The Seine-Maritime coastline, shaped by constantly eroding Mesozoic chalk cliffs, experiences significant and poorly understood sandy siltation, particularly to the east of Saint-Valéry-en-Caux. To better determine the origin of this siltation and to follow the sedimentary dynamics, 45 surface sediment samples over a 10 km² area off the coast of Saint-Valéry-en-Caux were collected. Elemental chemical analyses (Ca, Sr, Si, BrOrg) were carried out: (i) on the bulk sediment, and (ii) on separate fractions. The GSTA (Geochemical Sediment Trend Analysis) method was applied to the bulk sediment, while the COVA (COmposition Variability Analysis) method was used for separate fractions. Carbonates produced in situ and likely to be fragmented during transport are excellent indicators of local dynamics. Their stock dynamics were monitored using an innovative approach (PASTA: PArticulate Stock Trend Analysis). The result is a complete picture of sediment dynamics. Three zones can be distinguished: (i) a steeply sloping western zone, in dynamic swell/tide equilibrium, where shells make little cross-shore transport towards the coast, (ii) a gently sloping eastern zone, also in dynamic swell/tide equilibrium, where shells and quartz migrate coastward through the minimum energy zone located at -15 m, and (iii) an intermediate zone, which appears to be much more mixed, with disrupted cross-shore exchange.