When Antarctic explores first discovered a cliff stained with blood-red water in 1911, they assumed that red-hued algae were responsible for the color. The place quickly became known as Blood Falls, although it turned out to be neither blood nor algae.

New evidence links Blood Falls to a large source of iron-rich salty water that may have been trapped under Taylor Glacier for more than 1 million years. The water is so salty, it’s more accurately described as brine.

According to new study led by researchers from the University of Alaska and University of Colorado Fairbanks the color of the falls can be traced to iron-rich salty water, since the iron turns the brine red when it meets the air.

Lead author Jessica Badgeley, then an undergraduate student at Colorado College, worked with University of Alaska Fairbanks glaciologist Erin Pettit and her research team to understand this unique feature. They used a type of radar to detect the brine feeding Blood Falls.

“The salts in the brine made this discovery possible by amplifying contrast with the fresh glacier ice,” Badgeley said.

They used radio-echo sounding to transmit and receive electrical pulses on the glacier. This allowed them to view what was happening under the ice.

The study shows that liquid water can persist for long periods of time — perhaps as long as a million years — within frozen glaciers.

“While it sounds counterintuitive, water releases heat as it freezes, and that heat warms the surrounding colder ice,” said Petit.

Pettit said the researchers made another significant discovery – that liquid water can persist inside an extremely cold glacier. Scientists previously thought this was nearly impossible, but Pettit said the freezing process explains how water can flow in a cold glacier.

“Taylor Glacier is now the coldest known glacier to have persistently flowing water,” says Petit.

The research was published in the Journal of Glaciology.