Theoretical consideration of the formation of plowzone archaeological deposits implicates artifact size as an important and heretofore under-used source of information. Modality in size distribution of degradable artifacts, such as low-fired pottery and bone, indicates the addition of stratigraphically deeper materials to a plowzone assemblage. This means that different ages and/or depostitional contexts are mixed in such asemblages. With sufficiently large and well-controlled samples, the location and characterization of sub-plow deposits may be possible from the analysis of size distribution of surface materials alone. Application to a "worst case" surface assembalge from SE Missouri demonstated the general feasibility of the approach.