Geography - Landforms

A desert is an arid region, usually partly covered by sand, having scanty vegetation or sometimes almost none, and capable of supporting only a limited and specially adapted animal population. An area having an annual rainfall of 10 in. (25 cm) or less is considered to be a desert. Some deserts have no rain for intervals of several years.
There are many different types of desert landforms, which are formed in numerous ways. Landforms such as Canyons and Alluvial fans are formed by water. This water formation may include erosion or stream deposition. Landforms such as Rock pedestal, Inselberg and Yardang are formed as a result of the wind, which may be wind erosion or wind deposition.
We have compiled an extensive project on desert landforms formed as a result of water and wind. Please sit back, relax and enjoy!

Water Action
Alluvial Fan
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Definition:
A broad, circular fan-shaped deposit of sediments found in deserts where erosional stream channels meet the valley floors and spread out, depositing the stream load. It typically spreads at the exit of a canyon onto a flatter plain.
Explain how it is formed:
When mountains shed sediment off their flanks, streams carry it away as alluvium. A mountain stream carries lots of alluvial sediment easily when its gradient is steep and energy is abundant. When the stream leaves the mountains and debouches onto the plain, it drops most of that alluvial sediment immediately. So over thousands of years, a wide cone-shaped pile builds up-an alluvial fan.
Example:
One example of an Alluvial Fan is in Montana, USA, near Bozeman.
Drawing or Photograph:

Mesa
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Definition:A Mesa is a portion of larger plateaus that have been detached by the winding of canyons. It is a landform that rises abruptly from the desert plains. It is broad and flat topped and bounded by steep slopes on all sides. Mesas consist of relatively easily weathered sedimentary rocks capped by nearly horizontal and more resistant rock layer. Formation: The Mesas are the remains of eroding plateaus. The main factor, which contributes to the eroding of the plateaus, is water. The reason is because when the heavy rain falls and washes it washes soft materials in the plateau away, leaving only the rocks that are steep and resistant to the water. The remnants then create landforms that raise abruptly in the desert, that is, the Mesas. How bad the water erodes the plateaus depends on the type of rock and also the type of climate.
Locations: These landforms can be found in western or southwestern United States of America, such as, New Mexico and Arizona.
Drawing or Photograph: INCLUDEPICTURE "http://www.scsc.k12.ar.us/2002Outwest/NaturalHistory/Projects/WylieT/Images/scan005.jpg" \* MERGEFORMATINET 
Wind Action (Wind Erosion)


Inselberg
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Definition:
An inselberg is an isolated hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. Explain how it is formed:
Inselbergs are typically, though not only, formed in tropical areas. Volcanic or other processes may give rise to a body of rock resistant to erosion, inside a body of softer rock such as sandstone which is more susceptible to erosion. When the less resistant rock is eroded away to form a plain, the more resistant rock is left behind as an isolated mountain - an inselberg.
Example:
Examples of inselbergs are  HYPERLINK "http://en.wikipedia.org/wiki/Gaff_Topsails" \o "Gaff Topsails" Gaff Topsails in  HYPERLINK "http://en.wikipedia.org/wiki/Newfoundland" \o "Newfoundland" Newfoundland,  HYPERLINK "http://en.wikipedia.org/wiki/Canada" \o "Canada" Canada and  HYPERLINK "http://en.wikipedia.org/wiki/Suilven" \o "Suilven" Suilven in  HYPERLINK "http://en.wikipedia.org/wiki/Scotland" \o "Scotland" Scotland.
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Rock Pedestal
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Definition: A Rock pedestal is a tower-like mass of rock made up of alternating layers of resistant and less resistant rock. They are one of the most striking manifestations of the processes of erosion and weathering. Explain how they are formed:They are formed over thousands of years when erosion of an isolated rocky outcrop progresses at a different rate at its bottom to that at its top. Abrasion by wind-borne grains of sand is most prevalent within the first three feet of the ground, causing the bases of outcrops to erode more rapidly than their tops. Running water can have the same effect. Its formation has also been attributed to chemical weathering at the base of the rock due to the collection of dew near the surface.Example:One example is at Yehliu, Taiwan.
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Bibliography