planet. We didn't know it was possible to trap this amount of fluid and gas for this kind of time scale."