Slow Soil Movement in Tarfala Valley, Kebnekaise Mountains, Swedish Lapland

ABSTRACT

Between 1982–1990, on the slopes of Tarfala valley above timberline, at an altitude 1140–1220 m a.s.l, soil movement was mesured by means of wooden pegs (columns) inserted in the soil. Three types of soil movement were distinguished: two were dominant slope processes (frost creep and gelifluction) and one was a dominant vertical movement. The two first movements are illustrated by curves in peg profiles which were either concave downslope (frost creep) or convex downslope (gelifluction). Frost creep is a movement of soil particles and also of soil layers reflecting the structures of segregated ice. It depends on conditions of zonal climate but chiefly on local factors, especially on soil moisture (the influence of permafrost, seasonally frozen layers and snow fields) as well as on the inclination of the slope surface.