Energy regimes for aeolian sand grain surface textures

An experimental study of aeolian sand grain surface texture development was undertaken with an air-driven grain-recirculating desktop apparatus. Scanning electron microscope analysis of resulting textures indicated that different texture types can be associated with distinct zones in a grain-shape/grain speed matrix. In particular, for subrounded and rounded grains, low and high energy transport can be unequivocally distinguished by the occurrence of upturned plates and Hertzian frustra respectively. Textural development does not have a simple relationship to grain velocity, but appears to relate to the energy expended per unit area within the contact zone generated by elastic deformation during impact. Hertzian theory was adapted to irregular sand grain shapes and close agreement was found between experimental results and theoretical predictions for textural development. Results of this study improve our ability to reconstruct palaeoaeolian environments and therefore our ability to determine grain provenance; in particular, the latter is shown to have direct relevance to forensic inquiries and terrorism investigations. (C) 2012 Elsevier B.V. All rights reserved.