Abstract
The geological structure of Ehime prefecture is classified into four terrains, from north to south; Ryoke terrains, Sambagawa metamorphic terrain, Chichibu terrain and Shimanto terrain. The land slide areas exist maily in Sambagawa metamorphic terrain and Mikabu tectonic terrain. Mikabu tectonic terrain lies along the southern periphery of Sambagawa terrain.
The clay samples used for experiments were collected from 24 points in Sambagawa terrain and 6 points in Mikabu terrain.
The results of X-ray diffraction showed that principal clay minerals of the land slide areas in Sambagawa terrain are Chlorite and Illite, and that those in Mikabu terrain are Montmollironite and Chlorite.
