Diatoms are powerful biological indicators preserved in lake, wetland, estuarine, and archaeological sediments. Their sensitivity to environmental conditions and excellent fossil record makes them ideal for reconstructing palaeoclimate, palaeohydrology, land-use changes, and past water quality. This session invites contributions that apply diatom-based methods in understanding Quaternary environmental change and archaeological contexts. We welcome interdisciplinary work linking diatoms with sedimentology, geochemistry, and archaeological findings to interpret ancient human-environment interactions, site settings, and landscape use.