Abstract
Mass movement process of a valley-head slope is studied at a site where Kanto-loam partly covers basal granite, by means of the investigations of microtopography, geologicalmicro-structure, vegitation, and tilt-fluctuation.
It is found that loam layer of the valley-head slope creeps with every rainfalls and increases the topographical instability at the lower end of valley-head slope. Consequently, slope failure on this slope is thought to occur at the lower end of valley-head slope periodically.
The above mass movement process is different from the past investigated case at other valley-head slope where soil-pipe has developed at the lower end of slope. The difference of the process is probably due to the difference of the position of ground water table in slope, namely creep dominant slope has a lower ground water table and soil-pipe dominant slope has a higher one.
