Deserts: Wind Erosion, Transportation & Landforms
Table of Contents
Perhaps the most powerful and effective phenomenon that occurs in deserts is wind, and is responsible for creating a wide range of desert features. Wind in deserts is able to erode and transport sand for considerable distances, locally, regionally or continentally.
For example, sand from The Sahara desert can be transported into Europe and can reach as far as England causing “red rain.”and some brilliant sunsets. Most landforms in deserts are carved and abraded by wind or sand blasted, the latter which erodes strata more quickly and effectively.
- The act of eroding and wearing down by wind
- The process whereby material is removed or scraped away from the surface.
Material in deserts is carried mainly by 3 processes, each depending on the size of material.
Very fine material can be lifted and carried in the air by wind. These suspended materials are responsible for dust storms in deserts. Depending on the wind speed these dust storms can be torrential and devastating with larger sediments being also lifted covering everything, e.g The Dust Bowl of 1939, Texas, USA.
Fairly large materials such as corestones can be transported in a series of ‘hops’. As these materials fall, they disturb the inertia of other lying materials causing them to also move or bounce.
Surface creep is the rolling of large stones that cannot be lifted along the surface. Sufficient strong winds are needed to roll these stops foward. As they roll, they can disturb other lying stones causing them to move
Wind produced features and landforms in deserts
Desert pavements are the surface of the desert occupied by coarse particles that are left when fine material is eroded away. These surfaces are durable and can resist future erosion. When insoluble material precipitate (removed from solution or water) under intense evaporation they cement together forming a hard layer called duricrust. Desert pavements have varying names in different locations; they’re called “gibber” in Australia, sai in Asia and hamada by the Arabs.
These are small to huge pits that are formed when wind gradually removes fine material from the surface (desert pavement). Erosion (deflation) stops when the material is large enough to be lifted or resistant to erosion.
Ventifacts are smoothened rocks that are polished and brushed by sand carrying wind.
Yardangs are ridges separated by troughs that are formed when wind erodes vertical bands of soft strata (troughs) leaving hard strata protruding as the ridges. Mega yardangs can be a kilometre long and can reach 100 m in height.
Zuegen / Rock Pedestals
Zuegens are formed when soft and hard strata lies horizontally causing the soft strata to be eaten more than the hard strata. Zuegens can take the form of a mushroom shaped rock pedestal resulting from the intense wearing down of the lower soft strata by sand blasting wind.
Mesas /Table Hills & Buttes
Mesas are flat topped, steep sided hills rising abruptly from a plain. When the surrounding soft area is eroded away, hard stands of hills can be left untouched or slightly weathered. Buttes are small than mesas
For example, in Monument Valley, Arizona USA the surrounding softer rocks have been eroded for millions of years living resistant sandstones standing as mesas.
Mesas can form structural benches (staircases) which are also resistant rocks that protrudes below the main hard rock. Continued denudation can reduce the mesa into a butte.
Several inselbergs such as bornhardts and whalebacks are also present in deserts. These are formed from the stripping and stripping of regolith by wind revealing deep seated basal surfaces as dome shaped bornhardts or or low lying bornhadts known as whalebacks.
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