The final mystery of Antarctica’s ‘Bloodfalls’ has finally been solved

There is a corner of Antarctica it looks like something out of a David Cronenberg movie. It is located in the dry valleys of McMurdo, a vast frozen desert where, from time to time, a jet of crimson liquid suddenly emerges from the brilliant white of the Taylor Glacier. They are called the Blood Falls, and since their discovery in 1911 by geologist Thomas Griffith Taylor, they have fueled a century of scientific speculation.

Recently, a series of observations made since 2018 have cleared up several mysteries, such as the nature of their reddish color and what keeps them liquid at nearly -20 degrees Celsius. New research published this week in the journal Antarctic Science add the last piece to the puzzle and explain what phenomena make the waterfalls flow from the underground.

The science behind the blood falls

At the time of their discovery, Taylor attributed the color to the presence of red microalgae. More than a century later, scientists determined that the red is due to iron particles trapped in nanospheres along with other elements such as silicon, calcium, aluminum and sodium. It was probably produced by ancient bacteria trapped underground in the area: Once in contact with air, the iron oxidizes, giving the mixture its characteristic rust color.

As for the presence of liquid water, it is actually a hypersaline brine, which was formed about 2 million years ago when the water of the Antarctic Ocean retreated from the valleys. The very high salinity of this brine prevents the water from freezing, thus allowing it to flow out from time to time.

The New Discovery

With the temperature mystery solved, the question remained as to what caused the liquid to physically erupt. The answer came from cross-referencing GPS data, thermal sensors and high-resolution images collected during an eruption in 2018. The analysis showed that the Blood Falls are the result of pressure variations affecting the brine deposits beneath the glacier.

As Taylor Glacier slides downstream, the overlying ice mass compresses the subglacial channels, building tremendous pressure. When the stress becomes unbearable, the ice gives way: Pressurized brine seeps into the cracks and is shot out in short bursts. Curiously, this release acts as a hydraulic brake, temporarily slowing the glacier’s advance. With this discovery, the mysteries of the Blood Falls should have finally been solved, at least for the time being. The impact of global warming on this complex system in the coming decades remains unknown.

This story originally appeared on WIRED Italy and was translated from Italian.