At the edge of Antarctica’s Taylor Glacier, a red stain sometimes spreads across the ice. It’s called Blood Falls, but nothing is bleeding. The color comes from salty, iron-rich water—brine—that emerges from beneath the glacier. The outflow is intermittent, so the ice does not continually pour red water into the valley.
The glacier sits in the McMurdo Dry Valleys, where the brine travels through ice before reaching the surface near Lake Bonney. Its high salt content helps it remain liquid in conditions that would freeze ordinary freshwater. Once exposed to air, iron in the brine oxidizes, leaving a rusty red-orange stain. The name is dramatic; the chemistry is familiar.
Where did the saltwater come from? Researchers think it is linked to ancient seawater that became isolated as the landscape and glacier changed. NASA’s account of Blood Falls describes an ancient saltwater lake as one explanation. Scientists have traced brine beneath Taylor Glacier, though the history of its buried source remains a subject of research.
The brine holds another surprise: microbes. Studies of the outflow have found organisms able to survive in a cold, dark environment with little oxygen. Instead of relying on sunlight, they can use chemical energy associated with iron and sulfur compounds. Blood Falls is therefore more than an unusual color on the ice; it offers researchers a glimpse of life beneath a glacier.
Even the timing of the red outflow is revealing. A 2026 study of Taylor Glacier linked one discharge to changes in the glacier’s surface, adding evidence that the ice’s weight and movement help push brine out. Blood Falls may look otherworldly, but its red streaks connect ordinary rust, moving ice, and remarkably resilient life.