18.6: Dune Types

Dune Types

Dunes are complex features formed by a combination of wind direction and sand supply, and in some cases interacting with vegetation. There are several types of dunes representing variable wind direction, sand supply, and vegetative anchoring.

Side view of a barchan dune, illustrating the slip face, and the dune movement with the wind direction.

Figure 18.13: Mesquite Flat Dunes in Death Valley National Park looking toward the Cottonwood Mountains from the north west arm of Star Dune. (CC-BY-SA 3.0; Daniel Mayer Links to an external site.; modified by Chloe Branciforte)

Crescent Dunes

  • Barchan dunes Links to an external site.form where sand supply is limited and there is a constant wind direction. Barchans migrate downwind and develop a crescent shape with wings on either side of a dune crest (Figure 18.13).  Barchan dunes are mobile enough that they can overtake homes or even towns.
  • Parabolic dunes Links to an external site.(coastal dunes) also have a crescent shape; however, they form when vegetation anchors parts of the sand and the unanchored parts are removed and form a blowout (Figure 18.14).
Aerial view of coastal dunes forming with the wind direction predominately blowing onshore.

Figure 18.14: Formation of coastal dunes in Marina Dunes Preserve west of Salinas, California. (CC-BY 4.0, Chloe Branciforte via Google Earth)

Linear dunes 

  • Longitudinal dunes Links to an external site. form when two dominant wind directions average towards the direction of elongation. This bi-directional wind flow typically produces two slip faces (Figure 18.15).
  • Transverse dunes form when abundant barchan dunes merge to form linear, slightly sinuous, dunes. They lie transverse, or across, the wind direction, with the wind blowing perpendicular to the ridge crest (Figure 18.15).
Top, formation of a longitudinal dune. Wind blows from right to left along the length of the dune, developing two slip faces. Bottom, formation of a transverse dune. Wind blows from right to left, at a right angle to the dune formation.

Figure 18.15: Formation of linear dunes. (CC-BY 3.0; Top, Po ke jung Links to an external site., Bottom, Po ke jung Links to an external site.)

The Eureka Dunes (Figure 18.16), are the tallest dunes in California, and the second tallest in North America. They are likely a combination of both longitudinal and transverse dunes, with winds averaging east-west.

Aerial view of linear dunes developing. North is to the right. Winds average east-west.

Figure 18.16: Eureka Dunes within Death Valley National Park, CA  (CC-BY 4.0, Chloe Branciforte via Google Earth)

Star dunes Links to an external site. form where the wind direction is variable, forming the distinct star shape. Sand supply can range from limited to quite abundant. Mobility is low, as they tend to not move in a dominant direction (Figure 18.17).

Aerial view of stary dunes developing. North is up. Wind direction is variable.

Figure 18.17: Panamint Dunes, which are star dunes, within Death Valley National Park, California. (CC-BY 4.0, Chloe Branciforte via Google Earth)