Characterization of barchanoid dune systems on the Cap Ferret spit (Aquitaine)

The Cap Ferret spit (Atlantic coast, France) is defined by barchanoid dune systems formed by a large input of sand remobilized by aeolian dynamics. GPR investigations have revealed distinct internal architectures within the barchanoid dunes, mainly characterized by eastward-dipping reflectors and complex structures illustrating sand remobilization. These structures highlight a progressive evolution in dune morphology, from west to east, i) low topographic and interconnected dunes without specific morphology (proto-barchans), ii) interconnected dunes with crescent-shaped morphology (barchanoid ridge) and iii) isolated dunes with a well-defined crescent-shaped morphology (isolated barchans). This study investigates these distinct stages of development, linking internal stratigraphy and geomorphological evolution, and provides insights on the dynamics of coastal barchanoid dune formation and migration.