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Marine Biodiversity Hotspot - Ancient Cultural Landscapes

On a remote island off the southern coast of Western Australia, a team of researchers (Finding Salisbury) have identified a connection between ancient landscapes and rich marine ecosystems. A massive limestone scarp sits atop a granite dome on the outer edge of the Recherche Archipelago. This scarp, now known as Salisbury Island, rises above a vast sandplain, submerged by the surging Southern Ocean. Rising some 80 to 100 metres above the flat coastal plain, this dramatic landform would have been a distinctive feature for the late Pleistocene inhabitants of this region. People roamed this area at a time when ocean levels were much lower, during the height of the last Ice Age (ca. 18,000 years ago).

Doc Reynolds, a Traditional Owner, is leading the cultural connections component of this project. “This place would have looked like Uluru in the red centre of Australia – a massive feature surrounded by low, flat bushland and rocky outcrops. It would have drawn my ancestors here, for the resources it provided.”

These resources include abundant freshwater, collected through the limestone pools and sand dunes, shelter from winds and storms in the mosaic of caves and overhangs, plentiful coastal resources like fish and shellfish, raw materials from the massive chert outcrops for making implements, cultural plants, and large game like wallaby - which still inhabit the island today.

Leading the archaeological investigations is David Guilfoyle, of Applied Archaeology Australia. “The present-day mainland is 26 nautical miles (50 kms) to the north of the Island, and this area has documented evidence of human occupation in granite caves, extending at least 13,000 years before present (Cheetup Cave). At this time, these caves would have been some 80-100kms from the coast. So we know people were living here, when they could walk to this limestone ridge. I am sure they would have targeted the coast and this unique landform that is now an island.”

The team was brought together by local marine wildlife expert, Marc Payne. He has spent a lifetime exploring the Archipelago, working as a commercial abalone diver, collaborating in scientific expeditions, and working to document and protect the marine habitats. Most recently, he has come to apply his knowledge of Great White Sharks, having studied patterns in their movement and behavior, from three decades working on, and under, the sea. “I have noticed a lot of patterning in how the sharks use this Archipelago here. They have structure – they work movement corridors that link up habitats. We have been documenting how they congregate around this Island. They prey on the sea lion colony and the abundant schools of fish that have colonized the granite outcrops and limestone reefs.”

Marc has also mapped the submerged environment, documenting a vast underwater limestone ridge that runs from the present-day mainland, in an arc that links up to Salisbury Island. His observations have directed the research program to explore potential patterns of prehistoric movement through this ancient coastal plain. “The Great Whites likely follow this limestone scarp, from the island, connecting other nodes and islands, and patrol this underwater ridge, where marine life congregates.”

Doc has an understanding of the ancient cultural landscape, “These sharks may very well be the corridor of movement that our Ancestors followed, when they explored and memory-mapped this scarp. Our People, our Ancestors, created this landscape. We understand biodiversity, as the central component of our lifeways. This work is as much as about understanding the message of sustainability from our People, as it is filling the gaps of archaeology and our understanding of the marine environment.”

The team are working to simultaneously study the marine habitat, but also explore the archaeology of the island – both above and below the water. David Guilfoyle and his team have identified small chert flakes on the island that represent the debris of people making and maintaining their stone implements. They have also identified evidence of ancient quarrying – with flake scars observed on chert outcrops within sheets of exposed limestone. “What we think we are seeing here, on the island, is evidence of people hiking up this scarp, to acquire sources of chert, quarrying nodules and then bringing them back down to base camp. They likely used the upper reaches for cultural practice, and as lookouts. But we predict that people would have set up major settlements at the base of this limestone ridge. The upper reaches, where we are standing today, are quite steep and exposed. So the real potential for documenting evidence of the prehistoric landscape now lies underwater.”

With Marc’s knowledge, the team have identified an underwater cave system that remains relatively sheltered form the Southern Ocean storms. A project is now underway to get inside these caves and explore the potential for the preservation of ancient cultural material. The caves were first covered by drifting sands as the ocean slowly crept up over the continental shelf, fueled by the melting polar ice caps, creeping towards the base of the limestone ridge. Wind-blown sands swept up and created massive coastal dune systems. As the ocean slowly inundated the limestone base and separated this landform from the mainland, water would have eroded the dune systems. “There is a chance,” says Guilfoyle, “that this process trapped enough sediment in the cave, and water pressure has preserved intact cultural deposits. A chance worth exploring.”

This avenue of investigation has many challenges – perhaps the biggest though is the numbers of Great White Sharks that patrol the very shallow corridor around the island, as they prey on sea lions and other marine animals – right in front of the submerged cave systems. Marc and his team have built a special-purpose dive cage that will allow them to move along the sea floor and close in on the submerged caves. The cage is equipped with state-of-the-art cameras for live video feeds to the boat, so the archaeologists can observe and communicate with the divers as they map and document the cave systems. Even without finding direct evidence of human use, the work is important in recreating the pattern of island formation, environmental change, and habitat creation.

Doc Reynolds reflects, “I am the first of my People to stand here in maybe 12,000 years. This is a humbling experience. So, yes, this work is challenging, but it is upholding the spirit of our Ancestors. We are here to protect this special place. Understanding the values – past and present – to ensure we are managing everything the right way, for the future.”

Guilfoyle agrees, adding, “Management plans today may not be accounting for all the values that are out here. Scientific expeditions are quite often organized around short, intense periods of fieldwork. Our work is based on data from people like Marc who have lived a lifetime out here – weekly, monthly observations over prolonged periods of time – like the Traditional Owners. Of course this type of information should be used as the basis of all conservation planning.”

Follow the team's progress at Finding Salisbury and a series of video diaries:

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