Formation of Landscape and its Effect on Clay Mineral Variability at Dharwarean formation

Three pedons were studied along a toposequence from rain shadow area of the Western Ghats at Dharwad district, Karnataka. The hilly terrain around the study site is subdued which are characteristics of the rain shadow belt of the Western Ghats. The two parallely placed iron ridges and valley to have formed in the study area are expected as a result of the Plio-Pleistocene crustal movement and tectonic activity during the formation of the Western Ghats. The distribution of different sized coarse fraction along the toposequence was the result of colluvial movement. The particle-size distribution with depth and the parent material uniformity index gave an idea about the variable nature of parent material. These also indicate the nature of weathering of soil. The clay minerals were identified based on their characteristic basal reflections and their approximate abundance based on the intensity of the peaks. The presence of high amount of kaolin minerals in saprolite of the Summit pedon were expected of geogenic origin. The presence of comparative higher amount of 2:1 and interstratified minerals at foot slope pedon was due to its position in toposequence. Relief aids in the redistribution of the matter and energy forming different types of soil at different positions on the landscape.