Researchers discover submerged ancient civilization archaeological sites in Australia

A study published in the journal PLOS One describes how researchers in Australia discovered the country’s first underwater archaeological sites: Cape Bruguieres, which included more than 260 "lithic artefacts" found 2.4 meters below sea level, and Flying Foam Passage the site of a submerged freshwater spring 14 meters down. 

Archaeologists used aerial and underwater remote sensing techniques as part of the research strategy, along with divers to investigate the sites and to map the landscape between 0 and 20 meters beneath the ocean surface.

During the Last Glacial Period, the sea level was lower expanding the continental area of present day Australia by more than 2 million kilometers. Major transformations were occurring in human history at this time and therefore researchers say that these underwater sites can help us understand how rising seas affected the cultures, populations and socioeconomic development of communities around the world.

Determining the age of finds in the sediment starved seabeds, like in Western Australia, presents two challenges, the study says.

The first challenge involves deep water logistics and costs: "This requires larger vessels equipped with a full range of acoustic equipment for surface mapping and sub-bottom and seismic equipment for sub-surface mapping as well as facilities for coring and dredging, remotely operated vehicles and, in the event of discoveries that need closer inspection, submersibles and diving teams trained in deep diving techniques and a regulatory compliance environment which allows for scientific diving at those depths."

"The second challenge is to develop predictive models that can pinpoint target areas of interest with sufficient precision to focus search and discovery and justify the greater costs of deep-water investigation," the study says.

The minimum age of the Bruguieres Channel site is 7000 calibrated years before the present (cal BP), but the site next to the submerged freshwater spring at Flying Foam Passage is 8500 cal BP, based on when the sites would have been drowned by Holocene sea level rise. Researchers currently have no methods to further pinpoint the age of these sites.