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113:-shaped landform that is formed by the action of wind erosion. At an average height of two to three feet (0.6 to 0.9 m) from the base, the material-carrying capacity of the wind is at its maximum, so abrasion (erosion by wind in which transported materials hit an exposed rock surface and polish it or scratch it) is also maximized. In some cases, harder rocks are arranged horizontally over a softer rock, resulting in such erosion.
160:. Weathering of the exposed hard rock layer eventually exposes the lower rock to erosion from wind, water, salt intrusion, etc., depending on local conditions. The layer of softer rock is more readily eroded, leading to the formation of a depression or blowout. The overlying harder rocks are resistant to this process, and may ultimately end up as isolated mushroom rocks standing above the new, lower plain.
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Occasionally, the chemical composition of the rocks can be an important factor; if the upper part of the rock is more resistant to chemical erosion and weathering, it erodes more slowly than the base. For example, erosion attributed to chemical weathering at the base of the rock due to the collection
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of an isolated rocky outcrop progresses at a different rate at its bottom than at its top. Abrasion by wind-borne grains of sand is most prevalent within the first three feet (0.9 m) above the ground, causing the bases of outcrops to erode more rapidly than their tops. Running water can have the
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The nature of wind erosion is that it concentrates a few feet over the ground - wind speeds increase with height, but sediment load reduces. This means that the combination of highest sediment loads and fastest wind speed exist a few feet over the ground, leading to the characteristic narrowing of
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that formed from two separate rocks, one of which came to rest on top of the other. Typically, the uppermost rock was transported and deposited by the slow action of a
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92:, is a naturally occurring rock whose shape, as its name implies, resembles a mushroom. The rocks are deformed in a number of different ways: by
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A mushroom rock may ultimately form from an originally flat area of hard rock overlying soft rock, similar to the pattern of rocks that form a
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same effect. An example of this type of mushroom rock is the one in
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Naturally occurring rock whose shape resembles a mushroom
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areas, these rocks form over thousands of years when
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A mushroom rock, rock pedestal, or gour is a typical
318:Mushroom Rock State Park, Ellsworth County, Kansas
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298:The Facts on File. Earth Science Handbook
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313:Ciudad Encantada - Visitor information
164:the support pedestal at this height.
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46:"Chicken and Mushroom" rocks in the
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338:Erosion landforms
264:Aeolian processes
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269:Hoodoo (geology)
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147:Timna Park
98:weathering
63:Kelchstein
279:Ventifact
158:waterfall
258:See also
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248:Wadi Rum
212:Gülşehir
196:, Mexico
184:Examples
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244:, Egypt
178:glacier
117:Erosion
103:yardang
94:erosion
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