CHARACTERISTICS OF 14 A CLAY MINEI~ALS IN THE B HORIZONS OF PODZOLIZED SOILS OF ALBERTA by

Recent investigations of soils from widely distributed sites reveal the presence of clay minerals with 14/ ~ d spacings in the B horizons of podzolized soils in Alberta. The minerals appear to be concentrated in the 2.0-0.2 micron clay fraction, the fraction less than 0.2 micron being comprised primarily of material amorphous to X-ray. Despite the presence of montmorillonite in the eluvial horizon and soil parent material only interstratified minerals of this group appear in association with the 14 ~- mineral. Smaller amounts of quartz, kaolinite and illite are also noted in these B horizons. The data available reveal that the 14 A mineral is derived from montmorillonite and that formation occurs in situ in the B horizons. It is apparent from the investigations conducted that weathering of associated feld-spars under mildly acid conditions, releases hydrated alumina ions. These ions not only move into the interlayer regions of montmorillonite of fine clay size, where they exist in a discontinuous manner, but are also adsorbed onto the surfaces of these minerals binding adjacent particles into aggregates of coarse clay size. Adsorbed hydrated alumina hy-droxy ions in the interlayer region are responsible for the observed 14 A d spacings