Six contrasting benchmark Oklahoma soils underlain by sedimentary rock were selected and sampled by horizon to parent material or a 2‐m depth. Total Co, Cu, Ni, Pb, and Zn concentrations by horizon in total soil and clay fractions were determined by x‐ray fluorescence. Total concentration of heavy metals in these soils is dependent on clay content. There are fivefold more Cu, twofold more Zn and Ni, and 1.5‐fold more Co and Pb in the clay fraction than in the total soil. The clay fraction of surface horizons contains a greater concentration of Cu, Zn, and Co than subsoil horizons due to biogeochemical cycling of these micronutrients from the subsoil to the surface during melanization. Biogeochemical cycling reduces the total amount of heavy metal loss from surface to subsoil horizons by clay translocation but doesn't offset the illuviation of total heavy metals sorbed to clay. Higher levels of total heavy metals in each profile for each element are found in the B horizons than the A horizons (77% of the samples). Characterization of soil for total heavy metal content should include a sample from the B horizon especially in soil with higher clay content in the B than the A horizon. Soil parent material discontinuities cause changes in concentration of several heavy metals within two of the six soil profiles. Identification of soil parent material discontinuities is not a consistent factor causing change in heavy metal concentration within the soils studied.

Recognition of pedogenic gypsum is particularly needed in parts of arid and subhumid climates to apply the suffix “y” to master horizons and to understand soil‐forming processes. Soil micromorphology provides correlation between field and laboratory observations, and recognition of pedogenic gypsum for the refinement of the “y” horizon suffix designation. Seven soils were described and sampled to (i) identify pedogenic gypsum, (ii) determine the distribution of pedogenic gypsum across a hillslope, and (iii) explain the occurrence of gypsum in residual‐derived soils. Gypsum content, saturated paste extracts analyzed for Ca2+ and SO2‐4, and micromorphology indicated gypsic horizon formation within the summit position. Small amounts of pedogenic gypsum occurring with allogenic and bedrock gypsum were identified in soils using micromorphology. Pedogenic gypsum accumulation was greatest in soils with higher contents of total gypsum and relatively longer periods of soil formation. In situ dissolution of gypsum during wet springs (March–June) followed by reprecipitation during hot dry summers (July and August) is proposed to explain the formation of pedogenic gypsum. An accumulation of pedogenic gypsum in the B horizon may indicate a net upward movement within the solum or a lateral movement of gypsum within the landscape. The compaction of diagenetic gypsum during geologic burial is proposed to explain gypsum form and formation within veins and joints in Cr and R horizons. Rock fragments containing vein and joint fillings of gypsum persisted within the solum and were identified as bedrock gypsum.