Five year measurements of rock tablet weathering on a forested hillslope in a humid temperate region

In order to elucidate the effects of rock type and geomorphic setting on weathering rates, field experiments using microweight-loss techniques were carried out. Rock tablets for eight kinds of rock types: granite; granodiorite; gabbro; limestone; andesite; rhyolite; crystalline schist; and tuff, with a diameter of 3.5 cm and a thickness of about 1 cm, were enclosed in a nylon mesh bag and placed in the four corners of a soil–bedrock interface on a granodiorite hillslope of central Japan for over 5 years. The results show that: (1) the saturated grus layer is the main locus of solutional denudation; (2) the 18 and 11% weight losses of limestone and tuff under a saturated soil layer were clearly the largest of all the rock types examined; and (3) the weight loss is smaller for granite, gabbro, crystalline schist, and andesite, while it is larger for tuff and rhyolite at every location. These results suggest that weathering rates are influenced by both lithology and environmental conditions.