Australia's Jenolan the oldest caves

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Australia's Jenolan the oldest caves

Postby Wayne Harrison » Jul 25, 2006 12:51 pm

Jenolan the oldest caves
Leigh Dayton
July 26, 2006

THE Jenolan Caves in the NSW Blue Mountains are the world's oldest known open caves, beating the Dead Sea Scroll caves by over 240 million years.

The geological one-upmanship came after Australian scientists dated the cave system to 340 million years.

"Even in geological terms, 340 million years is a very long time," said team leader Armstrong Osborne, a geologist at the University of Sydney.

Until 20 years ago most scientists thought the Jenolan Caves were only a few thousand years old. More recent estimates said they might be between 90 and 100 million years old, similar in age to the limestone caves near Qumran where the Dead Sea Scrolls were discovered.

"These are extraordinary dates," said Professor Osborne.

"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 (still) joined to the mainland as recently as 10,000 years ago."

<a href="http://www.theaustralian.news.com.au/story/0,20867,19914644-30417,00.html">Full Story</a>
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Postby Amemeba » Jul 26, 2006 4:55 am

340,000,000 years old, huh?

Yeah, and pigs climb trees and cats swim seas
Sing polly waddle doodle all day.

:caver:
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Postby Wayne Harrison » Jul 26, 2006 9:24 am

Deborah Smith Science Editor
Sydney Morning Herald
July 26, 2006

THE Jenolan Caves in the Blue Mountains have been dated at 340 million years old, making them the oldest known open caves in the world.

In a five-year study, a team of Australian scientists tested clay from caves regularly visited by tourists, such as the Orient Cave and Temple of Baal Cave, to determine their ancient origins.

Team member, ArmstrongOsborne, of the University of Sydney, said it had been thought for many years that the limestone caves were only a few thousand years old.

Then, about six years ago, geologists estimated they could have formed as long as 100 million years ago.

The new finding was a shock.

"The dates we got are much older than anticipated. It is quite dramatic," Dr Osborne said.

The second oldest known open cave is in the Guadelupe Mountains in New Mexico, US, which is 65 million years old. Most other famous caves, such as Postojna Cave in Slovenia, are thought to be only about 5 million years old, he said.

For the study, CSIRO scientists, led by Dr Horst Zwingmann, used a method they had developed to help oil exploration companies find oil deposits. By testing minerals in mud samples from the floors of the caves at Jenolan, they were able to show that the clay had formed in the distant past from ash blown in from a nearby volcano.

Dr Osborne said 340 million years was a long time, even in geological terms. "To put it in 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."

He said the discovery, published in the Australian Journal of Earth Sciences, could assist in a push for Jenolan Caves to gain world heritage listing in their own right, not just as part of the Blue Mountains listing.

"They deserve it. They are one of the world's most complicated cave systems," he said.

Most ancient caves around the world have filled up with rock, and are no longer accessible, Dr Osborne said.

http://www.smh.com.au/news/national/joy ... 2378.html#
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Postby Dwight Livingston » Jul 26, 2006 10:22 am

Wayne Harrison wrote:The second oldest known open cave is in the Guadelupe Mountains in New Mexico, US, which is 65 million years old. Most other famous caves, such as Postojna Cave in Slovenia, are thought to be only about 5 million years old, he said.


Cave of the Domes and the many other caves in the Redwall formation in Grand Canyon are at least 285 million years old. I would expect many other examples older than that to turn up.

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Postby Amemeba » Jul 28, 2006 5:24 pm

It would be neat to know how a void could remain stable for such a long time.

Maybe five million years....tops.

And that's a stretch.


This smacks of voodoo speleogenesis
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Postby Dwight Livingston » Jul 28, 2006 6:05 pm

Amemeba wrote:It would be neat to know how a void could remain stable for such a long time.


Not hard. They get buried. The top of the Redwall Formation was a karst topography. It was buried under the Supai group of formations and many formations above that. Much more recently the Colorado River cut down through the Redwall, intersecting the old caves, much as more recent caves are cut open by the rivers they drain to.

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Postby Amemeba » Jul 28, 2006 10:35 pm

Hmm...fuzzy semantics. Paleozoic caves, then, remain caves although they are 300 million years filled with fill. Well then, do caves that are eroded away by surface erosion remain caves even after they are gone?

Not that it much matters, but to me a "cave" has to have some geological continuity through time. The pre-existing conditions that develop a cave are but an aspect of speleogenesis.

Of course if an aspect of caveness can be discerned from Paleozoic time then I will defer to that judgment.

Aren't I magnanimous? :grin:
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Postby Dwight Livingston » Jul 29, 2006 8:50 am

Amemeba wrote:Hmm...fuzzy semantics. Paleozoic caves, then, remain caves although they are 300 million years filled with fill.


I wouldn't have said dirt-filled, but then I don't know what the case is for Cave of the Domes. You've sent me scurrying for information, and I've found less than I'd like. The most definite is from Ford & Williams *Karst Geomorphology and Hydrology," page 512, describing a Paleogene cave system on the Adriatric and Black sea coasts: "Because they contain groundwater (i.e. they are not entirely infilled by detritus) the must be classified as 'relict' rather than 'paleo' karst features." Oh, all right. Perhaps I mean relict caves. But in other places I've seen reference to oil-filled paleocaves, which cuts a rather fine line to the definition, even if oil and water don't mix.

