In Antarctica, among swathes of ice and rock, there’s a waterfall running red with blood – or so it seems.
You’ll find this grisly looking sight in the McMurdo Dry Valleys, in eastern Antarctica.
The Valleys are among of the most extreme environments on Earth. Together, they form the coldest and driest desert in the world and the largest ice-free region on the continent.
All this makes it a hotbed of scientific activity. And there are more unusual features in the region, including a hypersaline lake, Antarctica’s longest river and the aptly named Blood Falls.
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The mystery of Blood Falls
Blood Falls flows 50 feet (roughly the same height as a five-storey building) from the Taylor Glacier into West Lake Bonney. The lake is saline but has a permanent covering of ice.
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It’s not a permanent stream of water, but instead sporadically emerges from the ice. Its chilling appearance has confused scientists since its discovery in 1911.
Several studies have investigated the phenomenon, and it was once believed that its scarlet hue was caused by red algae. However, it has since been confirmed that a significant amount of iron oxides give the salt water its blood-red shade.
Although researchers knew why the water appeared red, they didn’t know why it seemed to spurt out of the glacier with such irregularity.
That’s until a team of scientists carried out an observational study of Blood Falls in 2018. Combining GSP data, time-lapse camera images and temperature sensors, they saw that when the Taylor Glacier subsided, saltwater would begin to flow down from the glacier’s opening, and the water temperature around where it joined West Lake Bonney would suddenly drop.
As the authors write in their study, this provides a “rare, coherent signal of a subglacial brine drainage event”.
Beneath Taylor Glacier, several kilometres away from where Blood Falls emerges, there is a subglacial pool. It formed millions of years ago below hundreds of metres of ice. The water there has very high salinity and is rich in reduced iron.
When the ice on Taylor Glacier slides downwards (only millimetres at a time), immense pressure pushes down onto the subglacial pool. When this pressure becomes too intense, water within the subglacial pool rushes through cracks to the tongue of the glacier, where it spurts out. Once the brine reaches the surface and oxidises, it turns rust (or blood) red.
While the mystery of this striking sight has finally been solved, it’s currently unclear how Blood Falls will respond to long-term environmental change.
Life under Taylor Glacier
A 2009 study also found that there were at least 17 types of microorganisms surviving in the dark, oxygen-free environment of the pool underneath Taylor Glacier.
Those findings provide insight into how life might have survived during ‘Snowball Earth’ – a time around 720 to 635 million years ago where some scientists have hypothesised that the Earth was almost entirely frozen over.
Top image: Blood Falls seeps from the end of the Taylor Glacier into Lake Bonney, with the tent on the left providing scale. Credit: National Science Foundation/Peter Rejcek, Public domain, via Wikimedia Commons
