THE oldest ground-edge tool in the world has been discovered in Arnhem Land, prompting scientists to reconsider exactly when the technique of grinding to make tools sharp entered the Stone Age.

Unearthed from a sandstone cave in a remote part of south-west Arnhem Land in May, the basalt axe piece measuring 4 centimetres in length has been radio-carbon dated at 35,000 years old.

Dr Bruno David examines the 35,000-year-old axe fragment found at the Nawarla Gabarnmang site. Credit:Rebecca Hallas

The discovery is significant as it predates by at least 5000 years the oldest known examples of other ground-edge implements from Japan and Australia, which have been dated at 22,000 to 30,000 years old. By comparison, the earliest ground-edge axes from Europe, West Asia and Africa are about 8,500 years old.

Archaeologist Bruno David from Monash University's school of geography and environmental science said the dating results of the axe found in a rock shelter in Jawoyn country were unanimous.