Spin the Globe with Justin Butner

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Naracoorte Caves

Written 13 May

Naracoorte Caves are South Australia’s only UNESCO World Heritage listed site. If you are a fan of pretty caves, you can certainly do better. But if you are a science nerd (yes, I’m a science nerd), then they have something to offer.

The information center offers something for children and something for adults. The children portion is the first half, a collection of animatronic extinct animals crushed together in a room-sized diorama. It is cheesy for sure, and a pretty solid way to cause you to question the money you just spent to get in, but it does give a view of how the animals all came together in a way that really helps out later on.

The adult portion is the second half, placards of text on global climate cycles complete with graphs and diagrams. Explanations of Oxygen 18 isotope testing from core samples, fluctuations in the earth’s course around the sun, and the results of the ebbs and flows of the glacial cycles. When laid out the way they are, the factors all clearly tie together in ways that I had been previously unaware.

The highlight of the park, and the reason anyone cares about it, are some of the caves. The tour we took led us through the Victoria Fossil Cave. It had the usual stalactite/stalagmite formations, pretty enough to merit a visit if you live near it, but not rivaling those found in many other caves. But more importantly, the caves serve as a graveyard of sizeable proportions.

The story goes like this. The water table comes up and forms the caves. At some point, one part of the roof gets too weak and collapses. Animals on the surface are walking or hopping along and find the pit trap. They fall in and have one of three fates. They die on impact. They break themselves on impact and starve to death. Or they are consumed by animals that have a bit more ability to climb back out. Whatever the course, the end result is the same – a body in a hole in the ground. Slowly over time the hole absorbs more and more bodies as it also takes in some dirt and organic material. A cone builds up slowly, with layers being slightly intermixed by frantic and terrified dying animals, but largely staying intact. Over time eventually the material plugs up the hole. Now the animal graveyard is sealed to the outside world, unaffected, and safe from interference, until some people come along and start cave exploring.

Various holes in various caves around the area opened up for distinct periods in time ranging from about 20,000 to 500,000 years ago. And by dating the isotopes in the layers, scientists assemble a picture of the past half million years in animal evolution in a completely isolated continent. The mega-fauna that died off about 23,000 years ago. The medium sized marsupials that went extinct much later on. Even the small animals that were piled up in owl caves over times. The graveyards are meters and meters deep in points, tens of thousands of metric tonnes of former fauna.

The place is one of the world’s clearest windows of evolution, of the change in animal populations, that when paired with the climate data, can be used to draw conclusions about the way the environment, the plants, and the animals all tie together and changed over time.

One of my passengers jokingly told the tour guide he was a Creationist. For him, she said, her dates may have been a bit wrong, but the caves are evidence pointing towards the great flood.

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This entry was posted on May 21, 2012 by in Australia, South Australia (Adelaide) and tagged .

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