Rising Seas Swallowed Countless Archaeological Sites. Scientists Want Them Back
From Doggerland to Beringia, the sea took some of prehistory’s most important archaeological sites. All over the world, scientists are beginning to find them again.
— Read on discovermagazine.com/2019/june/return-to-aquaterra
New Open Access Article (Free to download)
Shell middens, or shell-matrix deposits, occur in large numbers across the coastlines of the world from the mid-Holocene (ca. 6000–5000 cal BC) onwards, often forming substantial mounds. However, they become smaller, rarer or absent as one goes back into earlier periods, suggesting a world-wide process of economic intensification. Since sea level was generally much lower during these earlier periods, a critical question is the extent to which mounded shell middens could have accumulated on now-submerged palaeoshorelines, and if so, how they were affected by the potentially destructive impact of sea-level rise. Further, and important to modern practice, it is essential that archaeologists consider how such sites can be discovered through underwater investigation. Here we offer a proof of concept that shell middens can survive submergence and can be detected, using systematic investigation of a rare example of a confirmed underwater shell midden at the Mesolithic site of Hjarnø (ca. 5300–4300 cal BC) in Denmark. We compare the excavation results with the results of geophysical survey, explore the problems of distinguishing underwater cultural shell middens from natural shell beds and conclude that shell middens can survive inundation by sea-level rise and can be detected by remote sensing, but require at least minimally invasive sampling to establish their cultural status. We suggest the methods developed may be applicable to coastal and marine sites impacted by postglacial sea-level rise worldwide.
Keywords: Mesolithic, Ertebølle, underwater archaeology, submerged landscapes, sidescan, sub-bottom profiling
As a PhD candidate on the DHSC project my research focuses on an international comparative study of submerged landscapes. I am starting with an existing knowledge of the submerged Neolithic sites off the Carmel Coast of Israel, an area I have studied for some time and on which I wrote my Honours thesis. Understanding how these sites were formed, transgressed by postglacial sea-level rise, and preserved – eventually to be found and recorded by archaeologists, will help me to complete my aim to compare these submerged sites with prospective areas in other areas around the world, including in the DHSC study area in NW Australia. In a similar way to the DHSC project’s ongoing work in Denmark, this allows us to move from a known example of submerged landscape archaeology in the Eastern Mediterranean, learn from it, and extrapolate what I can to better understand the potential in Australia.
I began my PhD in early 2018 and while it has certainly been a steep learning curve, it has also been immensely rewarding. In April 2018, I attended the meeting of the Scientific and Technical Advisory Body for the UNESCO 2001 Convention on the Protection of Underwater Cultural Heritage, held in Paris, France. I also took the minutes for the meeting of the UNESCO UNITWIN Network for Underwater Archaeology. Both meetings provided an ideal opportunity to learn more about the increasingly global community involved in underwater archaeology, and to be present for the discussions surrounding the implementation of the 2001 Convention. Amongst the subjects raised at both meetings was the upcoming Decade of Ocean Science (2021-2030), and the involvement of the underwater cultural heritage community. There is certainly potential for the contribution of submerged landscape research, with both meetings emphasising the integration of underwater cultural heritage with spatial planning, and the development of palaeoenvironmental knowledge bases.
In May/June and again in September/October of last year, I assisted with a series of marine geophysical surveys conducted by the DHSC team in the Dampier Archipelago. Along with other members of the project team, I spent several weeks conducting surveys with a sidescan sonar to better understand the features at the bottom of the ocean around the Dampier Archipelago. The sidescan sonar provides high resolution imagery of the sea floor, allowing the team to analyse the seabed textures and associated features as we refine our survey strategy to analyse submerged landscapes. We’re now working through the data to search for areas which might be conducive to the preservation of archaeological material, and other noteworthy features on the seabed.
Also in 2018, I joined the DHSC team in Hjarnø, Denmark, where I assisted Francis Stankiewicz and Paul Baggaley in conducting sidescan sonar and sub-bottom profiler surveying. The data from these surveys will be analysed alongside marine sediment cores, and this combination of marine geophysics and coring provides information about how sediments developed over time, and allows us to reconstruct the past (now submerged) landscape. I was also able to join the underwater team and assist in the excavation of a submerged Mesolithic settlement. This field season marked an important milestone for me: my first dives on a submerged prehistoric site. The bulk of my undergraduate training was in terrestrial archaeology, so I learned to dive specifically to transfer my archaeological abilities to underwater prehistory. The cultural material obtained from these sites is remarkably preserved, and the knowledge to be gained from the analysis of submerged sites is critical in furthering our understanding of human interactions with the marine and coastal environment.
Last July, I travelled to Israel, where I joined a team of researchers on the Bronze and Iron Age site of Tel Dor to undertake further training in underwater archaeological methods. The Near East has an extraordinary amount of archaeological material in both the terrestrial and underwater environment, and the team at Dor aims to integrate the data from its terrestrial and underwater excavations for a rounded view of the maritime history of Dor. We also held a 2019 joint field school between Flinders University and the University of Haifa as part of the UNESCO UNITWIN Network for Underwater Archaeology.
In the past year of eclectic experiences in underwater archaeology in different parts of the world, it has become especially evident that international and interdisciplinary collaboration is key not only to my own professional development, but to undertaking well rounded and widely contextualised archaeological research. It is especially important to me as well as to the DHSC team, in our efforts to illuminate and better understand the submerged past.
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.
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.
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?
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
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!
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.