Surface weathering of gneiss, northwestern higher Himalaya, India
Abstract The use of the Schmidt hammer to interpret the relative surface weathering of rocks at different elevation in the Satluj and Alaknanda valleys is outlined. The study carried out in the Higher Himalayan terrain on crystalline gneisses under similar climatic conditions suggests that the rocks at higher elevations are more weathered compared with those at lower elevations. There is also a great variability of Schmidt hammer rebound values (R-values) at higher elevation, which further indicates great roughness of the rock surface owing to differential weathering of the grains. It has also been noted that the R-values for the crystalline gneisses of the Alaknanda valley are lower than those for the crystalline gneisses of the Satluj valley. This is mainly attributed to the varying proportion of mineral constituents of these two crystalline gneisses.