Solving for the unknown: the dynamics of drowned archaeological landscapes and early marine resources use. Examples off northwestern Australia
Dr Ingrid Ward, Flinders University
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.
The Bering Land Bridge during the last glacial maximum: a good place to live?
Dr Nancy Bigelow, University of Alaska
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.
Pathways to Ancient Britain
Dr Rachel Bynoe, University of Southampton
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.
Beringia and the Arctic: submerged landscapes and receding glaciers
Professor Emeritus E. James Dixon, University of New Mexico
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.