The hyper arid Central Namib gravel plains to the north of the Kuiseb River feature a series of playa clusters which are nested in shallow drainage channels. The playas form primarily as the result of groundwater water ponding at bedrock obstructions which produces surface salts such as halite and gypsum on top of thin stream sediments. They differ considerable in size, shape and composition when compared with playas elsewhere in the region such as the Kalahari and Karoo.