May 17, 2007
The above photo shows the largest free hanging shawl in the Jenolan Cave System, which is located about 175 km west of Sydney, Australia. This shawl, called the “Angel’s Wing,” measures nine meters in length and is the highlight of the Temple of Baal Cave. A shawl or curtain is a calcite formation, in the form of wavy or folded sheets hanging from the wall or roof of a cave. This amazing structure forms when water runs down the gentle slopes of the cave walls rather than falling directly onto the floor. Where this water seeps down the walls it looses carbon dioxide to the atmosphere of the cave, and as a result deposits calcite in a thin vertical line. Once a small rim is built up, the water follows the same path, and over time a thin sheet of translucent calcite crystals is formed. The alternating dark and light bands are produced by a fluctuation in the amount of iron oxide in the water.