Late Cenozoic landform development in East Africa: The role of near base level planation within the dynamic etchplanation concept

The Late Cenozoic landform development history of East Africa is explained insufficiently by the available landform genesis concepts. Although the 'dynamic etchplanation' concept is well able to explain the development of lithologically controlled relief, its explanation of planated areas does not fit reconstructed characteristics of the East African landscape history. Late Cenozoic lain formation in East Africa was an episodic event caused by contemporaneous erosion and deposition near base level. It is therefore proposed to elaborate the etchplanation concept with fluvial dynamics. Late Cenozoic planation events in East Africa were triggered by a major base level rise due to the combined effects of eustatic sea level rise and crustal movements associated with rift valley dynamics. The relative base level rise caused a sequence of active fluvial lateral aggradation and erosion within the landscape followed by lagoonal and sometimes even marine conditions shaping extensive plains. The interacting fluvial and etchplanation dynamics make a more comprehensive theory to explain the Late Cenozoic landscape development in East Africa.