![Mushroom in Timna Park in summer 2011 (1)](https://upload.wikimedia.org/wikipedia/commons/0/02/Mushroom_in_Timna_Park_in_summer_2011_%281%29.JPG)
A mushroom rock, also called rock pedestal, or a pedestal rock, 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
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
and
weathering
Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...
, glacial action, or from a sudden disturbance. Mushroom rocks are related to, but different from, ''
yardang
A yardang is a streamlined protuberance carved from bedrock or any consolidated or semiconsolidated material by the dual action of wind abrasion by dust and sand and deflation (the removal of loose material by wind turbulence.) Yardangs become e ...
''.
A mushroom rock, rock pedestal, or gour is a typical
mushroom
A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans.
The standard for the name "mushroom" is t ...
-shaped landform that is formed by the action of wind erosion. At an average height of 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.
Erosion
Usually found in
desert
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
areas, these rocks form over thousands of years when
wind erosion
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials ...
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 above the ground, causing the bases of outcrops to erode more rapidly than their tops. Running water can have the same effect. An example of this type of mushroom rock is the one in
Timna Park
The Timna Valley (תִּמְנָע, ) is located in southern Israel in the southwestern Arava/Arabah, approximately north of the Gulf of Aqaba and the city of Eilat. The area is rich in copper ore and has been mined since the 5th millennium ...
, Israel.
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 of dew near the surface.
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
waterfall
A waterfall is a point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf.
Waterfalls can be formed in several wa ...
. 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.
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 the support pedestal at this height.
Glacial action
In contrast to a mushroom rock formed by erosion of a single rock, these mushrooms are a type of
balancing rock
A balancing rock, also called a balanced rock or precarious boulder, is a naturally occurring geological formation featuring a large rock or boulder, sometimes of substantial size, resting on other rocks, bedrock, or on glacial till. Some formati ...
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
glacier
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...
. The lower part of the rock formation might or might not have also undergone a degree of erosion to accentuate the mushroom shape. Examples of this type of rock are Mushroom Rock in
Chickamauga and Chattanooga National Military Park
Chickamauga and Chattanooga National Military Park, located in northern Georgia and southeastern Tennessee, preserves the sites of two major battles of the American Civil War: the Battle of Chickamauga and the Siege of Chattanooga. A detailed h ...
,
Tennessee
Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...
, and ''Le Champignon'' in
Huelgoat
Huelgoat (; meaning "High Forest") is a commune in the Finistère department of Brittany in northwestern France.
Population
Inhabitants of Huelgoat are called in French ''Huelgoatains''.
Geography
Huelgoat is popular with tourists and holiday ...
, France.
''Le Champignon''
/ref>
Examples
*Sierra de Organos National Park
Sierra (Spanish for "mountain range" and "saw", from Latin '' serra'') may refer to the following:
Places Mountains and mountain ranges
* Sierra de Juárez, a mountain range in Baja California, Mexico
* Sierra de las Nieves, a mountain range i ...
, Sombrerete
Sombrerete () is a town and municipality located in the northwest of the Mexican state of Zacatecas, bordering the state of Durango.
It was founded in 1555 by Spanish conquistador Juan de Tolosa as a mining center, due to the wealth that the mine ...
, Mexico
*Ciudad Encantada
The Ciudad Encantada (English: Enchanted City) is a geological site near the city of Cuenca, in the autonomous community of Castilla–La Mancha, Spain in which the erosive forces of weather and the waters of the nearby Júcar river have formed ...
, Cuenca, Castile-La Mancha, Spain
*Goblin Valley State Park
Goblin Valley State Park is a state park of Utah, in the United States. The park features thousands of hoodoos, referred to locally as goblins, which are formations of mushroom-shaped rock pinnacles, some as tall as several yards (meters). The ...
, Utah, United States
*Gülşehir
Gülşehir, formerly Aravissos and Arapsun, ancient Zoropassos (Ancient Greek: ''Ζωρόπασος''), is a town and district of Nevşehir Province in the Central Anatolia region of Turkey, in the vicinity of the Fairy Chimney valley of Göreme. A ...
, Nevşehir, Turkey
*Mushroom Rock State Park
Mushroom Rock State Park is noted for its mushroom rock formations. It is located in the Smoky Hills region of north-central Kansas in Ellsworth County, Kansas, United States.
These rocks are the remains of beach sands and sediments of the C ...
, Kansas, United States
*Phae Mueang Phi
Phae Mueang Phi ( th, แพะเมืองผี, ) is a place with original rock formations in the Phi Pan Nam Range, Thailand. It is about eight kilometres northeast of Phrae town in Mueang Phrae District, Phrae Province.
Named after the ...
, Thailand
* The stone mushrooms, Bulgaria
*Hopewell Rocks
The Hopewell Rocks, also called the Flowerpots Rocks or simply The Rocks, are rock formations known as sea stacks caused by tidal erosion in the Hopewell Rocks Ocean Tidal Exploration Site at the Hopewell Rocks Provincial Park in New Brunswick, ...
, New Brunswick, Canada
*White Desert, Egypt
*Wadi Rum
Wadi Rum ( ar, وادي رم ''Wādī Ramm'', also ''Wādī al-Ramm''), known also as the Valley of the Moon ( ar, وادي القمر ''Wādī al-Qamar''), is a valley cut into the sandstone and granite rock in southern Jordan, about to the east ...
, Jordan
See also
*Aeolian processes
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials ...
*Hoodoo (geology)
A hoodoo (also called a tent rock, fairy chimney, or earth pyramid) is a tall, thin spire of rock formed by erosion. Hoodoos typically consist of relatively soft rock topped by harder, less easily eroded stone that protects each column from the ...
*Precarious boulder
A balancing rock, also called a balanced rock or precarious boulder, is a naturally occurring geological formation featuring a large rock or boulder, sometimes of substantial size, resting on other rocks, bedrock, or on glacial till. Some formati ...
*Ventifact
A ventifact (also wind-faceted stone, windkanter) is a rock that has been abraded, pitted, etched, grooved, or polished by wind-driven sand or ice crystals. These geomorphic features are most typically found in arid environments where there is lit ...
References
External links
Ciudad Encantada - Visitor information
Mushroom Rock State Park, Ellsworth County, Kansas
{{DEFAULTSORT:Mushroom Rocks
Rock formations
Erosion landforms