That Blood-Red Stain in Antarctica

A strange red and orange patch visible from satellite imagery on Antarctica looks almost like something has spilled across the frozen landscape. The coordinates lead to James Ross Island, off the northeastern tip of the Antarctic Peninsula, where exposed rock, sediment and ice create a landscape much more colorful than the endless white normally associated with Antarctica. At first glance, the discoloration looks similar to Antarctica's famous Blood Falls. There is an important problem with that explanation, however. The real Blood Falls is at Taylor Glacier in the McMurdo Dry Valleys, roughly 4,000 kilometers, or about 2,500 miles, away on the other side of Antarctica. The reddish area on James Ross Island therefore appears to be a different phenomenon. One likely explanation is iron oxidation. Scientists studying James Ross Island have documented extensive red staining on exposed rocks there. Some rocks develop what geologists call red desert varnish, a thin coating enriched in iron oxides. Iron can be released from minerals inside the rock and deposited on exposed surfaces, producing rusty red and orange colors that stand out dramatically against snow and ice. Researchers have also measured iron-bearing minerals and evidence of chemical weathering in sediments from James Ross Island. Even in Antarctica's extreme cold, rocks are still altered by water, freezing, thawing and chemical reactions. Where iron-bearing material is exposed to oxygen, the result can essentially be natural rust. James Ross Island is especially interesting because large portions of it are ice-free. Strong winds remove fine sediment, glaciers expose fresh rock, and the island's dry climate leaves colorful geological surfaces visible instead of covering them with vegetation. That combination can produce satellite views that look almost unnatural. The exact composition of the reddish patch at these coordinates has not been specifically sampled and identified in readily available scientific records, so calling it an iron-rich stream or another Blood Falls would go beyond the evidence. It may involve iron-stained sediment, weathered rock, meltwater carrying mineral material, or a combination of those processes. The genuine Blood Falls works differently. There, extremely salty, iron-rich water emerges from beneath Taylor Glacier. When dissolved iron in the brine reaches the surface and encounters oxygen, it oxidizes and produces the famous red-brown stain across the glacier. The James Ross Island feature may look remarkably similar from space, but it sits in a completely different geological setting. So the unsettling red patch is probably not evidence of anything mysterious beneath Antarctica's ice, and it definitely is not the famous Blood Falls. It is more likely an enormous patch of naturally rust-colored Antarctic geology that becomes especially dramatic when viewed against a landscape dominated by white snow, dark volcanic rock and blue ice.