The Lower Rhine (Germany) in Late Antiquity: a time of dissolving structures

From the middle of the 1(st) century AD, the Lower Rhine was part of the frontier of the Roman Empire (Limes). However, this Limes was not an impermeable line, but rather an open corridor that served as march area and as a trade and supply route for the adjacent military and civilian settlements as well as the hinterland. This required access to the river and permanent harbours. When planning military camps and towns along the Rhine, the existing topography and the challenge of a dynamic riverine landscape had to be taken into account. The prefered location for forts and towns were the raised edges of the Lower Terraces close to the undercut bank of a meander. For many years, research assumed that the river bend adjacent to a Roman site had to be an oxbow lake. The main argument being that only an oxbow situation would have protected the Roman sites against strong currents and the risk of demolition of land and settlements by the main stream (abandoned channel hypothesis). A re-evaluation of the extensive archaeological, sedimentological and palynological archive and published data from the Rhine plain, as well as of supplementary data from new boreholes, lead to a considerable increase in the previously incomplete knowledge of the fluvial history, especially regarding the timing of palaeomeander infilling. It showed that most of the meanders and river bends of the Rhine with Roman settlements on their banks not silted up before Late Antiquity (from the end of the 3(rd) century AD on). Before that those meanders were part of the main stream. The advantage of steep undercut banks was that a quay could be built on a location that ensured mooring all year round, even at low water level. However, it was necessary that stabilising bank protections were present in order to avoid shifting the course of the river with subsequent destruction of the infrastructure. Such an antique bank protection construction (a so called Packwerk) could be recognised in front of the Colonia Ulpia Traiana (CUT, Xanten). With this knowledge in mind, other excavated structures on the banks of palaeomeanders, previously mostly interpreted as Roman harbour remains, could be interpreted as bank protections. At Wesel near the strategically important mouth of the Lippe, the archaeological, sedimentological and palynological data showed that a meander that had silted up in Prehistoric times (Bronze Age) had been reactivated in Roman times and silted up again in Late Antiquity. A man-made diversion (perhaps by building a groyne) of the main stream could have been responsible for this. With the beginning of the Late Antiquity crisis of the Roman Empire at the end of the 3(rd) century, it presumably became increasingly difficult to maintain these water works. This enabled the river to regain its morphodynamics, by cutting of the meanders that were active during Roman times. We hypothesise that this increase in fluvial activities of the Lower Rhine from the end of the 3(rd) century onwards is due to an anthropogenic trigger: the collapse of the Roman Empire

Postglazialer Meeresspiegelanstieg in der südwestlichen Ostsee - Geoarchäologische Ergebnisse aus der Niederung des Oldenburger Grabens (Ostholstein). In:

The lowland of the Oldenburger Graben was investigated in an interdisciplinary cooperation between Geologists, Archaeologists and Palaeobotanists. The postglacial sea level rise was reconstructed by combining and evaluating different methods and results. A new preliminary shoreline displacement curve for the south-western Baltic was created on the basis of reliable sea level data from adjacent regions. The shoreline displacement curve for the Oldenburger Graben mainly covering the time interval from 5100 to 3000 BC cal suggests an oscillating sea level rise. Two periods of intensive sea level rise can be distinguished from two periods of modest rise. The duration between two periods of intensive rise mounts up to 900 years. These oscillations correspond with climatic variations in the North Atlantic. The new preliminary shoreline displacement curve for the south-western Baltic reveals at least eleven oscillations during the last 9000 years

Geoarchaeological and archaeobotanical investigations in the environs of the Holsterburg lowland castle (North Rhine-Westphalia) - evidence of landscape changes and saltwater upwelling

The excavations at the Holsterburg site started in 2010 and revealed an octagonal castle from the medieval Staufer era of the 12th and 13th centuries AD of which only a few are known in Europe. The castle was built before 1170/1180 AD and its destruction is dated to 1294 AD. The site is located south of Warburg in North Rhine-Westphalia in the loess landscape of the so called Warburger Borde. As specific characteristic the castle is located in the midst of the floodplain of the Holsterbach which is a creek draining a small catchment towards the Diemel River valley. While archaeological investigations concentrated on the architecture and structure of the octagonal castle, geoarchaeological and archaeobotanical studies yielded substantial information on the hydro-geological characteristics of the castle subground and on the overall landscape evolution. The interpretation of earth resistivity transects in combination with vibracores showed that the castle was built on a construction layer which was founded on silt dominated alluvial and colluvial deposits within the valley bottom. This result is contrasting the former assumption that the castle was founded on gravels of the Weichselian Lower terrace. Geochemical studies of vibracore samples give evidence for salt enrichment within greyish laminated colluvial and alluvial deposits and for saltwater upwelling right underneath the castle. Most likely, these phenomena are due to the position of the castle in the midst of the Warburg fault system and to leaching processes bound to salt resources within the Rot or Zechstein formations in the subground. Archaeobotanical investigations by means of pollen analysis of samples from the castle infill and of core samples, both from below and above the construction layer, document a rapid accumulation of more than 3.5 m of sediments within less than 400 years prior to the construction of the castle. After its destruction in 1294 AD, the castle was filled up artificially with top soil material of the surrounding area

From point to area: Upscaling approaches for Late Quaternary archaeological and environmental data

The study of past socio-environmental systems integrates a variety of terrestrial archives. To understand regional or continental socio-environmental interactions proxy data from local archives need to be transferred to larger spatial scales. System properties like spatial heterogeneity, historical and spatial contingency, nonlinearity, scale dependency or emergence make generalizations from local observations to larger scales difficult. As these are common properties of natural and social systems, the development of an interdisciplinary upscaling framework for socio-environmental systems remains a challenge. For example, the integration of social and environmental data is often hindered by divergent methodological, i.e. qualitative and quantitative, approaches and discipline-specific perceptions of spatial scales. Additionally, joint approaches can be hampered by differences in the predictability of natural systems, which are subject to physical laws, and social systems, which depend on humans' decisions and communication. Here we present results from an interdisciplinary discussion of upscaling approaches in socio-environmental research with a special focus on the migration of modern humans in Central Europe during the last 30,000 years. Based on case studies from different disciplines, we develop a classification system for upscaling approaches used in past socio-environmental research. Finally, we present an initial upscaling framework that fosters the development of an interdisciplinary concept of scales and allows for a consideration of system properties like scale dependency, nonlinearity and contingency. The upscaling framework includes the following steps: i) the identification of relevant spatial and temporal scales at which socio-environmental interactions operate; ii) the definition of appropriate parameters to describe scale-specific interactions; iii) a comparison of process and observation scales to evaluate the potential of local archive data for larger scale generalization and for reconstructing scale-specific past socio-environmental interactions; iv) the identification and adaption of appropriate upscaling approaches for the relevant scales; v) the development of scale-specific models of socio-environmental interactions, and vi) the connection of models in a nested hierarchy. Our intention is not to present final results, but rather to stimulate future discussions and to provide a basic reference on scale issues in the emerging field of integrated socio-environmental research