Colluvium

Abstract

Onshore colluvial deposits mantle most parts of the natural hillsides in Hong Kong. Colluvium is heterogeneous in nature and its physical properties vary from one location to another. Colluvium is often looser and more permeable than the underlying in-situ materials. Landslides in the colluvial deposits are common on natural hillslope surfaces and man-made slopes in Hong Kong due to their physical properties. Mass wasting phenomena have been suggested to be the major processes to form colluvium. These processes have occurred since the geological past but they can be predicted based on the physical characteristics of the transported sediments and the hypothetical models. The study under this dissertation mapped areas of Tai O, Shing Mun and Ki Lun Shan (Hadden Hill) to record the physical characteristics of colluvium. The solid geology at the three study areas are different; being at scattered locations around Hong Kong. The empirical classification of colluvium in Mid-levels study was used to subdivide the colluvium for relative dating. The results show that examination of the degree of decomposition of clasts in colluvium is probably the most useful tool to subdivide the colluvium based on their relative age. Mass wasting processes at the three study areas studied, and it is believed that the mass wasting process for the formation of colluvium are periodic and on-going processes.