Antarctica's Blood Falls discharges a vivid red brine from the terminus of Taylor Glacier onto the frozen surface of Lake Bonney in the McMurdo Dry Valleys.

The color comes from dissolved ferrous iron that oxidizes rapidly upon contact with the atmosphere.

A new study published in Frontiers in Astronomy and Space Sciences analyzes the geochemistry of the brine to constrain its origin.

Researchers measured major ion concentrations and isotope ratios in samples collected from the outflow.

The chemical signature closely matches that of seawater that has undergone extensive water-rock interaction and concentration through freezing.

The authors conclude the data provide further evidence that the brine derives from marine water trapped in the valley when flood waters retreated during the Miocene epoch, millions of years ago.

Isolated from the open ocean, the ancient seawater evolved into a hypersaline, iron-rich reservoir beneath the glacier.

The subglacial environment hosts a microbial ecosystem that persists in cold, dark, anoxic conditions by cycling iron and sulfur compounds.

Sources and further reading

Why Does Antarctica's Blood Falls Spew Ruby Red Water? Microbes Offer New Clues About the Geologic Feature's Ancient Origins

This is an independent summary. The complete reporting, supporting context and any primary documents remain with Smithsonian Magazine.

Read the original report Visit Smithsonian Magazine