To reveal the relationship between landslide occurrence and long-term development of mountain topography in a tectonically active area, distributions of knickpoints, convex slope breaks, and landslides have been investigated in the watershed of the Totsugawa River, central Kii Mountains, southwestern Japan. We found that there are 2 laterally-continuous convex slope breaks on the hillslopes and that the slope break lines intersect main channels at knickpoints of the river profiles. These facts suggest that knickpoints, which had been created by the base-level lowering, retreated upstream, forming the convex slope breaks on valley slopes downstream of the knickpoint. Two events of this nucleation and migration of knickpoints are recorded in the present landscape. Slope breaks were not well preserved in some locations, where large slope deformation occurred particularly on cataclinal slopes. These gravitational slope deformations were induced by the undercutting of a slope, which should have made a convex slope break if gravitational slope deforma- tions had not occurred.
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