Smectite in Some Gangetic Alluvial Soils of West Bengal

Clay fraction of the Gangetic alluvial soils from four districts of West Bengal was examined by X-ray diffraction analysis supplemented by chemical and physicochemical data, for their clay mineral composition. Contrary to earlier belief, it was established that in addition to illite and kaolinite, smectite is invariably a component of the soil clays of Gangetic alluvial origin. In some of the soil clays smectite was the dominant mineral. Vermiculite was also detected in one sample of the lower Gangetic alluvium. Except for two samples, chlorite was recorded as one of the constituent minerals in the clays.