Well, scientists have discovered just that—an isolated reservoir 2.4 kilometers underground in Ontario. They examined fluids seeping out of fractures in a mine and found particular isotopes of the noble gas xenon. By comparing these isotopes to those known to have been in the ancient atmosphere, the researchers dated the slowly escaping water to be at least 1.5 billion years old, some of the oldest known. As the rocks around the water are 2.64 billion years old, the water may be too. The finding is in the journal Nature. [G. Holland et al., Deep fracture fluids isolated in the crust since the Precambrian era]
The liquid also contains dissolved gases such as methane and hydrogen, which in sunless environments support microbial life. The discovery of any microbes would support the hope that similar underground life might exist on Mars and elsewhere. In short, this ancient water could hold gas, microbes and hints about extraterrestrial life. So let’s forego finding out how it tastes.
—Sophie Bushwick
