Last years, archaeological fieldwork has provided a chance to study specific contexts of edges of ancient banks, where the conditions of pollen trapping and preservation are favourable to their analyses. Moreover, these layers being precisely dated through archaeological artefacts - here from the middle and late Neolithic and Bronze age- the chronological context is much more precise and reliable than that of sequences in natural contexts, where dating is based on correlations with other sequences and radiocarbon dating.

Two cores, at Bazoches-sur-Vesle "Le Muisemont" (Aisne) and Houplin-Ancoisne "Le Marais de Santes" (Nord), show the environment during the Subboreal, a quite stable landscape compared to the preceding period.