Antarctica’s Mysterious ‘Blood Falls’

The “falls” are actually a brine, or salt water, mixed with iron from the bedrock below. As bacteria slowly chew the rock, the iron is released into the brine. The salt water and iron combination creates a distinct rust color when it mixes with oxygen as it reaches the surface, according to National Geographic.

Blood Falls is a bright red waterfall oozing from Antarctica’s ice. It’s nearly five stories high, in the McMurdo Dry Valley region, one of the coldest and most inhospitable places on Earth, a place scientists like to compare to the cold, dry deserts of Mars. Geomicrobiologist Jill Mikucki, now at the University of Tennessee, Knoxville, published what’s still accepted as the best explanation for Blood Falls in 2009.