Figure 1.
Fossa Carolina bridging the Central European Watershed.
a) The outstanding role of the Fossa Carolina for Early Medieval shipping by bridging the Central European Watershed between the Rhine-Main and the Danube catchments. b) The Fossa Carolina was constructed by Charlemagne for linking the Swabian Rezat and the Altmühl Rivers. The figure is not similar to formerly published figures.
Figure 2.
The local topographical setting of the Fossa Carolina.
The canal is located across a valley watershed between the Altmühl River (Danube catchment) and the Swabian Rezat River (Rhine-Main catchment) within the Treuchtlingen valley junction at the piedmont of the Franconian Jura escarpment. Data source: Open access SRTM data (3 arc-second, 90 m raster, [72]) and OpenStreetMap [73].
Figure 3.
The course of the Fossa Carolina and the subdivision in six sections.
I) Central Section, II) West-East Section, III) Northern Section, IV) North-Eastern Section, V) Rezat Headwater with cores 7 and 12 [35] within the former assumed dam for a Rezat reservoir [15], and VI) Altmühl Floodplain. For detailed drilling positions of the sections I, II, III, and IV see Figs 4, 8 and 12. Raw data source: LIDAR data are cordially provided by Bavarian Land Surveying Office for illustrative purposes.
Table 1.
Radiocarbon ages of the Fossa Carolina trench fill (Part 1).
Table 2.
Radiocarbon ages of the Fossa Carolina trench fill (Part 2).
Figure 4.
Types of sediment texture in the Central Section and the West-East Section.
a) fluvial type and b) ponding type.
Figure 5.
Digital elevation model of the Central Section including detailed drilling positions.
Raw data source: LIDAR data are cordially provided by Bavarian Land Surveying Office for illustrative purposes.
Figure 6.
Chronostratigraphical documentation of the Central Section of the canal.
Raw data from the cores A and B are published in Leitholdt et al. [17], those from the cores E, F, G, H and I are published in Leitholdt et al. [36]. The figure is not similar to formerly published figures.
Figure 7.
West-East Section of the Fossa Carolina.
The figure shows a digital elevation model with detailed drilling positions, electrical transects, and the flux gate magnetic survey. White dots mark the drilling positions. The black lines show the geo electrical transects 1 and 2. Raw data source: LIDAR data are cordially provided by Bavarian Land Surveying Office for illustrative purposes.
Figure 8.
Longitudinal profile of the West-East Section including an electrical resistivity profile.
Figure 9.
Cross section of the West-East Section at core O position.
Figure 10.
Airborne LIDAR scan with drilling positions in the Northern and North-Eastern Sections.
White arrows indicate the assumed course of the canal. The cross sections are documented in Figs. 14, 15, and 16. Raw data source: LIDAR data are cordially provided by Bavarian Land Surveying Office for illustrative purposes.
Figure 11.
SQUID magnetogram from the Northern Section.
White dots mark the drilling positions. White arrows feature the course of canal. The image represents an area of 600 m×400 m. The magnetogram is embedded in a LIDAR illustration, which raw data are cordially provided by Bavarian Land Surveying Office.
Figure 12.
Stratigraphical documentation of the QP cross section within the Northern Section of the canal.
The drawing shows a 42 m long cross section with the different facies types and the Carolingian level of excavation.
Figure 13.
Stratigraphical documentation of the KG 407 cross section within the Northern Section of the canal.
The drawing shows a 90 m long cross section with the different facies types and the Carolingian level of excavation.
Figure 14.
Stratigraphical documentation of the KG 256 cross section within the North-Eastern Section.
The cross section shows the in situ layers of the Rezat fen in the East and the trench structure in the West. For the first time there is in situ evidence for a Carolingian trench in the North-Eastern Section. The trench bottom is shown by horizontal bars.
Table 3.
Geoarchaeological findings of the different canal sections: summarizing overview.
Figure 15.
Synthetic longitudinal profile of the Fossa Carolina from Graben to Rezat River.
a) The red line shows the Pre-Carolingian surface and watershed, the red dot indicates the summit the natural watershed. b) The short horizontal bars feature the Carolingian levels of excavation deduced from the drilling stratigraphies, and the blue dot indicates the artificial summit of the Carolingian trench bottom. c) The solid black line represents the level of the recent trench surface following the course of the canal.