In 1911, during an expedition to the McMurdo Dry Valleys of Antarctica, geologist Thomas Griffith Taylor discovered something strange: a glacier gushing blood-red water.
Decades later, researchers figured out that this waterfall owes its brilliant hue to iron oxide—basically rust. But they weren’t exactly sure where the red rivulet originated. In 2015 a team of scientists speculated that there was a system of underground waterways full of briny water flowing through the ice, Rachel Feltman reports for Popular Science. Now, in a follow-up study published last week in the Journal of Glaciology, the team has mapped the Taylor Glacier’s innards, showing the path that water takes to Blood Falls and many other unusual features beneath the ice.
The researchers tracked the path of the briny water beneath the ice using radio-echo sounding, which is kind of like how a bat emits clicks or squeaks to navigate and find food in the dark. The researchers bounced short radio waves into the glacier. The waves bounced back from the ice and water at different speeds creating a map of the salty streams and reservoirs. Past research suggests that the water may have been trapped under the ice for 1 million years—part of a salty lake that was covered by the glacier.
They were able to trace the water that feeds Blood Falls from a reservoir in the glacier along a 300-foot path. Occasionally, cracks within the glacier open up, allowing the salty, iron-rich water to squirt through the crevasses from areas of higher pressure to lower pressure and eventually making their way to the falls. When the water hits the open air the iron in the water reacts with oxygen, producing the blood red pigment.
Read more at Smithsonian Magazine.