In the marginal regions of the Namib desert between the rivers Gaub and Tsondab - the basal terrain in front of the Great Escarpment - calcretes have been found. These duricrusts have not been sufficienrly recognized in their signification for the younger development of landscape in several parts of SWA. Within the drainage-area of the river Gaub (tributary river of the Kuiseb) three plains in different altitudes can be found. They all are indurated with calcretes on and under the surface: they have been named "Oberste Krustenflaeche", "Hauptkrustenflaeche" and "Mittlere Krustenflaeche ". The recent valley floor terminates this sequence of plains, but without any sign of calcretes. For at least two of the plains, their origin can be proved as a pedimental process connected with ranges or mountain slopes. The detritus-covered pediment (,Faenger') has been extremely hardened by calcium carbonate . Near to the watershed and within the drainage-area of the Tsondab river geomorphological circumstances occur less obviously. In comparison to the Kuiseb, the Tsondab river is much more inactive; therefore it is probable that not all active morphogenetic phases are represented in the sense of valley erosion. Concerning the calcretes in the Tsondab region, it means that these duricrusts might be of polygenetic origin. Resembling observations have been obtained in the Erongo region. A central problem within the geomorphological interpretation represents the question of the morphological originality of the duricrust-plains. Only if this character is proved, they can be recognized as independent relief-generations. Keywords: Namibia, Namib Desert, Kuiseb River, Gaub River, ephemeral river, arid ecosystem, arid environment, geomorphology, calcretes, aeolian deposits, fluvial deposits, duricrusts, palaeoclimate.