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Lithological variations often contribute to differences in strength, weight, and permeability of rocks and soils, which in turn can affect the weathering of rocks and thickness of generated soils. A soil weathering index map was generated using lithologic and textural information portrayed in geologic maps, topographic characteristics, and inferences from remote sensing to classify each pixel in the study area into one of four groups in accordance with the inferred levels of weathering and soil thicknesses. Foliated mafic rock units (e.g., amphibolite schist) on gentle slopes or flat areas are more likely to give rise to highly weathered thick soils than massive granitoids exposed on steep slopes. Highly vegetated areas (bright on NDVI images) were considered to have highly weathered thick soils. Soils rich in hydroxyl-bearing clay minerals appear as bright areas on Landsat TM band 5/7 ratio image.Legend: Pink: slightly weathered or fresh, blue: moderately weathered, yellow: highly weathered, and green: completely weathered or residual soil. |