Mass movement in the Chilton Valley

Abstract

Slow mass movement processes in the Chilton Valley (South Island High Country) were measured using different techniques. Analysis of this data showed a rate of soil creep slightly greater than that measured in ether humid temperate areas and much smaller than rates measured in sub-arctic -and some semi-arid regions. Beth vegetation and angle of slope affected the measured rates. The main cause of soil creep was shown to be freezing and thawing of the soil moisture Movement of scree surface material was comparable to rates measured in most other studies of this process. Freezing and thawing of the interstitial moisture also caused most of this type of movement. Comparison of these rates with those of other processes (measured by other workers in this area) showed that slew mass movement processes contributed only a small amount to total erosion and transportation compared with debris flows. Slope wash was shown to be more important than soil creep but less important than talus creep. The total rate of deposition since deglaciation of this area (derived from the volume of the alluvial fan at the bottom of the valley) was shown to be much larger than the rates of measured processes.