The Kuiseb River, an ephemeral watercourse, demarcates the northern boundary of the main Namib Sand Sea, except in the coastal tract where dunes extend from the Kuiseb Delta northwards in a narrow belt to the Swakop River. This study addressed the nature of this boundary with respect to the Cenozoic history of the Kuiseb Valley west of the Escarpment. The Cenozoic succession consists of ten sedimentary units; their nomenclature, distribution, composition, origin, age and correlation are presented here. A new lithostratigraphic, and provisional geochronologic, framework is also proposed.