<a href="https://en.wikipedia.org/wiki/Blood_Falls" class="extiw" title="w:Blood Falls">Blood Falls</a> seeps from the end of the Taylor Glacier into Lake Bonney. The tent at left provides a sense of scale for just how big the phenomenon is. Scientists believe a buried saltwater reservoir is partly responsible for the discoloration, which is a form of reduced iron.
National Science Foundation/Peter Rejcek
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