There are three major types of desert landscapes: reg, hamma and erg.

Reg is a large, flat area strewn with gravel and small stones. Hammada contains desolate areas of bare rock. The erg, or sandy desert, which is characterized by sand dunes, is the most commonly known desert landscape.

Erg covers about 20 per cent of all the deserts in the world.

Sand Dunes

The sand dune is one of the man features of erg landscapes.

The wind deposits these mounds of sand in the desert and shapes them.

Sand dunes also exist in sandy coastal areas.

One type of dune, the barchan, is crescent-shaped, with two long, curved arms pointing in the direction of the prevailing wind.

Another type, the seif (from the Arabic word for sword) dune, is a long ridge of sand which develops parallel to the wind direction.

The smallest dunes are merely ripple marks, but some are hundreds of meters high. They can move at a rate of about 10 meters a year.

Flash Floods

Occasionally,  thunderstorms cause flash floods in deserts.

Torrents sweep along gorge-like channels called wadis. This causes temporary lakes, called shotts (sometimes spelled chotts), to be formed in the mountains.

These flash floods have enormous erosive power.

After such a flood, dormant plants spring to life, often scattering their seeds only two weeks after flowering.

For a short time, the desert is alive with color.

Loess Deposits

Loess is a type of aeolian, or wind-blown, deposit.

It is a yellowish, fine-grained material made up of dust that usually origi-nates in deserts.

A vast belt of loess stretches from Germany and France, where it is thin and glacial in origin, across northern Europe and Asia, to China, where it is derived from desert erosion.

The loess layers in China are very thick. The yellow color of the Hwang Ho comes from the loess that it transports.

Loess deposits can also be found in the Great Plains of the United States.


An oasis is a fertile areas in the desert, characterized by the existence of date palms. Oases can range from small water holes, where an underground aquifer meets the surface, to an area is large as the Nile valley in Egypt

Most human settlements in the desert were founded around oases.