Birkas svarta jord 1969–2021
– Utvecklingen av en stratigrafisk metod
Birkas black earth 1969–2021 - the development of a stratigraphic method. Birka’s role is a main reference point in discussions on land upheaval chronology, which is important in understanding prehistoric settlement in Scandinavia. Birka was also the central point of a wide-reaching hinterland throughout the Lake Mälaren region on the eastern coast of central Sweden. This was apparent at the restart of investigations into the settlement history of this area during the 1960s, and it was easy to incorporate in the post-war research into the history of West European towns. The complexity of the cultural layers of this settlement together with numerous small finds was a challenge already from the beginning of the Black Earth investigations in 1969–1971. It quickly became evident that new, more effective and rational excavation techniques and methods of documentation were needed. These were further developed at the beginning of the project, Excavations in the Black Earth 1990–1995, which was generously financed by Tetra Pak AB along with several companies and foundations. A concise account of how these problems were solved is described in this paper. The stratigraphic analysis of this extensive material is especially interesting. Thanks to these techniques and methods of documentation, it has been possible to construct a new relative chronology based on short intervals of only 5–10 years for the greater part of the Viking Age, although dendrochronological material is not preserved in these dry cultural layers.