Lost and future worlds: marine palaeolandscapes and the historic impact of long-term climate change

Alice Roberts explores the importance of coastal routes to our ancient ancestors, colonising the globe in the Palaeolithic, and looks at sites through prehistory which show how humans exploited and adapted to watery places, from Pinnacle Point in South Africa to the earliest humans in the Americas, and the Bronze and Iron Age landscapes of the Somerset levels and the Cambridgeshire Fens. Submerged landscapes hold the key to understanding so much about our ancestors, but can the ancients’ flexible approach to their environment also hold lessons for us, today?

Professor Alice Roberts, University of Birmingham

Professor Alice Roberts, University of Birmingham

Alice Roberts is an anthropologist, author and broadcaster, and Professor of Public Engagement in Science at the University of Birmingham. She is an honorary fellow of the British Science Association and a Fellow of the Royal Society of Biology. She has received honorary doctorates from Royal Holloway University of London, Bournemouth University, Sussex University and the Open University.

Alice has presented a wide range of television programmes, often considering the role of climate and environment in the evolutionary trajectories of humans and other species. One of the original presenters of BBC 2’s long-running Coast series, she went on to present many other programmes and series for BBC2 and BBC4, including The Incredible Human Journey, Digging for Britain, several Horizon programmes, Origins of Us, Ice Age Giants and Digging for Britain. She is also a regular presenter on Radio 4’s environment series, Costing the Earth. 

She has written seven popular science books. Her book on human embryology and evolution, The Incredible unlikeliness of Being, was shortlisted for the Wellcome Trust Book Prize in 2015.

Inundated and submerged prehistoric landscapes on the continental shelf have been studied internationally for decades, but, in the early years, only by individual scholars and local research groups.  The academic and political status of the topic has increased recently and the value of the research has been noted in the 72nd session of the Oceans and Law of the Sea report to the Secretary General of the United Nations for 2017. There are no formal national or multi-national commitments specifically to this research area, although numerous treaties, conventions and regional agreements are structured in such a way that submerged landscapes and prehistoric sites are included in their provisions. The definition of Underwater Cultural Heritage in the UNESCO Convention includes prehistoric sites, as does the United Nations Convention on the Law of the Sea. In Europe DG-MARE recognises the value of mapping submerged landscapes, and maps and data bases are being developed by EMODNet. The European Marine Board and the European Archaeology Council supported the publication of a joint report on the subject. Regional groups such as SINCOS and NSPRMF have supported work in the Baltic and the North Sea, while a longstanding sequence of INQUA-IGCP projects has been organised in the Black Sea. In the USA NOAA has a budget line for submerged landscapes, while the SPLASHCOS project supported by the COST Action Office integrated available data across the European seas with budget support for 4 years. As yet there are no permanent institutional or treaty-type commitments specifically aimed at supporting submerged landscape research, and this is a point of weakness. Everything still depends on individuals persuading their host institutions or agencies to provide support for the research. In spite of the high status of some of the support being provided, and the excellent research undertaken in many countries, the financial support is still minimal, and there are no long term commitments or funded institutions

Dr Nicholas Flemming, National Oceanography Centre

Dr Nicholas Flemming, National Oceanography Centre

Dr Flemming has, since 1960, studied Pleistocene and Holocene relative sea level change and its interaction with prehistoric archaeological indicators. Most of his work before 1980 was in the Mediterranean, but more recent studies have been in North Australia, the Middle East, and the southern Red Sea. He co-edited the first global review of known seabed prehistoric sites, which was published in 1983.  In 2002 he convened an international meeting to integrate prehistoric studies in the North Sea, and in 2008 was active in launching the Deukalion and SPLASHCOS projects studying the European continental shelf. He has recently edited the SPLASHCOS volume on European Continental Shelf Palaeoenvironments, and has published a review of the connection between human submerged prehistoric landscapes with identified archaeological sites and their role in ground-truthing global human dispersal where part of the route was probably on the continental shelf.

