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.
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.
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.
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.
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.
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.
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.
This is the airborne component of the DHSC project. We fly our small research aircraft, an ECO- Dimona motorglider (DIMO) custom-built by Diamond Aircraft in Austria for research flying. The aircraft (VH-EOS and its identical sister ship, VH-OBS) are owned and operated by Airborne Research Australia (ARA) in Adelaide. The ARA is a Not-For-Profit Approved Independent Research Institute. Jorg Hacker is the Director and Chief Scientist of ARA, as well as a Professor of Airborne Environmental Research at Flinders University. Shakti is employed by ARA as field assistant, operating the airborne instrumentation and arranging logistics support.
Our “magic carpet” carries a very comprehensive array of sensors – most importantly two state-of-the-art and powerful airborne LiDARs, one for topographic measurements, the other one for bathymetric measurements, with the latter one also capable of seeing dry surfaces over land. The LiDARs are a Riegl Q680-i-S and a Riegl VQ-820-G, funnily enough also manufactured in Austria, so they fit our aircraft perfectly. Each LiDAR has its own top-of-the-range GPS/IMU system mounted to it to determine the position and attitude (pitch and roll angle and heading) at extremely high accuracy (a few cms for the position and altitude and about 1/100th degree for the angles) 200 times per second. If the reader does not know what an airborne LiDAR is, have a read here. The DIMO also carries a Canon EOS 5D DSLR-camera looking downwards and taking images every few seconds, as well as a GoPro video camera. The instrumentation we carry is worth about $1M, so we better are very careful in what we do with it.
In this Blog, I thought it may be interesting to read how we got from Adelaide to the field site in NW-Australia and back home. This journey is quite different from how the rest of the project team gets there – by taking the airline to Karratha. The way to tell the story is through the regular reports I emailed to the DHSC project team – somewhat shortened as not make this Blog too long.
Excerpts from our trip journal:
Report #1 sent to the DHSC team on 20 Sep (after flying 750km from Adelaide)
I just wanted to let you know that Shakti and I have left Adelaide this morning for Karratha. The past few days have been very hectic and I think it may well be of interest to you to hear what it means to fly very expensive instrumentation in a small aircraft. As some of you know, we had problems with the bathy lidar on the trip preceding this one (mapping mangroves and fishtraps in the Gulf of Carpentaria for 70 flying hours within 3 weeks between Weipa and Groote Eylandt, based out of Burketown). This is not really surprising, because the way we are flying that LiDAR is rather unusual. Normally these instruments are flown in much larger and air-conditioned aircraft, not in a simple pod under the wing of a motorglider. After our return from this trip (on Thu, 7th Sep), we immediately attempted to rectify the problem. With great assistance from Riegl, we have (hopefully) repaired the bathy lidar (treating it with due care) and proved that it works again during a (short) testflight yesterday. The topo lidar had worked perfectly during the Gulf of Carpentaria trip generating more than 3TB of raw data.
Next, we had to do a “quick” change of aircraft. The plan was to perform a 100-hourly maintenance inspection on the same aircraft (VH-OBS) that we used in the Gulf of Carpentaria where it performed flawlessly. However, when we started the inspection, we detected a small fault in its engine which needed to be rectified before flying thousands of kilometers through remote Australia (again) and then being based about 3,000km away from our facilities in Adelaide. To deal with this fault will take about a week, so we decided to transfer the instrumentation to our other aircraft (VH-EOS) – about a 2-day job. And this is what we are flying today.
Report #2 sent to the DHSC team on 22 Sep (after flying 2,100km from Coober Pedy to Broome)
We have now arrived at Broome, our last stop before the final section of the ferry flight planned for tomorrow (from Broome to Karratha, about 650km following the coastline to the WSW).
This trip again illustrated what one faces when ferrying a small research aircraft from the south coast to the north coast of Australia. The flight from Adelaide to Coober Pedy (Australia’s premiere Opal town) was relatively eventless (on the 20th), flying at around 8,500ft into a headwind of sometimes up to 25 knots. In Coober Pedy, we stayed in a nice motel that is constructed in the same way as our own house in the Adelaide hills, the Mud Hut Motel. The people there took the trouble to drive us with our jerry cans twice to the main service station in town, so that we could fill up our tank with Premium Unleaded Petrol. Good.
The next stage of the ferry flight (on the 21st) again required struggling with strong headwinds, so that it took 4.5 hours to reach Alice Springs. The visibility was not great, because there was a lot of smoke and dust in the air. Air Traffic Control in Alice Springs gave us a bit of a “run-around” on arrival, but we arrived safely finding the air temperature at 37deg C – everybody said this is unusual for this time of the year. We refuelled and after having a bit of “fun” starting our engine due to the heat, we were ready for take-off for the next sector – to a cattle station on the edge of the Tanami Desert, Vaughan Springs, also known at Mount Doreen Station. Taking off with a fully laden Dimona in this heat is an interesting “balancing act”. The engine only develops 115HP to lift off an aeroplane weighing 930kg – and that for 5 minutes maximum only. After that it is back to 90HP or less. The engine also gets rather hot during a slow climbing flight, so one needs to be quite carefully monitoring the oil and water temperatures. The Tower was friendly enough to give us the full length of the 3km runway at Alice Springs and when we were very slowly climbing out to the West and hit a thermal at low altitude, they allowed us to circle in this thermal, this way gaining height rather quickly until we reached our cruising altitude of 8,500ft.
