Decoding the interplay between tidal notch geometry and sea-level variability during the Last Interglacial (Marine Isotopic Stage 5e) high stand

Abstract

Relic coastal landforms (fossil corals, cemented intertidal deposits, or erosive features carved onto rock coasts) serve as sea-level index points (SLIPs) widely used to reconstruct past sea-level changes. Traditional SLIP-based sea-level reconstructions face challenges in capturing continuous sea-level variability and dating erosional outcrops, such as ubiquitous tidal notches, carved around tidal level on carbonate cliffs. We propose a novel approach to such challenges by using a numerical cliff erosion model embedded within a Monte-Carlo simulation to investigate the most likely sea-level scenarios responsible for shaping one of the best-preserved tidal notches of the Last Interglacial age in Sardinia, Italy. Results align with Glacial Isostatic Adjustment model predictions, indicating that synchronized or out-of-sync ice-volume shifts in Antarctic and Greenland ice sheets can reproduce the notch morphology, with sea level confidently peaking at 6m. This new approach yields continuous sea-level insights, bridging gaps in traditional methods and illuminating past Interglacial sea-level dynamics.