Consequences of Lake Expansion and Disappearance for the Complex of Bronze and Iron Age Settlements at Bruszczewo (Western Poland, Central Europe)

The archaeological microregion in Bruszczewo located along the middle course of the Samica River, was inhabited during the Bronze and Iron Ages by Únětice and Lusatian Urnfields culture people. Earlier literature emphasised that the valley floor was an extensive lake during the Bronze Age. Our research aimed to reconstruct the Bronze and Early Iron Age development of the lake and its transition into peatland. Using environmental archaeology methods, we marked the significant turning points in the lakes history. During the Early Bronze Age, a deep eutrophic lake was present on the valley floor, which supported the defensive nature of the nearby Únětice culture settlement. Around ca. 1880–1690 cal. BC, the lake underwent transgression, forcing people to create a fascine in the shoreline zone of the settlement. Terrestrialization of the lake began ca. 790–540 cal. BC with a gradual overgrowing that ended around the threshold of the eras. When compared to the results from other sites, it seems that these turning points were probably instigated by local triggers rather than global climatic events.