Soil archives of a Fluvisol: subsurface analysis and soil history of the medieval city centre of Vlaardingen, the Netherlands – an integral approach

Abstract

Abstract. The medieval city of Vlaardingen (the Netherlands) was strategically located on the confluence of three rivers, the Maas, the Merwede, and the Vlaarding. A church of the early 8th century AD was already located here. In a short period of time, Vlaardingen developed in the 11th century AD into an international trading place and into one of the most important places in the former county of Holland. Starting from the 11th century AD, the river Maas repeatedly threatened to flood the settlement. The flood dynamics were registered in Fluvisol archives and were recognised in a multidisciplinary sedimentary analysis of these archives.To secure the future of these vulnerable soil archives an extensive interdisciplinary research effort (76 mechanical drill holes, grain size analysis (GSA), thermo-gravimetric analysis (TGA), archaeological remains, soil analysis, dating methods, micromorphology, and microfauna) started in 2011 to gain knowledge on the sedimentological and pedological subsurface of the settlement mound as well as on the well-preserved nature of the archaeological evidence. Pedogenic features are recorded with soil description, micromorphological, and geochemical (XRF -X-ray fluorescence) analysis. The soil sequence of 5 m thickness exhibits a complex mix of "natural" as well as "anthropogenic" layering and initial soil formation that enables us to make a distinction between relatively stable periods and periods with active sedimentation. In this paper the results of this interdisciplinary project are demonstrated in a number of cross-sections with interrelated geological, pedological, and archaeological stratification. A distinction between natural and anthropogenic layering is made on the basis of the occurrence of the chemical elements phosphor and potassium.A series of four stratigraphic and sedimentary units record the period before and after the flooding disaster. Given the many archaeological remnants and features present in the lower units, in geological terms it is assumed that the medieval landscape was submerged while it was inhabited in the 12th century AD. In reaction to a final submersion phase in the late 12th century AD, the inhabitants started to raise the surface of the settlement. Within archaeological terms the boundary between natural and anthropogenic layers is stratigraphically lower, so that in the interpretation of archaeologists, the living ground was dry during the 12th and the 13th centuries AD. In this discussion, the geological interpretation will be compared with alternative archaeological scenarios.

Downstream Distribution and Postdepositional Mobilization of Cadmium in Alluvial Soils

“…Chronological markers, such as 137 Cs (e.g., [18,21]) and 210 Pb (e.g., [19,21,25]), are used as a proxy for the age of the sediments, as well as radiocarbon ( 14 C) [6,20,23,26,27] and luminescence dating [24,28]. Spatial variations in metal(loid) concentrations and dendrochronology can also be used to date overbank sediments in a laterally mobile river reaches [28].…”

“…Spatial patterns of metal(loid) distribution can be used to construct contamination risk maps, which are the bases to mitigate and control the contamination [5]. Additionally, information concerning leaching of metal(loid)s in alluvial soils is important because they are used for the reconstruction of the pollution history of a river catchment [6].…”

Using 14C-Dated Peat Beds for Reconstructing Subsidence by Compression in the Holland Coastal Plain of the Netherlands

“…Additional overburden was deposited on the coastal wetland peat by the ingressions, inducing further compression and vertical lowering of the peat. Inhabitants reacted to these floods by artificially raising the land surface with sediments and household waste (Koster, 2016), thereby locally compressing and vertically displacing the peat even more (Kluiving et al, 2016). Peat mining independently has caused surface lowering, mainly in areas that escaped ingressions and river flooding (Borger, 1992).…”