Introduction to Eolian Forms

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Introduction to Eolian Forms
The effects of the transportation of soil grains by eolian (wind) action are very similar to those of
the transportation of materials by stream (fluvial) action. Eolian transported particles are carried
to the atmosphere, either close to the surface of the ground in a fashion similar to stream
bedloads, or higher above the surface of the ground in a fashion similar to suspended stream
loads. The lower layer consists of sands which scatter and bounce along the surface, perhaps
never rising more than four feet. The upper layer, or suspended load, contains fine-grained, siltsized particles where are carried for great distances at high altitudes. Eolian deposits include (1)
sand dunes, which occur near the source of the material, and (2) loess, or silt deposits, which are
often carried great distances by the wind covering large areas.
Distribution- Eolian landforms occur widely through all parts of the world, but are especially
common adjacent to glaciation zones and large flood plains, in arid climates, and along coastal
area.
 North America, United States and Canada- Belts of sand dunes are formed along the
coasts of the Atlantic and Pacific Oceans and the Great Lakes. Extensive inland dune
formations are found in the Great Basin in Nevada and in the deserts of southern
California. Loess deposits are found adjacent to the large rivers of the Mississippi Valley
and cover significant portions of Iowa, Illinois, northern Missouri, southwestern
Wisconsin, western Tennessee, western Mississippi, and others.
 Sand dune deposits in Canada are few and scattered. Loess is found in small, localized
deposits through southern Saskatchewan.
 South and Central America- Sand dune formations occur in the central basins of Peru and
Chile. Extensive deposits of loess cover most of northern Argentina, southern Uruguay,
and southern Paraguay.
 Africa- Extensive areas in Africa are covered with sand dunes. Loess cover is found
along the coastal sections of Morocco, Algeria. Libya, and the United Arab Republic.
Scattered small deposits occur across north central Africa from Senegal to Ethiopia.
 Europe- Sand dunes are dominant features along the French coast of the Bay of Biscay,
and the coasts of Belgium, the Netherlands, Denmark, and eastern Russia along the Baltic
Sea. Dune formations also occur along the major rivers in southern France, Spain, and
southern Russia north of the Black Sea.
 Asia- Sand dunes occur in many areas of Asia, including Mongolia to northern India, the
Gobi Desert, the region from Syria through Iran, and most of Saudi Arabia.
 Major deposits of loess are found throughout the Hwang-Ho River Valley in China and
along the northeastern edge of the Caspian Sea.
 Australia- Much of central Australia contains sand dune formations, including the Great
Sandy, Gibson, Great Victoria, Tanami, and Simpson Deserts.
 Thin loess deposits cover the central portion of Australia. Thicker deposits occur along
the southeastern coast of South Island, New Zealand.
 Pacific and Caribbean Regions- Small, calcareous sand dunes of local origin are scattered
through the regions. No significant deposits of loess are found.
Source: Terrain analysis procedural guide for surface configuration, US Army engineer
topographic laboratories, p. 7-47
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