Most sand seas and dune fields exhibit clear spatial patterns of dune morphological type as well as variations in sediment thickness, dune size, crest length, and spacing. These patterns are the geomorphic expression of the factors that have controlled sand sea development in time and space. They reflect the self-organizing nature of dune systems as well as the external geomorphic and climatic environment (boundary conditions) in which the sand sea has evolved.

Dune height and spacing are commonly closely related. Sand particle size, airflow patterns, atmospheric boundary layer height, sand supply, and dune field geometry have all been suggested as controls on dune size and spacing, as have dune–dune interactions and pattern coarsening as part of self-organization of dune morphologic patterns.

Changes in the rate and direction of sand transport in space and time give rise to patterns of erosion and deposition on dunes on a range of timescales that range from individual transport events, through seasonal changes in wind direction, to decadal and longer periods of dune growth, migration, and extension. Flow acceleration results in erosion of windward or stoss slopes. Flow separation in the lee gives rise to avalanching and deposition of sand, leading to dune migration. These processes are manifested in different ways on dunes of differing types, indicating a series of interactions between dune topography and processes.

Dunes are created and modified by a series of interactions between the sand surface and the local topographically modified atmospheric boundary layer. Airflow over dunes is characterized by flow acceleration on windward slopes and a complex pattern of flow separation and secondary flows on lee slopes. Spatial and temporal changes in airflow give rise to nonlinear changes in sand transport rates, which in turn determine the initiation, development, and equilibrium morphology of all dunes.

Sandstones of aeolian origin have been identified from many periods of Earth’s history. They provide a record of the extent of ancient desert conditions and associated (paleo-) wind regimes. The creation of an aeolian stratigraphic record involves construction and accumulation of a sand sea or dune field and its preservation through subsidence, a rise in the regional water table, or burial. Comparisons between the environments of ancient aeolian sandstones and modern sand seas indicate that few are likely to be preserved in the rock record.

The directional variability of sand-transporting winds is a key control of dune morphology, with sand supply and mobility playing modulating roles. The cover and growth rate of vegetation have been shown to strongly influence the morphology of parabolic dunes and the transition between active and stabilized dune systems.

The formation of sand seas and dune fields is governed by sediment supply, availability, and mobility. Accumulation will occur when sediment budgets are positive in time in space, and it occurs as a result of bedform climbing and vertical growth by accretion in multidirectional wind regimes. Timescales for sand sea and dune field accumulation are strongly influenced by Quaternary climate and sea level changes.

Desert sand dunes form part of self-organized complex systems of aeolian bedforms that comprise sand seas and dune fields. They form part of local to regional-scale sand transport systems in which sand is moved by the wind from source zones to depositional sinks via transport pathways. The state of these systems can be evaluated in terms of sediment supply, availability, and mobility, which in turn are controlled by changes in climate and sea level on a range of spatial and temporal scales.