A typical romanticized desert scene involves camels picking their way across immense expanses of sand dunes.  This is a rather simplistic view which ignores the wide variety of environments and cultures found in the world's deserts.

Nevertheless, these vast expanses of sand do indeed exist, seas of sand which have built up over thousands of years. Nearly all of the Earth's moving sand is held in large areas of active sand dunes.  They take various names:

erg (plural areg) - Arabic for 'ocean'
koum - Turkic for 'sand'
nefud - Arabic, a smaller, elongate sand sea
sha-mo - Chinese for 'sand river'.

(not referring to sand: reg (Arabic) = gobi (Mongolian) = desert pavement = gibber plain)

The generic landform term preferred by geographers is 'erg'.   An arbitrary cutoff size of 125 km2 has been adopted; areas smaller than this are simply "dune fields".

Every erg in the world was formed from a specific source of sand, from a specific event of desertification. For some of them, the sand collected in low basins.  Frequently, sand piles up against the hills or mountains ringing such a basin, and spills out through the passes.   Other masses of sand are still moving, and are where they are simply because that was how far the wind could push them in the time since they were formed.    Most ergs are still accumulating sand.  A few have been stabilized by vegetation.


OK, I said to myself.  85% of all the Earth's mobile sand is found in ergs that are larger than 32,000 km2 (a little bit bigger than Belgium).  How many of them can there be?  This led me on a frustrating search for the world's big ergs.  Starting from an unlabeled world map in an old geomorphology textbook, I hunted through the Web for dune fields around the world.   Most of my virtual journey involved dozens of travel sites, too numerous to name here, from which the name of a single erg was extracted.   The list below probably resembles a list of the world's deserts as much as a list of actual sand seas.

The sizes of the ergs listed below are quite uncertain.  Not only do people frequently confuse the sand sea with the desert (none are all sand), these things are growing because of climate changes around the Earth.

Namibia

  • Namib Sand sea  (34,000 km2)

Botswana

  • Kalahari Desert (stable, into Namibia and South Africa) It's difficult to find a good map of Botswana, let alone one that shows where the dunes are.

Morocco

Algeria

Mauretania

Mali

Niger

Chad

Libya

Sudan

Egypt

Saudi Arabia

Iran

Pakistan and India

Kazakstan

Turkmenistan

  • Kara Kum "Black Sand" (300,000 km2)
  • Turan
  • Zaunguz

China

Many of the names here are tentative, as I had to transliterate Wade-Giles spelling into Pinyin via a table.

  • Takla Makan, (Taklimakan Shamo) Xinjiang
  • Guerbantonggude Shamo, Xinjiang (Dzungaria)
  • Surprisingly, the Great Gobi has few sand dunes, except for its southern extensions in north-central China.
    • Badain Jaran or Badanjilin Shamo, Gansu (Inner Mongolia?)
    • Tengger or Tenggeli Shamo, Gansu-Ningxia
    • Ordos (Mu Us Shamo)
      • Wulanbuhe Shamo, Ningxia
      • Maowusu Shamo, Inner Mongolia
      • Gubuqi Shamo, Inner Mongolia
  • An unidentified sandy area appears on the atlas in eastern Inner Mongolia, about 200 km due north of Beijing. The atlas also shows large sand dune areas around Tongliao in Jilin, but does not name them.  These could be loess dunes, however.

Mongolia

Peru

Chile

United States

Mexico

Australia

About one-sixth of Australia is covered with sand dunes. These are typically thin, with the underlying rock appearing bewteen widely spaced dunes.


Embassy of Niger - Niger Profile (recovred from Google cache)
www.nigerembassyusa.org/profile.html

Geomorphology from Space: A Global Overview of Regional Landforms
http://daac.gsfc.nasa.gov/DAAC_DOCS/geomorphology/GEO_HOME_PAGE.html

Global Desert Monitoring with ASTER
http://elwood.la.asu.edu/grsl/deserts/

Times Atlas of China, 1970

Chorley, Richard J, et. al.  Geomorphology, p. 411.
Methuen and Co, New York/London, 1984.

La Ruta de Sonora Ecotourism map
http://www.laruta.org/borderlands.htm

Erg (?), n. [Gr. work.] Physics

The unit of work or energy in the C.G.S. system, being the amount of work done by a dyne working through a distance of one centimeter; the amount of energy expended in moving a body one centimeter against a force of one dyne. One foot pound is equal to 13,560,000 ergs.

 

© Webster 1913.

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