Survey of fossilized ridge and furrow in a forested area near Rastatt, South West Germany

Woodlands near Rastatt in Central Baden include large remains of an exceptionally well preserved pattern of ridge and furrows. The present project aims to document this medieval field system. In an initial terrestrial mapping done by Karl Hauger, the extent of areas of ridge and furrow earthworks has been sketched at 1:10000 scale. With more than 300 ha in size, this is probably the largest continuous coverage of ridge and furrow in Southern Germany. It deserves therefore a more detailed documentary assessment. An interdisciplinary programme involving a common effort of landscape ecologists, historians, soil scientists and archeologists has been designed to assess in greater detail and to understand these agricultural remnants.
Laser Scanning has been tested in a pilot study to depict and assess the pattern of these ridge and furrow displaying altimetric differences between 30 and 80 cm.

Data for this pilot study were obtained from flight missions carried out by the State Survey Agency of Baden-Württemberg for the purpose of upgrading altimetric data base. Filtering and processing of row data with subsequent use of GIS enabled to generate realistic 3D terrain models representing the Earth's surface void of any forest or vegetation structure.

Fig. 1a: Part of the study site derived from first pulse laser scan data (left picture)

Fig. 1b Patterns of the fossilized open field landscape as revealed by last pulse data (right picture)

The resolution of this data that creates true-to-life renderings compares favourably with terrestrial mappings, allowing large areas of landscape to be captured as three-dimensional surface data. This technology promises to open historic structures as well as the landscape topography to more visually detailed, accurate and efficient examination. As another approach, soil profiles done by Renate Riedinger across ridges and furrows are examined to reveal whether ancient ploughing practices involved a transfer of topsoil from the furrows towards the ridges. Further archeological reconnaissance will have to focus on deserted settlement earthworks, while desk based research of written sources and archives will help tracing back historical patterns of settlement and land use in this region.

In this regard, preliminary analysis of available sources suggests that this relict agricultural landscape was established as an open field system during the medieval period (1100 - 1300). It was probably abandoned during the modern period (around 1650) as a consequence of the Thirty Year's War., with arable land returning to woodland by scrub and tree invasion. This process later contributed preserving the microrelief of the ridge and furrow system. Findings of this project should contribute to bring to greater prominence these surviving remains and to promote their conservation, since as many other earthworks, they are vulnerable to damage or destruction (encroachment for road construction, etc.).

Institutions and departments associated with this project include: University of Freiburg (Institute for Landscape Management and theDepartment for Remote Sensing), Landesdenkmalamt Baden Württemberg (Commission on the Ancient and Historic Monuments of Baden-Württemberg), Landesvermessungsamt (Land Surveying Office), Landratsamt Rastatt (Regional Administrative Office Rastatt) as well as many individual contributors.
The project participants would of course welcome any exchange of ideas on approaches and results with researchers involved in similar programmes elsewhere.

References:

Hauger K., Riedinger R., Sittler B., 2000. Wölbäcker bei Rastatt - eine Dokumentation zur Analyse und Erhaltung überkommener Altackerkomplexe. Kulturlandschaft - Zeitschrift für Angewandte Historische Geographie. Jg. 10 (2) 113-118.

Sittler, B. (2004): Revealing historical landscapes by using airborne laser scanning. A 3-D model of ridge and furrow in forests near Rastatt (Germany). International Archives of Photogrammetry. ISPRS. Vol. 26. 258-261.