Mushroom rock
Also called: Pedestal rock, Gour · Topic: Landforms and their Evolution: Rivers, Groundwater, Glaciers, Waves and Wind · NCERT: Class 11, Ch 6 "Landforms and their Evolution"
Meaning
A mushroom rock is a desert rock with a thin stalk and a broad cap on top, so it looks like a mushroom. It forms because wind abrasion (blown sand scraping rock) is strongest close to the ground. The bottom of the rock wears away faster than the top. Other leftover rocks of the same kind may have flat tops (table rocks) or stand on a narrow base (pedestal rocks). Mushroom rocks show clearly that wind is shaping a dry landscape.
Example
The White Desert near Farafra in western Egypt (part of the Sahara) has many chalk rocks shaped like mushrooms. Blown sand has worn their lower parts into thin stalks.
Don't confuse with
- Inselberg: a large hill with steep sides, left behind when desert mountains are worn back. A mushroom rock is a small rock carved by sand near the ground.
- Yardang: a long, smooth rock ridge that runs in the same direction as the wind. It is not a single rock with a cap.
Related concepts
- Aeolian processes
- Deflation
- Wind abrasion
- Sheet flood
- Erg, reg and hamada
- Pediment
- Parallel retreat of slopes
- Pediplain
- Inselberg
- Playa