A bright red waterfall bursting out of eternal ice, right in the middle of one of the coldest regions on Earth: Blood Falls are among the most mysterious natural phenomena in Antarctica. For a long time, it was assumed that red algae were responsible for the striking color. A new study has now brought clarity and paints a completely different picture.
Using modern radar technology, researchers examined the layers of ice that feed the waterfall. The results showed that the blood-red color does not come from biological material, but from extremely salty, iron-rich water hidden beneath the ice.
A River Beneath the Glacier
Among those involved in the studies was National Geographic Explorer Erin C. Pitt. Her team investigated the Taylor Glacier, from which Blood Falls emerge. It is located in the Antarctic Dry Valleys, one of the driest and coldest landscapes on Earth. The average temperature here is around minus 17 degrees Celsius conditions under which liquid water should hardly be able to exist.
This made the long-standing mystery all the greater: why does liquid continuously flow out of cracks in the glacier? Imaging techniques provided the crucial explanation. Beneath the glacier lies a complex network of subglacial rivers and an underground lake. The water there is a highly concentrated brine, extremely salty and rich in iron.
Why the Water Does Not Freeze
The special chemical composition explains several mysteries at once. Saltwater has a significantly lower freezing point than freshwater. In addition, it releases heat when it freezes. This so-called latent heat of fusion causes the surrounding ice to partially melt, allowing the water to continue flowing even under extreme subzero temperatures.
When the iron-rich brine reaches the surface and reacts with oxygen, the iron oxidizes. The water turns a rusty red, giving Blood Falls their blood-like appearance.
A Unique Glacier
Measurements also showed that the closer the water gets to the waterfall, the higher the concentration of iron-rich brine becomes. A relationship between water temperature and salt content was also identified. Cracks of varying sizes in the ice act as channels through which the brine rises, melts ice and becomes further concentrated.
The Taylor Glacier is thus considered the coldest known glacier on Earth in which water flows permanently. A paradoxical system of ice, salt, iron, and heat, hidden beneath a seemingly lifeless ice desert.
What looks like a bloody fissure in the ice is, in reality, a fascinating example of how complex and dynamic even the most extreme regions of our planet can be.
Heiner Kubny, PolarJournal