Test: Biogeography: World Environment - 1 - UPSC MCQ

Approximately one-fifth (20%) of the world's land is made up of deserts. These arid regions are characterized by insufficient and irregular rainfall, high temperature, and rapid rate of evaporation.

True deserts are absolutely barren, where no vegetation can survive due to extreme arid conditions and lack of water resources.

Hamada, also known as rocky desert, consists of large stretches of bare rocks that are swept clear of sand and dust by wind. The exposed rocks in these deserts are thoroughly smoothened, polished, and highly sterile.

Reg, also known as stony desert, is composed of extensive sheets of angular pebbles and gravels. These deserts are more accessible than sandy deserts and are often used for camel herding.

Erg, also known as sandy desert, is characterized by vast stretches of undulating sand dunes in the direction of winds. These deserts are often referred to as a sea of sand due to their extensive sand coverage.

Badlands are deserts that consist of gullies and ravines formed on hill slopes and rock surfaces due to the extent of water action. These areas are not fit for agriculture or survival and often lead to the abandonment of the entire region by its inhabitants.

Mountain deserts are found on highlands such as plateaus and mountain ranges. These deserts are characterized by rough chaotic peaks and uneven ranges, with their steep slopes consisting of dry valleys (Wadis) carved due to the action of frost.

Weathering is the most potent factor in reducing rocks to sand in arid regions. The process involves the weakening and cracking of rocks due to temperature fluctuations and the action of water that penetrates into the rocks.

Deflation is the process that involves lifting and blowing away loose materials from the ground by the wind. This process is responsible for the formation of deflation hollows and other landforms in arid regions.

Rock pedestals, or mushroom rocks, are formed by the sandblasting effect of winds against projecting rock masses. The process wears down the softer layers, leading to the formation of irregular edges on alternate bands of softer and harder rocks.