Earth's oldest pool of water (2 billion yrs old) found 2 mi down a Canadian mine

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Deep within a mine in Canada, there is a pool of water bubbling out of the ground. It’s close to 2 miles below the surface of the earth and, according to the scientists who discovered it, it’s been there for 2 billion years, making it the oldest pool of water in the world.

Previously that record was held by a pool further up in the mine, about 1.5 miles down, which was discovered in 2013 and given the age of 1.5 billion years.

The scientists date the water by analysing the gases trapped inside. As the CBC explains, gases like helium and xenon accumulate in the water while it’s stuck in rock fractures. Measuring those concentrations can tell the researchers how old the water is.

What’s unique about this water is that it’s been conserved for all that time. Much of the water on this planet has an even older origin: half of the water on Earth is actually melted interstellar ice that predates the sun.

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