The endoreic Tumas River rises on the inner margin of the Namib Platform at the base of the Great Escarpment 120 km from the Atlantic Ocean. The Tumas basin lies between the major exoreic Swakop and Kuiseb Rivers in the Central Namib Desert. The Namib Platform is known as a feature of particular flatness. The Platform in the Central Namib is disrupted not only by the well-known 200 m deep Swakop and Kuiseb River canyons, but by the broad trough of the lower course of the Tumas River valley (an area known until the beginning of this century as the Naarip Plain or Desert). Keywords: Namibia, Namib Desert, Kuiseb River, Tumas River, arid zone research, desert geomorphology, erosion, sediment transfer, sedimentation, fluvial processes, rainfall, weathering, aeolian deposits, desert geology, drainage.