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Compound dunes are large dunes on which smaller dunes of similar type and slipface orientation are superimposed. Complex dunes are combinations of two or more dune types. A crescentic dune with a star dune superimposed on its crest is the most common complex dune.
Dunes take three general forms. Linear dunes, also called longitudinal dunes or seifs, are aligned in the direction of the prevailing winds. Transverse dunes, which include crescent dunes (barchans), are aligned perpendicular to the prevailing winds. More complex dunes, such as star dunes, form where the directions of the winds are highly variable.
The majority of dunes in Olympia Undae are transverse dunes. Their spacing ranges from 200 to 800 m apart crest to crest, and comparison to terrestrial dunes with similar spacing indicates that they are 10 to 25 m high. [18] On Earth, dunes are produced by saltating grains of sand. The requirement that dunes are produced by saltation allows ...
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] Death Valley Mesquite Flats ...
Transverse aeolian ridges (TARs) are visually bright features commonly found in topographic depressions on Mars. [ 1 ] [ 2 ] [ 3 ] These small-scale and relict bedforms were first seen in narrow-angle images from the Mars Orbiter Camera (MOC) [ 2 ] [ 3 ] and were called “ridges” to preserve both dunes and ripples as formative mechanisms.
The dune field is composed of reversing dunes, transverse dunes—also called crescentic or barchan dunes—and star dunes. The sand sheet is the largest component of the system, comprising sandy grasslands that extend around three sides of the dune field.
Analysis of high resolution photos from New Horizons taken on 14 July 2015 of Pluto's Sputnik Planum region in 2018 has confirmed the presence of transverse dunes (perpendicular to the wind streaks) within the cellular nitrogen plains, spaced about 0.4 to 1 km apart, that are thought to be composed of 200-300 μm diameter particles of methane ...
Dunes There are various kinds of dune in tropical deserts. Representative dunes include dome dunes, transverse dunes , barchans , star dunes, shadow dunes, linear dunes and longitudinal dunes.