The African lower latitudes covered by dense evergreen and semi-deciduous rain forests, high woody biomass mosaics and savanna woodlands have long been recognized as evolutionary ancient ecosystems and were assumed to be climatically stable over a

long time. Species richness in places and deeply weathered soils and saprolites on ancient Gondwana rocks supported generalized hypothesises that, at least throughout the Cretaceous and Tertiary period the vegetational features remained relatively unchanged. This perception of tropical geomorphological stability within the zone of predominantly peneplanated surfaces, and the possible variations of morphodynamic processes within river catchments and on slopes, have been neglected for a long time (compare Runge, 2001, 2008). This is surprising because in neighbouring (partly former) desert regions, like on the margins of the Sahara and the ‘Mega-Kalahari’ on the southern hemisphere, considerable changes in the environmental settings have been early detected in the form of palaeodunes, lake sediments, palaeontological evidence, artefacts, rock art, and others, that had been correctly interpreted as representing major climate and associated environmental change (a Neolithic “green” Sahara) (e.g., Monod, 1938; Williams and Faure, 1980; Woodward et al., 2007; Baumhauer and Runge, 2009).