Dunes

Andrew Warren is Emeritus Professor of Geography, University College London where he taught between 1964 and 2002. He had previously worked as soil surveyor in Pakistan. His dune research has taken him to the Sudan, Nebraska, Libya, Algeria, Saudi Arabia, Niger, Israel, Oman and Chad. His books include Geomorphology in Deserts, (1973) with Ron Cooke, Desert Geomorphology (1992) with Ron Cooke and Andrew Goudie, and Aeolian Geomorphology (1996) with Ian Livingstone.

“This is a terrific read for both specialists and nonspecialists.  Summing Up: Highly recommended.  Upper-division undergraduates through professionals/practitioners.”  (Choice, 1 February 2014)

• List of Figures xi Acknowledgements xvIntroduction 1Part One <10 m2; <10 years 51 Wind and Sand 7Wind versus Bed 7The Law of the Wall 8Improving the wind/bed model 9Lift-Off 12Holding down by gravity 12Holding down by cohesion 12Raising by lift 13Raising by drag 13Raising by bombardment 14Thresholds 14Grain size 16The slope of the bed 17The dynamics of water content 17Crusts 19Pellets 20Sand in Motion 20Saltation 20Streamers and other medium-scale patterns of saltating sand 22Reptation 22Creep 23Other near-surface activity 23Suspension 24The vertical distribution of load and grain size 24The saturation length 24The fetch effect 26The response of a loose bed to erosion by the wind 27The Transport Rate 27Shapes, densities and mixtures of size 29Hard surfaces 30Rough surfaces 30Moisture, temperature and humidity 31Rain 31References 312 Ripples 32Subtypes 35Models 36Flow response 36Gravity wave 36Saltation length 37Shadow zone 37Mathematical 37Pattern 383 The Form and Behaviour of Free Dunes 39Definitions 39Early Stages 39Start 39Minimum size 40The Profile of a Fully Grown Dune 41Toe 41Windward slope (or ‘stoss slope’) 43Crest 45Lee slope 46Movement 53Turnover time, bulk transport 56Size 56Flow-hierarchy models 57Grain-size models 57The time/supply model 58References 58Part Two 1000 to 10,000 m2; 100 to 1000 years 594 Pattern in Free Dunes 61Definitions 61Wind-Directional Regimes 62Global winds 62Local wind systems 62The Classification of Wind-Directional Regimes 65Wind-Directional Regimes and Dune Pattern 66Transverse Dunes 66Two-dimensional pattern: vertical and downwind 67Two-dimensional pattern: horizontal and transverse to the wind 68Self-organisation 69Barchans 71Quasi-transverse patterns 75Linear Dunes 80Introduction 80Models of formation 82Sand Sheets 88Dunes with Distinctive Sand 90Gravel dunes 90Zibars 91Clay dunes 92Lunettes 92Gypsum dunes 93Diatomite sands 93Volcanic sands 93Snow and ice dunes 94Niveo-aeolian deposits 94References 945 Forced Dunes 96Dunes Built around Bluff Obstacles 96Climbing and echo dunes 96Flanking and lee dunes 97Cliff-top and falling dunes 99Dunes on Gently Sloping Terrain 99Reference 996 Dunes and Plants 100Wind, Sand and Plants 100Rigid objects 100Spatial pattern 101Porosity 102Flexibility 102Plants as living things 103The broader time/space framework 104Dunes among Plants 104Nebkhas 104Blowouts 107Parabolic dunes 109References 1117 Coastal Dunes 112Coastal Dunes and Climate 112The Beach–Dune System 114Exclusively Coastal Dunes 117Embryo dunes 117Fore-dunes (‘frontal dunes’ or ‘retention ridges’) 118Tsunamis 120Coastal sand sheets 120References 121Part Three >0.3 mm; <2,200,000,000 years 1238 Sand Seas 125Terms 125Large Sand Seas 127Growth and Development 127Sand Seas in Tectonic Basins 129Topographically Unconfined Sand Seas 131Transfer between Sand Seas 1339 A History of Dune Sand 134Provenance 134Recycling 137Maturation 139Mineralogy 139Size characteristics 141Shape and surface texture 141Redness 144Relationships between Dune Fields and the Sources of Their Sand 145Source-bordering dune fields 145Dune fields that have migrated away from their source 145Sand seas that have taken sand from many local sources 146The Australian sand seas and some aeolian sandstones 146References 14610 A History of Inland Dunes 147Very Ancient Dunes: Siliceous Windblown Sandstones 147The Emergence of Familiar Spatial and Dynamic Patterns 151Dune Historiography 153Dating 153Dune-building environments 156The long-term development of sand seas: sediment state 160Quaternary Dune-Building Climates 160Dunes in the Early- and Mid-Pleistocene 162Late Pleistocene Dunes 163The main theatres of dune formation in the Late Pleistocene 165Dunes in the Holocene 175The deglaciated North 176The mid-latitudes 177The semi-arid tropics 178The present deserts 178References 17911 A History of Coastal Dunes 181Long Sequences 181Sea Level 181Other Controls 182Calcareous Aeolianite 184Reference 18512 Mars, Venus, Titan 186Similarities 186Differences 187Sand 188Ripples and Transverse Aeolian Ridges 190Dunes 191Mars 191Venus 194Titan 194Reference 195Part Four Care 19713 Local, Short-Term Care (<1000 m2; <10 years) 199Dunes in Deserts 199Folk science 199New approaches 200Stabilised Dunes in Semi-Arid Areas 204Coastal Dunes 204References 20714 Sustainability (>100,000 m2; >10 years) 208Constraints 208Complexity 208Uncertainty 210Environmental change 210Sustainability 211Coastal dunes 211Stabilised inland dunes 212References 213Index 214