Anatomy of foredunes progradation: successive phases of erosion and recovery related to storm scarping and post-event reconstruction (Normandy, France)

This study provides a detailed stratigraphic characterization of the successive stages within the erosion–accretion cycle of a beach–foredune system. We combine high-resolution ground-penetrating radar (GPR) data with targeted trenching across multiple field sites on the western coast of Cotentin (Normandy, France) to reconstruct the internal architecture and depositional history of foredunes in relation to known storm-induced erosion and recovery events. Radar profiles reveal multiple erosion scarps bounded by surfaces exhibiting a concave geometry, with steep upper slopes and flatter lower slopes. Slump blocks and debris fan deposits overlie the scarps, formed by wave undercutting and gravitational collapse. These deposits are subsequently overlain by onlapping foresets that drape the scarps, slump blocks and debris fans marking successive reconstruction phases. The foresets display high-angle dips subparallel to the underlying scarp surfaces. Narrow, convex cross-beds landward of the crest, record post-scarping crest accumulation, followed by sub-horizontal reflectors indicating renewed dune accretion or progradation. Together, these sequences capture the stratigraphic expression of scarping and recovery, and improve understanding of how short-term erosional events are archived within coastal dune stratigraphy, with implications for interpreting relict foredune records.