Antarctica’s Blood Red Waterfall

A few years ago, I saw a photograph somewhere (probably in a magazine) showing a red waterfall flowing out of an Antarctic glacier. It piqued my curiosity and I eventually looked into what it really was with the results coming as a surprise.

One of the world's most extreme deserts is probably the last place anyone would expect to find a waterfall. However, in Antarctica's McMurdo Dry Valley, a five-story waterfall pours slowly out of the Taylor Glacier into Lake Bonney. And it's not just the idea of a flowing waterfall in the frozen world of Antarctica that's strange. The waterfall is bright red, resembling blood running from a cut in the glacier.

Before you start scratching your head and wondering how that's possible—it's obviously not blood that lends Blood Falls its unique red color. Five million years ago, sea levels rose resulting in the formation of a salty lake in East Antarctica. Millions of years later, glaciers formed on top of the lake, cutting it off from the rest of the Antarctic continent, which makes the water in Blood Falls an aqueous time capsule preserved 400 meters (1300 feet) underground. As the glaciers on top of the lake began to freeze, the water below became even saltier. Today, the salt content of the subglacial lake under Blood Falls is three times saltier than seawater which makes it too salty to freeze. The subglacial lake that feeds Blood Falls is trapped beneath a quarter mile of ice.

But in addition to being cut off from the rest of the continent, the water that feeds Blood Falls is completely cut off from the atmosphere—it has never seen sunlight and is completely devoid of oxygen. It's also extremely rich in iron. And it's that iron, scraped into the water by glaciers sliding across the bedrock below the lake, that's responsible for the red color. When water from the subglacial lake seeps through a fissure in the glacier, the salty water cascades down the Taylor Glacier into Lake Bonney below. When the iron-rich water comes into contact with the air, it rusts which stains the ice a blood red color as it falls.

The color of Blood Falls isn't the only weird thing about it. What lives inside the subglacial lake interests scientists more than the waterfall's creepy color. Millions of years ago, when those glaciers covered the salt lakes, there were microbes living in the water, and those microbes haven't gone anywhere, even though the water is now an extremely salty, oxygen-free bowl of complete darkness buried 400 meters under a glacier. Much like bacteria found living near deep sea thermal vents, the microbes of Blood Falls get their energy from breaking apart sulfates which contain oxygen. After that, something eerily magical happens with the by-products—the iron in the water interacts with the microbes to restore the sulfates, basically recycling the sulfates for the microbes to break down into oxygen over and over again. Possibly a life form to be considered immortal.

If you're thinking about visiting Blood Falls, McMurdo Dry Valley and the Blood Falls can only be reached by helicopter from nearby Antarctic research stations or from cruise ships visiting the Ross Sea.