Fossa Carolina
The Fossa Carolina ( also Karlsgraben ) was a connection between the Swabian Rezat and Altmühltherme and thus between the river system of the Rhine and the Danube. The Karlsgraben in this respect is the precursor of the Ludwig-Danube- Main Canal and the Main- Danube canal, overcame the European watershed but further southwest than this.
History
According to current knowledge, Charlemagne had in the year 793 at the present location ditch near Treuchtlingen one about three kilometers long canal dug. The aim of the company was to improve the traffic situation for the traders who sailed the route from the Rhine to the Danube with their ships first on the Main all the way to White Castle at the Swabian Rezat where the convenient trade ended shortly before the main European watershed. Through the channel, it was possible that traders from the two adjacent river systems arrived by ship in each other and were able to expand their scope of action. The frequently found in the literature arguing that the channel had been built for military reasons, to bring Charles' war fleet of the river Danube and the Rhine, is now no longer tenable. Strategic motives were probably not decisive, especially as the King and later Emperor Karl stood in two river systems enough ships for military operations.
The statements of chroniclers, by which unfortunate soil and climatic conditions that led to the termination of the project, are now considered as not applicable, because the contemporary sources reported in the majority of a finished and usable channel. That he was still little used and was abandoned shortly after its construction, was due to the great effort that required the channel passage. The efforts were worth it for the dealers in daily business obviously not.
Nevertheless, there are other hypotheses, according to which the channel had been in use longer.
Refit is also a time much earlier classification of Karl trench, which would have as an employment measure for the nearby Roman garrison in the fort Biriciana at Wissembourg ( 90-253 AD) also made a navigable connection to other units on the Lower Rhine. This theory speaks in particular, that the damage caused by the trench waterway would partially located on non- Roman territory.
The early canals consisted of a series of limited water dam poses to the development of the chamber lock. In between, the level differences were overcome on slides or rolls. Near the Karlsgraben was built to supply water to the apex level, a dam. Also, a recently discovered at the Altmühltherme at Treuchtlingen early medieval dam was interpreted initially as a dam to supply water to the canal, to a C - 14 dating of the lower, high medieval age spoke. Furthermore, it was demonstrated that the stream bed of the young Rezat was moved to the care of the northern channel section with water. After all the Karlsgraben for the usual at that time Barges was quite suitable.
Today from the Fossa Carolina are to receive an approximately 500 m long water surface and adjacent earthworks.
Geotop
The Fossa Carolina is presented by the Bavarian State Office for Environment as Geotop 577G003. See also the list of geological sites in the district of White Castle -Gunzenhausen.