Identification and Genesis of Clay Minerals of Some Alfisols of Northern Bihar

Clay minerals of four typical Alfisols of the Indo-Gangetic plain of northern Bihar, undergoing decalcification, were identified with the help of chemical, mineralogical and X-ray data. The clays invariably indicate the characteristic peaks of mica, kaolinite, vermiculite, chlorite, quartz, feldspar and intergrades. Soil clay of pedous 1 and 2 indicates the presence of vermiculite and smectite. Clay mica, chlorite and kaolinite are inherited from the alluvium while the formation of chlorite did occur by hydroxy interlaying of vermiculilte, a weathered product of mica.