EMAS Members’ Favourite Archaeological Sites
Submitted by David Beard
The southern end of water filled section of the canal at Graben
(click on the photos to enlarge)
In 793 Charlemagne ordered the construction of a 2 kilometre canal from Graben in Treuchtlingen to Weißenburg which would link the Altmühl and the Schwäbische Rezat rivers, ultimately linking the Danube to the Rhine, across the European Watershed.
It is uncertain whether the main raison d’etre for this project was for trade or military purposes, but according to Einhard, the Frankish scholar, the scheme was never completed because of the marshy ground which caused the excavated material to slide back into the excavation.
Today, only one section of the intended canal remains filled with water. It begins in Graben and extends northwards for c. 500m. The excavated material is piled alongside the structure, reaching a height of up to 10 metres. To the north of this structure is a second section extending for c. 700m, but this has been filled in at some point.
Research in 1992/3 carried out by Robert Koch showed that the floor of the canal was not level, but became deeper further to the south, suggesting that the original intention would have been to dam the Schwäbische Rezat and flood the canal from the north (Koch, R., “Fossa Carolina. Neue Erkenntnisse zum Schiffahrtskanal Karls des Großen”, in: Elmshäuser, Konrad (ed.), Häfen, Schiffe, Wasserwege. Zur Schifffahrt des Mittelalters, Bremerhaven 2002, p. 54-70.).
Work in 2009 showed that what had been considered an early medieval dam at Dettenheim was probably of later medieval date. However, this does not negate the hypothesis that the original intention was to divert water from the Schwäbische Rezat.
In 2012 a project by the Deutsche Forshungsgemeinschaft entitled “Fossa Carolina: Bindeglied der Hafennetzwerke an Rhein und Donau. Studien zur Überwindung der Europäischen Hauptwasserscheide im Mittelalter” to look for evidence of how far the original excavations extended. This is part of the “Häfen von der römischen Kaiserzeit bis zum Mittelalter” (Ports from Imperial Roman times to the early Middle Ages) project.
See also: Fossa Carolina