Abstract Two zones of reworked deposits are identified in the Quaternary succession exposed in the Bouchon quarry at Ivry, Seine, France. Atypical upper Acheulian artifacts found in loams produced by alteration of the older loess cannot therefore be dated as upper Acheulian without further study of the stratigraphic relations of the enclosing loam, whose age may vary from Riss to Wuerm (Pleistocene) depending upon the circumstances of reworking.