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
Mushroom rock formations, which might have taken millions of years to take the shape, have particularly remained great attractions.
The most common way of formation of mushroom rocks is erosion and weathering. This is a long drawn process, thousands or even millions of years in some cases. Erosion is normally non-uniform which results in slow vanishing of the lower parts of the rocks. Weathering is mainly on the upper part of the rocks when there is resistance offered by hard mass to erode. This protects the lower part of the rock and the process results in giving a shape and sometimes the shape has a striking resemblance to mushroom. Many of the mushroom rocks are found in desert areas where winds cause erosion.
This, however, may not be the only way of such rock formations. Glacial action or sudden disturbances like Earthquakes may also be responsible for such formations. 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 is also maximised. In some cases, harder rocks are arranged horizontally over a softer rock, resulting in such erosion.
Usually found in desert areas, these rocks form over thousands of years when wind erosion 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 above the ground, causing the bases of outcrops to erode more rapidly than their tops. Running water can have the same effect.
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. 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.
Some of the famous rock formations are:
1.Bathsheba, Barbados
2.Fungo, Lacco Ameno, Italy
3.White Desert, Western Egypt
4.Timna, Israel
5.Oppedal, Norway
6.Tisa Walls, Czech Republic
7.Babele, Romania
8. Vila Velha, Brazil
9.Toadstool shaped Hoodoo, USA