In the Upper Harz mining area, while renovating an old shaft, workers came across a well-preserved medieval water-solution tunnel. It was once used to drain pit water and was probably built in the 16th century – possibly even earlier. Because the tunnel was blocked with sediment for centuries, many traces of old mining activities have been preserved in it.
The Upper Harz was already an important mining area in the Middle Ages. The rich deposits of silver, copper, lead and iron were mined on a large scale from the 13th century. To get to the ore, vertical shafts were driven into the subsoil and piston pumps driven by water wheels were used to drain the shafts and tunnels. Slightly sloping water solution tunnels also served to drain the pit water from the mine areas deeper in the mountain.
Accidental discovery during renovation work
Workers have now discovered one of these medieval water solution tunnels while renovating a shaft on the Brauhausberg in Clausthal-Zellerfeld. The renovation work started when the ground subsided after a period of heavy rain and thaw in January 2019. An approximately 50 centimeter deep and four meter wide hollow formed in a road above the old mine area because the ceiling of the “Silberkrone” shaft gave way would have. This well-known shaft was operated from around 1660 to 1760 and has a depth of around 46 meters, according to the State Office for Mining, Energy and Geology (LBEG).
In order to prevent further break-ins, security measures have been started at the Silberkrone shaft, as part of which the old mine shaft will be exposed and supported. The workers have now come across an old water solution tunnel, the so-called Johannes tunnel, at a depth of around 20 meters. “That wasn’t completely unexpected, but that it is still in such good condition is a great discovery,” says Thomas Finkeldey from the LBEG. This tunnel is mentioned in the documents from the mine archive, some of which are centuries old, but the existing plans are very sketchy.
Insights into the work of medieval miners
According to archaeologists’ estimates, the tunnel dates from at least the first half of the 16th century, perhaps it is much older. The special thing about it is its almost original condition. “His appearance and the traces that we discover here give us information about his age and how the miners worked at the time,” explains Katharina Malek from the Mining Archeology Department of the Lower Saxony State Office for Monument Preservation. For example, the wooden treads are well preserved, but you can also see the holes in the beams of the working platforms.
“From a scientific point of view, this offers a unique opportunity to examine the tunnel, which has been completely backfilled for centuries, with the historical traces of work,” says Malek. She and her team hope to learn more about the history of the gallery and mining in the Upper Harz. The documentation of the finds and the tunnel structure is carried out using the most modern technical processes. To do this, the scientists create thousands of photos from different perspectives and use an algorithm to calculate a high-resolution 3D model of the Silberkrone shaft and the Johannes tunnel. Only when this work has been completed, the shaft and tunnel should be backfilled and thus permanently saved from deterioration.
(Video: Geochannel LBEG)
Source: State Office for Mining, Energy and Geology (LBEG)