森林で覆われた斜面の地形, 土層構造及び土の物理的性質 -奈良県明日香村花崗岩の場合-

Abstract

The authers found several presumptive evidence concerning subsurface soil movement and mass movement of topsoil on the forested hillslope, by practices of topographic survey, trench, simplified corn penetration test, physical analysis of soil and X-ray diffraction.The thickness of topsoil increased and then decreased along the slope. It should mean that soil is moving along the slope. At the upper part of topsoil, soil pipes were found. Some of them contribute to soil particle transfer.At the lower half of the upper slope, slip failure was found. And at the middle slope, loose soil was observed. Topsoil is thought to be failing at about 60cm. In depth. Clay content in the soil varied according to the locations on the slope and in the soil profile.Fine material are considered to be moving with subsurface water.