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Purkajasuo

Purkajasuo today

A wetland site discovered accidentally in the western part of the Kierikki area in Yli-Ii, Northern Ostrobothnia, Finland, surprised archaeologists in the mid 1990’s by its size and the rare degree of preservation of the organic finds. A number of wooden objects had already been found during the draining of the present-day peatland agricultural field in the 1950’s, but the age and the tremendous scientific value of the prehistoric fishery were only recognized later. Since none of the wooden structures were intact, it has been challenging to reconstruct the Stone Age fishing methods in detail, but most of the finds point to ethnographically described weir fishing with lath screen traps set in shallow water. All of the radiocarbon samples returned Middle Subneolithic dates ranging between 3692-2876 cal BC, but the relative dendrochronological dates indicate a distinct activity phase of only 19 years. The site is still in the process of being destroyed due to the progressive lowering of the water table.  After a few decades, or a century at the most, a significant portion of the wooden artefacts of Purkajasuo will be deteriorated.




A pencil-shaped point of a Middle Subneolithic pile

A pencil-shaped point of a Middle Subneolithic pile



Field conservation at Purkajasuo in 1996
Field conservation at Purkajasuo in 1996

The stationary fishing structures erected in a shallow, nutrient-rich inlet of Purkajasuo could in season have taken large catches of fish. Information from the ethnographic and historical record point that a significant amount of time, energy and craftsmanship have been invested in the manufacturing and maintaining of lath screen traps and weir fences that may have functioned together as an effective fishing system. The wood for manufacturing the fishing structures have been obtained from the nearby woodlands in the wintertime. A special technical feature, the use of tree bark as a lath screen binding material, can be distinguished in the eastern Baltic Sea region during the Middle (Sub) Neolithic period. In Finland, which forms the northwest corner of the lath screen trap zone, birch bark rather than bast was adopted as a binding material possibly for local vegetation historical reasons.

The rare state of preservation of the Purkajasuo site is the outcome of several strokes of luck. The area containing wooden artefacts may well extend much further than is currently believed, especially into previous littoral zones facing east and southeast of the site. Geophysical surveys and test excavations applied in potential areas are essential in defining the total scale of the site. Evidently, though, similar wetland sites still exist in thousands of Finnish peatland and alluvial deposits, but the main question is, for how long? The increasing peat extraction volume in Finland, in addition to drainage, is the major reason why wetland archaeology is topical today and call for drastic action.

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