(THEME)
VOICE ONE:
This is Steve Ember.
VOICE TWO:
And this is Mary Tillotson with the VOA Special English programEXPLORATIONS. Today we tell about one of the world’s great naturalwonders, White Sands National Monument. It is in the southwesternAmerican state of New Mexico. Nature has created huge moving hillsof pure white sand.
(THEME)
VOICE ONE:
At White Sands National Monument, winds have formed great hillsof sand called dunes. The sand dunes cover more thanseventy-thousand hectares of desert.
It is one of the largest sand dune fields in the United States.The bright white sand dunes are always changing, always moving, likewaves on the ocean. Driven by strong winds, the sand moves andcovers everything in its path. It is like a huge sea of sand.
VOICE TWO:
The sand dunes have created an extreme environment. Plants andanimals struggle to survive. A few kinds of plants grow quickly tosurvive burial by the moving sand dunes. Several kinds of smallanimals have become white in color in order to hide in the sand.
White Sands National Monumentprotects a large part of this dune field. It also protects theplants and animals that live there. More than five-hundred-thousandpeople visit White Sands National Monument each year. They climb onthe dunes and observe the moving sea of sand.
VOICE ONE:
You may wonder how all this sand arrived in the area. Tounderstand that, you would have to travel back in timetwo-hundred-fifty-million years. An inland ocean once covered thearea. The minerals calcium and sulfur were at the bottom of theocean. Over time, the water slowly disappeared. The calcium andsulfur remained. The minerals formed gypsum rock.
Then, seventy-million years ago, the Earth’s surface, or crust,pushed upward. The rocks formed two groups of mountains. Later, thecrust pulled apart. The area between the mountains broke and felldown. It formed a half-circle shape of a bowl. This bowl of rock isknown as the Tularosa Basin.
VOICE TWO:
About twenty-four-thousand years ago, it rained a great deal inthe area. The rain filled the Tularosa Basin and formed Lake Otero.The rain and snow that washed down the mountains into Lake Oterocarried gypsum with it.
Later, Lake Otero almost completely dried up. Gypsum remained. Astrong wind moved into the area. It blew across the land forthousands of years. Pieces of gypsum broke off. The wind wore themaway to a size small enough to pick up and carry for shortdistances. Wherever the wind dropped sand, dunes formed.
(MUSIC)
VOICE ONE:
The sand dunes at White Sands National Monument are unusualbecause they are made of gypsum. Gypsum sand is different fromcommon sand. Most sand is made of quartz, a hard silicon crystal.Gypsum sand is made of softer calcium sulfate. It dissolves easilyin water. So it is rarely found in the form of sand dunes. Mostgypsum would be carried away by rivers to the sea. But the TularosaBasin is enclosed. No rivers flow out of it. So water with dissolvedgypsum has nowhere to go.
Gypsum sand is being made all the time. The dunes continue toform and move under the influence of water and wind. Water continuesto wash down from the mountains carrying dissolved gypsum into theTularosa Basin. Wind continues to blow across the Basin carrying thegypsum.
The gypsum sand grains crash into each other. The crash createstiny lines or scratches on the surface of the sand. These scratcheschange the way light shines off the surface. This makes the sandappear white. The sand dunes look like great masses of bright whitesnow. But they are not cold and wet. It only rains about eighteencentimeters each year.
(MUSIC)
VOICE TWO:
There are four kinds of sand dunes at White Sands NationalMonument. Some of the dunes are small and fast-moving. They arecalled dome dunes because they are shaped like a half-circle. Few ifany plants grow on them. These dunes move the fastest, up to twelvemeters a year.
Other dunes are called transverse dunes. They form in long linesacross the dune field. They can grow to be one-hundred-twenty metersthick and eighteen meters high.
Another kind of dunes are barchan dunes. They form in areas withstrong winds but a limited supply of sand. These dunes have sand inthree parts, like a body in the center and two arms on the sides.The sand in the two arms moves faster than the sand in the center.
Parabolic dunes are the opposite of barchan dunes. They form whenplants hold sand in the outer parts of the dune but the center ofthe dune continues to move.
(MUSIC)
VOICE ONE:
You may wonder how anything can live in this extreme environmentof a white sand desert. There is not much rain. The heat in summeris intense. The sand lacks nutrients.
Yet almost four-hundred kinds of animals live in White SandsNational Monument. Many of them are birds or insects. There are alsotwenty-six kinds of reptiles, including rattlesnakes and lizards.And there are more than forty kinds of mammals. They includerabbits, foxes and coyotes.
Scientists know that plants and animals often change to be ableto live in extreme environments. For example, they change color toprotect themselves from enemies. Many of the animals that live inthe sand dunes have become white. So it is difficult to see theanimals in the sand.
There is another reason why you may not be able to see theanimals. Many of them remain underground during the day when it isvery hot. They come out at night when it is cooler. You may be ableto see their footprints.
VOICE TWO:
Plants do grow in the White Sands dune field. But even plantsthat grow in most deserts have trouble surviving. A major reason isthat the dunes bury any plants in their way as they move across thedesert. Yet, a few plants have developed techniques to avoid beingburied by moving sand.
For example, some plants grow taller and their roots grow deeperinto the sand. The soaptree yucca plant can make its stem growlonger to keep its leaves above the sand. The plant grows up tothirty centimeters a year.
(MUSIC)
VOICE ONE:
White Sands National Monument is about twenty-four kilometerssoutheast of the city of Alamogordo, New Mexico. In the visitorcenter at the entrance of the park, you can find out about specialactivities and guided walks. From the visitor center, you can driveabout thirteen kilometers into the center of the dunes. It is likedriving on a lonely white planet. Along the way there is informationthat tells about the natural history of the white sands.
You can also explore the dunes on foot. There are four markedtrails. Signs along the trail tell about the plants growing in thesand. You can see some unusual and beautiful plants and flowersgrowing in the sand dunes. But you may not remove or destroy anyplants or animals at White Sands.
You can even camp there overnight. But you must be careful. It iseasy to get lost in the waves of moving sand especially duringsandstorms. There is no water to drink. The temperature can rise tothirty-eight degrees Celsius in summer. There is no shelter from thesun’s rays.
VOICE TWO:
There is another reason to be careful at White Sands NationalMonument. The White Sands Missile Range completely surrounds thepark. It covers one-million hectares. The missile range was firstused as a military weapons testing area after World War Two. It wasused to test rockets that were captured from the German armedforces. The missile range continues to be an important testing areafor experimental weapons and space technology.
These tests take place about two times a week. For safetyreasons, both the park and the road from it south to Las Cruces, NewMexico may be closed for an hour or two while tests are takingplace.
VOICE ONE:
White Sands National Monument is part of America’s National ParksSystem. The park system includes more than three-hundred-seventyprotected areas. White Sands National Monument is just one of themore unusual examples of America’s natural and cultural treasures.
(THEME)
VOICE TWO:
This program was written by Shelley Gollust. It was produced byPaul Thompson. I’m Mary Tillotson.
VOICE ONE:
And I’m Steve Ember. Join us again next week for EXPLORATIONS, aprogram in Special English on the Voice of America.