Geomorphology in the tropics faces a number of contradictions. Most water-based processes proceed more rapidly in the humid tropics (and sub-tropics), including rock decay, mass movement, sometimes sediment transport. Yet, while mainstream geomorphology has pursued event-based studies of surface processes, geomorphology in the tropics is accused of emphasising models of long-term landform development within 'cratonic regimes'. Calls are made to abandon such traditional concepts and to embrace process studies of more direct relevance to sustainable development. But one key to understanding many economic and environmental issues (mineral resources, basement aquifers, slope failures, soil erosion), is the chemical decay of rocks and the transfer of weathering products as colluvium. The role of this regolith cover is neglected in many texts, and the development of geomorphological theory is constrained by this neglect, through attempts to limit the relevance of weathering to tropical cratons or temperate palaeoplains.

Weathering rates in the humid tropics allow the formation of deep saprolites within Quaternary time and demonstrate the importance of weathering in Neogene terrain, while the antiquity of many weathered mantles has also been demonstrated. A fresh perspective on the role of weathering as a landforming process is required; one which focuses weathering in all environments (climatic, tectonic, lithologic). This can be linked to studies of episodic erosion on timescales from those of the cratonic regime, through the Quaternary climate oscillations, to the impact of individual events. The viability of geomorphology as an earth science depends on its wider relevance and the quality of its explanations. Studies from the tropics can offer many insights of importance to higher latitude research as well as vice versa, and new work on 'regolith studies' should off one such example.