LAST year, archeologist Mike Morwood and rock art specialist June Ross took the ride of their lifetime across the northwest Kimberley. They hired a helicopter and flew across largely trackless territory, their pilot landing periodically in spots where he felt he could get his helicopter down safely and where they believed a good rock art site might lie.

Their journey took them from Bigge Island, one of the Kimberley's largest offshore landmasses, east to inland pastoral stations, and north as far as the rugged Drysdale River National Park, the Kimberley's largest park that lacks an airstrip, ranger station or even a single road.

Across the Kimberley, hundreds of thousands of paintings lie in rock overhangs and caves, often behind curtains of tropical vines. Dappled light plays over the surface of hauntingly beautiful images that have made the region famous: Gwion Gwion or Bradshaw paintings depicting slender dancing figures in mulberry coloured ochre or younger images of Wandjina spirits, wide-eyed and startlingly white despite the passage of years.

But who were these prodigious artists, when did they come and what other traces did they leave of their presence? Such questions are among the most crucial in Australian archeology, according to Morwood and Ross. Like Arnhem Land in the Northern Territory, they say, the Kimberley may hold vital clues to understanding the origins of the first Australians.