The second half of 2018 was a very busy time for the DHSC Project. Our blog couldn’t keep up with the various fieldwork, publication and future preparation that our project team was busily undertaking. However we will be rectifying this soon — stay tuned for more posts and updates on the Deep History of Sea Country Project.
DHSC’s Team of International Volunteers: Katie and Kat
Katie Woo and Katarina Jerbic are PhD students from two Australian universities. They join the DHSC core team here in Hjarnø this month to contribute to the project and to learn about submerged archaeology in a new environment. Both Kat and Katie focus their own research on past environments and their influence on prehistoric human populations. This week they undertook the task to core marine sediments at a new site in order to characterise the formation and distribution of geological and cultural sediments.
Kat finished her MA in Archaeology and Ethnology at the Faculty of Humanities and Social Sciences at the University of Zagreb, Croatia in 2009. Participation in prehistoric digs excavations throughout her university years resulted in a keen interest in prehistoric archaeology. Her MA thesis, which focussed on the prehistoric pottery of the Jačmica cave, led to an on-going position at the Archaeological Museum of Istria in Pula. That’s when she began excavating a 6000-year-old submerged prehistoric pile-dwelling settlement in Zambratija Bay in the Adriatic Sea, which resulted in her training to be a diver to help assist with the recording of the site. That led to an opportunity to undertake a PhD at Flinders University. Katarina’s contribution to this year’s fieldwork in Hjarnø was to core the seabed around the excavation trenches in order to determine the extents of the cultural layers as well as to reconstruct the past sea-level change on the site by looking at the presence of microfossils in the cultural sediment layers from the site.
Katie is an archaeomalacologist (shellfish analyst) doing her PhD at the University of Sydney. Her research focusses on shell midden sites located in Western Arnhem Land, in the north of Australia. She is using a combination of archaeological, ecological, and biological data to reconstruct the diets, landscape use patterns, and environmental impacts of the groups inhabiting the area throughout the Early to Mid-Holocene (9000-2000 years ago). Previous excavations in Hjarnø have uncovered a significant amount of shellfish material which relates to the Ertebølle Culture. Katie was invited to join the Deep History of Sea Country project to analyse the shellfish material, and to bring a new perspective to the study.
Their main role so far has been to collect data to reconstruct the development of the sediments in the fjord. The layers found within these cores have been described, drawn and photographed for documentation. This data will then be compared with the sub-bottom and side scan sonar data, being collected by the marine geophysicists, to reconstruct how the sediments in the fjord have been laid down over time.
Kat and Katie have been enjoying their time on the fieldwork, learning from each other as well as the rest of the team. They are looking forward to integrating their results with the rest of the team’s data to help answer questions about the submerged prehistoric past.
Australia Versus Denmark
It is June 21st 2018. Today is the big day: Australia versus Denmark in the World Cup. Both teams had two years of tough qualification rounds to make it into the Cup – but more importantly, our Danish colleagues tell us that the Islanders have been looking forward to us coming to watch the game – presumably because Denmark are the heavy favourites to win today.
This week is also a big week for DHSC. The team of Australia-based researchers and students are back in Denmark, to excavate the submerged Mesolithic site at Hjarnø with our DHSC colleagues from the Moesgaard Museum. The local community members come down to visit us daily to remind us that we are welcome. It’s the Danish summer but we still get our fair share of weather and, more often than we would like, strong winds. We can’t dive on those days and that can be frustrating. But underwater archaeology is incredibly rewarding because, until relatively recently, the technology didn’t exist to explore these sites so, unlike dry land sites, they’re much less likely to have been raided by looters and they haven’t been built over. But it is up to the sea and the wind and ‘call off days’ (or half days) are common.
Today was a half day. That means only two dives this morning excavating – though fortunately the site is shallow and so the dives are nice and long. But just for today, the team is less heartbroken to have to spend the afternoon topside. Kickoff is at 14:00h CET. Just enough time to get our morning work done, warm up with lunch, and then do some community engagement. The Islanders invited us down to the local community centre. How could we possibly say no?
Game on.
GOAL Denmark 1:0
That didn’t take long! We hadn’t even blown up the green and yellow balloons we brought to the community centre. This could be a long day…
So why does an international team of researchers and research students from Australia come all the way to Jutland to dive in these shallow, cold waters? Because of what we can learn about the past! The submerged prehistoric landscapes and underwater sites, predominantly from the Mesolithic (about 7000 – 6000 years ago) are plentiful in Denmark, and there is no better place to work with experienced professionals. This is especially great for our early career researchers who don’t have access to this kind of site or material and would otherwise have no chance to train to become specialists. But that is not because the submerged sites don’t exist in Australia and elsewhere – they just haven’t been found! Not yet anyway. Training here will supply Australia with its own experienced, professional teams of future experts.
