Holocene shoreline displacement, land-cover change and human settlement distribution on the southeast coast of Sweden

Abstract

In this study, we investigate the interplay between relative sea-level changes, the development of human settlements and land-cover changes in the Västervik–Gamlebyviken region on the southeast coast of Sweden, an important archaeological area from the Mesolithic until recent times. The reconstruction of shore displacement was based on diatom analysis of radiocarbon-dated sediment cores from three lake basins combined with previously published lake isolation data. The resulting curve was used to construct palaeogeographical maps for selected time windows. Land-cover changes were inferred from pollen data from three lakes using the Landscape Reconstruction Algorithm with its two models REVEALS and LOVE. Our data suggest that people took advantage of the land gained due to an overall fall in relative sea level from ~35 to ~3 metres above sea level (m a.s.l.) over the last 10 000 years, interrupted by periods of transgression and highstands. A sea-level regression of ~16 m occurred between 10 000 and 8500 cal a bp followed by an ~3–4-m sea-level rise, reaching ~22 m a.s.l. at ~7500 cal a bp, which corresponds to the maximum Littorina Sea shoreline in the area. The available archaeological findings for the Mesolithic and Early Neolithic (8950–5450 cal a bp) agree well with the shore displacement curve showing that settlements and human activities were concentrated along or above the shorelines as defined from our study. During the transgression after 8500 cal a bp, however, seasonal settlements were submerged (as shown by findings of polished stone tools and hearths buried in sand) and used again during the subsequent regression after 4600 cal a bp. The Iron Age (2450–900 cal a bp) corresponds partly to a highstand at ~11 m a.s.l. between 3600 and 2000 cal a bp and partly to a rapid regression of ~8 m between 2000 and 1500 cal a bp, and both periods coincide with known human activities along the contemporaneous shoreline. The rapid regression after 2000 cal a bp corresponds to an increase of both regional and local landscape openness and the beginning of a continuous record of crop cultivation.