Australia: The Land Where Time Began

A biography of the Australian continent 

This is a series of caves that have been accumulating very well-preserved fossils for about 300,000 years. It covers an area of 300 Ha about 320 km southeast of Adelaide, South Australia, and is comprised of flat country with a series of stranded coastal dune ridges that run parallel to the modern coast. They are in the Oligocene-Miocene Gambier Limestone, that is overlain by the Naracoorte East Dune. This is the oldest of a series of stranded coastal dunes ranging as far inland as the town of Hynam. The caves were open during the Late Pleistocene, sediment and bones accumulating in their entrances and dolines. Victoria Fossil Cave contains the most significant of these accumulations of fossils.

Naracoorte East Range is a linear ridge of Oligo-Miocene Gambier Limestone in which the caves have formed. The limestone was formed beneath a warm, shallow ocean until the Early Miocene when there was a marine regression (Sprigg, 1952), after which erosion and cave formation took place. A series of marine dune ridges were deposited across southeastern Australia during the Early Pliocene. During the following regression, fluvial sand (Parilla Sands) was deposited between the ridges in valleys and watercourses. During this phase high phreatic water levels formed caves, such as Blanche Cave and Victoria Cave

It has proven to be complementary to Riversleigh, and as with Riversleigh, has a continuous series of fossils, in this case going back 300,000 years. The Naracoorte Caves contain fossils that form an unbroken series from about 350,000 years ago, demonstrating how the fauna changed as several ice ages came and went and the arrival of humans. It is believe the caves may also contain fossils from the Pliocene, and possibly even the Miocene. If this proves to be the case it will be possible to compare the faunas of this site with that of Riversleigh, 2000 km to the north.

By studying the record of climatic change at this site it was found that the megafauna had no problem surviving either cold or dry periods, always bouncing back with the return of more favourable conditions. All except the last one when humans were also present in Australia.

Some of the animal fossils found at Naracoorte

• Thylacoleo carnifex, the marsupial lion.
• Thylacinus cynocephalus, the Tasmanian wolf,
• Macropus rufogriseus, the red-necked wallaby,
• Megalibgwilia ramsayi,
• The living red-bellied black snake,
• Pseudechis porphyriacus,
• Diprotodon australis,
• Procoptodon goliah,
• Megalania prisca, the largest ever lizard,
• Phascolarctos stirtoni,
• Phascolarctos cinereus
• Simosthenurus occidentalis
• Palorchestes azael
• Barn Owl (Tyto alba)
• Wonambi naracoortensis
• Sarcophilus harrisi
• Varanus varius, the living lace monitor
• Bullockornis planei

Links

Naracoorte

• Naracoort Caves National Park
• The Story of the Naracoorte Caves
• The Thylacine Museum

Sources & Further reading

1. Chris Johnson, Australia's Mammal Extinctions, a 50,000 year history, Cambridge University Press, 2006
2. Patricia Vickers-Rich, Thomas Hewitt Rich, Wildlife of Gondwana, Reed Australia, 1993