Drowned landscapes of the Belgian Continental Shelf : implications for northwest European landscape evolution and preservation potential for submerged heritage

The expansion and reduction of ice masses across the North Sea Basin has a profound impact on eustatic sea levels and glacio-isostasy across northwest Europe. The complex interaction between eustatic sea level and glacio-isostatic adjustment of the landscape, from the time of ice mass expansion to their deglaciation, exerts a major control on local/regional landforms such as rivers and how fast or slow relative sea level movement occurs on a local/regional scale. Proglacial lakes in the North Sea Basin may have been a common landform during glacial periods. They were fed by meltwater from the Fennoscandian and British-Irish ice- sheets causing their levels to rise and exert major pressure on their confining barriers. During ice mass disintegration major volumes of meltwater enter proglacial lakes and may cause them to burst out of their confinements resulting in catastrophic glacial lake outburst floods. A high-resolution depth-converted structure map of the pre-Quaternary surface combined with regional palaeogeographic reconstructions demonstrates that the late Middle to Late Pleistocene geological evolution of the Belgian Continental Shelf is very complex. The various regions in which different depositional environments are preserved testify this. The Coastal Plain-Inner Shelf comprise the buried incised-valley system of the palaeo-Scheldt River and is mostly controlled by local/regional-scale processes, whereas the Middle-Outer Shelf landforms are controlled by southern North Sea glacial lake outburst floods from the Penultimate and Late Glacial period. The formational process interactions of and the interactions between depositional environments control the preservation potential of submerged heritage. Preservation of archaeological artefacts and palaeontological and human bone material is different for each depositional environment. Landforms and local palaeotopography control deposition and erosion in the landscape, which in turn determine if any form of submerged heritage can be preserved or accumulated within a primary, secondary or tertiary context. The preservation potential for archaeology and palaeontology has been visualised for the first time. Profile type mapping was used as a technique. The maps can be used as a guidance tool for preservation potential assessment at sea. This helps commercial-industrial end-users and policy makers to determine the risk for damage to the submerged heritage. Vice versa this pro-active engagement helps them save time and money for offshore activities because unexpected delays are prevented this way

Targeting the mesolithic: Interdisciplinary approaches to archaeological prospection inthe Brown Bank area, southern North Sea

YesThis paper describes some results of the research undertaken over the Brown Bank area during recent (2018/2019) geoarchaeological surveys in the North Sea which included seismic imaging, shallow (vibro)coring and dredging. It examines the benefits of simultaneous high-resolution (0.5 – 1m) and ultra-high-resolution (10 – 20cm) seismic survey techniques and a staged approach to resolving the submerged Holocene landscape in the highest possible detail for the purpose of targeted prospecting for archaeological material from the Mesolithic landscape of Doggerland. The materials recovered from such surveys offer significantly greater information due to an enhanced understanding of the context in which they were recovered. The importance of this information cannot be understated archaeologically, as few locations on land provide the opportunity to recover archaeological finds in situ within preserved landscapes. Moreover, it allows offshore areas of potential human activity to be prospected with some certainty of success.ER

A high-resolution DEM for the Top-Palaeogene surface of the Belgian Continental Shelf

A 1: 250,000 scale map of the surface of the Top-Palaeogene for the Belgian Continental Shelf was created based on extensive analyses of older and recent geological and geophysical datasets. The Top-Palaeogene surface is an important polygenetic unconformity that truncates older strata of the Palaeogene and to a smaller extent some of Neogene age from the overlying Quaternary deposits. As such it represents the base of the latter. The represented surface has been diachronously shaped and reworked through Late Quaternary times by different geological processes (e.g. fluvial, marine, estuarine, periglacial). Additionally, the offshore surface has been attached to the landward Top-Palaeogene surface and was transformed into a uniform 3D surface allowing new and better interpretations to be used in fundamental and applied research underpinning both scientific purposes (e.g. geology, archaeology, palaeogeography), and commercial applications (e.g. wind farms, aggregate extraction, dredging)

Characterisation of Middle-Late Pleistocene groove-and-ridge landforms incised across the Dover Strait

