A microscopic study has been carried out on medieval levels successively corresponding to the floor of a church and of a presbytery at Saint-Victor-de-Massiac (Cantal, France). These levels are composed of alterning yellow or reddish hard-packed floors and humus-rich " living " levels, covered by a mixture of rubified soil aggregates and charred debris which could represent the remnants of a burnt floor. The comparison of these deposits with the soil outside the house clearly shows the importance of transformations in the open air due to biological mixing of sediments, translocation of fine particles under precipitations and phosphates accumulation coming from cattle urine.Des niveaux d'occupation médiévaux à l'intérieur d'un locus apparten...