Middle Palaeolithic, Upper Palaeolithic and Mesolithic flint artefacts dredged from the offshore Last Glacial Rhine-Meuse valley floor. The Maasvlakte 2 and Zandmotor sites (The Netherlands)

The southern North Sea overlaps the northwestern limits of known Neanderthal distribution. This area was low lands for most of pre-Holocene time which explains why the seabed holds a rich archaeological and palaeontological archive, crucial to our understanding of hominin behaviour in northern latitudes. In the course of large scale coastal defence and harbour infrastructural works along the Dutch coast, sediments coming from dredging sites 10-15 km offshore are used to build new and replenish existing beaches. By now numerous finds by a crowd of beach walking citizen scientists (>1600 lithics registered formally) provide ample evidence of Palaeolithic and Mesolithic occupation of the Last Glacial Rhine-Meuse valley, which we have systematically inventoried, described, sorted culturally and placed in reconstructed stratigraphic context. Detailed studies have focused on typo-technological characteristics of flint and other stone artefacts, raw material procurement, postdepositional surface modifications, and the integrated work allows assessing and assigning ages of the majority of finds and placing them in original geographic context. Our poster presents the results for the two major sites Maasvlakte 2 (seaward harbour extension of the Port of Rotterdam) and Zandmotor (‘Sand Engine’) large scale beach nourishment, drawing from reports [1,2] commissioned by BOOR archaeological service of the municipality of Rotterdam and National Heritage Agency (RCE) respectively. Special identifications have been a handaxe made of Wommersomquartzite, transported over a distance of more than 150 km, from Maasvlakte 2 [3], and the tar-hafted Neanderthal tool from the Zandmotor dated to ̴50ka BP [4]. The oldest replenished beach finds are attributed to the Acheulian, presumably c. 250-170 ka (i.e. shortly predating the Saalian glaciation in MIS 6). A considerable number of artefacts is attributed to the late Middle Palaeolithic (c. 115-40 ka; Early to Middle Weichselian, MIS 5d-MIS 3), and ascribed to several variants of the Mousterian Complex, particularly the Moustérien de tradition acheuléenne (MTA) and the Moustérien type Quina, and the Keilmessergruppen (KMG). Several small bifacial tools may indicate the presence of the ‘Mousterian with Bifacial Tools’ (MBT) [5]. A small number of artefacts probably dates to the earlier Upper Palaeolithic (Late Aurignacian and/or Early Gravettian), and Ahrensburgian and Federmessergruppen are also attested, intriguingly significantly more at Maasvlakte 2 than at Zandmotor. Mesolithic finds are numerous and at Zandmotor include Late Mesolithic core axes and trapezes, which seabed depth, valley rim setting and sea-level history constrain to be older than 6100 BCE. A few core axes from Maasvlakte 2 are older and can be attributed to the Early Mesolithic Maglemose-Duvensee group. References: [1] Niekus, M.J.L.Th., Johansen, L., Stapert, D., 2021. Een inventarisatie van opgespoten vuurstenen artefacten van Maasvlakte 2 en Hoek van Holland (Gemeente Rotterdam). In: Carmiggelt, A., Schiltmans, D.E.A. (Eds.), Doggerland en Rotterdam. Een inventarisatie van opgespoten paleolithische en mesolithische artefacten van (vuur)steen, bot en gewei van Maasvlakte (1 en 2) en Hoek van Holland (gemeente Rotterdam): een aanzet voor vervolgonderzoek (= BOORnotitie 41). Archeologie Rotterdam, Rotterdam, pp. 31-123 [2] Niekus, M.J.L.Th., Johansen, L., Stapert, D., Cohen, K.M., 2021. Opgezogen, opgespoten en opgeraapt. Vuurstenen artefacten van de Zandmotor en hun sedimentaire context (Steekproef-rapport 2020-07/05). De Steekproef, Zuidhorn [3] Niekus, M.J.L.Th., Amkreutz, L.W.S.W., Johansen, L., Stapert, D., 2017. Een bijzondere vuistbijl uit de Noordzee gevonden op Maasvlakte 2 bij Rotterdam. Grondboor & Hamer 5/6, 162-169 [4] Niekus, M. J.L.Th., Kozowyk, P.R.B. Langejans, G.H.J., Ngan-Tillard, D., van Keulen, H., van der Plicht, J., Cohen, K.M., van Wingerden, W., van Os, B., Smit, B.I., Amkreutz, L.W.S.W., Johansen, L., Verbaas, A., Dusseldorp, G.L., 2019. Middle Paleolithic complex technology and a Neandertal tar-backed tool from the Dutch North Sea. Proceedings of the National Academy of Sciences 116 (44), 22081-22087 [5] Ruebens, K., 2013. Regional behaviour among late Neanderthal groups in Western Europe: A comparative assessment of late Middle Palaeolithic bifacial tool variability. Journal of Human Evolution 65 (4), 341-362