The NSPRMF 2009 (Peeters et al. 2009) had a clear aim: to facilitate the large-scale systematic and interdisciplinary study and preservation (where possible) of a unique sedimentary and archaeological record potentially extending back over the entire period of human history, now submerged beneath the shallow waters of the North Sea and English Channel. The NSPRMF 2009 encouraged targeted archaeological research in the context of development-led and research-driven projects with the expectation that outcomes would inform and underpin submerged cultural heritage management strategies.
The NSPRMF 2009 comprised four sections: Section 1 addressed the scope (in terms of chronology, geography and scale) of the NSPRMF and provided a brief outline of current spatial developments and how cultural heritage management is embedded in them. Section 2 summarised the current state of knowledge and focused on the archaeological understanding of the area in the broader context of research on early prehistoric landscape use, thus permitting the identification of gaps in the current state of knowledge and definition of research potential. Section 3 outlined research themes and questions, particularly identifying knowledge gaps and priorities, methods and initiatives were defined in the form of a strategy. Section 4 focused on matching research needs to anticipated developments and provides a structure to link the research agenda with unanticipated developments.
When revising and updating the NSPRMF for the Dutch sector of the North Sea, Peeters et al. (2019) provided a summary of key projects and publications that contributed to improving the understanding of each of the themes, topics and priorities outlined in the NSPRMF 2009 (Table 4).
Table 4 Research themes and topics from the NSPRMF 2009 (Peeters et al. 2009)
|A. Stratigraphic and chronological frameworks
|A.1: Lithostratigraphic classification and chronological anchoring A.2: Sea level change and glacio-isostacy A.3: Survival of deposits of archaeological significance A.4: Biostratigraphies and absolute dating
|B. Palaeogeography and environment
|B.1: Middle/Late Pleistocene reshaping of topography and river drainage B.2: Development of the Weichselian/Devensian landscape B.3: Palaeogeographic evolution after the Last Glacial Maximum (LGM) B.4: Quaternary palaeoecology
|C. Global perspectives on intercontinental hominin dispersals
|C.1: North Sea coastal dynamics and human uses of the coastal zone C.2: Pleistocene North Sea level oscillations and population of islands
|D. Pleistocene hominin colonisations of northern Europe
|D.1: Early human exploitation strategies in changing environments D.2: Natural barriers for hominin expansion
|E. Reoccupation of northern Europe after the Last Glacial Maximum (LGM)
|E.1: Post-LGM occupation flux E.2: Occupation strategies
|F. Post-glacial land use dynamics in the context of a changing landscape
|F.1: Changing landscape structure F.2: Behavioural diversity among hunter-gatherers F.3: Maritime archaeologies of the North Sea
|G. Representation of prehistoric hunter-gatherer communities and lifeways
|G.1: Spatial perspectives on North Sea palaeolandscapes G.2: The distributional nature of early hominin communities G.3: Enculturated hunter-gatherer landscapes
Stratigraphic and chronological frameworks were identified as one of the key themes of the NSPRMF 2009. Understanding and defining the archaeological significance of landscape features and sedimentary deposits requires a baseline knowledge of what deposits are preserved at and/or below the seabed, the timing and nature of their formation and what, if any, post-depositional changes have occurred. Stratigraphic and chronological frameworks therefore should provide a foundation to any submerged palaeolandscape or prehistoric archaeology studies.
The subdivision of the Quaternary geology of the UK continental shelf has relied heavily on the application of relative chronostratigraphy which broadly considers lithology and stratigraphy (principally seismo-stratigraphy) relative to cyclic climatic changes at the glacial to interglacial timescale to give a ‘presumed age’ (e.g. Cameron et al. 1992; Hamblin et al. 1992). Very few absolute dates (direct or ex-situ) were available to chronometrically constrain the frameworks developed by the British Geological Survey (BGS) in the 1990s with the exception of a few radiocarbon dates that were limited to the maximum age of range of the technique at the time (~26 ka). Instead, age information was primarily derived from biostratigraphy, principally dinoflagellate cysts, foraminifera and nannoplankton (Stoker et al. 2011). Despite advances in optically stimulated luminescence (OSL), amino acid racemization (AAR) and Argon-Argon dating techniques that could potentially date older and non-organic deposits, the chronology of Quaternary sequences and associated cultural material was far from resolved.
