• Great Sand Dunes and Sangre de Cristo Mountains

    Great Sand Dunes

    National Park & Preserve Colorado

Dune Types

Dunefield and Sangre de Cristo Mountains

The main dunefield of Great Sand Dunes is primarily made up of reversing dunes and star dunes.

NPS/Fred Bunch

Great Sand Dunes National Park contains different types of dunes, each explained below through images and animations. Each dune type is the result of different wind patterns, and the presence or lack of vegetation on the ground.

 
Reversing Dunes: The Most Common Dune in the Dunefield
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Chinese walls on reversing dunes

NPS/Great Sand Dunes NPP

"Chinese Walls" form on tops of reversing dunes (see animation above).
 
Star dune formation

Star dunes have three or more arms, formed from multiple wind directions.

NPS/Great Sand Dunes NPP

Star Dunes

Where star dunes are present, an area's wind regime is complex. Star dunes form only in places where wind blows from varied directions over the course of a year. At Great Sand Dunes, a large star dune complex occurs in the northeast corner of the dunefield. The tallest dune at Great Sand Dunes is 750' (229m), and known simply as The Star Dune.

 
Parabolic dune animation

Animation showing the formation of a parabolic dune.

NPS/David Zelenka

Parabolic Dunes

Much of the sand sheet is covered with vegetation. If strong winds erode a section of the vegetated sand (commonly referred to as a blowout), a parabolic dune may form. Leeward motion occurs if sand from the blowout is deposited on the opposite slope of the parabolic dune. Vegetation holds the "arms" of the dune in place as the leeward "nose" of the dune migrates forward toward the main dunefield. Parabolic dunes are common in the sand sheet southwest of the main dunefield.

 
Aerial photo showing parabolic dunes

Purple lines mark parabolic dunes that are migrating with southwesterly winds toward the main dunefield.

NPS/Great Sand Dunes NPP

On the sand sheet, parabolic dunes are still migrating today toward the main dunefield. Vegetation on the valley floor causes them to become parabolic dunes rather than barchan dunes (below).

 
Barchan dune diagram

Barchan ("BAR-kahn") dunes form in areas with only one wind direction, and little or no vegetation.

NPS/Patrick Myers

Barchan Dunes

If conditions were "perfect"—the landscape was flat, winds blew from only one direction, vegetation could not grow, and sand was available but limited —barchan dunes would dominate a sandscape. Since those conditions are rarely found at Great Sand Dunes, a very complex dune system emerges. Even so, classic barchan dunes can be found at various locations throughout the park. Look for classic barchan dunes directly across from the main Dunes Parking Area. As the sand supply increases, barchan dunes begin to connect with others forming barchanoid ridges. If the ridges become fairly straight, scientists call them transverse dunes (below).

 
Barchan dunes near Medano Creek join together to become transverse dunes

Barchan dunes along Medano Creek can eventually align and join into long ridges called transverse dunes.

NPS/Patrick Myers

Transverse Dunes

Barchan dunes (above) can become aligned together along a plane perpendicular to the wind. If the line becomes somewhat straight, dune scientists refer to these forward marching ridges as transverse dunes. They progress forward as their leeward slipfaces release sand one avalanche at a time. Along the southern boundary of the dunefield, a series of transverse dunes are fed by recycled sand transported by Medano Creek.

 
Coppice or Nebkha dune

NPS/Andrew Valdez

Nebkha or Coppice Dunes

Nebkha dunes (also known as coppice dunes) are simple dunes that form around vegetation, primarily on the sand sheet. Clumps of shrubs and grass begin to gather windblown sand; as the sand gets deeper, the plants also grow taller, allowing more sand to gather around them.

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