"Rock art is notoriously difficult to date," says David.
"Most pigment art contains no dateable carbon, and therefore radiocarbon dating is usually not feasible." What is known as the oldest rock art in the world - cave paintings in Indonesia and Spain — was dated using a more complex method that measures the age of a microscopic layer of minerals deposited after the art is created. Instead of measuring the decay of radioactive carbon, this method relies on measuring the decay of uranium in the microscopic layer to provide a minimum age for the art.
but it's an inference." Pillans and colleague Keith Fifield have argued that rocks bearing Aboriginal engravings on the Burrup Peninsula have the potential to preserve the engravings for 50,000 to 60,000 years, but they have done no direct dating of the engravings themselves.
According to archaeologist Dr Bruno David of Monash University the oldest reliably-dated rock engravings in Australia are 13,000 to 15000 years old, and are in Laura, Queensland.
"It's very likely that there is something extremely old in Australia but it's just very hard to date," says David.
"And there are very few people doing research on rock art." David says there are hand stencils in some limestone caves in North Queensland that are believed to be more than 30,000 years old, and he hopes to be involved in dating these in the future.
In some cases a similar layer beneath the art gives a maximum age for the art.
In both Spain and Indonesia, the cave art appeared in deep limestone caves.Indeed, he says, the richest collections of rock art in the Kimberley, Arnhem Land, Cape York Peninsula, are on sandstone.Take the ochre painting of a giant emu-like bird found on the Arnhem Land plateau, which some believe could be 40,000 years old — as old as the paintings in Spain and Indonesia.This suggests that, while art may have been part of the baggage of the first immigrants, regional cultural traditions had already been developed by the Terminal Pleistocene, if not earlier.The result is evidence for the development of regional cultural diversity in the Americas by Paleoindian times."We don't have the [dated] art itself, but we've found the tools that were used to make the art.