Why Are Deserts Made Of Sands?

The loose sand is picked up by the wind and carried inland. Sometimes, so much sand is moved in this way that a whole forest may be covered by sand dunes. Most of the loose sand there has been brought to this place or to desert by wind. In some cases, the desert sands may have been formed by the decay of rocks. In still other cases, the desert was once really a sea bottom and the water retreated thousands of years ago, leaving the sand. So, the sand is often found in deserts.

Sand is a very useful substance. It is used a great deal in modern building. When mixed with cement and water, it forms a sticky, mud like paste called "mortar", which hardens quickly into a solid mass called "concrete". It is also used in making glass, in sand paper and as a filter in helping keep water pure.