Many settlements were built in areas that were on dry land at the end of the Ice Age, when sea levels were lower, but were submerged as the sea rose, according to a study published Wednesday in the journal PLOS ONE.
The Australian coast extended 100 miles farther out to sea than it does now, say a team of researchers led by archaeologist Jonathan Benjamin of Flinders University in Adelaide, so it is likely that many ancient sites are underwater.
Scientists sent divers to explore likely sites and also used a number of techniques, such as aerial and underwater remote sensing.
They found two sites off northwestern Australia. The first, in Cape Bruguieres Channel, contained artifacts that are at least 7,000 years old. At the second site, Flying Foam Passage, they found a single artifact that is 8,500 years old.
Many of the artifacts had marine life growing on them, but the team were able to identify a number of worked stone tools, including two possible grinding stones.
The findings show that these exploratory techniques are useful in detecting underwater archaeological sites, said the authors, who hope they can be used to systematically recover and investigate ancient artifacts.
The team urged the Australian government to enact legislation that would protect and manage Aboriginal sites along the coastline.