The Mystery of Antarctica’s Blood Falls Is Finally Revealed

Credit: Peter Rejcek, National Science Foundation

A century-old mystery has its final answers, according to scientists who now have an explanation for the naturally occurring “Blood Falls” in Antarctica.

A horrifying sight greeted Australian explorer and geologist Griffith Taylor 106 years ago: blood-red water pouring from the side of a glacier, like the elevator doors in The Shining but bigger, colder, and it’s not just inside someone’s head.

Initially it was thought that a unique bacterial content in the water was giving the falls their deep red color, but in 2003 it was determined that the red color “results from iron oxides precipitating when the iron-bearing suboxic brine comes in contact with oxygen in the atmosphere.”

The remaining question, which scientists believe they’ve now answered, is where the water is coming from in the first place. It’s not from a melting glacier, which would provide neither the volume of water nor the conditions for the uniquely colored stream.

A study from the University of Alaska Fairbanks and Colorado College, which used radio echo sounding to sonically scan underground rather than drilling, found that the fall comes from a subglacial ecosystem — a vast, hydrothermally heated reservoir of high-salinity water rich in reduced iron. The mixture of salt content and geothermal energy keep it from freezing.

It’s basically a massive lake under the glacier, resting on bedrock. It’s red and salty, and is pushed out by the sheer weight of the glacier itself through the ice until it emerges into Lake Bonney through the exit space known as Blood Falls.

That doesn’t make the image any less unsettling, but it does make the water’s journey more impressive. As for those rare bacteria, check out this video for an explanation of just how they make it so red.

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