Scientists Discover the Oldest-known Pool of Water

But you wouldn’t want to drink from it

Ancient Water
Barbara Sherwood Lollar sampling dissolved hydrogen and sulfate found in the oldest-known pool of water. G. Wunsch/University of Toronto

About two miles below the Earth’s surface, researchers digging in a mine in Ontario, Canada have discovered a remarkable time capsule: the oldest-known pool of water on the planet.

The mine was originally dug to excavate minerals like copper, zinc and silver, but this new find is far more precious, scientifically speaking. The water has bubbled below the surface for nearly two billion years, and may contain hints about what our planet looked like all those eons ago, Rebecca Morelle reports for the BBC.

"If water has been down there for up to two billion years, it can tell us something about the atmosphere at the time, or the state of the Earth, which previously we've not been able to get much insight into," University of Toronto researcher Oliver Warr tells Michelle Cheung at CBC News.

And the find is no tiny trickle. “When people think about this water they assume it must be some tiny amount of water trapped within the rock,” Barbara Sherwood Lollar, who lead the study, tells Morelle. “But in fact it’s very much bubbling right up out at you. These things are flowing at rates of litres per minute—the volume of the water is much larger than anyone anticipated.”

The scientists were able to figure out the water’s age by measuring how much helium, argon, neon, krypton and xenon had been trapped in the water over time, reports Cheung. Analysis of water samples also revealed chemicals that were left behind by single-celled organisms that once made their home in the two-billion-year-old liquid, Morelle reports.

“The microbes that produced this signature couldn’t have done it overnight. This isn’t just a signature of very modern microbiology,” Sherwood Lollar tells Morelle. “This has to be an indication that organisms have been present in these fluids on a geological timescale.”

This isn’t the first time researchers have found an ancient pool of water in this particular mine. In fact, the previous oldest-known water pool was found in 2013 about a half-mile higher up, and was dated to be about 1.5 billion years old, Sarah Laskow reports for Atlas Obscura.

While the water is much too salty to drink (Warr tells Cheung it’s about eight times saltier than ocean water), it  may still hold hints about what the Earth looked like billions of years ago.

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