A glacier nestled in the white expanse of Antarctica has been ‘bleeding’ for years.
Known as Blood Falls, the shocking red colour pours into Lake Bonney in the southernmost of the three largest McMurdo Dry Valleys.
And now scientists have discovered it not only leads to a network of salty lakes, but these lakes are full of microbial life – some of which gives the waterfall its scarlet hue.
In particular, the deep red is caused by the discharge of iron-rich, brine liquid.
Its chemistry is changed by bacteria, which transforms sulphur and iron compounds in order to survive, and when the liquid oxidises at the surface, it creates the blood-red colour.
The aquifer network of lakes extends to a depth of up to 1,148ft (350 metres) below the Dry Valleys – the coldest and driest desert on Earth.
The find could help to shed light on how the icy region is coping with climate change, and could even hint at how life could survive on Mars.
A hoop-like electromagnetic sensor suspended beneath a helicopter was used to map the hidden subsurface.
Measurements of electrical resistivity revealed extensive connected bodies of liquid salty water deep beneath the region’s glaciers and lakes.
It’s the first time the frozen lakes populating the Dry Valleys’ surface have been found to be connected by a subterranean groundwater network.
But further evidence is needed to be certain of its existence.
Ice Crystals and algae can cause snow to look red and blue
Snow appears white because it reflects most visible light that strikes it. Anything that does this means you see the whole spectrum of visible light, which looks white.
Other objects appear different colours because they absorb certain wavelengths of visible light but reflect others – a green apple, for instance, reflects only mostly the green wavelength.
‘As light waves travel into the snow or ice, the ice grains scatter a large amount of light,’ the NSIDC explains.
While most of the light is reflected, there is a very small tendency towards more red light being absorbed than blue.
When you see just the surface of a pack of snow, the scattering of the blue light is almost completely impossible to notice.
But if you look into a significant amount of snow, about 3.3ft (one metre) or so, more photons emerge towards the blue end of the spectrum than the red end.
When snow appears red, though, it is for an entirely different reason. This effect is due to cold-loving, fresh-water algae known as Chlamydomonas nivalis that contain a bright red pigment.
Also known as ‘watermelon snow’, it is ‘most common during the summertime in high alpine areas as well as along coastal polar regions’.
The network stretches from the coast for a distance of at least 7.5 miles (12 km) inland.
US lead researcher Dr Jill Mikucki, from the University of Tennessee, said: ‘It may change the way people think about the coastal margins of Antarctica.
‘We know there is significant saturated sediment below the surface that is likely seeping into the ocean and affecting the productivity of things that feed ocean food webs.
‘It lends to the understanding of the flow of nutrients and how that might affect ecosystem health.’
The findings, which are published in the journal Nature Communications, may shed light on how Antarctica has responded to climate change.
They may even help scientists understand whether similar conditions could exist elsewhere in the solar system, especially beneath the surface of Mars.
Cold and vegetation free, the Dry Valleys represent the nearest thing on Earth to a Martian environment.
Evidence suggests that the salty groundwater exists at below-freezing temperatures, within the range tolerated by microbial life.
A strange feature in the region, called Blood Falls, which is salty, slushy, red ooze that emerges from the boundary between Taylor Glacier and Lake Bonney, has previously been shown to contain a diverse microbial community.
This hinted to experts that a deeper brine ecosystem could lie beneath the ice.
The McMurdo Dry Valleys, situated along the Ross Sea coastline and discovered by polar explorer Robert Scott in 1903, is the largest region in Antarctica not covered by an ice sheet.
It consists of an arid expanse of mostly dirt, small rocks and large boulders, dotted with a few frozen lakes.
Co-author of the study, Professor Ross Virginia, from Dartmouth College in New Hampshire, said: ‘This fantastic new view beneath the surface will help us sort out competing ideas about how the McMurdo Dry Valleys have changed with time and how this history influences what we see today.’
The McMurdo Dry Valleys – the largest ice-free region in Antarctica – is a rather alien landscape, populated by glaciers, isolated lakes and frozen soils.
It’s the coldest and driest desert on Earth, measuring 1,900 square miles (4,800 sq km).
The valleys are dry because of ‘katabatic’ winds up to 200 mph (320km), caused by cold, dense air being pulled down by gravity.
In the Wright Valley, the mean annual temperature is -19.8°C and there is less than four inches (10cm) of frozen rain every year.
One strange feature is Blood Falls, a salty, slushy, red ooze on the boundary between Taylor Glacier and Lake Bonney.
The ooze has been shown to contain a diverse microbial community and gave scientists the idea that a deeper brine ecosystem lay beneath the ice.
This theory has now been proved largely true with the use of an electromagnetic sensor suspended beneath a helicopter, which mapped the hidden surface.
The network stretches from the coast for a distance of at least 7.5 miles (12 km) inland at depths of up to 1,148ft (350 metres).
Photo: A glacier nestled in the white expanse of Antarctica has been ‘bleeding’ for years. Known as Blood Falls, the shocking red colour pours into Lake Bonney. Scientists have discovered it not only leads to a network of salty lakes, but these lakes are full of microbial life – some of which gives the waterfall its hue.