Jenolan Caves

Jenolan Caves lie in the Central Tablelands of New South Wales, Australia, about 175 kilometers west of Sydney, where more than forty kilometers of limestone passages and over three hundred entrances follow the underground course of the Jenolan River. Clay within the cave system has been dated to roughly 340 million years old, making Jenolan the world's oldest known and dated open cave system. Eleven of the caves have been developed as show caves open to the public, prized for calcite formations described as sometimes pure white. James Whalan is credited with discovering the caves in 1838 while chasing an escaped convict, and his brother Charles later explored them further and opened them to visitors from the 1840s onward.