水中の洞窟

今から約6000年前、オーストラリアのシドニーの海岸線は２０－３０ｋｍほど現在よりも沖にあったそうです。つまり、当時の生活の跡は海の底にあるはずです。特に、現在入り江になっている場所では波の影響などを受けにくいので遺跡が現在でも存在している可能性があります。さらには現在海底にある洞窟では遺跡が撹乱されず残っているはずです。しかし、このような調査はあまり積極的に行われていないのが現状のようです。

New South Walesの水中考古学チームが海底の洞窟の分布を調査し、幾つか候補地が挙げられています。現在、アボリジニーから調査の許可などを得るのと同時に助成金など調査費用の確保を進めているそうです。

Underwater caves in sheltered bays could house a wealth of untapped pre-European archaeological treasures, say Australian researchers.

And people involved in coastal developments need to be more aware of the potential for disturbing this underwater heritage, they say.

Sydney-based archaeologist Cosmos Coroneos and colleagues will report on possible underwater sites in Sydney at the Australian Archaeology Conference at the University of Sydney next month.

“About 6000 years ago, the coast of Sydney was probably about 20-30 kilometres off shore,” says Coroneos. “As the sea levels rose people retreated inland.”

He says this means that there is probably a lot of evidence of Aboriginal occupation that is now under water.

Aboriginal people are known to have occupied rock shelters around Sydney that are currently above water.

So Coroneos and colleagues reasoned there must be equivalent sites under water that contain archaeological treasures dating back at least 6000 years.

Previous attempts to find such submerged sites in Australia have so far not been very successful, says Coroneos.

He says one reason is that many sites have been exposed to wild waves that have washed away sediments that might contain archaeological material.

So the researchers decided to focus on sheltered bays in Sydney. One area they chose was in Port Hacking where there were known to be caves above water that Aboriginal people had inhabited.

“Because the area is so sheltered, you’re not going to get wave action pounding these little bays,” says Coroneos.

With help from volunteer divers from the Underwater Research Group of New South Wales the researchers systematically surveyed below the water and found some likely candidate sites.

“We’ve basically found caves under water,” says Coroneos. “If they were dry, up on land, we would consider an excavation of these areas as being prospective rock shelters.”

The researchers now hope to get permission from the local Aboriginal landowners to collect sediment cores from the caves in the hope of finding stone tools.

He says other protected coastal sites, including around the Burrup Peninsula in Western Australia, are likely to contain preserved archaeological material.

It’s just a matter of having the funds to research such sites, he says.

Submerged coastal archaeological sites are being excavated around the world.

These include parts of the ancient city of Alexandria in Egypt and submerged Neolithic villages in Israel, Denmark and the US, says Corneos, who has worked on such sites in the Mediterranean.

He says compared with other parts of the world, there is relatively little exploration of submerged archaeological sites in Australia.

“It’s taken seriously in other countries but in this country for one reason or another it isn’t,” he says.

Disturbing sites

Coroneos says people involved in activities like reclaiming land, building sea walls or pipelines need greater awareness of the potential for disturbing such underwater heritage.

Even when underwater archaeological surveying is carried out the focus tends to be on European cultural heritage including shipwrecks, rather than Aboriginal heritage, says Coroneos.

“From an archaeological perspective we think there’s a blind spot when it comes to what’s under the water’s edge,” he says.

Other members of the research team are Jim Wheeler and David Nutley of the New South Wales Department of Planning’s Heritage Office, who has written a masters thesis on submerged sites.

引用元：http://abc.net.au/science/news/stories/2007/2012104.htm