Post by Sharon Faulkner on Jul 26, 2006 18:23:58 GMT -5
Found! World oldest cave (at least according to this article)
by Stephen Pincock
ABC Science Online
Wednesday, 26 July 2006
The Jenolan caves west of Sydney date back some 340 million years, making them the oldest known open caves in the world, Australian geologists say. Dr Armstrong Osborne from the University of Sydney and colleagues used clay dating methods to show the caves have been open since the Carboniferous period. Their results are published recently in the Australian Journal of Earth Sciences. "We've shown that these caves are hundreds of millions of years older than any reported date for an open cave anywhere in the world," Osborne says.
The oldest previous dating for an open cave was around 90 million years, he adds. "Even in geological terms, 340 million years is a very long time. To put it into context, the Blue Mountains began to form 100 million years ago; dinosaurs became extinct 65 million years ago, and Tasmania was joined to the mainland as recently as 10,000 years ago."
Until recently, scientists had thought the caves were relatively young. But Osborne thought the underground system might be older. "It always struck me as weird that in a country where everything is so old, that the caves should be young," he says. The challenge was finding something inside the caves that could be accurately dated.
So when a chance meeting revealed that Dr Horst Zwingmann from CSIRO Petroleum Resources had a technique that could be used to date the clay inside the caves, they set about finding their real age.
Borrowing from the oil industry
The researchers used dating methods developed to help oil exploration companies find oil deposits. The techniques are based on potassium-argon dating, which can calculate the age of minerals by measuring levels of decay caused by radioactive potassium. The results were a complete surprise. "No one imagined that they would be more than 300 million years old. This was totally off the planet," Osborne says. "We were able to provide evidence that the clays did form in-situ in the caves and that the sections regularly visited by tourists actually formed in the Carboniferous," Zwingmann says.
The clay now forms much of the mud in the popular Temple of Baal and Orient caves. The discovery opens the possibility that there could be evidence of other ancient geological events in the caves that scientists haven't looked for yet. For example, the researchers think the clay in the cave was formed when volcanic ash entered.
www.abc.net.au/science/news/stories/s1696410.htm
by Stephen Pincock
ABC Science Online
Wednesday, 26 July 2006
The Jenolan caves west of Sydney date back some 340 million years, making them the oldest known open caves in the world, Australian geologists say. Dr Armstrong Osborne from the University of Sydney and colleagues used clay dating methods to show the caves have been open since the Carboniferous period. Their results are published recently in the Australian Journal of Earth Sciences. "We've shown that these caves are hundreds of millions of years older than any reported date for an open cave anywhere in the world," Osborne says.
The oldest previous dating for an open cave was around 90 million years, he adds. "Even in geological terms, 340 million years is a very long time. To put it into context, the Blue Mountains began to form 100 million years ago; dinosaurs became extinct 65 million years ago, and Tasmania was joined to the mainland as recently as 10,000 years ago."
Until recently, scientists had thought the caves were relatively young. But Osborne thought the underground system might be older. "It always struck me as weird that in a country where everything is so old, that the caves should be young," he says. The challenge was finding something inside the caves that could be accurately dated.
So when a chance meeting revealed that Dr Horst Zwingmann from CSIRO Petroleum Resources had a technique that could be used to date the clay inside the caves, they set about finding their real age.
Borrowing from the oil industry
The researchers used dating methods developed to help oil exploration companies find oil deposits. The techniques are based on potassium-argon dating, which can calculate the age of minerals by measuring levels of decay caused by radioactive potassium. The results were a complete surprise. "No one imagined that they would be more than 300 million years old. This was totally off the planet," Osborne says. "We were able to provide evidence that the clays did form in-situ in the caves and that the sections regularly visited by tourists actually formed in the Carboniferous," Zwingmann says.
The clay now forms much of the mud in the popular Temple of Baal and Orient caves. The discovery opens the possibility that there could be evidence of other ancient geological events in the caves that scientists haven't looked for yet. For example, the researchers think the clay in the cave was formed when volcanic ash entered.
www.abc.net.au/science/news/stories/s1696410.htm