Coastal dunes in De Panne, Belgium
This conical hill in Salar de Arizaro, Salta, Argentina called Cono de Arita constitutes a landform.
Coastal dunes at the Yyteri Beach in Pori, Finland
Karst towers landforms along Lijiang River, Guilin, China
Cadiz Dunes Wilderness
Sand dunes of the Empty Quarter to the east of Liwa Oasis, United Arab Emirates
Sand hitting sand is more likely to stick; sand hitting a more coherent surface is more likely to bounce (saltation). This exacerbating feedback loop helps sand accumulate into dunes.
Isolated barchan dunes on the surface of Mars. Dominant wind direction would be from left to right.
Schematic of coastal parabolic dunes
Reversing dune showing short minor slipface atop the major stoss (upwind) face
Dune Nine in Sossusvlei, Namibia, is over 300m high.
Coastal dunes covered in grasses around the mouth of the Liver Å river in Denmark
Sand dunes of Hyypänmäki in Hailuoto, Finland
Gypsum dune fields, White Sands National Park, New Mexico, United States
Cross-bedding in lithified aeolian sand dunes preserved as sandstone in Zion National Park, Utah
Sand blowing off a crest in the Kelso Dunes of the Mojave Desert, California, USA
A dune in Sossusvlei, in the greater Namib-Naukluft National Park, Namibia. Note the trees being engulfed for scale.
Camelthorn trees and bushes scattered on dunes in the Kalahari Desert in Namibia (2017)
Sand dune in the Libyan Desert near Dakhla Oasis at sunset.
Wind ripples on crescent-shaped sand dunes (barchans) in southwest Afghanistan (Sistan)
Fronting the Mediterranean Sea in Oliva, Valencian Community, Spain
50 m tall dune in Salir do Porto, Portugal
Sand dunes of Lemnos, Greece
Guadalupe-Nipomo Dunes
Cadiz Dunes Wilderness, California
White sand dunes in the Lençóis Maranhenses National Park, Maranhão, Brazil
Sand dune on Mars
Rub' al Khali (Arabian Empty Quarter) sand dunes imaged by Terra (EOS AM-1). Most of these dunes are seif dunes. Their origin from barchans is suggested by the stubby remnant "hooks" seen on many of the dunes. Wind would be from left to right.
Large linear seif dunes in the Great Sand Sea in southwest Egypt, seen from the International Space Station. The distance between each dune is 1.5–2.5 km.
The average-direction-longitudinal model of seif dune formation
alt=Transverse dune with wind blowing across crest|By contrast, transverse dunes form with the wind blowing perpendicular to the ridges, and have only one slipface, on the lee side. The stoss side is less steep.
alt=Animation of wind pushing transverse dunes along. The sand blows from the stoss side down onto the less side, where it is buried by the next layer. The dune thus moves, and a cross-section through it shown diagonal cross-bedding|Transverse dunes lie perpendicular to the wind, which moves them forwards, producing the cross-bedding shown here.

A dune is a landform composed of wind- or water-driven sand.

- Dune

Biological factors can also influence landforms— for example, note the role of vegetation in the development of dune systems and salt marshes, and the work of corals and algae in the formation of coral reefs.

- Landform
Coastal dunes in De Panne, Belgium

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