Aeolian Landforms

Desert

Deserted / unoccupied. Barren rocky outcrops with steep angular slopes are common. Not dominated by a single geologic process. Common in arid regions. Very low annual rainfall and meagre vegetation.

Lag deposits

Thin veneers of gravel, or coarser material, that overlie predominantly finer materials. Result from the deflation of poorly sorted deposits, such as alluvium, that contain a mix of gravel, sand, and silt.

Stone pavement

A layer of coarse pebbles and gravel created when wind removed the finer material. Controls wind erosion. Overlies a layer of silt and sand.

Blowout

Shallow depression made by wind erosion. Depth controlled by water table. Deflation hollows.

Pan

Closed depressions that are common in many dryland areas and that seem to be at least partly formed by deflation.

Steppe

Found in semi-arid regions. Marginal, more humid version of desert. Bounds a desert.

Low-latitude desert

Created at 20-30 degrees North and South latitudes from descending dry air. Characterized by clear skies, sunshine, and ongoing drought.

Middle-latitude desert

Not controlled by subsiding air masses. Sheltered in the deep interiors of large landmasses. Dry because air reaching leeward side of mountains are already deprived of moisture.

Rainshadow desert

A dry area on the lee side of a mountain range. Many middle-latitude deserts are of this type.

Yardang

A streamlined, wind-sculpted ridge that has the appearance of an inverted ship's hull that is oriented parallel to the prevailing wind.

Zuegen

Perched or mushroom rocks. Related to yardangs. Produced by the wind eating away strata, and especially soft strata close to the ground.

Ergs

A great sea of sand with tall and large dune fields.

Regs

A desert whose pavement is filled with pebbles.

Hoodoo

Tall, thin spire of rock that protrudes from the bottom of an arid drainage basin or badland. Consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the elements.

Badland

Rocky wasteland that has been carved by erosion into intricate and fantastic shapes.

Ventifact

Rocks shaped by abrasion. Side of stone facing wind is abraded, leaving it polished, pitted, and with sharp edges.

Loess

Windblown silt deposits. Forms vertical cliffs when cut. No layering.

Wind ripple

Smallest aeolian bedform. They are regular, wave-like undulations lying at right-angles to the prevailing wind direction.

Dune

Collections of loose sand built piecemeal by the wind.

Draa

Mega-dune. Largest form of dune that may stand 400m high and sit more than 500m apart.

Transverse dune

A relatively straight, elongate dune oriented perpendicular to the wind. One wind direction, abundant sand supply.

Barchan dune

A solitary sand dune shaped like a crescent with its tips pointing downwind. One wind direction, small sand supply.

Dome

Lack slip faces but have an orientation and pattern of sand transport allied to transverse dunes.

Reversing dune

Asymmetric ridge of sand caused by opposing wind directions.

Barachnoid dune

Intermediate between barchan and transverse dune. Perpendicular to wind direction. One wind direction, moderate sand supply.

Longitudinal dune

A long ridge of sand generally parallel to the direction of the prevailing wind. Multiple similar wind directions, small sand supply.

Parabolic dune

A sand dune similar in shape to a barchan dune except that its tips point into the wind. These dunes often form along coasts that have strong onshore winds, abundant sand, and vegetation that partly covers the sand.

Star dune

An isolated hill of sand that exhibits a complex form and develops where wind directions are variable.

Zibar

Coarse-grained bedforms of low relief with no slip faces. Their surfaces consist exclusively of wind ripples and local shadow and shrub-coppice dunes. They are common on sand sheets and upwind of sand seas.

Streak

Sand sheets or stringers. Large bodies of sand that bear no obvious dune forms. They occupy larger areas of sand seas than accumulations with dunes.

Anchored dune

Impeded. Controlled by vegetation, topography, or local sediment sources.

Lee dune

Foredune. Connected to a pattern of airflow around obstacles.

Climbing dune

Irregular accumulation going up the windward side of a topographic obstacle.

Echo dune

Elongated ridge lying roughly parallel to, and separated from, the windward side of a topographic obstacle.

Falling dune

Irregular accumulation going down the leeward side of a large topographic obstacle.

Lunette

Crescent-shaped dunes that open upwind and are associated with pan.

Dunefield

Accumulations of sand, occupying areas of less than 30,000 km2 with at least ten individual dunes spaced at distances exceeding the dune wavelength.

Nabkha

Most common type of plant-anchored dune. Form around a bush or clump of grass which acts as an obstacle for sand entrapment