Helena Alexanderson

Influenced by climate warming and sea-level rise, seacoasts in many parts of the world are undergoing regime shifts, including increased coastal erosion in the southeastern Baltic Sea. The aim of this study is to reconstruct the depositional and erosional history of the Järve coastal scarp using sediment stratigraphy, new luminescence and radiocarbon dates, ground-penetrating radar, and LiDAR data. The seaward ridge, where the 3.5-m-high sandy scarp is located, began to form around 1600 years ago, in front of a 3500–4000-year-old palaeospit system that developed through sediment accumulation and postglacial uplift. The lower section of the outcrop was deposited in the shallow nearshore zone, where underwater sandbars acted as nuclei for spit formation. Darker sediment layers and variations in lamination patterns reflect changes in sediment sources and storm activity. Above the marine-deposited sandy layers lies a thin aeolian unit, which is only weakly developed at the Järve outcrop. Dune features occur only in a few blowouts, likely associated with the Little Ice Age (~1300–1850 CE) and anthropogenic vegetation disturbance, such as logging or slash-and-burn agriculture. Over the past ~100 years, the formerly emergent system of beach ridges and spits has shifted to an erosional regime. The earlier relative sea-level fall has ceased, seasonal sea ice is diminishing, the impacts of winter storms are intensifying, and the scarp is retreating. This study demonstrates how global changes are manifested on seacoasts at a local scale and highlights methodological difficulties in using seashells for coastal stratigraphic dating.