Geoscience Reference
In-Depth Information
Dome
Small oval dunes with no
slip face
Barchan
Strong wind in one direction,
limited amounts of sand
Barchanoid ridge
Formed from rows of merged barchans
Transverse
Weak wind in one direction,
large amounts of sand
deposited perpendicular to wind
Longitudinal
Opposing winds flowing in similar
directions, two slip faces, aligned with
wind
Star
Multidirectional winds, largest dunes
grow tall instead of moving
Reversing
Two winds in opposite directions,
changes shape periodically
Blowouts
Localized deflation basins in partially
vegetated landscape
Parabolic
Arms stabilized upwind by vegetation,
often start as semicircular blowouts
that elongate downwind
Figure 18.18 Sand dune classification.
Eight major varieties of sand dunes occur, with form depending on wind direction, sand
supply, and amount of vegetation cover. Arrows represent the direction of prevailing winds.
(b)
(a)
Figure 18.19 Dome dunes and barchan dunes.
(a) A typical dome dune (foreground). Note the oval shape, lack of a slip face, and low
relief of this dune. (b) A well-developed barchan dune. Airflow is from left to right across the image. Note the crescent form, lee slope, and
tapering cusps.
