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

Japanse excursie- en workshopindrukken XIX INQUA 2015 congres, Nagoya, Japan

Afgelopen juli en augustus waren wij twee weken in Japan als deelnemers van INQUA’s vierjaarlijkse internationale Kwartairgeologische congres. Vóór het eigenlijke congres hebben we deelgenomen aan de PALSEA2 workshop (Paleo constraints on sea-level rise) en gingen we met collega’s van de Japanse geologische dienst op excursie naar de Kanto kustvlakte met haar opgeheven strandwal en laguneafzettingen uit het Laatste Interglaciaal (MIS5e). Na het congres volgde een excursie naar de prefectuur Chiba, het zich dramatisch snel opheffende schiereiland tussen de Baai van Tokyo en de Grote Oceaan. Hier ligt een voorgestelde type-locatie voor de basis van het Midden-Pleistoceen, met daarin de Brunhes-Matuyama magnetische omkering

Japanse excursie- en workshopindrukken XIX INQUA 2015 congres, Nagoya, Japan

Afgelopen juli en augustus waren wij twee weken in Japan als deelnemers van INQUA’s vierjaarlijkse internationale Kwartairgeologische congres. Vóór het eigenlijke congres hebben we deelgenomen aan de PALSEA2 workshop (Paleo constraints on sea-level rise) en gingen we met collega’s van de Japanse geologische dienst op excursie naar de Kanto kustvlakte met haar opgeheven strandwal en laguneafzettingen uit het Laatste Interglaciaal (MIS5e). Na het congres volgde een excursie naar de prefectuur Chiba, het zich dramatisch snel opheffende schiereiland tussen de Baai van Tokyo en de Grote Oceaan. Hier ligt een voorgestelde type-locatie voor de basis van het Midden-Pleistoceen, met daarin de Brunhes-Matuyama magnetische omkering

Fluvial evolution of the Rhine during the last interglacial-glacial cycle in the southern North Sea basin : A review and look forward

This paper presents the current state of knowledge on the evolution and depositional history of the River Rhine in the southern part of the North Sea basin during the upper Middle and Late Pleistocene, and its response to climate change, sea-level oscillation and glacio-isostasy. The study focuses on the development of the Eemian interglacial lower-delta in the central Netherlands and its relation to records of climate and sea-level rise, and uses the Saalian and Weichselian pre- and postdating periods to place its development in context. The Rhine fluvial system fills the gradually subsiding North Sea basin, but its development has strongly been affected by the Saalian glaciation and its remaining topography. Ice-pushed ridges originating off the limit of maximum glaciation basically divided the central Netherlands into two sedimentary depocentres: a central depocentre within the former ice-limit, and a southern depocentre south of it. The sedimentary record of the central depocentre, including an incised-valley fill, shows a 20-40m thick stacked sequence consisting of three units. The incised-valley fill consists of a Late Saalian to early Eemian age lower fluvial unit and a Weichselian age upper fluvial unit, both composed of coarse-grained channel deposits. Sandwiched in-between is a 5-15m thick record composed of fine-grained fluvial and estuarine (tidal) floodbasin and shallow-marine deposits. It is of Eemian interglacial and Early Weichselian age, and comprises transgressive and highstand deposits that show the drowning of a fluvial system. Inland parts transformed from fluvial to deltaic and estuarine environments, and the most downstream parts transformed to a shallow-marine embayment. Preservation of these units occurred, despite considerable sea-level fall and climate-controlled erosion taking place in the last-glacial. Preservation potential was increased by the fact that the Rhine system avulsed away to the southern depocentre, halfway the Weichselian Pleniglacial. Consequently, the infill of the southern depocentre is of an entire different nature, and last-interglacial transgressive or highstand units are hardly preserved. Because of glaciation and resulting depocentre configuration, the Netherlands in NW Europe thus offers a very good opportunity to study the transgressive interglacial lower-deltaic records and falling-stage preservation thereof - both key elements for understanding sedimentary development over full 100-ky glacial-interglacial cycles of climate and base-level change

Pre-Weichselian Quaternary glaciations of the British Isles, The Netherlands, Norway and adjacent marine areas south of 68°N : implications for long-term ice sheet development in northern Europe

Within this paper we review the pre-Weichselian glacial history of northern Europe focussing on evidence from the British Isles, Netherlands, Norway and adjacent marine areas that record the activity of the British (BIS) and Scandinavian (SIS) ice sheets. The objective of the paper is to examine the long-term evolution of the two ice sheets in order to determine their level of synchronicity and their relationship to the Plio-Pleistocene record of Northern Hemisphere Glaciation. Geological evidence demonstrates striking long-term similarities between the behaviour of the BIS and SIS, with a step-wise intensification in the glacial signal: (1) first Ice Rafted Debris (IRD) input onto the continental margin at ca 2.7–2.6 Ma and restricted glaciation prior to ca 1.1 Ma; (2) initiation of more lowland-style glaciation from 1.1 Ma; (3) repeated shelf-edge glaciations from 0.45 Ma. These ‘steps’ coincide with a major intensification of the Northern Hemisphere climate signal at the beginning of the Quaternary, and the Mid Pleistocene Transition. Temporal and spatial variabilities in the behaviour of different sectors of the BIS and SIS appear to reflect regional-scale geographic (latitude, elevation), climatic (moisture, temperature) and glaciological (deformable beds) controls that modulate the build-up of ice volume in the main ice accumulation areas relative to global climate forcing and its subsequent lateral expansion

