Work in Progress
Upcoming field work
- August 2013: 3rd Magnetic prospection (contacts: Lukas Werther, Stefanie Berg-Hobohm, Sven Linzen)
- September 2013: Drilling campaign (contact: Eva Leitholdt)
- September-Oktober 2013: archaeological excavation in the canal area and prospection in the surrounding of the canal (contact: Lukas Werther)
The archaeological research is focused on surveys in the surroundings of the Fossa Carolina. At the one hand we hope to find remains of potential constructing site facilities and further early medieval sites. At the other hand we want to diachronic investigate land use and the development of the cultural landscape within the circle of influence of the canal. The survey area covers ca. 500 ha along the known canal route. The land owners and tenants of more than 450 parcels have been contacted and informed about our work. Thanks to their willingness of cooperation it was possible to start our large-scale field investigations in March 2013.
Our team of students from the Universities of Jena, Göttingen, Halle and Leipzig did systematic field walks on nearly 80 ha within 5 weeks. The 25% finding rate with single find surveying is used to localize archaeological sites in the archaeologically elusive canal environment. Roughly 8000 finding spots will enable a diachronic investigation of the development of the cultural landscape. All findings are salvaged – also those from late middle ages and post medieval periods. The up-coming age determination and mapping of these findings is quite promising – many archaeological sites of various epochs that were unknown so far became already apparent in the field. Soil mapping based on Pürckhauer soil sampling is an important complement to the field walks because every parcel is affected by erosion and accumulation processes. The soil samplings provide information about sediment relocation that is essential for interpreting spatial distribution of findings. The first net of 80 bore holes was drilled in the spring-time campaign. It will be gradually intensified in up-coming campaigns.
Shovel pit testing as an alternative survey method is used on the numerous meadow fields in a 20 m raster. Therefore the topsoil is removed and sieved to salvage findings and get information about the soil composition.
Besides the students of various Universities, there are also volunteers from the region that participate at the field campaigns. These assistants were trained on-site in cooperation with the Bavarian State Agency for Heritage Protection. The State Agency accompanies up-coming building projects in the canal surroundings that maybe provide useful information for our research about settlement and landscape development. The file inventory of the State Agency has been started as well as the inspection of various aerial image collections. The aerial images will be merged with Lidar data and historical maps and interpreted by using GIS software.
The past field campaigns took place in October 2010, June and November 2012, and March 2013. The first campaigns were focused on hammer drillings directly into the trench fillings. We could drill 22 open corings with a distance of 30 m – 9 corings in the west of the railway track (north of the recent pond) and 13 corings in the subsequent west-east-directed canal section in the east of the railway track. The bore holes reached down to a depth of 5 to 9 m below surface. We could identify the former trench bottom in a mean depth of 5 m below surface based on the stratigraphy and the designation of sediments in the open cores. The decreasing of the trench bottom depth from the recent pond onward in northern direction to the railway crossing provides the first indication of stairs-like arranged ponds. Between the trench bottom and the present surface are 1-2 m thick peat layers that indicate a very high groundwater level. Intercalated sapropel layers and clayey layers suggest the existence of stagnant water. The high organic layers are superimposed by terrestrial sediments that are similar to those below the former trench bottom. It is very possible that the excavated material from the lateral banks was relocated back to the trench and filling it up till today.
The March campaign was focused on the banks as well as on the surroundings of the canal. There have been drilled 3 open corings into the banks down to a depth of 6 m below surface. Additionally, we drilled 2 corings (3 m below surface) outside the canal area in the near surrounding that provide insights into the undisturbed underground.
A cross section by 4 open corings (3-6 m below surface) was drilled north of the connection road between Dettenheim and Grönhart. It spans across the very low banks, the canal fillings and the near surrounding. The recent field works have been in May 2013 with students from the Leipzig University.
The drilled sediment material is being analyzed in the lab with focus on grain size compositions and soil organic matter. The grain size compositions show two clearly distinguishable patterns that indicate two different sedimentation processes: the fluvial facies and the limnic (pond) facies. In addition, results of macro remain analysis and radiocarbon datings are involved in the interpretation process.
Geophysical investigations are a very important element regarding the research at the Fossa Carolina. Within the focus are large-scale magnetic measurements processed by the Jena Institute for Photonic Technologies (IPHT) and financed by the Bavarian State Agency for Heritage Protection. The measurements of the total area of 100 ha are motor driven. The SQUID technology provides good interference shielding and high sensitivity. Therewith, the logging of various components of the magnetic field provides best prerequisites for modeling. A large area has been measured in February 2013. The remaining fields will be measured as soon as soil conditions are getting better.
Colleagues from the Osnabrück University did additional measurements on selected areas using a Fluxgate sensor. The State Agency also plans to measure those areas with a cesium-magnetometer. Comparing the different magnetic measurement systems and combining the data with the geoarchaeological findings provide new insights into the methodic basic knowledge and into possibilities of surveying in the threshold region between land and water. Susceptibility measurements by the Osnabrück University of drilled inliners are also playing an important role. Geoelectric 3D tomography is planned to clarify the cross section of the canal and further hydrological point of interests.
Historical sources, data base and GIS
Historical sources about the Fossa Carolina are early medieval and more recent written sources as well as many maps, pictures and photographs. The combination of all sources plus archaeological and geo-scientific information takes place in an interdisciplinary data base. Every data set is linked with geometrical data in a geographical information system as far as it is able to be located. One important aim within the first project phase is to design and advance this recording and analyzing package. Many methodic problems can be solved together with colleagues from the other sub-projects, e.g. within the workshop “information interfacing”. The current results as well as further exploitation of written sources is based on a closely cooperation with the SPP-involved medieval historians from Jena University. Unpublished sources of different archives have to be processed during the up-coming months. Historical maps and images as well as modern building documents are very important to get information about usage history of the canal and its surrounding cultural landscape with potential harbor sites.