ABSTRACT
In this chapter, the concept of etchplanation are applied to: landforms that may have been produced by one or more distinct episodes of stripping of a relict saprolite mantle; and landforms continuing to evolve by surface erosion acting on preweathered materials. It also applied to landscapes within which emergent rock forms coexist with more rapidly evolving forms controlled by the shifting balance between weathering penetration and surface lowering within a system involving active or dynamic etchplanation. The enquiry attempts to consider the questions for a humid tropical rainforest area of West Africa, the Koidu etchplain, where recent vegetation clearance and mining activity have revealed clearly the morphology and the surface deposits. Sierra Leone, together with the adjacent parts of Guinea, Upper Volta, Liberia and Ivory Coast, occupies an emergent dome or cymatogen over much of which are exposed Archaean or ‘Basement Complex’ rocks of the West African craton, and it is with these areas that this study is concerned.
