Finding an Aboriginal rock shelter in Australia’s Blue Mountains has usually meant pushing through dense scrub on foot, one steep slope at a time.

That work is so slow and costly that most of the region has never been checked. Now, archaeologists using laser-equipped drones have located three shelters missing from the state’s official site list.

All three hold rock art, including red hand stencils, along with stone artifacts. The researchers see the approach as a faster way for Aboriginal communities and heritage managers to find and protect cultural sites across Australia. Jacob Bongers, a digital archaeologist at the University of Sydney, led the drone research. He worked with colleagues from the Australian Museum and alongside the Dharug Custodian Aboriginal Corporation. “This work is exciting because it offers an efficient and accurate way to locate sites in rugged environments, which are notoriously arduous, expensive and time-consuming to survey,” Bongers said.

Rock shelters are shallow overhangs in cliffs. In Australia, many of them hold evidence that Aboriginal people lived there and made art. In the Blue Mountains, thick bush and trees block the view from above. A laser on the drone fires rapid pulses down at the land. The light that comes back is turned into a detailed 3D map.

That map shows the shape of the ground even where trees would hide it from a camera. The method is called LiDAR, short for Light Detection and Ranging. Archaeologists elsewhere have used laser mapping to find lost structures under the jungle. Bongers’s team built computer models that searched two kinds of laser scans for likely shelters. One came from the team’s own drone flights and was finely detailed. The other was a coarser public set that the New South Wales government had collected from aircraft. Before anyone set out on foot, the team could inspect each flagged spot on a screen in 3D.