Aeolian landforms are features of the Earth's surface produced by either the erosive or constructive action of the wind. These features may be built up from sand or snow, or eroded into rock, snow, or ice. Aeolian landforms are commonly observed in sandy deserts and on frozen lakes or sea ice. They have also been observed and studied on other planets, including Mars and Pluto
Aeolian landforms are formed when wind moves sediment. Sediment particles move when they are lifted by upwards Bernoulli forces that exceed their downwards weight. Depending on the balance of these forces, particles may either creep across the surface; saltate from point to point; or be suspended entirely in the air. Once sediment transport begins, it continues with considerable momentum: particles that fall out of the air typically impact the surface with enough force to dislodge further particles. These impacts are separated in space by the saltation hop length of the traveling particles, which creates distinct areas of erosion and/or deposition. As time passes, the surface rises in areas with net deposition, and lowers in areas with net erosion, creating landforms. Larger aeolian landforms alter the surface wind field in patterns that promote their growth. They are thus very stable, once formed. Aeolian landforms are typically described in two categories: erosional and depositional.
Depositional landforms
Depositional landforms grow when sediment is deposited into an area faster than it is removed. These bedforms grow from snow during blizzards, or from sand and dust in areas where wind patterns trap particles. For example, the Great Sand Dunes in Colorado grow as sand blown from a wide plain is deposited against the edge of the Sangre de Cristo mountains. Depositional landforms include dunes, barchan dunes, ripple marks, and loess.
Erosional landforms
Erosional landforms grow when more sediment is removed from an area faster than it is deposited. They are widespread in hardened, wind-swept snow surfaces, such as the Antarctic Plateau: see sastrugi. In sand and rock, they are rarely preserved except in arid regions. Outside of arid regions, moving water - which is heavier and more erosive than wind - erases aeolian landforms. There are several types of landforms associated with erosion: lag deposits, ventifacts, yardangs and pans. Large basins are complex and there is often one or more non-aeolian process at work, including tectonics, glacial and alluvial forces.
