The Namib Sand Sea of south western Africa is dominated by large north-south trending linear dunes. Interdune areas, however, comprise about 50% of the area of the Sand Sea and may consist of exposures of the pre-dune surface or sediments deposited between the dunes. Four major types of interdune deposits are identified and described: (1) coarse poorly sorted aeolian sands, (2) localized calcareous lacustrine deposits, (3) silty deposits of ephemeral rivers that have flooded into the Sand Sea margins, (4) sabkhas and salt marshes near the coast. The preservation potential of these sediments is poor, except where they are buried and protected by dunes or stabilised by high groundwater levels in coastal areas.