Many of the micaceous soils of the Indo‐Gangetic alluvial plain of northwestern India are sodic and have clay‐enriched textural B horizons. These soils sometimes lack identifiable clay skins. In order to determine the genesis of the textural B horizons of these soils, both with and without identifiable clay skins, one Natrustalf (Sakit soil) and one Aeric Halaquept (Rahamabad soil) were selected for study.The results indicate that (i) the parent material and the mineralogy of the clay fractions are uniform, thus discounting stratification; (ii) the clay in the B horizon is not formed in place, as evidenced by increase in the K2O content of the sand and silt fractions with depth; (iii) the fine clay (<0.2 &mgr;m) resulting substantially from weathering of biotite has preferentially translocated in a deflocculated form, causing an apparent decrease of clay mica with depth; (iv) the void argillans are typically of the type “impure clay pedofeatures,” which seem to have resulted from the impairment of the parallel orientation of the clay platelets induced by dispersion of both clay and silt size layer silicates in sodic environment; and (v) the decrease in the clay mica (<2 &mgr;m) with depth could be a sure test of clay illuviation, even when clay skins identifiable in the field are absent, as a step toward precise and unambiguous definitions of soil taxa.