The Dimona has so far behaved extremely well giving us no trouble at all. I hope it stays like this.
The plan is to arrive tomorrow in the early afternoon at Karratha and establish ourselves there. Sunday we have planned a day off to start the campaign with a first data capture flight on Monday. I haven’t checked the tides yet….
Report #3 sent to the DHSC team on 23 September:
We made it to Karratha today!
The aircraft is safely tied down, with the nose pointing into the strong wind that slowed us down considerably on our flight from Broome today. This also means that we had strong headwinds for just about the whole 3,500km long ferry flight. Tomorrow we will have a day off and then do the first flight on Monday.
Report #4 sent to the DHSC team on 3 Oct:
This is just to report to you that we have completed all flying here at Karratha. And I can report that everything worked 100%.
I attach an image showing all flightlines for which we have topographic and bathymetric lidar (except the very dense pattern over Enderby and the small dense one directly over Goodwyn Island, where we have very high resolution topographic lidar only. For all of these lines, there are also high resolution RGB-images taken every 4 seconds (approximately 11,000 of them). You will have to look at each one of them ! And we have also really nice GoPro footing for all flights looking vertically down plus several hundred oblique photos out of the window of the aircraft.
The bottom line is – we have collected 2.5TB of raw data.
Report #5 sent to the DHSC team on 5 Oct:
Originally we had planned to fly that task today in the afternoon, but decided that the wind may be friendlier tomorrow morning. So instead we went to one of the beaches looking west across Ningaloo Reef. And there we were presented with a most amazing sight: mating turtles in the surf about 20m from the water’s edge.
Report #6 sent to the DHSC team on 8 Oct:
On the 7th Oct, we laser-scanned the coastline and some underwater areas near Coral Bay, then re-fuelled at Carnarvon before continuing along the coast. Further South, we flew over Hamelin Pool and laser scanned (and photographed) the Stromatolites (I guess everybody knows them…). We re-fuelled and overnighted in Geraldton and then proceeded in rather bad weather to Kalgoorlie. The closer we came to Kalgoorlie, the better the weather became. But not only that – for the first time for the whole trip, we actually encountered better and better tailwinds – a sign of what coming tomorrow on the last leg home.
And his evening we arrived back in Adelaide. We had an incredibly quick flight from Kalgoorlie to Adelaide, 1,711km in about 7 hours, with only one refuelling stop at Forrest in the Nullarbor. We used just 140 litres of Premium Unleaded petrol. Try this with any other means of transport! The flight was so quick, because we had an ever increasing tailwind of up to nearly 100km/h, flying at 3,000m AGL. The attached photograph was typical for what we saw during the flight.
During the whole trip, we flew 67 hours which equals about 10,000km and it took us 18 days.
Thanks for reading this long Blog – more to come.
It’s late July, and Peter Ross and I are here joining in the very last field trip at Watering Cove for Murujuga: Dynamics of the Dreaming ARC Linkage project, led by one of our Sea Country CIs, Jo McDonald. It is another opportunity to familiarise ourselves with the kinds of landscapes and archaeological sites that might have been drowned during the post-glacial transgression.
Watering Cove has great diversity of landscapes – towering boulders and cliffs overlook dune deposits, mangrove and salt flat environments, and wide beaches, seaward of which is an extensive reef limestone platform. At the northern end of Watering Cove, is an ancient eroded dyke on which the majority of rock art is found. This extends right down into the ocean. We look hopefully for rock art in the shallow waters around the dkye but find nothing. Further south is the wide dry creek above which we are camped.
Peter has already been here a week, helping to excavate the dune deposits. There were a range of midden deposits which have been explored by the team, and at their deepest (over 2m) it would seem likely that these are still only early Holocene in age. When I turn up, some of the team is moving to an inland valley to excavate a dense midden site in an area known as “Old Geos”, named after the many ancient geometric rock art motifs in the surrounding galleries. The area also hosts a number of stone circle arrangements and some possible standing stones. The surface midden here is Anadara (known to be a late Holocene phenomenon): below this is an older Terebralia (Mangrove species) layer, and below this is an artefacts layer with no shellfish remains. As is typical, on the last day, in the last spit, Peter finds a horsehoof core – an indication that the earliest occupation of this site may be even older and more complex than initially thought.
These archaeological sites and the landscape features around them, record the changing dynamics of the region. Although the resolution in most sites is coarse, covering millennia rather than centuries, the combined record provides the detail of this change. In the same way, no single underwater site can reveal the nature of the drowned coastline. The current archaeological landscapes will provide the critical analogues to guide our underwater explorations.