Changing landscapes forced rock art site selection

Why Australia’s earliest inhabitants chose specific rock shelters as sites for art is a question long puzzling archaeologists, but now it seems it was all about location, location, location.

Rock art sites in Arnhem Land in the continent’s north are among some of the oldest records of human habitation, however interpretation of these illustrations and the purpose of rock shelters are subject to ongoing debate.

A new collaboration between researchers and Traditional Owners has combined interpretations of these sites with new data tracking of the historic change in landscape throughout the region.

It found that the art sites scattered across the Red Lily Lagoon, south of the Gunbalanya community were vantage points, from where inhabitants could clearly see the landscape.

Nt red lilly lagoon map

Their findings suggest that sites were characterised by major changes in sea levels, which gradually shifted the open plains of the region to muddy and mangrove-covered coastline around 6,000 years ago, and to today’s wetland terrain.

How they did it

  • 103 rock art sites across the Arnhem Land study area were identified and categorised into four time periods by the art styles displayed.
  • These periods were named based on the geographic characteristics of the landscape at the time: Sea Level Rise, Transgression, Big Swamp and Freshwater.
  • A digital elevation model was created using existing space-based radar, LIDAR and drone photogrammetry data.
  • Sites were then placed into this model as part of a “visibility analysis” to determine likely vantage points near the rock art.

“When archaeologists interpret rock art, they often assume the landscape hasn’t changed since the art was first inscribed which certainly isn’t the case at Red Lily Lagoon,” says Associate Professor Ian Moffatt, an archaeologist at Flinders University who contributed to the study.

Key points

  • Australian scientists have used elevation modelling and drone-based analysis to rethink why ancient rock sites were selected in Arnhem Land in the continent’s Top End.
  • Changing coastlines after the Last Glacial Maximum 14,000 years ago reshaped the landscape and brought groups closer together.
  • These changing features could explain why artistic styles of ancient rock art changed over time.

“This landscape has changed dramatically from being on the coast, a swamp, woodlands and freshwater – and sometimes in just one lifetime.

“Modelling the changes in environmental conditions over time sheds new light on the locations, where they were in these landscapes, how they were selected and used, and the roles they held in community and clan life.”

Thousands of years in the shaping

Before Australia, there was Sahul – a paleocontinent where modern-day Australia and New Guinea were connected by a large land bridge.

This land bridge was slowly inundated by rising sea levels after the last glacial maximum around 14,000 years ago.

Over the next 6,000 years, inhabitants of Red Lily Lagoon were brought together as the coastline moved hundreds of kilometres inland.

As this environment changed, groups would have erected new sites, with the researchers noting changes in artistic styles likely reflect shifting cultural systems and social structures, as well as being placed at new vantage points overlooking the changing landscape.

“When the sea level was rising, rock art was preferentially made in areas with long distance views over areas that had open woodlands at the time,” says the study’s lead author, archaeologist Dr Jarrad Kowlessar. “So we can suggest these views may help facilitate hunting, or even to more closely watch areas at a time when many people were being displaced by the rising water.”

The growth of mangrove forests during the ‘Big Swamp’ period 6,800-4,400 years ago changed where new rock art sites were selected.

Rock art in red lily lagoon.
Rock art in Red Lily Lagoon. Credit: Supplied, Flinders University

“This may be because the mangroves provided abundant resources to sustain a large and stable human population at the time, or because the land had simply contracted so much due to the rising sea level that more people were in closer proximity,” says Kowlessar.

“Most sites during this time were selected with views specifically overlooking mangrove areas.”

The research is published in the journal Archaeological and Anthropological Sciences.

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