A Wonder of Nature
Welcome to THIS IS AMERICA IN VOA Special English. I'm Faith Lapidus. One of the world's great natural wonders is in the bridesmaid dressesstate of New Mexico, in the American Southwest. Nature has created huge moving hills of pure white sand. These sand dunes cover more than seventy-thousand hectares of desert. Now, Steve Ember and Mary Tillotson are your guides as we explore White Sands National Monument.
(MUSIC) VOICE ONE: White Sands National Monument It is one of the largest sand dune fields in the United States. wedding dressesThe bright white sand dunes are always changing, always moving, like waves on the ocean. Driven by strong winds, the sand moves and covers everything in its path. It is like a huge sea of sand. VOICE TWO: The sand dunes have created an extreme environment. Plants and bridesmaid dressesanimals struggle to survive. A few kinds of plants grow quickly to survive burial by the moving sand dunes. Several kinds of small animals have become white in color in order to hide in the sand. White Sands National Monument protects a large part of this dune field.unlocked phones It also protects the plants and animals that live there. More than five-hundred-thousand people visit White Sands National Monument each year. They climb on the dunes and observe the moving sea of sand. VOICE ONE: You may wonder how all this sand arrived in the area. To understand that, cheap phoneyou would have to travel back in time two-hundred-fifty-million years. An inland ocean once covered the area. The minerals calcium and sulfur were at the bottom of the ocean. Over time, the water slowly disappeared. The calcium and sulfur remained. The minerals formed gypsum rock. Then, seventy-million years ago, the Earth's surface, or crust, lost wax castingpushed upward. The rocks formed two groups of mountains. Later, the crust pulled apart. The area between the mountains broke and fell down. It formed a half-circle shape of a bowl. This bowl of rock is known as the Tularosa Basin.
VOICE TWO: About twenty-four-thousand years ago, it rained a great deal in the area. The rain filled the Tularosa Basin and formed Lake Otero. The rain and snow that washed down the mountains into Lake Otero carried gypsum with it. Gypsum Dunes Later, Lake Otero almost completely dried up. Gypsum remained. ignition coilA strong wind moved into the area. It blew across the land for thousands of years. Pieces of gypsum broke off. The wind wore them away to a size small enough to pick up and carry for short distances. Wherever the wind dropped sand, dunes formed.
(MUSIC) VOICE ONE: The sand dunes at White Sands National Monument are unusual because they are boat modelmade of gypsum. Gypsum sand is different from common sand. Most sand is made of quartz, a hard silicon crystal. Gypsum sand is made of softer calcium sulfate. It dissolves easily in water. So it is rarely found in the form of sand dunes. Most gypsum would be carried away by rivers to the sea. But the Tularosa Basin is enclosed. No rivers flow out of it. So water with dissolved gypsum has nowhere to go. Gypsum sand is being made all the time. The dunes continue to form nfl jerseys supplierand move under the influence of water and wind. Water continues to wash down from the mountains carrying dissolved gypsum into the Tularosa Basin. Wind continues to blow across the Basin carrying the gypsum. The gypsum sand grains crash into each other. The crash creates tiny lines or endoscope surgery appliancescratches on the surface of the sand. These scratches change the way light shines off the surface. This makes the sand appear white. The sand dunes look like great masses of bright white snow. But they are not cold and wet. It only rains about eighteen centimeters each year.