This project and these particular sites are special. They are submerged prehistoric settlements, with incredibly well preserved material: stone tools, bones, ceramics, wood, antler, and shell. We can learn so much here! Shell midden sites are found all over the world, not just in Denmark, so by studying these submerged deposits, we can not only answer questions about European archaeology, but we can begin to understand how sites like this may exist – and be found – all around the world. Shell middens from the early to mid Holocene are also found in the Americas, Africa, Asia and, of course, Australia. There is a very good chance that earlier coastal sites exist in all of these places, around the world. They’re just offshore now, due to rising sea levels in the past. We hope that our research here will inform how our team, and others, might treat the search for, and excavation of, submerged sites.
GOAL Australia 1:1
Australia equalise! Which is exactly what we hope to do in the future; find and explore Australia’s Deep History of Sea Country. We hope to learn as much as we can, build capacity in our junior scholars and early career researchers while we are in Denmark. Our Danish hosts have been amazing colleagues and the dialogue and experience makes us better at what we do.
FULL TIME: 1:1
Everybody wins.
Stay tuned for more blog posts about the team, our students and volunteers and progress this week in Denmark and throughout the remainder of the project!
Deep History of Sea Country Stakeholder Workshop
For most of the 65,000 years or so of occupation in Australia, sea level has been lower than present, yet we know almost nothing about submerged landscapes and their associated cultural heritage. The key to unlocking this unknown potential is through collaborative efforts between different stakeholder and interest groups, maximizing benefits from meaningful collaboration in offshore development activity and allowing for better documentation, management, regulation and discovery of past cultural and other seabed resources.
On 13th March we held a workshop on the Deep History of Sea Country at the University of Western Australia. The Workshop was aimed at organisations and people working in marine and coastal environments including developers and operators, environmental and heritage consultants, regulators, independent scientists, indigenous groups and other stakeholders. Each of these ‘interest groups’ have different aims, perspectives and expectations, with a focus ranging from economic to ecological and heritage.
A series of presentations were given by project team members, which explored the key issues surrounding submerged cultural resources, including what we know, what we need to know and what we need to do to achieve this. Sean McNeair from Murujuga Aboriginal Corporation also gave a presentation on the Indigenous perspectives on Sea Country. Attendees were given opportunities to discuss their perspectives on data, resource management and policy related to submerged cultural landscapes in northwest Australia. These discussions were very helpful and we hope to hold another stakeholder workshop in a years’ time. If you are interested in being invited to this next workshop, please feel free to register your interest with any of the project team members.
In the meantime, we have a forthcoming paper in Ocean and Coastal Management, entitled ‘Recognition and value of submerged prehistoric landscape resources in Australia’, which explores some of these issues. A link will be added when this becomes available.
Australia’s coastal living is at risk from sea-level rise, but it’s happened before
This article was originally published on The Conversations. Read the original article.
With global sea levels expected to rise by up to a metre by 2100 we can learn much from archaeology about how people coped in the past with changes in sea level.
In a study published this week in Quaternary Science Reviews, we looked at how changes in sea level affected different parts of Australia and the impact on people living around the coast.
The study casts new light on how people adapt to rising sea levels of the scale projected to happen in our near future.
Read more: Cave dig shows the earliest Australians enjoyed a coastal lifestyle
Coastal living
More than eight out of every ten Australians live within 50km of the coast.
The Intergovernmental Panel on Climate Change says global sea levels may increase by more than 8mm/year, four times the average of the last century.
A major challenge for managing such a large increase in sea level is our limited understanding of what impact this scale of change might have on humanity.
While there are excellent online resources to model the local physical impacts of sea level rise, the recent geological past can provide important insights into how humans responded to dramatic increases in sea level.
The last ice age
At the height of the last ice age some 21,000 years ago, not only were the Greenland and Antarctic ice sheets larger than they are today, but 3km-high ice sheets covered large parts of North America and northern Europe.
This sucked vast amounts of water out of our planet’s oceans. The practical upshot was sea level was around 125m lower, making the shape of the world’s coastlines distinctly different to today.
As the world lurched out of the last ice age with increasing temperatures, the melting ice returned to the ocean as freshwater, dramatically increasing sea levels and altering the surface of our planet.
Arguably nowhere experienced greater changes than Australia, a continent with a broad continental shelf and a rich archaeological record spanning tens of millennia.
A bigger landmass
For most of human history in Australia, lower sea levels joined mainland Australia to both Tasmania and New Guinea, forming a supercontinent called Sahul. The Gulf of Carpentaria hosted a freshwater lake more than twice the size of Tasmania (about 190,000km2).