Without absolute dating, stratigraphic frameworks became stagnant, and correlation, internationally, or between onshore and offshore settings was problematic (Stoker et al. 2011). Furthermore, limitations in adopting a chronostratigraphic approach were recognised in the early 2000s in the Netherlands resulting in separation of the stratigraphic framework into a lithological and chronological component that can be correlated or interpreted independently. This approach provides a distinction between ‘presumed age’ and absolute age and only highlights just how limited, both spatially and temporally, chronological information from submerged contexts is.
When considering chronological information, the NSPRMF 2009 identified four dating options:
The direct dating component of the above categories referred principally to OSL and radiocarbon dating techniques which at the time spanned the age range of 180-400 ka and ~26 ka respectively, albeit with error margins becoming increasingly larger with time. Indirect dating by comparison relies on comparative data or context to estimate age. The term absolute dating was used for scenarios where age could be determined in numerical form (i.e. years) and relative age used where the only information available was related to the relative order or sequence of events.
In the absence of direct absolute dating evidence, emphasis was placed on the use of time-depth data relative to MSL to determine an indirect age estimate to constrain chronological frameworks. The success of this approach is variable and depends on choosing the ‘right’ sea-level curve which is influenced by Glacio-isostatic Adjustment (GIA) models, the availability and accuracy of constraining sea-level index points (SLIPs), other sea-level limiting points, and inter-regional variability in relative sea level records in general.
Reconstructions of past landscapes and palaeogeography have been a key focus of submerged prehistory. Historically, these have relied heavily on lithological descriptions of very widely spaced boreholes, bathymetric data and rare archaeological and palaeoenvironmental records. The spatial and temporal resolution of the maps and models produced was coarse and focused on general sea-level and ice-sheet history to identify broad areas of seabed that would have been subaerially exposed at different times. Improving the resolution of these models was highlighted as a priority in the NSPRMF 2009 and renewed research in two specific geographic areas, the English Channel and Dogger Bank, which was being driven partly by the public release and development-driven acquisition of new high resolution bathymetric and seismic geophysical data.
The archaeological significance of submerged palaeolandscape and paleogeographic reconstructions was, and still is indisputable as they provide a climate and landscape context to human history, but can also be used to identify areas and deposits within a landscape that have greatest potential to preserve archaeological material. The NSPRMF 2009, recognised the need for dynamic landscape evolution models alongside identification of intact land surfaces that could be linked to archaeological ‘stray finds’.
Palaeoenvironmental datasets are of central importance for assessing the environmental and landscape context of submerged prehistoric archaeology. The NSPRMF 2009 reviewed extant palaoenvironemntal data, subdividing it between palaeontological (vertebrate and non-vertebrate fauna) and palaeobotanical evidence, considered some of their limitations and identified associated strategic research priorities.
Palaeoenvironmental evidence from the North Sea region recovered prior to 2009 is dominated by sub-fossil terrestrial mammal bones recovered through trawling and dredging as part of the fishing and aggregate industries. Additional palaeoenvironmental datasets recovered before this date are limited and consist principally of palynological assemblages and plant macro-fossils, focussed on sediments and finds from shallow coastal and intertidal locations (e.g. submerged forests and basal peats). Relatively few microfossil studies (diatoms, dinoflagellates, foraminifera), which can inform on depositional environments and landscape change, had been carried out prior to 2009.
There is a long history, stretching back to the nineteenth century, of ad hoc recovery of sub-fossil fauna from the North Sea. The history of modern investigations can be traced to the 1980s, when museum staff in the Netherlands developed collaboration with the fishing industry, which included targeted palaeontological ‘fishing’ expeditions (Glimmerveen et al. 2004; 2006; Mol et al. 2006).
These investigations targeted the Brown Bank and Eurogeul areas and recovered remains of terrestrial and marine species. The terrestrial assemblages are dominated by herbivores, most frequently mammoth and horse, whilst they also include very rare carnivore finds, including sabre toothed cat and wolverine. Biostratigraphically informative species can be divided between occasional discoveries of Lower and Middle Pleistocene species (mastodon, southern mammoth, rhino, musk ox and giant beaver), common occurrences of Late Pleistocene ‘mammoth-steppe fauna’ (woolly mammoth, woolly rhinoceros, bison, horse and reindeer), occasional warm stage Pleistocene species (straight-tusked elephant and hippopotamus), and mammals indicative of Pleistocene/Holocene temperate conditions (including aurochs, various species of deer, and wild boar).