Recent investigations have revealed several sets of linear ridges and grooves located in the seafloor of the submarine Dover Strait. The formation of these features is associated with the occurrence of megaflood flows during Middle-Late Pleistocene glacial stages. These megaflood events are also linked to the formation of a prominent inner channel within the Lobourg Channel and the incision of streamlined islands and longitudinal scours into its bed. However, the erosional origin of the linear ridges and grooves and their possible relationship to megaflood erosion have never been demonstrated. In the present study, high-resolution geophysical data were combined with geological data and direct observations to better understand the mechanisms that caused the formation of linear ridges and grooves in the Dover Strait. The combined interpretation of these datasets corroborates that those features are carved into a hard substratum. However, the linear ridges and grooves are truncated by scours, the formation of which is associated with the last episodes of megaflood erosion that imprinted the seafloor of the Dover Strait. Therefore, the linear ridges and grooves were carved by erosional/weathering processes that took place before the incision of those scours. Based on their morphology and regional palaeogeographic reconstructions, it is proposed that the incision of the linear ridges and grooves was caused by fluvial and high-magnitude (not necessarily mega) flood erosion. The linearity of these features and their location in carbonate rocks might also indicate some control of the erosion by permafrost processes, chemical weathering and/or the rock's fabric

A well-preserved Eemian incised-valley fill in the southern North Sea Basin, Belgian Continental Shelf - coastal plain : implications for northwest European landscape evolution

This paper demonstrates that the Belgian Continental Shelf and coastal plain occupy a key position between the depositional North Sea Basin and the erosional area of the Dover Strait as it is an area where erosional landforms and fragmented sedimentary sequences provide new evidence on northwest European landscape evolution. The study area hosts 20–30 m thick penultimate to last glacial sand-dominated sequences that are preserved within the buried palaeo-Scheldt Valley. Here, we build on the results of previous seismo- and lithostratigraphical studies, and present new evidence from biostratigraphical analysis, OSL dating and depth-converted structure maps, together revealing a complex history of deposition and landscape evolution controlled by climate change, sea-level fluctuations and glacio-isostasy. This study presents strong new supportive evidence on the development of the incised palaeo-Scheldt Valley landform that became established towards the end of the penultimate glacial period (MIS 6; Saalian) as a result of glacio-isostatic forebulge updoming, proglacial lake drainage and subsequent collapse of a forebulge between East Anglia and Belgium following ice-sheet growth, disintegration and retreat in areas to the north. The majority of the incised-valley fill is of estuarine to shallow marine depositional context deposited during the transgression and high-stand of the last interglacial (MIS 5e: Eemian). A thin upper part of the valley fill consists of last glacial (MIS 5d-2: Weichselian) fluvial sediments that show a gradual decrease and retreat of fluvial activity to inland, upstream reaches of the valley system until finally the valley ceases to exist as the combined result of climate-driven aeolian activity and possibly also glacio-isostatic adjustment. Thus, strong contrasts exist between the palaeo-Scheldt Valley and estuary systems of the penultimate glacial maximum to Last Interglacial (Saalian, Eemian), the beginning of the Last Glacial (Weichselian Early Glacial and Early-Middle Pleniglacial), and the Last Glacial Maximum to Holocene.</p

Targeting the Mesolithic: Interdisciplinary approaches to archaeological prospection in the Brown Bank area, southern North Sea

This paper describes some results of the research undertaken over the Brown Bank area during recent (2018/2019) geoarchaeological surveys in the North Sea which included seismic imaging, shallow (vibro)coring and dredging. It examines the benefits of simultaneous high-resolution (0.5 – 1 m) and ultra-high-resolution (10–20 cm) seismic survey techniques and a staged approach to resolving the submerged Holocene landscape in the highest possible detail for the purpose of targeted prospecting for archaeological material from the Mesolithic landscape of Doggerland. The materials recovered from such surveys offer significantly greater information due to an enhanced understanding of the context in which they were recovered. The importance of this information cannot be understated archaeologically, as few locations on land provide the opportunity to recover archaeological finds in situ within preserved landscapes. Moreover, it allows offshore areas of potential human activity to be prospected with some certainty of success