Our study shows that lower sea levels resulted in Australia growing by almost 40% during this time – from the current landmass of 7.2 million km2 to 9.8 million km2.
The coastlines also looked very different, with steep profiles off the edge of the exposed continental shelf in many areas forming precipitous slopes and cliffs.
Imagine the current coastline where the Twelve Apostles are on Victoria’s Great Ocean Road and then extend them around much of the continent. Many rivers flowed across the exposed shelf to the then distant coast.
The steep cliffs at the Apostles, off Victoria’s Great Ocean Road, look like parts of the ancient coastline of Australia. Flickr/portengaround, CC BY-SA
When things warmed up
Then between 18,000 and 8,000 years ago, global climate warmed, leading to rapid melting of the ice sheets, and seeing sea levels in the Australian region rising from 125m below to 2m above modern sea levels.
Tasmania was cut off with the flooding of Bass Strait around 11,000 years ago. New Guinea was separated from Australia with the flooding of Torres Strait and creation of the Gulf of Carpentaria around 8,000 years ago.
We found that 2.12 million square km, or 20-29% of the landmass – a size comparable to the state of Queensland – was lost during this inundation. The location of coastlines changed on average by 139km inland. In some areas the change was more than 300km.
Much of this inundation occurred over a 4,000-year period (between 14,600 and 10,600 years ago) initiated by what is called Meltwater Pulse 1A, a period of substantial ice sheet collapse releasing millions of cubic litres of water back into the oceans.
During this period, sea levels rose by 58m, equivalent to 14.5mm per year. On the ground, this would have seen movement of the sea’s edge at a pace of about 20-24m per year.
Impacts of past sea level rise
The potential impacts of these past sea-level changes on Aboriginal populations and societies have long been a subject of speculation by archaeologists and historians.
Map of Australia showing sea-level change and archaeological sites for selected periods between 35,000 and 8,000 years ago. PMSL=Present Mean Sea Level. Sean Ulm, Author provided
In his 1970s book Triumph of the Nomads: A History of Aboriginal Australia, the Australian historian Geoffrey Blainey hypothesised that:
Most tribal groups on the coast 18,000 years ago must have slowly lost their entire territory […] a succession of retreats must have occurred. The slow exodus of refugees, the sorting out of peoples and the struggle for territories probably led to many deaths as well as new alliances.
Archaeologists have long recognised that Aboriginal people would have occupied the now-drowned continental shelves surrounding Australia, but opinions have been divided about the nature of occupation and the significance of sea-level rise. Most have suggested that the ancient coasts were little-used or underpopulated in the past.
Our data show that Aboriginal populations were severely disrupted by sea-level change in many areas. Perhaps surprisingly the initial decrease in sea level prior to the peak of the last ice age resulted in people largely abandoning the coastline, and heading inland, with a number of archaeological sites within the interior becoming established at this time.
Cross-section profiles of the continental shelf at Port Stephens, NSW (top) and Cape Otway, Vic (bottom). PMSL=Present Mean Sea Level. Sean Ulm, Author provided
During the peak of the last ice age, there is evidence on the west coast that shows people continued to use marine resources (shellfish, fish etc) during this time, albeit at low levels.
A shrinking landmass
With the onset of the massive inundation after the end of the last ice age people evacuated the coasts causing markedly increased population densities across Australia (from around 1 person for every 355 square km 20,000 years ago, to 1 person every 147 square km 10,000 years ago).
Rising sea levels had such a profound impact on societies that Aboriginal oral histories from around the length of the Australian coastline preserve details of coastal flooding and the migration of populations.
We argue that this squeezing of people into a landmass 22% smaller – into inland areas that were already occupied – required people to adopt new social, settlement and subsistence strategies. This may have been an important element in the development of the complex geographical and religious landscape that European explorers observed in the 18th and 19th centuries.
Following the stabilisation of the sea level after 8,000 years ago, we start to see the onset of intensive technological investment and manipulation of the landscape (such as fish traps and landscape burning).
We also see the formation of territories (evident by marking of place through rock art) that continues to propagate up until the present time. All signs of more people trying to survive in less space.
Read more: Buried tools and pigments tell a new history of humans in Australia for 65,000 years
So what are the lessons of the past for today? Thankfully, we can show that past societies survived rapid sea level change at rates slightly greater than those projected in our near future, albeit with population densities far lower than today.
But we can also see that sea level rise resulted in drastic changes to where people lived, how they survived, what technology they used, and probable modifications to their social, religious and political ways of life.
In today’s world with substantially higher population densities, managing the relocation of people inland and outside Australia, potentially across national boundaries, may provide to be one of the great social challenges of the 21st century.
Note, this article was amended on Friday 19 January 2018 at the request of the authors to correct the IPCC’s projected rise in global sea levels.
