Dana Epeing, age 9, of Florence, S.C., for his question:

WHAT EXACTLY IS A DESERT?

A few animals and plants have become adapted so they can live comfortably on desert land. They have changed the way they live and require less water than most plants and animals. Camels, for example, do not sweat very much, and they can go without water for long periods of time. Cactuses and other succulent plants store water in their stems so they can survive long dry spells.

Almost one fifth of the earth's land surface is covered with desert regions. A desert is an arid area where little water or vegetation can be found. The countryside isn't necessarily flat and covered with featureless drifts of sand. Rather, deserts can be mountainous or rocky. Parts can be deeply cut with canyons where rushing streams of water occasionally flow when there is a burst of rain. Winds often blow and shift the sand into dunes which change shapes endlessly.

All of the continents of the world except Europe have vast desert land. Largest in the world is the desert that stretches across Africa and Asia.  It extends from the Sahara across the Great Arabian Desert and into the deserts of Iran and Afghanistan.

Large deserts include the Atacama desert on the Pacific coast of South America, the Kalahari desert in southern Africa, the Gobi desert in Mongolia and China and the vast desert region in western and central Australia. A great deal of northern Mexico and the southwestern part of the United States is desert land.

The Sahara is extremely hot throughout the year while the Gobi is hot in summer and cold in winter. The term "cold desert'' is sometimes applied to the frozen arctic regions of North America as well as to Siberia.

Many deserts have soil that is extremely rich in minerals. With irrigation, the land can grow abundant and useful crops. Large sections of the desert around the Nile River, for example, have been turned into valuable farming areas. In California's Imperial Valley, a vast desert was turned into one of the world's best and largest vegetable gardens. And in Pakistan and India, water from the Indus River is moved through canals to irrigate large desert areas and to turn wasteland into productive land.

An oasis is like a green island in the middle of the desert. It's a spot where a spring or well is located, giving plants the water they need to grow.

In many large oasis areas travelers will discover groves of date palms, oranges, peaches and apricots. Farmers also grow grapes, corn, barley and wheat in desert oasis gardens.