Zeugens. Image credit Revisionworld.com

Zeugens. Image credit Revisionworld.com

ZIMSEC O Level Geography Notes: Hot Deserts: Yardangs

Zeugens

  • Pictured in the diagram above.
  • Zeugens are the ridges in “ridge and furrow” landscapes found in deserts.
  • These ridge and furrow landscapes sculpted found in hot deserts are a result of wind erosion.
  • Wind abrasion turns a desert surface which has a layer of resistant rock underlain by a layer of weak rock into ridges and furrows.
  • The wind usually takes advantage of joints and cracks created by dew and frost as part of weathering processes.
  • Zeugens may be as high as 30 meters in height.
  • With time the furrows are widened and the zeugens lowered and consequently they are undercut and worn away as the wind erosion and other denudation processes continue to act on them.

Yardang

Formation of yardangs. Image credit YourarticleLibrary.

Formation of yardangs. Image credit YourarticleLibrary.

  • Yardangs are ridges made of resistant rock which are developed and lie parallel to the direction of the prevailing wind.
  • When bands of resistant and weak rocks lie parallel to  the prevailing wind,
  • Wind abrasion produces another form of “ridge and furrow” landscape since the weak bands are readily eroded to leave the more resistant bands of hard rocks to stand as yardangs.
  • These yardang ridges vary in height from 5 to 15 meters and can be as long as a kilometer.
  • These landforms are usually undercut on their windward sides.
  • Yardangs can be found in Algeria and Egypt.

Rock Pedestal.

A rock pedstal. Image credit RevisionWorld.com

A rock pedstal. Image credit RevisionWorld.com

  • These are mushroom/tower-like shaped features formed as a result of wind abrasion.
  • Since the sand blasting of wind in deserts is mostly confined to a meter and below from the ground,
  • Rocks are undercut.
  • These rocks are usually made up layers with differing hardness resulting in the softer parts being worn away at a more rapid rate resulting in the formation of pedestals.
  • Continued erosion leads to the eventual collapse of the pedestal.
  • An example is Mukarob (“The finger of God.”) which was located in the Namib Desert before its eventual collapse in 1988.

To access more topics go to the Geography Notes page.

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