Western Australia’s archaeology beneath the waves

The submerged landscapes of the Australian continental shelf have an untapped potential for providing evidence of human occupation from as far back as 50,000 years ago to a more recent  6,000 year date.

Understanding the process of change

New understandings about the submerged landscapes of the now drowned North-West Shelf are emerging through recent geo-archaeological studies of the Dampier Archipelago  in conjunction with archaeological work on Barrow Island.

The islands of the Dampier Archipelago – named after William Dampier, an English buccaneer who visited the area in 1699 – preserves at least 30,000 years of archaeological record that reflects the change from a continental to an island environment following post-glacial sea-level rise.

The geomorphological history of the Dampier Archipelago region in combination with preliminary hydrodynamic modelling of past tidal regimes provides the basis for a new model of how the shelf landscape may have developed between the Last Glacial Maximum (c. 20 ka BP), through the Holocene marine transgression and up to the present day. Using first-order geomorphological principles, an assessment is made of the key Late Pleistocene and Holocene sediment bodies that may preserve archaeological deposits.

Locating submerged archaeological sites

The study demonstrates that archaeology is most likely to be present in deposits associated with the early phases of inundation of the Dampier Archipelago, nine to seven thousand years ago.

At this time sea levels were around 30 – 15 metres lower, which was represented by a complex coastal configuration and the variety and scale of intertidal and shallow sub-tidal environments was wider.  In contrast the coastal archaeology older than 12,000 years ago when the post-glacial sea levels were  as much as 50 metres lower, will have been exposed to a phase of faster tidal currents on the continental shelf, and hence be more eroded or poorly preserved.

The study aims to improve prospection for as yet-unknown submerged elements of West Australia’s rich archaeological heritage and then the management and protection of these resources.  These shoreline sequences provide the first indication where to begin to look for submerged archaeology, and what archaeological periods these sedimentary deposits represent.

Dampier Rock Art

The Dampier Islands were first occupied some 30,000 years ago, when they were the tops of volcanic mountains 60 miles inland. And although no one knows precisely when people first started etching designs into the black rocks it may be at least 20,000 years ago. Even as sea levels rose and turned the mountains into a 42-island archipelago the people visited these sites and continued marking the rocks with petroglyphs depicting kangaroos, emus and hunters carrying boomerangs—constituting one of the greatest collections of rock art in the world numbering between 500,000 to one million individual images.  What more lies beneath the sea?
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References:

Past Horizons. 2013. “Western Australia’s archaeology beneath the waves”. Past Horizons. Posted: July 26, 2013. Available online: http://www.pasthorizonspr.com/index.php/archives/07/2013/western-australias-archaeology-beneath-the-waves