Caves’ secret lay in lumps of clay: [1 All-round Country Edition]
John Stapleton, Leigh Dayton. The Australian [Canberra, A.C.T] 07 Aug 2006: 6.
Abstract
Until 20 years ago, most scientists thought the Jenolan Caves were only a few thousand years old. More recent estimates put them at between 90 million and 100 million years old, similar in age to the limestone caves near Qumran, in the Israeli-occupied territory of the West Bank, where the Dead Sea Scrolls were discovered.
The proof came thanks to a meeting with Horst Zwingmann of CSIRO Petroleum Resources at the Australian Museum in Sydney.
Dr Zwingmann then applied his technique — a variation of radioactive dating — to the minerals that had crystallised when a previously unknown volcano spewed ash into the caves. The technique showed the crystals were formed 340 million years ago.
Full Text
IT was good clay — the kind you could use for patching up leaks in sewers and water pipes.
In fact, that is exactly what workers at NSW’s Jenolan Caves used to do with the lumps of the tan-and-white material they found scattered around the site, little knowing its geological significance.
It took researchers hunting for minerals in the overlooked clay to unlock its secret — it was 340million years old.
That means the popular tourist site, in the Blue Mountains west of Sydney, has the world’s oldest known open caves, beating the Dead Sea Scroll caves by more than 240 million years.
“Even in geological terms, 340 million years is a very long time,” University of Sydney geologist Armstrong Osborne said.
Until 20 years ago, most scientists thought the Jenolan Caves were only a few thousand years old. More recent estimates put them at between 90 million and 100 million years old, similar in age to the limestone caves near Qumran, in the Israeli-occupied territory of the West Bank, where the Dead Sea Scrolls were discovered.
“Those of us who thought they were really old couldn’t find any evidence,” Dr Osborne said as he revealed the path he took in establishing when the caves were formed.
The proof came thanks to a meeting with Horst Zwingmann of CSIRO Petroleum Resources at the Australian Museum in Sydney.
Dr Zwingmann told him how he had devised a way to help companies find oil after realising reserves were more likely to be present in areas containing minerals of a certain age.
He had developed a technique to date minerals and it was this method that was applied to the clay found in the Jenolan Caves.
The project began at the Australian Museum, where researchers Ross Pogson and David Colchester used X-ray and electron microscope technology to identify minerals in the clay suitable for testing.
Dr Zwingmann then applied his technique — a variation of radioactive dating — to the minerals that had crystallised when a previously unknown volcano spewed ash into the caves. The technique showed the crystals were formed 340 million years ago.
“This study shows how industry-focused research techniques can also be used to solve more general geological mysteries,” Dr Zwingmann said.
He and his colleagues have published the findings in the latest issue of the Australian Journal of Earth Sciences.