吉野川中流域・祖谷川下流域の地すべり地について

Abstract

The writer has walked for survey along the Yoshino and Iya River, which areboth notorious for their landslides, and found out some relations the three subjects -landslide area, geology and landform. Those relations are summerized as follows:1) There are more landslides in the pelitic schist area, while fewer in the Psammiticschist area, that there are lower gradient slopes seen in the latter area than in theformer.2) Sediments of landslide area consist of thin detrital layer, in which the existencemust not be ignored, of colluvial deposits and weathering layer on erosional surface.