Landscapes have evolved throughout geological time through a combination of geological and climatic processes. On the time scale of Homo sapiens the dominant physical changes in global landscapes are a consequence of the ice ages with their concomitant rise and fall in sea level and flooding and re-emergence of the continental shelfs and islands. Flood legends from many parts of the world attest that humans have attempted to explain their experiences of these changes within their framework of knowledge and the present discussion on the subject is one further step in that process. As ice sheets wax and wane, sea levels globally and on average, rise and fall in unison.  But the local or regional response can vary significantly from place to place due to the response of the planet to the redistribution of ice and water. The Earth deforms internally and surficially in response to these changes and the ocean surface re-adjusts to this new shape and associated changes in gravity.  This response is not instantaneous but lags behind the glacial cycle by amounts that are geography dependent. The result is a complex spatially and temporally variable global pattern of sea level change that cannot be adequately represented by simple concepts such as eustasy but one that contains important information on both the response of the Earth to forcing and of the glacial history. Such variability is indeed observed world-wide but the evidence is sufficiently incomplete and often imprecise to give a comprehensive description of this change. Thus physics-based models, founded in well-tested theories and observations from other geophysical and geological disciplines, have provided the means to interpolate between the disparate observations and to provide a predictive capability of sea level change and shoreline migration (always putting aside that the glacial cycle is not the only process that operates).  These models and their limitations will be discussed in this presentation, tested against observational evidence, and used to reconstruct coastal landscapes for some of the regions that may be relevant to some of the following presentations during this meeting.

Professor Kurt Lambeck, Australian National University

Professor Kurt Lambeck, Australian National University

Kurt Lambeck FAA, FRS, is Emeritus Professor at the Australian National University; since 2011, a periodic visiting professor at the Ecole Normal Supérieure in Paris, and the 2016-2017 Johannes Geiss Fellow at the International Space Science Institute in Berne.  His current research interests are in the relationship between ice sheets oceans and the solid Earth through glacial cycles, including the consequences on past landscapes and human movements. 

Very high resolution (VHR) seismic imaging of buried palaeolandscapes in the southern North Sea poses a number of problems. The often sandy sea floor induces strong multiples that may obscure the data especially in shallow water (<10-15 m). Detailed imaging below sand banks is difficult because the short wavelength sound waves are quickly absorbed in the heterogeneous sandy sediments. Intertidal areas furthermore add additional challenges due to highly variable water depth (0-5m), wave action and strong currents. Within the framework of the SeArch project (www.sea-arch.be) an efficient survey methodology was developed for archaeological prospection of the subtidal and intertidal area. In the subtidal area this was done through the comparison of a range of seismic sources (covering a wide range of the frequency spectrum) and receiver combinations. The results show that sparker sources generally provide the best trade-off between image resolution and penetration depth. Surprisingly, multichannel recording significantly improved the image resolution already for shallow target depths. In the intertidal area a novel technique based on multi-transducer parametric echosounding was applied. This resulted in ultra-high resolution 3D images of the shallow sub-bottom (cm/dm range). Grid cell sizes as small as 20x20cm allowed to identify buried features in unprecedented detail. This opens important new perspectives for archaeological prospection in shallow water areas.

Dr Tine Missiaen, Ghent University

Dr Tine Missiaen, Ghent University

Dr Tine Missiaen has been involved in marine acoustic research since 1988. Since 1990 she has mainly been working at Ghent University, besides a short intermezzo in France (Ifremer, Centre de Brest) and a number of years part-time involvement in the Netherlands (Delft Technical University). Main research topics include very high resolution 2D and 3D seismic data acquisition/processing/interpretation, geo-acoustic parameter studies, subbottom imaging in intertidal areas and land-sea boundary areas, acoustic studies of shallow (biogenic) gas, munition dumpsite research, as well as non-conventional acoustic techniques for engineering and environmental studies. In recent years her research focus has been largely on marine archaeological studies, specifically the mapping of submerged prehistoric palaeolandscapes and detection/identification of buried archaeological remnants. At present she is coordinator of the successful Belgian research project ‘SeArch’ (Archaeological heritage in the North Sea; www.sea-arch.be).

