Development shifts on the emerging Järve coast (Estonia) in Late Holocene

Abstract

This study identifies a sequence of accretional paleospits and beach ridges at the Järve coast, which developed over the past 4000 years (4 ka) mostly through coastal progradation and land emergence driven by glacial isostatic adjustment (GIA). Using optically stimulated luminescence dating, LiDAR elevation data, historical cartography, and recent instrumental metocean forcing data, we analyze the historical developments in relative sea level (RSL) and major shifts in the region's geomorphology from the Mid- to Late-Holocene. From 7.3 to 4 ka, the GIA induced uplift with local rate of about 2.2 mm/a facilitated land emergence and the formation of the Järve shoal which was exposed to storms from west, south and east; from 4 to 3 ka, the shoal evolved into a sandy island with spits; between 3 and 1.5 ka, the barrier island became connected with the Saaremaa mainland while the still emerging paleospits distanced from the sea. From 1.5 ka to 1850 CE, westerly forces were cut off; cooling climate during the Little Ice Age and tree logging facilitated formation of nearshore dune belt. In the mid-20th century, a reversal in RSL occurred, as the global sea level rise exceeded the local uplift. Concurrently to the Baltic Sea winter ice extent decrease, Järve ice days have reduced by 46 % from 1750 to 2023 CE. This reduction has exposed the coast to increased wave energy and storm surges from winter storms, resulting in an approximate 85-m shoreline recession at Järve and sediment accumulation near downdrift Nasva port.