Marble Caves, Patagonia

The Marble Caves, or Capillas de Mármol, are a set of cave and cavern formations carved into a peninsula of solid marble on General Carrera Lake, straddling the Chile-Argentina border in Patagonia. The marble, a metamorphic rock formed from ancient limestone deposits some 300 million years old, has been sculpted over roughly 6,000 years by the constant wave action of the lake's mineral-rich, turquoise glacial meltwater lapping against the rock, which slowly dissolved and eroded the marble into a network of swirling caverns, columns and tunnels. The polished, wave-like patterns visible on the cave walls directly record the lake water's erosive path through the rock, and the caves' coloration shifts with the lake's water level and mineral content through the seasons, appearing more vivid blue in the austral summer.