Occupation in Australia is now dated back to 50 ky BP, and for the bulk of this period sea level was lower than present.  Nearly one-third of Australia’s landmass, hence a significant part of the archaeological record, was drowned by the post-glacial transgression. Despite this, research aimed at finding submerged prehistoric archaeology on the drowned shelf is only just beginning. Over the next few years, a pioneering, multi-disciplinary study of submerged landscape archaeology will investigate the records of the now-submerged Pilbara coast in NW Australia (spanning 50 to 7 ky BP) and contribute a unique southern hemisphere insight into world prehistory.  For Australia’s NW Shelf, knowledge is increasing rapidly on its preserved drowned palaeoshorelines through use of high-resolution remote sensing data, palaeotidal and 3D modelling.  Computer-based visualisations, which overlay relative post-glacial sea levels on the modern bathymetry, help conceptual understanding of the changing coastal landscape.  However, the past development of coastal resources, their potential human use and the preservation of this in the archaeological record is primarily controlled not by sea level per se but by second and third-order effects associated with variations in coastal sedimentary environments.  Considering such physical processes in archaeological thinking will help and improve targeted prospection of submerged cultural sites, and will help stimulate new ways to include such information in conceptual models of human occupation and help us solve for the unknown.

Dr Ingrid Ward, Flinders University

Dr Ingrid Ward, Flinders University

Dr Ward's background is multidisciplinary, including geological and archaeological research of terrestrial and marine environments.  She has worked in Australian and UK academic, consultancy and regulatory organisations, including English Heritage, where she became interested in submerged landscapes of the southern North Sea.  Since returning to Australia in 2011, she has promoted work on the prehistory of submerged landscapes, particularly off NW Australia.  In the last few years she has performed geoarchaeological research on an offshore island site (Barrow Island), where cave records preserve a record of occupation from ~ 53 ky BP and provides the earliest Australasian evidence for marine resource use by modern humans.  Recently, with European and Australian colleagues, we have received funding to explore what is known to Indigenous Australians as Sea Country.  This 3-yr project will investigate submerged sites off the Pilbara coast spanning ~ 50 ka, providing a unique southern hemisphere insight into world prehistory.

Human DNA evidence of living populations suggests that between ~30,000 and ~15,000 yr BP, people paused in their migration into the New World from Siberia.  Where did they pause? Was the now-submerged Bering Land Bridge (BLB) a suitable place to live?  Vegetation reconstructions based on a variety of proxies (pollen, plant macrofossils, aDNA) indicate wide-spread herb-dominated tundra on the BLB, though there is intriguing evidence that woody taxa may have been more abundant than is generally assumed. Full glacial and late glacial pollen distribution maps from across Beringia, of which the BLB is only the central region, suggest in situ expansion of key taxa (cottonwood/aspen, spruce, pine, birch, and alder) and not migration from outside the region.  In addition, DNA results on modern spruce indicate long isolation of Alaskan populations from those growing south of the Laurentide ice sheet, suggesting that some Alaskan populations could have survived the last glacial age in Beringia.  Finally, some localities on the BLB may have been somewhat mesic, thus providing suitable habitat for the woody taxa to occupy.  However, issues with chronology, site taphonomy, and pollen-vegetation linkages do cloud the issue.  This presentation summarises current data on the BLB and adjacent regions and presents the pros and cons of the BLB as a suitable landscape for long-term human occupation.

Dr Nancy Bigelow, University of Alaska

Dr Nancy Bigelow, University of Alaska

Vegetation and landscape change in Beringia (the Bering Land Bridge and adjacent landmasses) are the foci of Nancy Bigelow's research.  Using pollen and plant macrofossil remains, she reconstructs Beringian landscape at a variety of spatial scales and over a variety of time periods from the Last Interglacial (125,000 years ago) through the late Holocene. Most recently her interests have focused on the landscape as people would have encountered it.  Specifically, were woody plants present, either during the last ice age, or at high elevations during the Holocene? Has there been anthropogenic alteration of the landscape?  And do large-scale vegetation groups (biomes) shed light on local plant availability? Bigelow’s research is highly collaborative and it is only through multi-proxy studies that these questions can be addressed.

