Known. Researchers report a ground-edge stone axe at Madjedbebe, and they call it the oldest of that kind.
Madjedbebe is a rock shelter in Mirarr Country, at the base of the Arnhem Land escarpment, about 300 kilometres east of Darwin. The deepest layers are about 65,000 years old, a date checked by a second laboratory. The axe head was shaped by grinding, not only by flaking. The shelter also held seed-grinding tools the researchers call the oldest known in Australia, and fine stone points.
The page says an older fight about the date now looks finished, but it also says the new results are likely to be strongly criticised.