May 1 (UPI) -- A glaciological mystery that puzzled scientists for decades now appears to have an answer.

Researchers at the University of Alaska, Fairbanks and Colorado College have concluded in a new report that Antarctica's Blood Falls -- a waterfall mysteriously tinted red -- is crimson because it's fed by a large source of briny seawater that's been trapped beneath a glacier.


Discovered in 1911, Blood Falls is a colored plume of saltwater flowing out from Taylor Glacier onto West Lake Bonney in East Antarctica. For decades, though, experts were mystified as to why the falls were red -- appearing like a bloody puncture wound at the tongue of the glacier.

After extensive study, the researchers are now confident they know why.

"The brine discharges at the surface on the northern side of Taylor Glacier staining the ice red and depositing a red-orange apron of frozen brine," the report says. "The red color results ... when the iron-bearing suboxic brine comes in contact with oxygen in the atmosphere."

Scientists say the source of the falls has been trapped beneath Taylor Glacier for more than a million years.

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"Until now, a lack of evidence for active flow of englacial brine from the subglacial source to Blood Falls left this connection as speculation," it added.

"The salts in the brine made this discovery possible by amplifying contrast with the fresh glacier ice," study author Jessica Badgeley said in a news release.

Researchers said the team tracked the brine with radio-echo sounding, a radar method that uses two antenna to transmit electrical pulses and receive signals.

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The scientists also made another discovery with their research, that actual liquid water can exist inside an extremely cold glacier -- a prospect experts previously thought impossible.

"While it sounds counterintuitive, water releases heat as it freezes, and that heat warms the surrounding colder ice," glaciologist Erin Pettit said, noting that the heat and the freezing temperature of salty water make the liquid movement possible. "Taylor Glacier is now the coldest known glacier to have persistently flowing water."

The study, sponsored by the National Science Foundation, was outlined in the Journal of Glaciology.