desertification abrasion Chapter 15 Chapter 15 ventifact deflation Chapter 15 Chapter 15 desert pavement dune Chapter 15 Chapter 15 barchan dune longitudinal dune Chapter 15 Chapter 15 transverse dune parabolic dune Chapter 15 Chapter 15 loess Coriolis effect Chapter 15 Chapter 15 desert playa Chapter 15 Chapter 15 alluvial fan pediment Chapter 15 Chapter 15 mesa butte Chapter 15 Chapter 15 The expansion of deserts into formerly productive lands. The process whereby rock is worn smooth by the impact of sediment transported by running water, glaciers, waves, or wind. A stone with a surface polished, pitted, grooved, or faceted by wind abrasion. The removal of loose surface sediment by wind. A surface mosaic of closefitting pebbles, cobbles, and boulders found in many dry regions; results from wind erosion of sand and smaller particles. A mound or ridge of wind‐deposited sand. A crescent‐shaped sand dune with its tips pointing downwind. A long ridge of sand generally parallel to the direction of the prevailing wind. A ridge of sand with its long axis perpendicular to the wind direction. A crescent‐shaped dune with its tips pointing upwind. Wind‐blown deposits of silt and clay. The apparent deflection of a moving object from its anticipated course because of Earth’s rotation. Winds and oceanic currents are deflected clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Any area that receives less than 25 cm of rain per year and that has a high evaporation rate. A dry lakebed found in deserts. A cone‐shaped accumulation of mostly sand and gravel deposited where a stream flows from a mountain valley onto an adjacent lowland. An erosion surface of low relief gently sloping away from the base of a mountain range. A broad, flat‐topped erosional remnant bounded on all sides by steep slopes. An isolated, steep‐sided, pinnacle‐like hill formed when resistant cap rock is breached allowing erosion of less resistant underlying rocks.