Limitations with these datasets highlighted in the NSPRMF 2009 included a lack of stratigraphic context for finds and the reliance for chronology on a small number of biostratigraphic indicator species and direct AMS radiocarbon dates. These issues were noted to limit the utility of palaeoenvironmental datasets beyond assessing broad environmental and landscape conditions and changes. Additionally, it was highlighted that the range of palaeoenvironmental techniques applied to investigations was limited (a lack of microfossil studies was notable).
Based on review of the submerged prehistoric resource, NSPRMF 2009 highlighted three strategic research priorities for future palaeoenvironmental investigations in the North Sea region. These were the provision of:
Former terrestrial, but now submerged, prehistoric landscapes of the North Sea region would have been occupied and enculturated by prehistoric populations, and provided resources. Consequently, identifying and investigating archaeological records from these landscapes is a key research objective. The NSPRMF 2009 resource assessment provided an overview of then extant prehistoric archaeological assemblages, highlighted limitations with these datasets and identified related strategic research priorities.
Archaeological evidence from the North Sea region recovered prior to 2009 exclusively comprised dredged material from fishing and aggregate extraction. Large scale collecting of such material began in 1970s, with prehistoric artefacts recovered from within a much larger corpus of mammalian palaeontological finds from the Brown Bank and Eurogeul areas. These early discoveries were principally Mesolithic worked antler and bone, which included diagnostic barbed points (Godwin and Godwin 1933; Kooijmans 1970).
These chance archaeological discoveries led to targeted trawling expeditions in collaboration with fishermen, which recovered Palaeolithic, Mesolithic and Neolithic artefacts (Glimmerveen et al. 2004; 2006). These targeted investigations were focussed on sea zones off Great Yarmouth, the Brown Bank, the Leman and Ower Banks, Eurogeul-Maasvlakte and the coastal zone off Zeeland (Glimmerveen et al. 2004; 2006; Mol et al. 2006; Verhart 2004). The archaeology identified included lithic artefacts, modified (cut-marked) bone, bone and antler artefacts, and human remains. Key archaeological discoveries during this period included Middle Palaeolithic artefacts from off the East Anglian coast (Wessex Archaeology 2011a), a Neanderthal frontal bone and handaxes from the Zeeland coast (Hublin et al. 2009; Hijma et al. 2012), Mesolithic material from the Brown Bank and Eurogeul, including human remains, shaft-hole picks, socketed axes and barbed points (Kooijmans 1970; Glimmerveen et al. 2004; Mol et al. 2006), and two Middle Neolithic flint axe blades from the Brown Bank (Lanting 1998; van de Noort 2006).
As the 2009 assessment noted, whilst these discoveries amply demonstrated the prehistoric archaeological potential of these North Sea landscapes, there were key limitations with these datasets. The principal limitations being a lack of detailed contextual information, a lack of chronology, and sample bias.
Archaeological discoveries from submerged contexts were highlighted to suffer from a lack of detailed information on their original sedimentological and stratigraphic context. Additionally, only limited absolute dates, all based on direct AMS radiocarbon dating of individual organic artefacts, were available to provide chronology. These combined limitations are problematic for prehistoric artefact assemblages, particularly lithics, as in the absence of dated contexts, chronology is only available for pieces exhibiting typo-technological features, leaving the bulk of prehistoric discoveries only very broadly dated, at best.
The 2009 assessment also highlighted the issue of bias reflective of artefact recovery techniques. As modes of recovery comprised either the collection of artefacts from large fraction reject-piles from aggregate dredging or as trawled material through relatively large sized nets, only large artefacts were being recovered.
Based on review of the submerged prehistoric resource, the NSPRMF 2009 highlighted three strategic research priorities for future archaeological investigations in the North Sea region. These were the provision of:
Image credit: Palaeolithic flint tools, Wessex Archaeology CC BY-NC 2.0