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Landforms of Wind Erosion in Desert

Rock pedestals / Mushroom rocks

  • Formed by the sand blasting effect of winds against any projecting rock masses
  • It wears down the softer layer leading to formation of irregular edges on alternate bands of softer & harder rocks.
  • Grooves & hollows cut in the rock surfaces, carve them into grotesque looking pillar known as rock pedestals.
  • Such rock pillars will be further eroded near their bases where friction is greatest.
  • This process of undercutting produces rocks of mushroom shape called mushroom rocks.
Rock pedestals
Mushroom rocks

Zeugen

  • Tabular masses which have a layer of soft rocks lying beneath a surface layer of more resistant rocks
  • Difference in erosional effect of the wind on soft & resistant rock surfaces, carve them into weird looking ridge & furrow landscape
  • Mechanical weathering initiates their formation by opening up joints of the surface rocks
  • Wind abrasion further eats into underlying softer layer so that deep furrows are developed

Zeugen

  • The hard rocks then stand above the the furrows as ridges or Zeugen
  • Zeugen may stand 10 to 100 feet above the sunken furrows
  • Continuous abrasion by winds gradually lowers the Zeugen & widens the furrow

 

Yardangs

  • Yardangs looks quite similar to Zeugen but instead of lying in horizontal starta upon one another, the hard & soft rocks of Yardangs are vertical bands
  • Rocks are aligned in the direction of prevailing winds.
  • Winds abrasion excavates the bands of softer rocks into long, narrow corridors, separating the steep sided overhanding ridges of hard rocks called Yardangs.

Yardangs

Mesas & Buttes

  • Mesa is a flat, table like land mass with a very resistant horizontal top layer & very steep sides, may be formed in canyon region.
  • The hard stratum on the surface resist denudation by both wind & water thus protects the underlying layer of rocks from being eroded.
  • Continuous denudation through ages may reduce Mesas in area so that they become isolated flat topped hills called Buttes.
  • Many of which are separated by deep gorges & canyons.

Mesas & Buttes

Isenberg (Island Mountain)

  • They are basically isolated residual hills rising abruptly from the ground level
  • Characterized by very steep slopes & rather rounded tops
  • They are often composed of granite or gneiss
  • Are probably relics of an original plateau, which has been almost entirely eroded away

Isenberg

Ventifacts & Dreikanter

  • Ventifacts are generally pebbles faceted & edged by sand blasting
  • Rock fragments weathered from mountains
  • Are shaped & polished thoroughly by wind abrasion
  • Smoothened on windward side
  • If wind direction changes another facet is developed.
  • Among the ventifacts, those with the three wind faceted surfaces are known as Dreikanter.
Ventifacts
Dreikanter

Deflation Hollows

  • Wind lowers the ground by blowing away the unconsolidated material & hence forms small depressions.
  • Similarly, minor faulting can also initiate depressions which along with the eddying action of oncoming winds will wear off the weaker rocks until water table is reached.

Deflation Hollows

  • Water then seeps out forming oasis or swamps in deflation hollows or depressions.
  • Large areas in western USA, was stripped of their natural vegetation & was completely deflated by strong winds, that moved materials as dust storms & creating what is now known as Great dust bowl.
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