Dune Paleoenvironments

The wind is an important agent of sediment movement and landform development in deserts and some coastal environments today. In line with major climate changes affecting earth history, the extent and locations of wind-shaped landscapes have changed over time. For the Quaternary period, these changes have commonly left a record in the landscapes of today: evidence of aeolian paleoenvironments in the form of sandy sediments and landscapes that are not experiencing aeolian activity today. This article analyzes the evidence for Quaternary desert Aeolian paleoenvironments: what that evidence is; how it can be interpreted in terms of extent and timing of occurrence; what the evidence means for understanding past climate changes; and examines key issues and debates in reconstructing past aeolian desert conditions. As techniques to interrogate Quaternary aeolian sediments have developed, especially optically stimulated luminescence dating, so simple models of climate change-desert expansion have been replaced by recognition of the complexity and multiple occurrence of aeolian system expansions and contractions. These in turn have led to debates about the climate signals that Quaternary aeolian sediments may represent, with simple assumptions of greater past aridity needing to be placed into explanations integrating changes in wind erosivity as well as surface erodibility. A further issue that challenges successful interpretation relates to record preservation. The chapter concludes by addressing these issues and the prospects for enhanced interpretations of aeolian paleoenvironmental data in the future.