September 8, 2009
Iron Hoop Cave, Alabama
Photograph by Stephen Alvarez
This Month in Photo of the Day: National Geographic Magazine
Millennia in the making, fantastical chambers like this are decorated by the infinitely slow accumulation of minerals (chiefly calcite) deposited by water dripping through rock. Encounters with such rare and fragile beauty are highly prized.
See more photographs from the June 2009 feature story "Deep South."