International audienceThe pollen analysis of a borehole from the Laigne Valley, in Molesme (21), gives the first complete Holocene reference for the southeast of the Paris Basin. This low altitude sequence differs from those obtained in mid-mountainous regions: the pine forest is not replaced by oak and beech woods until the end of the Atlantic chronozone. Certain fluctuations which reveal changes in humidity in the alluvial plain, also shown by malacological analyses on a nearby outcrop, could be the result of more global climatic changes. The first palynological clues to anthropisation do not appear until the Iron Age, and fit perfectly with local archaeological data.L'analyse pollinique d'un forage réalisé dans la vallée de la Laigne, su...