This webpage shows the preliminary outcomes of HERCULES WP 2, case study landscape Uppland, Sweden. More information about HERCULES can be foudn here:  www.hercules-landscapes.eu

 

 

 

 

CASE STUDY AREA UPPLAND

Daniel Löwenborg and Kim von Hackwitz (Uppsala University http://www.uu.se/)

The historic development of the landscape in Uppland is highly influenced by the marked regressive shoreline displacement after the Holocene. Today the land is rising by about 5 millimetres per year, but since this process is slowing down it has historically been faster, and has altered the character of the landscape considerably. This creates a horizontal stratigraphy in the landscape where prehistoric sites that was once water bound are now found further inland the older they are. The changing landscape also meant that the characteristics of the landscape changed, and new land with different geological characteristics became available for occupation. Since subsistence strategies changes over time, with different land use and landscape preferences, this means that long term settlement patterns become complex and an understanding of the changing shorelines are fundamental for understanding long term landscape use. Archaeological remains from different periods and of different character are distributed over the landscape in a reflection of these landscape changes. For these reasons, the Uppland case initially focuses on modelling the shoreline dynamics in relation to isostatic land rise. 

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Topography influences communication networks, and thus the development of regions and territories, as has been discussed for Central Sweden area previously (Löwenborg, 2007; von Hackwitz, 2012; Wijkander, 1983). In order to understand the development of these topgraphically based regions it is necessary to account for the changes of the actual topography of the landscape over the period of study. This has not been done before, and this work package will perform the first extensive evaluation of how these regions can be compared to cultural changes.

 

The model used for calculating historic shorelines is based on a shoreline method from archaeological sites combined with an isolation method built on analyses to determine when lakes were isolated from the sea. The benefit of using a regression equation is that the method considers both the isostatic uplift and the eustatic variations. This means that the shoreline reconstructions will be more accurately calculated, especially for larger areas, as the uplift is uneven between different land areas. Further, the shoreline can be modelled from any given BP value which means that a site can be put in its specific time context in terms of shoreline displacement as long as there is a valid BP value (Sund, 2010). The regression equation used here was originally developed by Jan Risberg et al. (2007) and further developed by Camilla Sund for the area of Eastern Central Sweden (Sund, 2010). The accuracy of Sund’s model is comparable with that of Risberg (Risberg et al., 2007), but with the advantage of generating a contemporary shoreline over a larger area (Sund, 2010:27). The applied model is generic and well suited to create a model for the area of Uppland as a whole. Local deviations might occur as topographic thresholds could later have been eroded, making it difficult to accurately model the shoreline in detail at every point, but overall the model would be fairly accurate and relevant for the analyses proposed here. While similar model have been developed by the agency the Swedish Geological Survey (www.sgu.se), they have not been published and made available, so model published by Risberg et al. Sund are the only ones that is available for the extensive geomorphological modelling needed for this project. 

 From the set of reconstructed paleotopographies a range of analyses will be performed. Initially a set of historic watershed catchemnts will be calculated for each period. A water catchment area constitutes the area from which all run-off water comes together in a point or in a stream. A watershed is the boundary between two such areas. Typically, a watershed is a height where the rain falls on two different sides forming two different water catchment areas. The map above shows preliminary results of these watersheds, along with prehistoric shore lines.

 Water catchments can be calculated from a digital elevation model (DEM) using a set of hydrological functions in a GIS (Geographical Information System). Relevant pour points are selected, considering the modelled shoreline, and from the pour points drainage basins can be calculated to identify the upland area that is hydrologically joint at the pour point. The pour point would also act as an important social node in the landscape, connecting everyone using the upstream watercourses, and thus forming a natural region that would be easily recognized. If there is a pronounced isostatic land rise in the area this will affect both shorelines, thus making different pour points relevant at different periods. In areas with level terrain this might also cause the inland boundaries of the watersheds to shift as the land surface is tilting. It is therefore necessary to use a DEM that has been modified to the relevant time period using a method like the one described above. Also the quality of the DEM is important, where poor quality of the DEM might make it impossible to use for hydrological modelling. In the Uppland study area, a high resolution DEM has been produced by the Swedish Cadastral Agency (Lanmäteriet) using LiDAR technology. Since the DEM also has been edited to account for bridges this makes the data very suitable for hydrological analysis.

 These datasets will then form the base for further analyses of a range of archaeological artefacts and features, and their distribution in the landscape and over the different catchment areas, interpreted as potential regions. Through a comparative analysis of historical remains a diachronic analysis of regionality will be performed. This will adress questions of how back in history these topographic regions can be traces, and how the are influenced by the changing lanscape that is transformed to an highly framgmented archepilago to a more homogeneous flat plain dominated by clay with extensive areas of morain.

  

 Using the shore line and watershed modelling together with the digital database from the National Heritage Board (Fornsök) the aim is to model the development of social relations through regions and regionalism in the area, in order to better understand the long term land use of the area starting with the early Neolithic (ca 4200 BC) and ending with the Viking Age (ca 1050 AD).  The analyses are being conducted in GIS software.

 

von Hackwitz, K. 2012. The Creation of Regions: An Alternative Approach to Swedish Middle Neolithic Boundaries and Cultures, Norwegian Archaeological Review, 45:1, 52-75.  

Löwenborg, D. 2007. Watersheds as a Method for Reconstructing Regions and Territories in GIS. I: Clark, Jeffrey T. & Hagemeister, Emily M. (red). Digital Discovery: Exploring New Frontiers in Human Heritage, CAA 2006. Computer Applications and Quantitative Methods in Archaeology. Proceedings of the 34th Conference, Fargo, United States, April 2006. Budapest.

Risberg, J. 2007. Strandförskjutningen i centrala/norra Uppland i relation till omlandet. In: E. Hjärnet-Holder, H. Ranehed & A. Seiler (eds). Land och samhälle i förändring. Uppländska bygder i ett långtidsperspektiv. [Arkeologi E4 Uppland. Studier 4]. Uppsala: Riksantikvarieämbetet.

Sund, C. 2010. Paleogeografiska förändringar i östra Svealand de senaste 7000 åren. Department of Physical Geography and Quaternary Geology. Stockholm University, Master´s thesis 45 hp. NKA 16. 72 pp.

 

Wijkander, Keith. 1983. Kungshögar och sockenbildning: studier i Södermanlands administrativa indelning under vikingatid och tidig medeltid. Nyköping.