Our planet, as insignificant as it may be compared to the vastness of the universe, is full of incredible wonders. Antarctica, one of the least inhabitable places in our world, is covered about 98 percent of its area with ice that has the average thickness of an astounding 1.9 kilometer (6,200 feet). As if the continent is not amazing on its own, it is home to what is called the Blood Falls towards the East. The Falls pours out red colored water from the end of a glacier into a lake. So, if you are not too squeamish at the sight of blood colored water, here are more details about the Falls and what gives it the color.

The Blood Falls is a five-story high outflow of red colored water from a Taylor Glacier into Lake Bonney in Victoria Land, East Antarctica. It was first noticed in 1911 by an Australian geologist Griffith Taylor who first explored the valley and after whom the glacier was named. 

The Taylor Valley, where the glacier and Lake Bonney are located, is part of McMurdo Dry Valleys in East Antarctica. These valleys are considered one of the world’s most extreme deserts because of their extremely low humidity and permafrost. Because of the tall mountains, the ice and snow doesn’t reach the valleys, leaving them mostly bare.

The Taylor Valley was discovered by British National Antarctic Expedition and explored between 1901 and 1913. The valley and the glacier in it were named after the Australian geologist Thomas Griffith Taylor, who also noticed the reddish deposits. The Antarctic pioneers first attributed the color to red algae, which was later proved wrong.

The source of this reddish water is a pool about 400 meters under the glacier several kilometers away from the Falls. The water emerges at the Falls through small fissures present in the ice cascades. 

The Taylor Glacier is about 54 kilometers long and, like all other McMurdo Dry Valleys which are full of “cold-based” glacier. That is, they are literally frozen to the ground below unlike wet-based glaciers, that are not. They are also comparatively flat and smooth on the surface unlike wet-based ones, which have deep cracks or fractures. However, Taylor glacier, despite being part of the Dry Valleys, is not frozen to the rock, probably because of its salt content in the crystalized ancient seawater imprisoned below. The source of Blood Falls, is a subglacial pool of unknown size with over 400 meters (1,300 feet) of ice above it and several kilometers away from its outlet.

The subglacial pool has high concentrations of salt, sulfate and ferrous ions. It is completely isolated from outer atmosphere and so when it comes into contact with atmospheric oxygen, the ferrous ions become ferric oxide giving the water red color. 

The old seawater trapped under the glacier is two to three times saltier than seawater as the pure ice crystalises and expels its dissolved salts. The high concentrations of ferrous ions is said to be due to more soluble ferrous ions dissolving in the old seawater in Miocene period, 5 million years ago when the sea levels were higher. This sea water from the Antarctic Ocean was trapped in an ancient pocket when a fjord was isolated by a glacier in its progression back then.

The subglacial pool is also home to 17 different types of microbes and supports biochemical interactions between ferrous and sulfate ions that are yet to be understood. 

According to geomicrobiologist Jill Mikucki from the University of Tennessee, the water samples contained various types of microbes and almost no oxygen. Analyses of the water also indicated that the pool supports a very rare ecosystem with autotrophic bacteria that metabolize sulfates and ferric ions. It is possible that they use sulfate as catalyst to respire with ferric ions and metabolize the small quantities of organic matter trapped with them. What puzzles to researchers that there seems to be no trace of sulfide (HS^–) ions despite the presence of sulfate (SO₄^2-)and ferric (Fe²⁺) ions.

Researchers believe that the “time capsule” nature of the pool will give an insight into what life was like 1.5 to 2 million years ago, when it was sealed off by the ice. Because of this the microbial population was forced to evolve independently, without any influence from other life forms and environmental conditionals on Earth. It is also a unique opportunity to research microbial life under extreme conditions without the need to drill polar ice caps risking contamination.

[sources: wikipedia, smithsonian]

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