The Jenolan Caves in western Sydney have been dated to 340 million years, making 
them the oldest open caves in the world.
Dr. Armstrong Osborne from the University of Sydney, Australia, and colleagues used clay dating methods to demonstrate that these caves opened during the Carboniferous period.
“These caves are hundreds of millions of years older than any previously reported cave anywhere in the world,” Osborne said. The oldest previously identified open cave is 90 million years old.
“Even from a geological perspective, 340 million years is an incredibly long time. In comparison, the Blue Mountains began forming 100 million years ago, dinosaurs went extinct 65 million years ago, and Tasmania connected to the mainland nearly 10,000 years ago,” Osborne added.
M.T
