Krufter Bachtal

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Krufter Bachtal, tunnel opening below the B256

The Krufter Bachtal is the valley of the Krufter Bach, which runs through the villages of Kruft and Kretz and flows into the Nette in Plaidt . In the area of ​​the Krufter Bachtal between Kretz and Plaidt there are deposits of the Laacher See volcanic eruption, traces of degradation from the Roman and modern times and the Pommerhof cultural monument, an estate from the early Middle Ages. Particularly striking traces of the tuff stone, large tunnel openings, can be seen below the B 256 between Kretz and Plaidt.

History of origin

The Krufter Bachtal is shaped by the eruption of the Laacher See volcano about 13,000 years ago. The eruptions resulted in massive deposits of volcanic rock. From the first eruption phase comes an approximately 1 meter thick, light pumice layer , which today lies at the bottom. Burning avalanches of the second eruption phase led to thick layers of tuff ; about 14 meters of solid tuff and about 12 meters of diving above it. The latter is ash that is less solidified. Above that follows a layer of tuff that came into contact with rainwater and thereby also turned into solid tuff. Only this 4 meter thick layer was accessible to the miners in Roman times and therefore bears the name "Römertuff". In the last phase of the volcanic eruption, there was intense pumice precipitation, which covered the layers below with a layer of pumice about 3 meters thick. A layer of humus and vegetation formed on the pumice. The Krufter Bach, which was spilled when it erupted, dug a new bed through the pumice and into the tuff layer.

Tufa mining

Roman times

Outcrops can be seen again and again along the stream . It is believed that the engineers of the Roman army came across tufa for the first time at these outcrops. Most of the traces of Roman mining are or were found underground. The old Plaidter parish church stood "on pillars", ie on a Roman tuff quarry. For safety reasons, the Romans left tuff “pillars” at intervals. A testimony of the Roman underground tuff mining that is still visible today is located not far from the Krufter Bachtal in the Meurin Roman mine . Here part of a 2,000 year old Roman tuff mine was exposed, conserved and made accessible for tourists.

17th to 19th century

Between 1627 and 1858, the tufa in the Krufter Bachtal was dismantled by blasting underground, as shown by boreholes in the walls. The definition of the period is based on the following facts: The use of blasting technology in European mining is first proven around 1627. Because of the dangers underground mining of tuff was banned in 1858. A good 3-meter-wide corridors were driven into the stone at a depth of around 15 meters for mining. The distance between the aisles was about 20 to 40 meters. A right-angled underground tunnel system of approx. 250 m × 150 m was created. The blasting cut the tuff into smaller pieces. Crushed again by hand, the stones were stacked on arcs for days. After a drying time of about 2 weeks, the stones were ground into fine rock flour, into trass . Trass has hydraulic properties and was used in conjunction with lime to make a waterproof mortar.

Discovery of the tunnel system

Tunnel cut during the 1997 excavation in the Krufter Bachtal

In 1957, a dam broke north of the Krufter Bachtal and the underground tunnel system in a sewage pond of a pumice washing plant in the Herfeldt trass pit. The water flushed part of the previously unknown tunnels free. The archaeologist Josef Röder examined the flooded corridors with Sepp Leiß from Plaidt, partly by boat, and made a detailed plan of the tunnel system. It turned out that the actual mining areas were much deeper. Over the course of time, the corridors had grown taller as the ceilings collapsed. Open questions about the mining technique and the age of the mine could not be answered at this time.

Due to the renewed collapse of the tunnel ceilings in the following years, the road running above the tunnel system (today the federal highway 256) subsided again and again. The tunnels in the road area were therefore filled with cement in the 1980s. When the tuff layers were removed from the field below the main road in 1970 (the pumice layer above was removed in the 1960s), an area of ​​the tunnel system became visible. In 1997, as part of the volcano park research, archaeologists from the Roman-Germanic Central Museum in Mainz cut a tunnel. The depth and extent of the tunnel could thus be determined exactly. Proof of the age of the tunnel was also found: two bores for explosives.

Pommerhof

The Pommerhof is an estate in the Krufter Bachtal, which was founded in the early Middle Ages. In 1953 a cemetery from Franconian times with 84 graves was discovered near the farm. The estate's deceased were buried here between AD 600 and 680. The number of graves suggests that there was a large estate on the site of the Pommerhof in the early Middle Ages, on which a court community of an average of 45 people lived.

leisure

The Krufter Bachtal is one of the landscape monuments of the volcano park . A hiking trail leads from the Vulkanpark information center through the Rauscherpark and the Krufter Bachtal to the Meurin Roman mine .

literature

Web links

Commons : Krufter Bachtal  - Collection of images, videos and audio files

Individual evidence

  1. Vulkanpark GmbH, information board 17 in the Krufter Bachtal
  2. Angelika Hunold, Peter Ippach, Holger Schaaff: Kirchen, Stollen, Steinbrüche, page 49
  3. ^ Vulkanpark GmbH, information board 14 in the Krufter Bachtal