Weathering is an important component of geomorphological change in the Central Namib Desert. Previous studies have reported on the weathering role of salt and dissolution, allied with wind abrasion. However, many surface are covered by luxuriant lichen growths, fed by fog precipitation, whose weathering role has not been clarified. Here we present preliminary investigations of the role of lichens and other rock surface microorganisms in weathering and surface protection, using field observations from a range of sites between 2 and 80 km from the coast, coupled with Scanning Electron Microscope (SEM) observations of lichen:substrate interactions. A model of lichen weathering activity is proposed, illustrating the different roles of lichens on various rock types. Spatial segregation of lichen and other weathering processes is seen to occur at a range of scales. Keywords: Biological weathering, salt weathering, rock-surface microenvironments.