Aeolian processes

Wind erosion of soil at the foot of Chimborazo, Ecuador.
Rock carved by drifting sand below Fortification Rock in Arizona (Photo by Timothy H. O'Sullivan, USGS, 1871)

Aeolian processes, also spelled eolian or æolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts.

The term is derived from the name of the Greek god Aeolus, the keeper of the winds.

Wind erosion

A rock sculpted by wind erosion in the Altiplano region of Bolivia
Sand blowing off a crest in the Kelso Dunes of the Mojave Desert, California.
Wind-carved alcove in the Navajo Sandstone near Moab, Utah

Wind erodes the Earth's surface by deflation (the removal of loose, fine-grained particles by the turbulent action of the wind) and by abrasion (the wearing down of surfaces by the grinding action and sandblasting by windborne particles).

Regions which experience intense and sustained erosion are called deflation zones. Most aeolian deflation zones are composed of desert pavement, a sheet-like surface of rock fragments that remains after wind and water have removed the fine particles. Almost half of Earth's desert surfaces are stony deflation zones. The rock mantle in desert pavements protects the underlying material from deflation.

A dark, shiny stain, called desert varnish or rock varnish, is often found on the surfaces of some desert rocks that have been exposed at the surface for a long period of time. Manganese, iron oxides, hydroxides, and clay minerals form most varnishes and provide the shine.

Deflation basins, called blowouts, are hollows formed by the removal of particles by wind. Blowouts are generally small, but may be up to several kilometers in diameter.

Wind-driven grains abrade landforms. In parts of Antarctica wind-blown snowflakes that are technically sediments have also caused abrasion of exposed rocks.[1] Grinding by particles carried in the wind creates grooves or small depressions. Ventifacts are rocks which have been cut, and sometimes polished, by the abrasive action of wind.

Sculpted landforms, called yardangs, are up to tens of meters high and kilometers long and are forms that have been streamlined by desert winds. The famous Great Sphinx of Giza in Egypt may be a modified yardang.

List of major aeolian movements

Major global aeolian dust movements thought to influence and/or be influenced by weather and climate variation:

  • From Sahara (specifically Sahel and Bodélé Depression) averaged 182 million tons of dust each year between 2007 and 2011 and carry it past the western edge of the Sahara at longitude 15W. Variation: 86% (2007/11). Destination: 132 mln tons cross the Atlantic (ave), 27.7 mln tons fall in Amazon Basin (ave), 43 mln make it to the Caribbean. Texas and Florida also receive the dust. Events have become far more common in recent decades. Source: NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data.[2] Harmattan winter dust storms in West Africa also occur blowing dust to the ocean.
  • Gobi Desert to Korea, Japan, Taiwan (at times) and even Western USA (blowing east). See also Asian dust.
  • Thar Desert pre-monsoon towards Delhi, Uttar Pradesh, Indo-Gangetic Plain. See also 2018 Indian dust storms.
  • Shamal June–July winds blowing dust in primarily north to south in Saudi Arabia, Iran, Iraq, UAE, and parts of Pakistan.
  • Haboob dust storms in Sudan, Australia, Arizona associated with monsoon.
  • Khamsin dust from Libya, Egypt and Levant in Spring associated with extratropical cyclones.
  • Dust Bowl event in USA, carried sand eastward. 5500 tons were deposited in Chicago area.
  • Sirocco sandy winds from Africa/Sahara blowing north into South Europe.
  • Kalahari Desert blowing east to southern Indian Ocean and Australia.
Other Languages
Afrikaans: Eoliese proses
العربية: عوامل ريحية
azərbaycanca: Eol prosesləri
français: Relief éolien
한국어: 풍식
Bahasa Indonesia: Proses Aeolian
Nederlands: Eolisch proces
Nedersaksies: Aeolische ôfzetten
日本語: 風食
norsk nynorsk: Eolisk prosess
português: Erosão eólica
Simple English: Eolian processes
српски / srpski: Еолски процес
srpskohrvatski / српскохрватски: Eolski proces
українська: Еолові відклади
中文: 風蝕