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Cecil's Answer for Week 22

Q: How many types of dunes are there?



Answer: 'There are five types of dunes.'

There are usually 5 types of dunes recognized:

1. Barchan Dunes Barchan dunes have a crescent shape formed by a constant wind coming from one direction. Their Horns result from the wind's moving faster around the edges of the dune. These are very mobile dunes which form usually over a rocky surface. Barchan Diagram
2.Parabolic Dunes Parabolic dunes are similar to barchan dunes, but their arms, usually stabilized by vegetation, face the wind stream. Wind scoops sand from the center of the dune and transports it to the steeper leeward side. Parabolic Diagram
3.Longitudinal Dunes Longitudinal dunes form parallel to strong, steady winds that gouge deep troughs in the desert floor, depositing sand on either side of the trough. Slight changes in wind direction give dune crests a wavy appearance. Longitudinal Diagram
4. Transverse Dunes Transverse dunes are formed by moderate winds that sweep up light grains of sand and form ripples perpendicular to the direction of the wind. They have gentle windward - and steep leeward - slopes and occur where there is little or no vegetation. Transverse Diagram

5. Star Dunes Star dunes, which are one of the characteristics of The Namib desert, result where winds converge from several directions. Buffeted by the wind from all sides, this dune remains largely immobile. Its arms have sharp ridges, sometimes over 250 feet in height, that radiate from a central point.

Star Dune Diagram

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