Långtidsbevaring av arkeologiska träkonstruktioner i en terrester miljö – fallstudie Kronholmskoggen

Abstract

Larger archaeological wooden objects such as a shipwreck are expensive to excavate and preserve. In the past, archaeological wood material has been abandoned or even burned due to lack of sufficient economic resources. There has been an increased interest in preserving archaeological wood as a source of historical information. The method of in situ preservation can be a way to achieve long term storage of the objects in their excavation site. By preserving in situ it is possible that the objects are still preserved for the future and available for later investigations using more modern sophisticated methods of analysis. Most of the archaeological wood found in waterlogged environments has shown microbial degradation. It is now known that oxygen is the most important factor to control in an in situ preservation environment to avoid attacks by microorganisms. An anaerobe waterlogged environment should work for long-term preservation storage. The wreck Kronholmskoggen is preserved at its excavation site, on a golf course in Gotland. In 1995, the wreck was discovered, an excavation and documentation were carried out by a team of archaeologists and conservators. The wreck was preserved in situ, and placed next to the hull 4 new healthy wood samples were deposited to act as biosensors in order to be able to carry out a later analysis of the environment the wreck is preserved in. This study presents a theoretical examination of one biosensor, describe the different steps of the examination and analysis of said sensor. Three methods were described theoretically in the study, the Needle Test, Light Microscope and Umax. Next, three possible and fictitious results are presented and discussed. Results are discussed to create an idea of the Kronholmskoggen environment and condition, and if one can recommend that the wreck continues to remain at this location. The environment determines the conditions for a successful long-term storage. A waterlogged anaerobic environment protects the object from fungal infestation and tunnelling bacteria that need a higher oxygen content to grow. Erosion bacteria are the microorganism that accounts for the greatest degradation in water-soaked environments as it, unlike the other microorganisms, thrives in a low oxygen environment.