The Atacama Desert rock coast: an underrated witnesses of long-term wave erosion

Abstract

The Atacama Desert rock coast has allowed for the study of tectonic and climate influences on landscape construction and evolution. This rock coast features important morphologies such as: (1) the Great Coastal Cliff, which runs parallel to the coastline for almost 1000 km, reaching heights between 800 and 2000 m a.s.l.; and (2) shore platforms and staircased marine terraces, which are discontinuously recognized along the extension of the Atacama Desert coast. These morphologies, especially marine terraces, have been studied to estimate rates of uplift in order to constrain the history of the Chilean forearc deformation. However, they have received little attention about the influence of surface processes such as wave erosion on their development and preservation. Certainly, it has been largely proven that wave erosion plays an important role in the development of shore platforms and the evolution of coastal areas. Despite this, its effects on the development of shore platforms and marine terraces and, thus, the landscape construction of the Atacama Desert coast have been scarcely investigated. In this work, we developed a numerical model to understand the influence of a set of processes on the long-term landscape evolution (104-106 years) on rocky coasts. The set of processes involves relative changes in sea level due to eustatic cycles and vertical landmass movements, as well as surface processes such as wave erosion and intertidal weathering. This model allows us to estimate rates of coastal erosion and, thus, morphology development (e.g., platforms and cliffs) to provide new insights for one of the longest but underrated erosive rock coasts. The research design consisted of two stages: (1) model development and testing, and (2) model validation. The model was validated using Atacama Desert coast geomorphology, including field data and morphometric analysis from high-resolution digital elevation models. The model results and the research itself are used to understand the influence of surface processes on the evolution of rock coasts in a tectonic uplift and hyperaridity context.