Editing Simpson Desert (section)

==Dunefields==
The extensive dunefields of the Simpson Desert display a range of colours from brilliant white to dark red, and include pinks and oranges.<ref name="laofex">{{cite web |url=http://www.ouramazingplanet.com/3492-australia-simpson-desert-picture.html |title=Australia's Simpson Desert: A Land of Extremes |date=17 September 2012 |work=OurAmazingPlanet |publisher=TechMediaNetwork.com |access-date=12 February 2013 }}</ref>

===Morphology===
[[File:PIA00115 Earth (Simpson Desert, Central Australia).jpg|thumb|upright|Simpson Desert visible dune lines and [[Lake Eyre]] at bottom left]]
The sand ridges have a trend of SSE-NNW and continue parallel for great distances.  This pattern is seen throughout the [[deserts of Australia]].  Some of the ridges continue unbroken for up to 200&nbsp;km.  The height and the spacing between the ridges are directly related.  Where five to six ridges occur in 1&nbsp;km, the dune height is around 15 m, but when only one or two ridges occur in 1&nbsp;km, the height jumps to 35–38 m.<ref name=Twidale/> In cross section, the lee side is the eastern slope with an incline of 34-38°, while the [[Ripple marks#Definitions|stoss side]] is the western slope with an incline of only 10-20°.  In cross section, the cross beds are planar with [[foreset bed|foresets]] alternating between east and west.  The foresets have incline angles of 10-30°.<ref name=Twidale/>

===Sediment===
The sand is predominately made up of [[quartz]] grains, which are [[Roundness (geology)|rounded and subangular]]. They range in size from 0.05 to 1.2&nbsp;mm with 0.5&nbsp;mm being the typical size for the crests and 0.3&nbsp;mm being the average size on the dune flanks. The active crests have sand sediment, but on the interdunes, the sediment is not as well sorted.<ref name=Twidale/> The sediment varies in colour from pink to brick red, but by the rivers and playas, the sediment colour is light grey. The progression of the colour from grey to red is due to the release of [[iron oxide]] from the sediment when weathered.<ref name=Twidale/>