Soil Mineralogy and Clay Mineral Genesis in Alfisols from Dhauladhar Range of Middle Siwaliks

Mineralogy of fine and coarse clay; fine, medium and coarse silt; and sand fractions of two Alfisol profiles from Kang a district of Himachal Pradesh, has bene characterised. Clay and fine silt are dominated by mica, while \he associated minerals are kaolinite, pedogenic chlorite and mixed-layer ones with some smectite, vermiculite quartz and feldspars. Coarser fractions consist mainly of quartz but mica, feldspars and some chlorite are present. Mica present in clay is of detrital origin, while kaolinite is neofarmed after hydrolysis of feldspar- Mica is considered to have weathered through mixed-layer minerals to smectite and vermiculite and the persistence of mixed-layer minerals observed in these profiles, possibly slowed down the intense weathering of mica to expansible layer silicates. Weathering sequence for mica and feldspars has been suggested the weathering means calculated for these soils show that they are in the mica-illite stage.