On the basis of compressional wave velocity, the deep‐sea sediment layer can often be divided into two zones: an upper zone where velocity appears to increase monotonically with depth, although secondary effects resulting from stratigraphic variability are usually present; and a lower zone where large velocity variations occur rapidly and unpredictably with depth. In the upper zone, physical properties were parameterized in terms of the single variable porosity, which is assumed to decrease exponentially with depth. This model incorporates mutually independent data sets, e.g., corrected core porosities from consolidation measurements, thermal measurements from bore holes, and compressional wave velocities from seismic measurements. These data are few and highly variable, but demonstrate general trends consistent with the simple compaction model. Only in the presence of biogenic material does the lower zone exist. Lithification in this zone appears to be dominated by chemical processes, and the term, ’’zone of induration,’’ is suggested. This simplistic model is based upon considerable speculation and imprecise data, and is thus proposed only as a working hypothesis for future investigations.