ABSTRACT
After an initial introduction on the development of studies of rates of slope processes, the present state of knowledge is summarized for rates of soil creep, solifluction, surface wash, solution, landslides, cliff and slope retreat, and total denudation. Other slope processes are noted, with special reference to the activities of animals. Representative rates for denudation as a whole are 50 B (predominant range 10–100 B) for gentle relief and 500 B (predominant range 100–1000 B) for steep relief. Denudation rates reach a maximum in the semiarid and tropical subhumid (savanna) climatic zones, and in montane climates with steep slopes. Problems in the interpretation of the results of process rate studies include sediment transfer paths, the spatial and temporal sampling frames, and relict landforms. Questions of the control of slope retreat, equilibrium and the steady state, time, space, and causality are discussed in the light of process rates. The influence of Man can accelerate denudation by 2, 10, or over 20 times, depending on the type of land use. Recommendations for future process studies are to employ a spatial sampling design; short-term instrumentation and measurement could usefully be supplemented by other independent means of checking the validity of the data, such as estimates of rates of landscape change over geologic time.
