Question

Where are mushroom rocks formed?
A. Deserts
B. River Valleys
C. Glaciers
D. None of these

Answer 1

HintA mushroom rock, also called rock pedestal, or a pedestal rock is a naturally occurring rock whose shape, as its name implies, resembles a mushroom. Mushroom rocks are formed by erosions or abrasions which are tougher to be achieved in places where the weather is damp or wintry.

Complete step-by-step solutionThe rocks are deformed in an exceeding range of various ways: by erosion and weathering, glacial action, or from an unexpected disturbance. Mushroom rocks are related to, however totally different from, yardang. A mushroom rock, rock pedestal, or gour could be a typical mushroom-shaped landform that is fashioned by the action of wind erosion. At a typical height of 2 to 3 feet from the base, the material-carrying capability of the wind is at its extreme, so abrasion (erosion by wind during which transported materials hit an exposed rock surface and polish it or scratch it) is additionally maximized. In some cases, firmer rocks are arranged horizontally over a softer rock, leading to such erosion. Typically found in desert areas, these rocks establish over thousands of years once wind erosion of an isolated rocky outcrop progresses at a unique rate at its bottom than at its highest. Abrasion by wind-borne grains of sand is most predominant among the primary 3 feet above the ground, instigating the bases of outcrops to erode sooner than their tops. Running water can have a similar outcome.

Thus, option (A) is correct.

NoteThe characteristic of wind erosion is that it concentrates a few feet over the ground - wind speeds increase with height, however, sediment load reduces. This implies that the blend of highest sediment masses and reckless wind speed exist a few feet over the ground, resulting in the characteristic narrowing of the support pedestal at this height.