At the fluvial/marine interface, the Orange River mouth is characterised by a wave-dominated delta. Fluctuating sea levels over the last 40 million years have given rise to a number of palaeo-shorelines both onshore ("raised beaches") and offshore ("submerged beaches") in the Sperrgebiet. During younger geological times, the wide Orange River mouth facilitated the formation of barrier beach placers. Further north, linear beach placers were emplaced under the influence of a northbound longshore drift driven by the prevailing southerly wind regime. This regime, with its origins as early as some 40 million years ago, not only generates a powerful northward-directed longshore current but is also, along with the cold-water Benguela upwelling system, responsible for maintaining the extreme-arid conditions along the south-western African coast. Consequently, sediment from the marine system is moved back onto the land and into the desert conveyor via log spiral and south-facing re-entrant bays. Within these coastal embayments, former sea level positions are demarcated by ribbon-like pocket beach deposits - the gravel bearing units of which are diamondiferous. From there, the harsh southerly winds drive sediment through aeolian transport corridors and deflation basins northwards into the main Namib sand sea. Within the deflation basins, a combination of ephemeral run-off, salt weathering and aggressive aeolian action upgraded those placers to such a degree that, in places, diamonds were initially literally picked up on the land surface - even by moonlight! Further north, aeolian placers were formed within the dune and sand feeder system leading into the main Namib sand sea.