Crossing the bog – Excavation and Documentation of a wooden track North-West Germany
Amandine Colson, DENKMAL3D, Vechta, Germany
Lower-Saxony is located in North-West Germany, East of the Netherlands and ending in the North Sea. This region is known for its wetlands and bogs, which represent today only about 5% of its total surface. These were and are mainly made of peat also called also turf, which is a deposit soil formed by the partial decomposition of vegetal matter in wet acidic conditions. Left in the sun for drying, peat was used as a fuel for cooking and heating.
Crossing a bog was dangerous, people and their cargo were sinking, some voyagers got lost and perished looking for their way. Building a safe passage was essential, which motivated people to construct wooden tracks over several kilometers to enable exchange and trade. Thanks to the anaerobic properties of this burial environment, organic material is extremely well preserved in bogs, and very valuable archaeological data can be retrieved form such sites. In Lower-Saxony the oldest example of such wooden tracksis the “PfahlwegPr XXXI” (Poles track Pr 31) dating from 4682 BC.
In 2019, the Dümmer Natural Park represented by DetlefTänzer, got financial support from the European Regional Development Fund to excavate and document one section of the “BohlenwegPr VI” (planks track Pr 6) located in the bogof Aschen. The project is a cooperation between the Dümmer Natural Park and the the State Authority for Heritage Protection in Lower-Saxony (NLD) . The area is about 60 km North of Osnabrück and 70 km South of Oldenburg and the site has been dated with dendrochronology around 60-55 BC. The planks found were until then were mostly made of alder wood, very little part of oak and other wooden species.
The company DENKMAL3D (D3D) was selected to undertake the project under the supervision of Dr. Marion Heumüller (NLD), archaeologist in charge of wetlands and bogs at the State Authority. On site, the operation was led by Eik Abbentheren (D3D), excavation technician, together with a team of 2-5 staff members.
The track was excavated in the summers 2019, 2020 and 2021 section by section, of about 20 meters each. The sections were then one by one carefully uncovered from the peat and each wooden plank was sampled. Future analyses will determine wood species and provenance, thus conducted by Dr. Hanns Hubertus Leuschner. The track is composed of two layers of wooden planks perpendicular to each other, placed horizontally on stakes rammed in vertically into the ground. For each section, the two wooden layers were documented in three dimensions individually using a 3D scanner (Leica RTC360) and images acquired by a drone (DJI Phantom 4 and Yuneec H520). The point clouds of the 3D scanning and the surface information from Structure-from-Motion (SfM) were first separately processed using Leica Cyclon and Agisoft-Metashapesoftware, and merged together into several 3D models. This acquisition was performed by several surveyors from D3D: Henryk Furs, Volker Platen, Karsten Schmidt and Alexander Schubert.
Within three campaigns a total of 540 meters were uncovered, and about 4,000 planks sampled. In terms of artefacts, 151 objects were retrieved, among others most probably the oldest leather shoe in Northern Germany, elements of wooden wagons, a few possible wooden measuring sticks and some ceramics. At the moment, the analyses are still running and will deliver more exciting results in the coming years. But the variety of wooden species has been very surprising, which enlarge the spectrum known form the site until now. The dating has been reviewed to 46 BC thanks to the new samples.
Concerning future perspectives, the 3D models of each section processed by Henryk Furs and Alexander Schubert (D3D) will be hopefully put together and presented into a Virtual Reality or an Augmented Reality environment for museums visitors.
 Niedersächsische Landesamt für Denkmalpflege