SEDIMENTARY ENVIRONMENTS/Deserts 549 the gross-scale preserved architecture of the system These ‘allocyclic’ (extrinsic) controls impose widespread change on the behaviour of the system The major external controls on sedimentary architecture in desert systems are climate and tectonic basin setting Together, these also determine the generation, supply, and availability of sediment for transport Temporal changes in these factors will have different effects on different parts of the desert system (Figure 8) For example, a switch to a more humid climate may result in playa lake expansion due to a rise in water table At the same time, elevation of the water table may restrict the availability of sediment for aeolian transport, causing dunes within an erg setting to stop accumulating and interdunes to expand or become flooded Thus, various subenvironments within the desert system expand or contract, and accumulate or become eroded, over time as external controls vary This is reflected in the preserved sedimentary architecture by large-scale shifts in the position of facies belts and the generation of surfaces of non-deposition and/ or erosion (supersurfaces) In attempting to understand the complexity present within desert successions and to be able to differentiate between the extrinsic and intrinsic controls, preserved sedimentary architecture needs to be investigated on a variety of scales See Also Arabia and The Gulf Palaeoclimates Sedimentary Environments: Depositional Systems and Facies; Alluvial Fans, Alluvial Sediments and Settings; Lake Processes and Deposits Sedimentary Processes: Depositional Sedimentary Structures; Aeolian Processes Sedimentary Rocks: Evaporites Further Reading Alsharhan AS, Glennie K, Whittle GL, and Kendall CGStC (1998) Quaternary Deserts and Climate Change Rotterdam: Balkema Brookfield ME (1992) Eolian systems In: Walker RG and James NP (eds.) Facies Models: Response to Sea Level Change, pp 143 156 St John’s: Geological Association of Canada Brookfield ME and Ahlbrandt TS (1983) Eolian Sediments and Processes Developments in Sedimentology 38 Amsterdam: Elsevier Cooke R, Warren A, and Goudie A (1993) Desert Geomorphology London: UCL Press Frostick L and Reid I (1987) Desert Sediments: Ancient and Modern Geological Society of London Special Publication 35 London: Geological Society of London Kocurek G (1991) Interpretation of ancient eolian sand dunes Annual Review of Earth and Planetary Sciences 19: 43 75 Kocurek G (1996) Desert aeolian systems In: Reading HG (ed.) Sedimentary Environments: Processes, Facies and Stratigraphy, pp 125 153 Oxford: Blackwell Science Kocurek G and Havholm KG (1993) Eolian sequence stratigraphy a conceptual framework In: Weimer P and Posamentier HW (eds.) Siliciclastic Sequence Stratigraphy American Association of Petroleum Geologists Memoir 58, pp 393 409 Tulsa, OK: American Association of Petroleum Geologists Kocurek G and Lancaster N (1999) Aeolian system sedi ment state: theory and Mojave Desert Kelso dune field example Sedimentology 46: 505 515 Lancaster N (1995) Geomorphology of Desert Dunes New York: Routledge McKee ED (1979) A Study of Global Sand Seas Geological Survey Professional Paper 1052 Washington: US Government Printing Office Mountney NP and Thompson DB (2002) Stratigraphic evo lution and preservation of aeolian dune and damp/wet interdune strata: an example from the Helsby Sandstone Formation, Cheshire Basin, UK Sedimentology 49: 805 833 Pye K (1993) The Dynamic and Environmental Context of Aeolian Sedimentary Systems Geological Society of London Special Publication 72 London: Geological Society of London Pye K and Lancaster N (1993) Aeolian sediments, ancient and modern International Association of Sedimentologists 16 Oxford: Blackwell Science Rubin DM (1987) Cross bedding, bedforms and palaeo currents SEPM Concepts in Sedimentology and Paleontology