ANNOUNCER: Welcome to THIS IS
AMERICA IN VOA Special English. I'm Faith Lapidus.
One of the world’s
great natural wonders is in the state of New Mexico, in the American Southwest.
Nature has created huge moving hills of pure white sand. These sand dunes cover
more than 70,000 hectares of desert.
Now, Steve Ember and Mary Tillotson are your guides as we explore White Sands
National Monument.
(MUSIC)
VOICE ONE:
It is one of the largest sand dune fields in the United States. The 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 animals
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. It
also protects the plants and animals that live there. More than 500,000 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, you
would have to travel back in time 250 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, pushed
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 24,000 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.
Later, Lake Otero
almost completely dried up. Gypsum remained. A 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
made 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 and 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
scratches 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.
(MUSIC)
VOICE TWO:
There are four kinds of sand dunes at White Sands National Monument. Some of
the dunes are small and fast-moving. They are called dome dunes because they are
shaped like a half-circle. Few if any plants grow on them. These dunes move the
fastest, up to twelve meters a year.
Other dunes are called transverse dunes. They form in long lines across the
dune field. They can grow to be 120 meters thick and eighteen meters high.
Another kind of dunes are barchan dunes. They form in areas with strong winds
but a limited supply of sand. These dunes have sand in three 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 when plants hold
sand in the outer parts of the dune but the center of the dune continues to
move.
(MUSIC)
VOICE ONE:
You may wonder how anything can live in this extreme environment of a white
sand desert. There is not much rain. The heat in summer is intense. The sand
lacks nutrients.
Yet almost 400 kinds of animals live in White Sands National Monument. Many
of them are birds or insects. There are also twenty-six kinds of reptiles,
including rattlesnakes and lizards. And there are more than forty kinds of
mammals. They include rabbits, foxes and coyotes.
Scientists know that plants and animals often change to be able to live in
extreme environments. For example, they change color to protect themselves from
enemies. Many of the animals that live in the sand dunes have become white. So
it is difficult to see the animals in the sand.
There is another reason why you may not be able to see the animals. Many of
them remain underground during the day when it is very hot. They come out at
night when it is cooler. You may be able to see their footprints.
VOICE TWO:
Plants do grow in the White Sands dune field. But even plants that grow in
most deserts have trouble surviving. A major reason is that the dunes bury any
plants in their way as they move across the desert. Yet, a few plants have
developed techniques to avoid being buried by moving sand.
For example, some plants grow taller and their roots grow deeper into the
sand. The soaptree yucca plant can make its stem grow longer to keep its leaves
above the sand. The plant grows up to thirty centimeters a year.
(MUSIC)
VOICE ONE:
White Sands National Monument is about twenty-four kilometers southeast of
the city of Alamogordo, New Mexico. In the visitor center at the entrance of the
park, you can find out about special activities and guided walks. From the
visitor center, you can drive about thirteen kilometers into the center of the
dunes. It is like driving on a lonely white planet. Along the way there is
information that tells about the natural history of the white sands.
You can also explore the dunes on foot. There are four marked trails. Signs
along the trail tell about the plants growing in the sand. You can see some
unusual and beautiful plants and flowers growing in the sand dunes. But you may
not remove or destroy any plants or animals at White Sands.
You can even camp there overnight. But you must be careful. It is easy to get
lost in the waves of moving sand especially during sandstorms. There is no water
to drink. The temperature can rise to thirty-eight degrees Celsius in summer.
There is no shelter from the sun’s rays.
VOICE TWO:
There is another reason to be careful at White Sands National Monument. The
White Sands Missile Range completely surrounds the park. It covers one-million
hectares. The missile range was first used as a military weapons testing area
after World War Two. It was used to test rockets that were captured from the
German armed forces. The missile range continues to be an important testing area
for experimental weapons and space technology.
These tests take place about two times a week. For safety reasons, both the
park and the road from it south to Las Cruces, New Mexico may be closed for an
hour or two while tests are taking place.
VOICE ONE:
White Sands National Monument is part of America’s National Parks System. The
park system includes more than 370 protected areas. White Sands National
Monument is just one of the more unusual examples of America’s natural and
cultural treasures.
(MUSIC)
ANNOUNCER: Our program was written by Shelley Gollust and read by Steve Ember
and Mary Tillotson. I'm Faith Lapidus. Internet users can find our programs at
voaspecialenglish.com. We hope you join us again next week for THIS IS AMERICA
in VOA Special English.
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