The topographic signature of relative sea level in numerical and real landscapes.

Crustal deformation along active coastline can be constrained with age and elevation of marine terraces. These are essentially the product of an erosive process (waves eroding bedrock) and a preservation process (rock uplift moving terraces up and away from subsequent wave erosion). The morphology that results from this combination depends nonlinearly on the characteristics of the two processes. In particular, variations in rock uplift rate can promote or hinder the creation of marine terraces at specific age and elevations (e.g., past sea level high stands).  While widespread and well-outlined in some coastal settings, marine terraces can be rare or absent from other areas despite the coexistence of the two driving processes. If they do not produce discrete terraces, wave erosion and rock uplift still contribute to shaping the coastal landscape in conjunction with subaerial processes, and their history is somehow encoded in the topography. Using the logic of a “sea level occupation map” that we introduced to describe the cumulative effect of wave erosion during the eustatic seesaw (Malatesta et al., 2022), we inspect the hypsometry of numerical and real landscapes whether or not they hold terraces. Hypsometry allows for a continuous representation, and inspection, of parameters in numerical models. In real landscapes, a hyspsometric survey does not require very high resolution digital elevation models, and produces tractable information from the entire topography. In this contribution we 1) explain our approach to create a metric that can be equally applied to numerical and real landscapes; 2) highlight threshold effects in numerical outputs that were difficult to identify previously; and 3) present preliminary results extracting valuable information about rock uplift rate and sea level occupation from coastal landscapes with limited or no marine terraces.