Odd Evidence

Why Blood Falls in Antarctica Runs Red

A blood-red waterfall really does pour from Antarctica's Taylor Glacier. The colour comes from iron in ancient brine oxidising on contact with air — not from red algae, which is the explanation most popular retellings still give.

The claim There is a waterfall in Antarctica that runs blood red, and the colour comes from red algae living in the ice.
Mostly True The story is real, but the popular version exaggerates or omits important context.

The waterfall is real and genuinely red. But the explanation repeated in most popular accounts — red algae — was ruled out decades ago, and the actual mechanism was only traced in 2017.

Basis 1 primary 2 peer-reviewed

The claim is broadly right

There is a waterfall of red liquid emerging from the snout of Taylor Glacier into Lake Bonney in the McMurdo Dry Valleys. Photographs are not enhanced. Against white ice, the colour is startling.

The Australian geologist Griffith Taylor recorded the feature in 1911 during Scott’s Terra Nova expedition. His initial explanation was red algae, and that explanation has proved considerably more durable than its evidence ever warranted.

What actually produces the colour

The source is a body of hypersaline water sealed beneath the glacier, isolated from the atmosphere for a very long time. It is roughly three times as salty as seawater, which keeps it liquid at temperatures well below the freezing point of fresh water, and it is rich in dissolved iron.

While sealed, that iron stays in its reduced form and the brine is not red. When it reaches the surface and meets oxygen for the first time, the iron oxidises. The waterfall is, in effect, rusting in real time as it emerges.

The brine also hosts a microbial community that metabolises without sunlight or oxygen — which is a substantial part of why the site attracts research attention. But the microbes are not the pigment.

The part that took a century

Knowing the brine was iron-rich did not explain how liquid water was moving through a glacier whose bulk sits below freezing. The 2017 radar survey resolved this: the brine travels through a network within the ice, and the latent heat released as saltwater freezes warms the surrounding ice enough to keep a liquid pathway open.

Why the verdict is Mostly True

The phenomenon is real, the colour is real, and it is as strange as advertised. The verdict is not Confirmed because the second half of the popular claim — red algae — is simply wrong, and it is the half most retellings lead with. A story can be true in outline and wrong in the detail people actually remember.

Sources

  1. peer reviewed
  2. peer reviewed
    Mikucki, J. A. et al. — 'A contemporary microbially maintained subglacial ferrous "ocean"', Science Characterises the subglacial microbial community and the iron chemistry.
  3. primary
    Griffith Taylor, journals of the British Antarctic Expedition, 1911 First European description of the feature, originally attributed to red algae.

Related investigations