Amemeba wrote:Not that it much matters, but to me a "cave" has to have some geological continuity through time.


I agree. Certainly if the sediment fill has lithofied and your ex-cave is now just a discontinuity in a outcrop, it doesn't make much of a cave trip. What if the dirt is diggable? Without tools? Even that seems questionable. Oil-filled? Seems like a cave to me.

I don't know if Cave of the Domes is relic or paleo. If I find out I'll certainly post it here.

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Oldest on Earth, Australia's Jenolan Caves Date Back 340 Mil

Postby Wayne Harrison » Jul 31, 2006 1:14 pm

<img src="http://www.ens-newswire.com/ens/jul2006/20060731_caveentrance.jpg" align="left" hspace=10 vsapce=0>The Jenolan Caves in central New South Wales are the world's oldest discovered open caves, formed 340 million years ago, new cave-dating research published by Australian geologists has found.

Until 20 years ago, most scientists thought the Jenolan Caves were no more than a few thousand years old. In 1999 geologists estimated that the caves, which attract thousands of tourists each year, might be between 90 and 100 million years old.

Dr. Armstrong Osborne, a senior lecturer at the University of Sydney, has long suspected that the caves are older than that, but Osborne says even he was surprised to find they dated back to the Carboniferous period - 290 to 354 million years ago.

"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 study used clay-dating methods that CSIRO's Petroleum Resources division developed to help oil exploration companies find oil deposits.

CSIRO Petroleum Resources researcher Dr. Horst Zwingmann says the age of the caves was determined by dating the clay minerals that crystallized when volcanic ash entered the caves. The ash now forms much of the mud in the Temple of Baal and Orient caves.

<a href="http://www.ens-newswire.com/ens/jul2006/2006-07-31-04.asp">Full Story</a>
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Postby Amemeba » Jul 31, 2006 7:57 pm

I hope the need for tourists to visit their caves didn't influence their observations.
It takes a quirk of nature for a quick uplift from the sea to allow the formation of a limestone cave
only to have the cavity quickly filled by a volcano and then have the rare fate be buried deep enough
to be be protected against Base Level Lowering for several hundred million years.

They haven't said, but yet I wonder, how old is the limestone itself?

As for the stratification of the intrusive volcanic sediments, so what?
It is obvious that if volcanic sediments intruded they had to intrude into something, and that something was the cave.

Yes, the volcanic rock they radio dated as Paleozoic is probably Paleozoic.

But still I wonder, when was this old Paleozoic ash washed into this nice new Pleistocene cave? :-)



http://www.usyd.edu.au/news/84.html?newsstoryid=1172
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Postby Evan G » Aug 16, 2006 11:17 am

Scientists date Australian caves back to 340


Sydney, Aug16: A series of limestone caves west of Sydney have been pronounced the oldest in the world, dating back 340 million years, according to Australian scientists.

The Jenolan caves, a popular tourist attraction, now surpass caves in New Mexico, approximately 90 million years old, as the oldest dated open caves on the planet.

Armstrong Osbourne, a scientist who helped date the caves, says it is a unique opportunity for tourists to walk around in caves so old.

"This is the oldest cave that we know of in the world which you can actually walk around in that's not filled up with solid rock", he said.

Australian scientists have only been able to access the dating research from the past two years, as it was previously only available to oil companies.

The researchers studied tiny amounts of radioactive potassium in clay to determine the age of the caves; however, before the significance of the clay was realised, it was used to repair sewer pipes because of its malleable composition.


<a href="http://www.zeenews.com/znnew/articles.asp?aid=315752&sid=FTP">Full text</a>
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Postby fuzzy-hair-man » Oct 12, 2006 2:03 am

Another article about dating Jenolan caves:
The Australian:Jenolan's ancient archives Kate Rossmanith October 11, 2006

IN June the Jenolan Caves in the Blue Mountains of NSW were dated at 340 million years old. This makes them the oldest known open caves in the world. One hundred million years before dinosaurs, when amphibians wandered through ferns and forests, warm water rose beneath the east coast of Australia, creating hollows under the earth. When the ground split, spewing molten lava and raining ash into watery openings, a fine clay formed. It is this clay that has made dating the caves possible.

Armstrong Osborne, a speleologist from the University of Sydney, led the research team that made the discovery. He's happily flustered when we meet. He has done three radio interviews, agreed to another four, taken calls from reporters and fielded inquiries from leading international journals. It is his moment. Even in academic terms, where a 50-year-old is a mid-career researcher, his moment has been a long time coming.

For 25 years, Osborne and other speleologists suspected the Jenolan Caves were many millions of years older than the few thousand widely accepted, but they had no way to prove it. He completed his PhD on Jenolan in the 1980s and was told it might not be passed because of its radical proposals. "Most people were convinced the caves were quite young and those of us who thought they were really old couldn't find any evidence. But not even I imagined they'd date as far back as hundreds of millions of years," he says........
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