From paleolandscape to seafloor: Holocene transgressive evolution of a low-relief landscape in the Eastern North Sea

Rising sea level threatens coastal communities globally, making it important to understand long-term landscape responses to anticipate future changes. Submerged paleolandscapes in the eastern North Sea offer an archive of past environmental changes due to sea level rise and coastal retreat. However, these paleolandscapes remain largely unstudied, and particularly their long-term geomorphological and sedimentary responses to sea level rise are still poorly understood. We present a five-stage conceptual model of landscape evolution since the Late Glacial, based on analysis of reflection seismic and geotechnical data from a 2200 km 2 area in the eastern Danish North Sea. The paleolandscape consisted of large channels and glacially formed highs. During stage 1, the channels flooded, creating a low-energy near-coastal environment that transitioned into an estuary as rising sea levels inundated the channels. In stage 2, the continued sea level rise formed an archipelago of elevated glacial deposits that amplified bi-directional currents between them. In stage 3 one of the islands flooded and exposed the remaining coastlines to a high-energy wave-dominated coastal environment. This exposure increased coastal erosion and sediment availability, causing increased deposition in the shoreface where several spits developed. In stages 4 and 5, the coastal environments drowned to form the present-day marine environment, dominated by storm waves and currents. This study highlights the dynamic nature of coastal landscape evolution under a rapidly rising sea level, illustrating how a sheltered, low-energy depositional environment gradually transitions into one dominated by erosion and sediment redeposition as sea level rises.