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Aeolian Processes and landforms

A number of major factors have driven the volume and nature of aeolian geomorphology in the second half of the twentieth century: the growth of process studies, the availability of remote sensing, the development of new dating techniques (e.g. optical dating), the utilisation of new technologies (e.g. data loggers and global positioning systems),computer modelling of dune forms and wind action and sediment movement, the recognition of the importance of aeolian forms and processes in extra-terrestrial settings (especially Mars), the role of aeolian dust in atmospheric processes, the search for analogues for ancient hydrocarbon-bearing strata, the appreciation of the importance of climatic changes in desert areas, a concern with what may happen to arid environments in a warmer world, and an increasing realisation that aeolian phenomena could be hazardous. This chapter does not deal with coastal dunes, but concentrates on those of the major lower latitude drylands. It discusses the main controls on dune forms, the nature of sand seas, ancient and modern, and the nature of dune sediments. It also shows that during the 1970s there was a burgeoning interest in dust storms. In addition, with the availability of remote sensing imagery it was possible to see for the first time that wind-furrowed yardangs were striking features with a wide global distribution. The origin of closed depressions (pans) generated a large literature and hypotheses for their formation were put forward which included wind erosion, solution, excavation by animals, karstic and pseudo-karstic solution, and tectonic subsidence. Remote sensing showed just how important they were in drylands. Other phenomena that attracted attention and some controversy were stone pavements and peri-desert loess. Finally, it is suggested that the nature of aeolian processes and forms will be modified in a warmer world.