The paper discusse the use of a small assemblage of potsherds as evidence of fluvial erosion and indicators of microstratigraphical and geomorphological processes. The potsherds, sandwiched between 2 alluvial deposits, providing dating criteria for the two stratigraphic units, very important for understanding the geomorphology of the whole region. By integrating evidence of negative interfaces on potsherds by fluvial erosion and sedimentological evidence, it is possible to reconstruct the local stratigraphic formation processes. Furthermore, the paper discusses some theoretical implication of this case study for stratigraphic analysis. Negative interfaces produced by erosion on sediments and ceramics are considered in the smae analytical framework; in both cases, they represent cumulative units preserving the record of complex stratigraphic processes. Far from being simple limits marking gaps in sedimentary deposition, eroxive interfaces are very particular types of strata to be recorded and studied with geoarchaeological methods and with the same detail of traditional sedimentary units.