Having booked an afternoon tour of the Naracoorte Caves, we drove the 200-plus kilometres from Hall’s Gap, in the Grampian Mountains, as fast as safety and the law allowed. Brendan, our son did the driving. Therese and I just clung to the seats. We need not have hurried. By crossing the border from Victoria to South Australia, we also stepped into another time zone, which gave us an extra half hour in the day. We were able to relax, therefore, with a light lunch and plenty to drink under the wooden shelter that allowed us at least some respite from the sun.
The day was extremely hot, so when our guide arrived, we were eager to follow her into the cave, where the temperature fell to a more comfortable 17°C. A descent through a long tunnel led us away from the daylight and into the first chamber, which opened out to reveal a magnificent array of stalactites, stalagmites and hanging curtains. Many of these were a pristine white. Others were stained every hue from pale yellow to mid-brown by the iron salts that had precipitated along with the calcite. They resembled frozen trickles of candle wax, and glistened like ice in the electric illumination of the cave.
In Your Bucket Because…
- You enjoy experiencing the wonderful scenery and natural sculptures that can be seen in a limestone cave.
- This is one of the finest places in the world to see fossil bones of extinct animals.
- Naracoorte Caves offer an exciting and educational experience for visitors of all ages.
The limestone had been deposited 200 million years ago, when coral seas covered this area, and again 20 million years ago, during a second period of inundation, after which the land had risen and dried out. Since then percolation by ground water had hollowed out the caverns, which then began to fill up again as water, dripping through the roof evaporated, leaving behind the beautiful structures we were now enthralled by.
This particular cave was discovered in 1894 by William Reddan, who dug through surface sand in search of a cave that might have been inhabited by bats, and hence would be a rich source of the bat guano he planned to sell as a fertilizer. He found no bats, but named his discovery Victoria Cave, after the British queen, and the first chamber, Albert Edward Grotto, after her eldest son. Together with a second chamber, Laurie’s Grotto, the cave reached 250 metres underground, and was opened to the public soon after its discovery, when the passages were cleared of rubble.
Until 1969, this remained the extent of the known system. Then a group of cavers, Grant Gartrell, Rod Wells and Bob Herzel, of the Cave Exploration Group of South Australia, reaching the farthest point, felt a strong breeze coming from a thirty-centimetre wide passage. Grant Gartrell crawled through this into what is now known as Grant Hall, where he was astonished to find the floor covered by an amazing array of animal bones. As a result of this discovery, Naracoorte Caves were listed as a UNESCO World Heritage Site in 1994.
We saw the narrow passage through which Grant Gartrell crawled. Our route involved no such heroics, as the rubble blocking Grant Hall has been removed to give easy access, not just to the public, but to the scientists from Flinders University, South Australia, under the supervision of Assistant Professor Rod Wells, who continue to excavate and study the fossil bonanza of the cave.
On arrival in Grant Hall, we took our places on a row of seats that overlooked a broad expanse of cave floor, measuring 60 metres by 20 metres. Though many bones had been removed for study, the scene was little different from that which greeted the cavers in 1969. Bones lay everywhere, scattered randomly across the floor. They had all ended up here through an almost unique set of circumstances.
Unlike most fossils, these bones have not been mineralised, but are classed as fossils because they are more than 10 thousand years old. Indeed, they range in age from 70 thousand to 200 thousand years and are the remains of creatures that simply fell into the cave and were preserved by the dry conditions. Over the millennia, they piled up, along with silt, until they reached what is estimated as a depth of 20 metres and a total mass of 5000 tonnes. The number of individual bone specimens is into the tens of thousands. They preserve a record of evolution that spans a period of major climate change and the coming of the first humans to Australia.
Around 130 species of vertebrate are represented by the bones. 40% of these are of modern animals that can still be seen in the region. 30% are of extinct megafauna that roamed the continent before humans arrived.
Our guide passed around a sliced stalagmite, the cross-section of which revealed a set of rings, rather like annual tree rings, which held a record of the climatic changes, including those of the ice ages, that had occurred as the calcite was deposited. We were also shown a reconstructed skeleton of an extinct marsupial lion, Australia’s largest marsupial carnivore.
We made our way back along the 400 metres to the open hillside, then drove to the Wonambi Fossil Centre that adjoined the Visitor Centre. Here we entered a simulation of the forests and wetlands as they might have looked when the extinct megafauna roamed the area. There were life-size models of thylacines, marsupial lions, brush-tailed possums, giant kangaroos, the hippo-like zygomaturus trilobus and diprotodon Australis, the continent’s largest marsupial. Continuing through a tunnel populated with snakes and lizards, we came to the Flinders University Gallery, where displays illustrated plate tectonics, the climate cycles of the last million years, the extinction of the megafauna and how the bones had accumulated in the caves.
Naracoorte Caves are the only World Heritage Site in South Australia, and share the title of Australian Fossil Mammal Site with Riversleigh, in North Queensland. In addition to the Victoria Cave are Bat, Blanche, Alexandra, Wet and Cathedral caves, which together make up just over half of the six square kilometres of the Naracoorte Caves National Park. There may be other caves that hold similar fossil accumulations, but until they are found, Naracoorte will remain among the ten richest deposits of fossil bones in the world.
- Naracoorte Caves are most easily reached from the Melbourne-Adelaide coast road by driving north from the equally geologically impressive Mount Gambier.
- Make sure you also visit the Wonambi Fossil Centre.
- The road between Mount Gambier and Naracoorte passes the Coonawarra wine-growing region, the produce of which is well worth sampling.