Geologists drilling almost two miles underground discovered a snapshot of ancient history in the form of flowing water isolated for at least 1.5 billion years and perhaps as long as 2.64 billion years.

“These are like trapped time capsules,” University Professor Barbara Sherwood Lollar, a geochemist in University of Toronto’s Department of Earth Sciences, said in a press release. “They may tell us about the atmosphere 2.7 billion years ago, and about the fluids that formed the valuable ore deposits that are the foundation of Canada’s mineral wealth.”

The water, bubbling out of fractures in the rocks, is similar, according to Sherwood Lollar, to the black smoker fluids emitted from deep sea hydrothermal vents. It’s the product of geochemical reactions with the rock and contains dissolved hydrogen as well as noble gases trapped since Earth’s early history.

The accumulation of these noble gas isotopes from radiogenic reactions in the rock are what enabled the researchers to determine that the waters have collected the by-products of water-rock interaction perhaps since the formation of the rocks themselves.

What’s more, because the water is rich in hydrogen and methane, the deposits may harbor ancient forms of life long cut off from the surface.

“The ancient waters of the Canadian Shield contain abundant chemicals that we know microbes can use as energy in the absence of sunlight-driven photosynthesis,” Sherwood Lollar said.

This, in turn, shows that ancient rocks have the potential to support life, whether that life is miles beneath the Earth’s or Mar’s surface.

Such a discovery is especially significant due to the fact that large regions of Mars are comprised of terrain similar to that of the Earth’s Precambrian Shield, including billions of years-old rocks with similar mineralogy.

Funding for the study was provided by a Discovery grant from Natural Sciences and Engineering Research Council of Canada and the Canada Research Chairs Program, the National Environment Research Council in the UK and the Deep Carbon Observatory Deep Energy Project.