Australia: The Land Where Time Began

A biography of the Australian continent 

Rising Water, Disappearing Continental Shelf

The people who had occupied the continental shelf when it was exposed by low sea levels would have been greatly affected as the sea gradually covered their territory, disrupting the social structure of communities whose ritual politic was embedded in the land they watched being submerged. For those people who were responsible for that land their social and political consequences must have been devastating as their power to stop the sea rising was shown to be non-existent. There would probably have also been increasing tensions between the communities losing their land and those in neighbouring country. Those groups who lived on land that was centred on high ground on coastal hills and ridges, though they were on the continental shelf, would also have had problems as their country on broad plateaus and mountains would have eventually have been surrounded by the sea as they became islands. They would have had no way of knowing is the high central parts of their territory would eventually be cut off from the mainland, or even be submerged, so not knowing if they should try to find space on the nearby mainland or trust that their upland home territory would be safe from the rising water and if there was enough remaining above water for them to survive if and when the rise stopped.

At some point the people living on the extrusive plains of the continental shelf would need to make a decision on what to do about the rising sea level, move to higher ground or off the plain altogether. Once a peninsula became an island it would be necessary to decide if they needed to move to the mainland as the water gap was increasing the island appeared to be getting further from the mainland, leaving the decision too late would mean they may be too far from the mainland to cross easily, and there was the problem of not knowing how high the water would rise. At some places on the more precipitous parts of the coast, such as east of Wallen Wallen Creek and Burrill Lake, and to the west of Mandu Mandu shelter. At places such as these there wouldn't be much social and territorial change to cope with, as effectively that had always lived on the coast and the lateral impacts of sea level change would have been minor in the context of the vertical shores they encroached upon. These groups were not without risk from a insidious threat, there was always the chance that they could change from a coastal people to an island people before they realised what was happening.

That process of entrapment occurred in the Whitsunday Islands over a period of 2,000 years. About 10,000 years ago people moved had moved to higher ground on Hook Island, camping in a small cave in Nara Inlet with the rising sea a few metes from the entrance, at a time when the island was connected to the mainland by a long narrow peninsula, but 1,000 years later this peninsula was cut and over the next 2,500 years the peninsula became a chain of islands. For some time they travelled between the islands by watercraft to South Molle Island that was newly formed, to collect stone for tools. They may also have travelled to the mainland, though by the time the gap to the mainland had widened to more then 30 km it was too wide, which meant they were isolated on their own. The specialised as marine foragers and developed their own artistic tradition as well as a distinct social and linguistic identity. New tools were invented that suited their subsistence needs such as fish hooks from shellfish and turtle shell, bone and wood were fashioned into spear points, and nets and scraping tools. They hunted everything available in the sea - turtles, small pilot whales, fish, crabs and shellfish.

The Keppel Islands of the present were mountains on the exposed continental shelf and people stayed on them as the water rose around them, the settlement contracting up the mountains 5,000 years ago, and the inhabitants of the Keppel Islands could reach the mainland by taking a dog-leg route via the Pelican Island, as they were 13 km from the coast of the continent. There were not many trips to the mainland, though it could be reached the distance was large, the people on the islands becoming effectively isolated. These now-island people underwent the same process as animal populations do, becoming smaller and more inbred (the island effect), and their language began to change and new rituals developed. As     with other groups of people who were isolated at this time they adapted their material culture to suit their new requirements, shields, ground-edge stone axes and boomerangs disappeared from their occupation deposits The also began making new tools such as fish hooks from turtle shell and coconut shell, stone drills for making fish hooks, yam-digging sticks, harpoons with detachable heads for hunting sea turtles and marine mammals. Their access to other islands and the sea was by communal logs that were paddled by hand.

According to Cane1 the people living on the coast of north Queensland at the time were impacted, though they were not devastated by the rising water, rather they were affected by the impact the isolation of parts of their extended society, as the people that once occupied territory adjacent to them that were restricted to their islands. The would also have had needed to adapt their material culture now that the coastal plain was gone, and with it rich hunting country, they were now living directly by the sea and needed to change their tools to take advantage of the new, different resource. They would still be able to see the smoke from the fires of those that were now just out of reach on the adjacent islands.

