Blood Falls
Later explainedSummary
A glacier in Antarctica bleeds. A plume of deep red liquid runs out of a crack in the ice face and spreads across the frozen surface of the lake below it.
The first explanation, offered in 1911, was red algae. It was wrong.
The liquid is brine, and it is red because it is rusting. It comes from a lake sealed under four hundred metres of ice, which has been cut off from the sky for something on the order of a million years, and which is full of things that are alive.
What is documented
The discovery. Griffith Taylor, an Australian geologist on Scott's Terra Nova expedition, described the feature in 1911. The glacier is named after him.
The appearance. A plume of intensely red liquid emerges from a fissure at the snout of the Taylor Glacier and flows out onto the ice-covered surface of Lake Bonney.
It is not algae. The original attribution, made in the absence of any means to test it, was to red algae in the ice. It is not. The colour is iron.
The brine. The liquid is water of extreme salinity, on the order of two to three times as salty as seawater, and heavily charged with iron. It is not fresh water and it is not ordinary meltwater.
Why it is red. The brine is anoxic: it has no dissolved oxygen. Its iron is in a reduced state and is not red. When it emerges from the glacier and meets the air, the iron oxidises.
It rusts. The falls are red for the same reason an old nail is red.
The source. A reservoir of brine beneath the glacier, sealed under roughly four hundred metres of ice, and isolated from the atmosphere for a very long time. Estimates of the isolation period run to something like one and a half to two million years.
What lives in it. Investigation of the brine, published from around 2009, found a microbial community surviving there without sunlight and without oxygen. The organisms make their living from iron and sulphur compounds in the water.
The mapping. In 2017, Jessica Badgeley and Erin Pettit, with colleagues, used radio-echo sounding to trace the brine's path through the body of the glacier, and published the result in the Journal of Glaciology.
Leading explanations
The case is closed. The interesting question is the one the 2017 work answered, and it is a genuinely good piece of physics.
How does liquid water flow through a glacier that is frozen solid?
The Taylor Glacier is well below freezing throughout. Liquid water in it ought to freeze and plug the channel, and that should be the end of the flow. It does not, and it is not.
Two things keep the channel open.
Salt lowers the freezing point. The brine is extremely salty. It stays liquid at temperatures at which fresh water would be solid ice.
Freezing releases heat. This is the elegant part. When water freezes it gives up latent heat to its surroundings. As the brine moves through the glacier, some of it does freeze onto the walls of its channel, and in doing so it warms the ice around it.
The brine heats its own passage by partially freezing in it. The flow sustains the conditions that permit the flow.
What the popular version gets wrong
"It's algae." It is oxidised iron. This was the first guess, in 1911, by a man with no way to check, and it has outlived its usefulness by a century.
"It's blood." It is not, and nobody has seriously thought so, but the name does a great deal of work and the photographs do the rest.
"Nobody knows where the water comes from." It comes from a brine reservoir under the glacier. This has been established, and the path it takes through the ice has been mapped.
"It's a curiosity." It is one of the more consequential sites in Antarctica. A body of liquid water, sealed under ice, isolated from the surface for a million years or more, without light or oxygen, containing a functioning ecosystem, is precisely the model system for asking whether anything is living under the ice of Europa or Enceladus, or was living in the subsurface brines of Mars.
Blood Falls is not strange because it is red. It is important because something has been alive down there, in the dark, since before there were people.
Current status
Later explained. Source identified, chemistry understood, transport mechanism mapped, biology characterised.
The registry keeps this record because the explanation turned out to be more remarkable than the anomaly, which is a pattern this archive keeps running into. Everyone wanted to know why the ice was red. The answer is rust. The interesting question was the one nobody was asking, which is what was in the water and how long it had been down there.
Sources
- Taylor, G. (1911). Description of the feature, Terra Nova expedition.
- Mikucki, J. A. et al. (2009). "A Contemporary Microbially Maintained Subglacial Ferrous 'Ocean'." Science 324, 397-400.
- Badgeley, J. A., Pettit, E. C. et al. (2017). "An englacial hydrologic system of brine within a cold glacier: Blood Falls, McMurdo Dry Valleys, Antarctica." Journal of Glaciology.
- Radio-echo sounding surveys of the Taylor Glacier.
- Analyses of the brine: salinity, iron content, anoxia, and the microbial community.
Last reviewed: July 2026. Records are provisional. Where the evidence changes, the entry changes. Found an error? Tell us.