Distribution of Holocene Marine Mud and Its Relation to Damage from the 1923 Earthquake Disaster in the Tokyo Metropolitan Area, Japan

Tokyo, which is located near the boundary between the North American and Philippine Sea plates, has been frequently struck by large earthquakes throughout the Holocene. The 1923 Taisho Kanto Earthquake is a rare historical earthquake that can be reconstructed in detail because abundant datasets were collected by investigations performed just after the earthquake. We examined 13,000 borehole logs from the Tokyo and Nakagawa lowlands to clarify the distribution and thickness of incised-valley fills and soft marine mud that had accumulated since the Last Glacial Maximum (LGM) on a grid with a resolution of 150 m × 150 m. We compared these datasets with the distribution of wooden house damage ratios caused by the Taisho Kanto Earthquake. Our results showed that the thickness of the soft mud, but not that of the incised-valley fills, was strongly correlated with the wooden house damage ratio. The mud content was >60%, water content was >30%, and S-wave velocity was ca. 100 m/s in the soft Holocene marine mud. The wooden house damage ratio was highest where the soft mud thickness was 20 m, because in those areas, both the soft mud and the wooden houses resonated with a natural period of ca. 1 s

Depth-limiting resistant layers tune the shape of tidal bar pattern of Holocene alluvial estuaries

Holocene fluvial and estuarine systems are commonly assumed to be entirely alluviated, which means that channels freely move in erodible substrates. This implies that the shape and tidal bar patterns are self-formed. Data analysis for estuaries and deltas worldwide, however, proves presence geological depth constraints in many, if not most systems. This potentially constrains estuary channel dimensions and planform shape. In this study we compare detailed historical bathymetry maps of the last two centuries and depths of resistant Pleistocene clays and tills in the Eems-Dollard estuary, located on the Dutch-German border. Based on this new historical and geological data we show how resistant layers forced bar patterns and channel dimensions in an estuary that was hitherto considered autogenically-formed. Resistant layers limit channel depth and consequently cause widening and mid-channel bar formation, increasing channel curvature over at least one bar length in both seaward and landward direction (Figure 1). Furthermore, channel confluences preferentially form where resistant layers are absent. These combined effects determine the position of confluences and bars on the scale of the entire estuary; they are tuned to the presence of the resistant layers. Our results challenge the view that bar-filled estuaries are predominantly self-formed. They show that apparently local obstacles have estuary-wide implications: they can, for example, force bar formation and increased channel curvature that may favor the stability a two channel system. Future sea-level rise may cause tidal prisms and consequently the channel volumes to increase. As a result, the resistant layers are expected to be more exposed on the bases and edges of estuary channels, leading to potentially unexpected channel behavior when their effects are not taken into account. This strongly highlights the need to incorporate inherited resistant layers into morphological models

Depth-limiting resistant layers tune the shape of tidal bar pattern of Holocene alluvial estuaries

Holocene fluvial and estuarine systems are commonly assumed to be entirely alluviated, which means that channels freely move in erodible substrates. This implies that the shape and tidal bar patterns are self-formed. Data analysis for estuaries and deltas worldwide, however, proves presence geological depth constraints in many, if not most systems. This potentially constrains estuary channel dimensions and planform shape. In this study we compare detailed historical bathymetry maps of the last two centuries and depths of resistant Pleistocene clays and tills in the Eems-Dollard estuary, located on the Dutch-German border. Based on this new historical and geological data we show how resistant layers forced bar patterns and channel dimensions in an estuary that was hitherto considered autogenically-formed. Resistant layers limit channel depth and consequently cause widening and mid-channel bar formation, increasing channel curvature over at least one bar length in both seaward and landward direction (Figure 1). Furthermore, channel confluences preferentially form where resistant layers are absent. These combined effects determine the position of confluences and bars on the scale of the entire estuary; they are tuned to the presence of the resistant layers. Our results challenge the view that bar-filled estuaries are predominantly self-formed. They show that apparently local obstacles have estuary-wide implications: they can, for example, force bar formation and increased channel curvature that may favor the stability a two channel system. Future sea-level rise may cause tidal prisms and consequently the channel volumes to increase. As a result, the resistant layers are expected to be more exposed on the bases and edges of estuary channels, leading to potentially unexpected channel behavior when their effects are not taken into account. This strongly highlights the need to incorporate inherited resistant layers into morphological models