The lateral encroachment of the sea would have been more noticeable to the inhabitants of the flatter coastal plains which would account for the of those living on high grounds escaping to the mainland before it was too late. Between 9,000 and 8,000 years ago vacated sites on the western coast of the continent such as Noala Cave and the Montebello Islands. The inhabitants of the nearby Barrow Islands and the Recherche Archipelago, and further to the south, Rottnest Island apparently escaped to the mainland before they were cut off. The people living the larger upland areas, promontories and peninsulas had more a problem knowing if they needed to escape to the mainland, it may have appeared to them that their home territory was large enough to avoid being cut off, or at least being large enough to survive if the remained in their country. Cane1 suggests other reasons why they would have been reluctant to leave, such as the possibility of regional territories being present on the soon-to-be-islands, and they had no way of knowing how much things would change if they stayed.

On the Bassian Plain people lingered as the water surrounded them, evidence of their decision to remain being a hearth found in Cave Bay Cave that has been dated to 15,400 years ago. As more people were crammed into the country the occupation intensified, the people of the plains were being forced to live in a country that was contacting as the area of the peninsula continued to diminish. By 6,500 years ago the peninsula was an island. As evidence of the most recent camp has been dated to 6,600 years ago is seems they escaped to the mainland just in time.

The occupants of Flinders Island apparently dallied too long being forced back into the uplands of this large island, about 1,300 km2 in area, by the encroaching sea. It appears to have been known to the people of the plains that the sea was rising, as is suggested by the abandonment of the hills that formed the smaller islands before they were surrounded. On Badger Island and Prime Seal Island there is no evidence of human habitation after 9,000 years ago, at which time occupation appears to have ceased abruptly, though it had been occupied since the glacial maximum 21,000 years ago. Cane1 suggests the decision to retreat to Flinders Island was a miscalculation, though at the time it probably seemed like a good idea. They could not have known that another climate change would make the island to small to sustain them all. It is not known how many of the people stayed as the island was surrounded by water, though managed to survive for 2,000 years after the sea level stabilised. Another unknown is what happened to them during those 2,000 years. Cane1 has suggested some possible scenarios such as a slow decline in population until there were not enough to survive genetically, though he suggests it is unlikely they ran out of food as not all the available resources were available to them, and being coastal foragers did not exploit near-shore resources such as abalone and crayfish. During the Holocene the climate became more variable with droughts becoming more common and extreme, so they may have died of thirst. There would have been no escape route available as the climatic conditions declined drastically in the Late Holocene. The water gap they needed to cross to escape to Tasmania would have been to difficult to cross as the tidal current in this water gap flows at 10 km/hour, one of the strongest currents in the world.

The same fate befell the people who retreated to Kangaroo Island, with the population moving to higher ground as the water encroached. This island had been a substantial promontory adjacent to the coast, the about 6,400 years ago it became an island. At 4 times the size of Flinders island it is a large island, though it was still not big enough. The inhabitants of the promontory and the surrounding plain had been there since 16,000 years ago, then about 11,000 years ago they are believed to have retreated to the island as the sea encroached. At Seton Site on Kangaroo Island there is evidence of occupation that was more intense at this time, including more stone, bone and charcoal among which are 2 bone points that seem to have been used for working skins. After this time there is decreasing evidence of occupation, with only sparse scatterings of stone and shell to indicate a small population on the island. The youngest site to be found has been dated to 4,300 years ago, though regular burning continued until about 2,500 years ago, Cane1 suggesting the people may have lived on the island until evidence of regular burning ceases 2,500 years ago.

Sources & Further reading

  1. Cane, Scott, 2013, First Footprints: The epic story of the first Australians, Allen & Unwin

Scott Cane has included in his book, written as a companion to the ABC TV series of the same name, a number of stories from his days living among Aboriginal people in the desert and moving around with them.

Author: M. H. Monroe
Last updated  15/12/2013
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