ABSTRACT
Over the last few years, a large number of augered boreholes have penetrated the archaeological deposits of the protected heritage site of the medieval town of Oslo, Norway, mostly as a result of large development projects. The archaeological observations and geochemical samples analysed from these investigations constitute the basic research material for evaluations of conservation state and preservation conditions. The data have been collected in collaboration between the Norwegian Institute for Cultural Heritage Research (NIKU) and Bioforsk. This paper presents the noted state of preservation of the archaeological deposits, groundwater levels, and assesses the conditions for continued in situ preservation. The question of in situ preservation is and has since the ratifi cation of the Valletta treaty (Council of Europe, 1992) been a major concern to the Cultural Heritage Management authorities in Norway (cf.
