World Book Trivia Challenge Advanced--3/19-deserts

Other human activities have also caused deserts to expand. The development of cities, excessive grazing by livestock, and certain other farming practices have reduced plant cover near desert borders. Without the protective cover of plants, wind and water erode the soil, causing a desert to expand. This continual loss of fertile land along the edges of deserts is called desertification

The most common type of mirage is the oasis mirage. Desert travelers sometimes experience it when they see a distant pool of water that appears to be an oasis. But when they reach the spot, they find only dry sand.

But in spite of these harsh conditions, many plants live in desert regions. These plants—sometimes called xerophytes—include acacias, cactuses, creosote bushes, Joshua trees, sagebrush, and yuccas. Wildflowers are also found in the desert.

Deserts cover one-fifth of Earth’s land. The most extensive deserts lie in the subtropical regions along the Tropic of Cancer and the Tropic of Capricorn.

Beginning about 1840, people in Australia used camels to help them explore and settle that continent. Today, about 1 million camels roam wild in Australia. They have become a major threat to many native plants and animals.

People have domesticated camels for thousands of years. Arabian camels may once have roamed the Arabian Peninsula, but no wild camels remain there. Desert-dwelling peoples of Africa and Asia keep several million domesticated Arabian camels. The first Bactrian camels probably inhabited Mongolia and Afghan Turkestan, an area associated with the ancient region of Bactria. Perhaps a few hundred wild Bactrian camels still survive in Mongolia, and over a million domesticated ones live in Asia.

Seth, also called Set, was an ancient Egyptian god of chaos, storms, violence, darkness, and desert land. He was also a god of desert animals, serpents, pigs, hippopotamuses, and crocodiles.

The desert has some of the highest sand dunes in the world. Some of them rise to more than 1,300 feet (400 meters). The Skeleton Coast, which forms part of the northern region, received its name because of the large number of shipwrecks that occurred there.

Scientists consider the Atacama Desert in northern Chile the world's driest desert. The Atacama Desert averages less than 0.5 inch (1.3 centimeters) of rain yearly.

Gila, «HEE luh», monster is a large lizard with a poisonous bite. It lives primarily in the Sonoran Desert of the southwestern United States and northern Mexico. The Gila monster is unusual among lizards for producing venom

Sand covers 10 to 20 percent of most deserts. The rest of the land consists of gravel-covered plains, rocky hills and mountains, dry lake beds, salt flats, and dry stream channels.