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FAITH LAPIDUS: This is Faith Lapidus.

STEVE EMBER: And this is Steve Ember with the VOA Special English program EXPLORATIONS. Today we visit the Indiana Dunes. These hills of sand are near Chicago, Illinois. They rise on the shores of Lake Michigan, one of America's five Great Lakes.

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FAITH LAPIDUS: More than two million people visit the sand hills in the middle-western state of Indiana each year. The winds along Lake Michigan created some of these dunes in ancient times. Other dunes may be building right now. The winds create dunes when they drop loose sand onto land. Some dunes look partly round. Others take the form of long, narrow hills.

Visitors from all over the world explore the area near the Indiana Dunes. They swim and sail on the lake. They watch birds in the wetlands. They study plant life in the rich forests of oak and maple trees. The smooth sands of the dunes and lakeshore make a clear musical sound when people walk on them. Some of these sounds can be heard ten meters away. Visitors often say that the sand dunes "sing."

STEVE EMBER: The Indiana state government and the federal government control more than 6,000 hectares of land along the lake. They operate parks with visitors' areas and scientific research stations. Supervision by these agencies guarantees that the land will always belong to the public. Laws protect the plants, animals, and natural and historical points of interest.

During the 20th century, many people worked hard to save the dunes from development for industrial and port uses. This was not easy. The land along that area of Lake Michigan is extremely valuable. Some of the land provides important lake ports. Industries and Indiana's natural gas company also operate along the lake.

FAITH LAPIDUS: In the early 1950s, some companies were removing five tons of sand each day from the dunes. Scientists of the Indiana Geological Survey investigated the sand supply in 1952. They said that the dunes would be gone in 50 to 100 years if companies continued to remove sand at that rate. The wind and waves of Lake Michigan created the dunes over thousands of years. Yet people could destroy the dunes in a lifetime.

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STEVE EMBER: The federal government established the National Park Service in 1916. A Chicago businessman named Stephen Mather was its first director. Mr. Mather created many national parks. He wanted the Indiana dunes to be a national park, too. However, the United States had entered World War One in 1917. Congress was not thinking about creating parks. It was thinking about soldiers and military supplies.

Public support for a protected dunes park continued to grow, however. In 1923, Indiana passed a bill providing tax money to buy property along the lake from its private owners. In 1926, the Indiana Dunes State Park opened. It contained more than 800 hectares of land.

FAITH LAPIDUS: Area citizens, scientists and visitors were pleased with the state park. But they did not feel satisfied. They wanted much more land along the lake protected from being used for more factories and industrial ports. Activist Dorothy Buell led the campaign for a national park in the dunes. She formed the Save the Dunes Council in 1952.

Indiana's representatives in the United States Senate opposed the proposed park. They said ports on the lake would provide more jobs for local workers than a national park. Yet the Save the Dunes Council found a powerful friend in United States Senator Paul Douglas. He represented the nearby state of Illinois. Senator Douglas loved the dunes. Every year he would introduce a bill to create an Indiana Dunes National Lakeshore. But every year the bill failed to pass.

STEVE EMBER: In 1966, people who wanted more development finally reached a compromise with people who wanted a national park. Congress first passed a bill to develop more ports. It also created the Indiana Dunes National Lakeshore. More land was added to the park in later legislation. Today more than 6,000 hectares of the federal Indiana Dunes National Lakeshore also include the Indiana Dunes State Park.

FAITH LAPIDUS: The Save the Dunes Council has been involved in many other battles. It has successfully fought a number of threats. These include the use of vehicles in the park. Sand mining. An airport on the lake. And a nuclear power center near the park.

The council has also pressed for stronger enforcement of air and water pollution control laws in the industrial areas near the park.

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STEVE EMBER: A modern federal road follows a walking path in the dunes called the Beach Trail. Long ago, this trail was a path between two forts. Settlers built the forts to provide protection against attacks by native Indian tribes. These forts became Chicago, Illinois, and Detroit, Michigan.

In 1822, a trader from the state of Michigan settled in the Indiana Dunes. This man, Joseph Bailly, opened a store and raised a family near Lake Michigan. He exchanged warm blankets and guns for the animal furs supplied by Indians and travelers.

At first, Mr. Bailly and his family lived in a small wood home. The trader was building a bigger house when he died. The National Park Service has repaired the outside of this large white home.

FAITH LAPIDUS: Later, a student from the University of Chicago brought scientific knowledge to the dunes. Henry Chandler Cowles received money from the university to study landforms and plant fossils from the time when ice covered much of the world. In 1896, Mr. Cowles decided the Indiana dunes would be an excellent place for his research.

Mr. Cowles' studies showed how plant communities could make important changes in land. His work demonstrated how groups of plants could create conditions for a sand dune to become a living forest. He became a well-known professor and researcher. The work of Henry Chandler Cowles in the Indiana Dunes helped spread the science of ecology throughout the world.

STEVE EMBER: Other scientists have explained how the sand hills formed. They say a huge thick river of ice helped create the Indiana dunes. Thousands of years ago this glacier moved over what is now central Indiana. As the glacier moved, heavy ice crushed rocks into very small pieces. Over time, part of the glacier became a body of water called Lake Chicago, an early version of Lake Michigan. The melting glacier dropped the sand it had created around the lake. The sands of the present-day Lake Michigan are always moving. The winds and waves of the lake carry sand to the surrounding land.

Strong winds lift the sand and drop it on the land below. This process starts building new dunes.

FAITH LAPIDUS: Over time, plant life develops on these sand hills. For example, the cottonwood tree is usually first to grow on a new dune. Then the winds dig a hole in the sand. The winds use loose sand from the hole to create a large dune that moves. Such a dune can damage or destroy anything in its way. But cottonwood trees can help. The trees grow roots along their trunks as sand buries them. The cottonwood roots help hold the dune in place.

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STEVE EMBER: A dune called Mount Baldy guards the northern end of the Indiana Dunes National Lakeshore. Beautiful trees encircle its lower parts. Thousands of people climb the 38 meters to the top of Mount Baldy each year. But getting there can be difficult. Climbers discover that their footsteps up the tall hill of sand often cause them to fall back again.

Local people tell about a mysterious woman who once lived in a small house not far from Mount Baldy. Alice Marble Gray moved to the Dunes from Chicago at age 35. Alice shocked people by swimming in Lake Michigan without a swimming suit. Fishermen compared her to the Roman goddess Diana. So began the traditional story of Diana of the Dunes.

FAITH LAPIDUS: This legend says Diana fell in love with a man who treated her badly. She died in 1925. Health officials said her body showed evidence of beatings. As the years passed, people have claimed that they sometimes see her swimming in the lake. They say that in the moonlight, you can still see Diana running along the sands of the Indiana Dunes.

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STEVE EMBER: This program was written by Jerilyn Watson. It was produced by Mario Ritter. I'm Steve Ember.

FAITH LAPIDUS: And I'm Faith Lapidus. Join us again next week for another EXPLORATIONS in VOA Special English.

dune: 沙丘

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Using national parks as classrooms

（來源：VOA 編輯：旭燕）