EARTH’S DUNE SYSTEMS – A SYNTHESIS

Inland dune systems occur on all continents and at all latitudes and are therefore one of the most widely distributed landforms on Earth. Characterizing their extent, morphology, dynamics, and relationships to sand supply, availability, and mobility has undergone several stages, in which information from individual dune fields and sand seas has been aggregated to provide conceptual and qualitative models for their formation. Mapping of dune types and their morphology and distribution was initially from field studies and aerial photography, an approach well-synthesized by Wilson (1973). The advent of satellite images in the 1970s catalyzed the global and regional approach to dune mapping and synthesis of information on dune morphology and relations to wind regimes by the USGS Global Sand Seas project (McKee, 1979). Recently, progressively higher spatial- and spectral- resolution satellite image data, digital elevation models, and geochemical and isotopic analyses of dune sand composition have provided an increasingly detailed view of sand sources, transport pathways, and patterns of dune morphology and morphometry. Parallel developments in luminescence dating of dunes are providing a spatially and temporally complex record of periods of dune accumulation and reworking. New models for the relationships between dune morphology and orientation are challenging previously long-held ideas about dune trends and wind regimes.

We are now at a point where the complex response of many dune systems to external forcing factors and internal dynamics is increasingly being recognized, but no overall synthesis exists, despite the existence of abundant (but spatially highly variable) information on dune system characteristics. Global mapping and inventory of dune fields and sand seas in a GIS (geographical information systems) database format using existing information and new mapping where needed can facilitate assessment of their relationships to boundary conditions for their formation and occurrence, including climate (past and present), topography, and geologic setting. It also provides a means to incorporate additional information (e.g. particle size and composition, chronometric data) to provide an integrated, holistic view of dune systems in space and time.

References

McKee, E.D. (Ed.), 1979. A Study of Global Sand Seas, 1052. United States Geological Survey.

Wilson, I.G., 1973. Ergs. Sedimentary Geology, 10, 77-106.