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A dune is a landform composed of wind- or water-driven sand. ... The largest crescentic dunes on Earth, with mean crest-to-crest widths of more than three kilometres, ...
Issaouane Erg, Algeria Linear Dunes, Namib Sand Sea. An erg (also sand sea or dune sea, or sand sheet if it lacks dunes) is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. [1] The word is derived from the Arabic word ʿirq (عرق), meaning "dune field". [2]
Barrier island – Coastal dune landform that forms by wave and tidal action parallel to the mainland coast; Bay – Recessed, coastal body of water connected to an ocean or lake; Baymouth bar – low and narrow strip of alluvial land made from sand or pebbles
Ridge and swale, or in dunal areas dune and swale, is a landform consisting of regular, parallel ridges alternating with marshy depressions. [1] Ridge-and-swale landscapes are most commonly formed by the gradual movement of a beach, for example as a result of gradually fluctuating water levels, or the shifting meanders of a river.
Landform Description Image Dunes: A dune is a large pile of wind-blown material, typically sand or snow. As the pile accumulates, its larger surface area increases the rate of deposition in a positive feedback loop until the dune collapses under its own weight. This process causes dunes to move in the direction of the wind over time. [6] [7]
Aeolian landforms preserved in the formation range from damp sandsheet and lake paleosol (fossil soil) beds to thin, chaotically arranged dune sets to equilibrium erg construction, with dunes 300 to 400 meters (980 to 1,310 ft) wide migrating over still larger draas. The draas survived individual climate cycles, and their interdunes were sites ...
Dune collisions [5] [6] and changes in wind direction spawn new barchans from the horns of the old ones and govern the size distribution of a given field. [7] As barchan dunes migrate, smaller dunes outpace larger dunes, catching-up the rear of the larger dune and eventually appear to punch through the large dune to appear on the other side.
A landform is a natural or anthropogenic [1] [2] land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain , and their arrangement in the landscape is known as topography .