The Pleistocene occupation of northwest Europe occurred during a period characterised by significant climatic changes. In Britain, hominin populations were present discontinuously through varied climates, from cool continental sites such as Happisburgh 1 and 3, to the balmy Mediterranean conditions of Pakefield. Whilst apparently able to survive through a range of conditions, the configuration of these landscapes, in particular the presence or absence of a land connection with the continent, would have had a fundamental impact on the density of hominin occupation in Britain at any given time. Similarly, the ecologies once present in the now-drowned North Sea Basin and Channel regions would presumably have played an important role in attracting and sustaining sporadic hominin populations. However, our understanding of the physical and environmental character of these landscapes, as well as the timing of transgressive and regressive periods, remains frustratingly murky, hindering the ability to imagine how these landscapes may have been used. A growing body of data from recent research and commercial offshore development is, however, beginning to address this issue: we can now start to piece together a more coherent picture of landscapes through time, but there is still an immense amount of work to do. By drawing some of this recent work together, this paper will discuss the potential configuration of these landscapes throughout the Pleistocene, the impact of fluctuating climatic changes upon them and the resulting implications for the hominins they sustained.

Dr Rachel Bynoe, University of Southampton

Dr Rachel Bynoe, University of Southampton

Rachel is a Palaeolithic archaeologist specialising in submerged archaeology, particularly of the North Sea basin. She completed her PhD at the University of Southampton in 2014 looking at the use of historic faunal remains to locate extant Pleistocene deposits in the North Sea. In the intervening years she has lectured on both Palaeolithic and maritime courses and continued to work on terrestrial and submerged sites, including the only diver-groundtruthed Pleistocene sites in the UK. Currently Rachel is in the middle of a post-doctoral research position at the Natural History Museum as part of the Pathways to Ancient Britain project, concentrating on developing methods to locate and investigate the submerged deposits off Happisburgh, Norfolk.

Events following the last glacial maximum (LGM) in high latitudes of North America illustrate the “push–pull” impacts of rising sea level and glacial recession on human and biotic communities.  These forcing mechanisms transformed northern North America resulting in: 1) separating the vast land connection between Asia and North America, 2) joining the Arctic and Pacific Oceans, 3) landward retreat (push) of human and near-shore biotic communities in response to rising sea level, and 4) the colonization (pull) of biota and humans in newly deglaciated regions.  Understanding and quantifying the timing and mechanisms of this dramatic reconfiguration of North America provides insights for the application of complex systems modeling to geographically predict and scale future “push-pull” events likely to result from climate change.

Professor Emeritus E. James Dixon, University of New Mexico

Professor Emeritus E. James Dixon, University of New Mexico

E. James Dixon served as Professor of Anthropology and Curator of Archeology at the University of Alaska Museum from (1974–1993).  He became curator of archeology at the Denver Museum of Nature and Science in 1993 and subsequently (2001–2007) joined the faculty at the University of Colorado as Professor of Anthropology and Research Fellow at the Institute of Arctic and Alpine Research.  He served as Professor of Anthropology and Director of the Maxwell Museum of Anthropology at the University of New Mexico (2007–2016). After attending Fairleigh Dickenson University, he enrolled in the University of Alaska, Fairbanks where he received his B.A. and M.A., and then attended Brown University where he received his Ph.D.  He was a Marshall Fellow for research at the National Museum of Denmark in 1972, a National Endowment for the Humanities Fellow in 1996-97, and awarded the Alaska Anthropological Association’s Professional Achievement Award in 2007. He specializes in North American archeology with particular focus on human colonization, high altitude and high latitude human adaptations, and early cultural development in the Americas.  He has led many large research projects and advised and participated in numerous educational films, videos, and museum exhibitions.  He also has lectured and published extensively including three books, Quest for the Origins of the First Americans (1993), Bones, Boats & Bison: Archaeology and the First Colonization of Western North America (1999), and Arrows and Atl Atls: A guide to the Archeology of Beringia (2013).