Deserts are found in areas where very little rain falls. Apart from in fertile spots called oases, there is little sign of life. Most deserts are just bare rock and gravel, although some deserts have vast areas of sand. Areas of desert are found in the west of the USA and South America, as well as in central and southwest Asia, Australia and both northern and southern Africa. Antarctica is also a desert: very little snow ever falls there.

Sandy deserts

We often think of deserts as sandy regions, but only about one fifth of the world’s deserts are sandy. Most of the Sahara Desert is covered by rock or gravel. Only one tenth is sandy. Where sand occurs in a desert, the wind sometimes piles up smooth mounds called dunes. Where the wind always blows in the same direction, crescent-shaped dunes called barchans are the result. They creep slowly across the desert, blown by the wind.

Wind erosion

In deserts, strong winds may blast tiny sand particles at the rocks, carving out some incredible shapes. In some desert landscapes you can see rock arches. Mushroom-shaped rocks are made when wind-blown sand blasts away at the base of a boulder, leaving a narrow neck.

Wadis

When rainstorms do occur in deserts, the fast-flowing water quickly wears away the rocks. Steep-sided gorges called wadis are the result.