VOA慢速英语2010年-EXPLORATIONS - Hoover Dam: Taming the

STEVE EMBER: I’m Steve Ember.

SHIRLEY GRIFFITH: And I’m Shirley Griffith with EXPLORATIONS in VOA Special English. Today we tell about Hoover Dam. It was the largest and most difficult structure of its kind ever built when work started in nineteen thirty-one. A new bypass¹ bridge that opened this month near the dam is also a wonder of engineering².

(MUSIC)

STEVE EMBER: Our report about Hoover Dam must begin with the Colorado River. This river made the dam necessary. The Colorado River begins high in the Rocky Mountains. It begins slowly, during the dark months of winter. Heavy snow falls on the Rocky Mountains.

The snow is so deep in some areas that it will stay on the ground well into the hot days of summer. But the snow does melt. Ice cold water travels down the mountains and forms several rivers -- the Gila River, the Green River, the Little Colorado, the San Juan, the Virgin³ and the Gunnison Rivers. These rivers link together and form the beginnings of the Colorado River. The Colorado River flows through the states of Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada and California. Then it crosses the border into Mexico.

SHIRLEY GRIFFITH: The Colorado River has always been extremely powerful. The river created the huge Grand Canyon⁴. Beginning thousands of years ago, the violent water cut hundreds of meters deep into the desert floor of Arizona. The power of this river has also been demonstrated⁵ in more modern times. Between nineteen-oh-five and nineteen-oh-seven, the Colorado River caused great amounts of flooding in parts of Arizona and California.

Hoover Dam at night

Huge amounts of water ran into a low area in the dry, waterless desert that had once been an ancient lake. In two years of flooding, the Colorado River filled the ancient lake. That lake is called the Salton Sea. Today, it is about fifty-six kilometers long by twenty-four kilometers wide. It is even larger in years of heavy rain.

STEVE EMBER: The flooding that created the Salton Sea also flooded homes, towns and farming areas. Many people were forced to flee their homes. Government leaders knew they had to do something to prevent such floods in the future. In nineteen eighteen, a man named Arthur Davis proposed⁶ building a dam to control the Colorado River. Mr. Davis was a government engineer. He said the dam should be built in an area called Boulder⁷ Canyon on the border between the states of Arizona and Nevada.

SHIRLEY GRIFFITH: Building the dam would not be easy. The people of seven states and the people of Mexico needed and used the water of the Colorado River. Much of that area is desert land. Water is extremely important. Without water from the Colorado River, farming is not possible. Without water, life in the desert is not possible.

Workers drill into the canyon wall above the Colorado River

On November twenty-fourth, nineteen twenty-two, officials signed a document in Santa Fe, New Mexico. That document is called the Colorado River Compact⁸. The document tells how the seven states would share the water of the Colorado River. It was agreed this could be more easily done with the aid of a dam. Later an agreement was signed with Mexico to supply it with water from the Colorado River.

(MUSIC)

STEVE EMBER: The area chosen for the dam was called Black Canyon. The walls of Black Canyon rise almost two hundred forty-three meters above the river. An ancient volcano⁹ formed the rock in Black Canyon. Engineers decided¹⁰ the rock would provide a good strong support for the proposed dam.

However, the area also presented problems. The nearest railroad¹¹ was sixty kilometers away. There was no electric power. And, in the summer, desert temperatures could reach as high as forty-eight degrees Celsius¹².

A great deal of work was done before operations started on the dam. Workers built a town called Boulder City to house employees working on the dam.

They built a large road from Boulder City to the area of the dam. They built a railroad from a main line in Las Vegas, Nevada to Boulder City. They built another railroad from Boulder City to the dam area. And they built a three hundred fifty kilometer power line from San Bernadino, California. This provided¹³ electric power to the area where the dam was being built.

The newly¹⁴ completed Mike O'Callaghan-Pat¹⁵ Tillman Memorial Bridge, with Hoover Dam in the background

SHIRLEY GRIFFITH: The work on the dam began in April of nineteen thirty-one. Workers called “high scalers” were some of the first to begin building the dam. They were suspended¹⁶ from ropes as they used heavy air-powered hammers to break any loose rock away from the face of the canyon walls. When they could not use hammers, they used dynamite¹⁷. One high scaler became very famous. His name was Arnold Parks. He caught another worker who had fallen off the top of the canyon.

Mr. Parks held the worker to the wall of the canyon until others came to help. Today, visitors can see a statue of the men who worked as high scalers to build Hoover Dam. The high scalers worked on the sides of the canyon. Other workers dug huge tunnels deep in the floor of the canyon. This was done to permit the Colorado River to flow away from the construction area. This had to be done so the floor of the dam could be built.

On June sixth, nineteen thirty-three, workers poured the first load of a building material called concrete. Men in two special factories worked day and night to make the concrete for the dam. Huge equipment moved millions of tons of rock and sand. In the summer months, the terrible desert heat slowed the work but did not stop it. Men who worked at night on the dam suffered less, but the heat was still as high as thirty degrees Celsius.

STEVE EMBER:

Slowly the great dam began to rise from the floor of the canyon. From the canyon floor it reaches two hundred twenty-one meters high. Workers poured the last of the concrete on May twenty-ninth, nineteen thirty-five. They had used almost four million cubic meters of concrete. Workers also used more than twenty million kilograms of steel to strengthen the dam’s concrete.

SHIRLEY GRIFFITH:

The work was dangerous for the more than five thousand men who worked on the structure. The extreme temperatures, falling objects and heavy equipment caused accidents. The workers were provided with medical care and two emergency vehicles to take them to a new hospital in Boulder City. However, ninety-six men lost their lives during the building of the great dam.

The companies building the dam had been given seven years to complete the work. They did it in only five. President Franklin D. Roosevelt dedicated¹⁸ the dam in September of nineteen thirty-five, although it was not completed until the next year. However, work on the dam continued so as to use the river to produce large amounts of electric power.

Today, seventeen huge turbine¹⁹ machines produce hydroelectric power. About one point three million people in Arizona, Nevada and southern California depend on the dam for their electricity.

(MUSIC)

STEVE EMBER: When Hoover Dam was finished, it was the largest and tallest dam in the world. It was also the largest power producer that used water to make electricity. Today this is no longer true. Taller dams, larger dams and a few that produce more power have been created. But Hoover Dam remains²⁰ an extraordinary example of engineering. In October, two thousand ten, another major engineering effort was completed about five hundred meters south of Hoover Dam. A concrete bridge was built about two hundred seventy-five meters above the Colorado River. The bridge connects Arizona and Nevada.

The official name of the Hoover Dam bypass is the Mike O'Callaghan-Pat Tillman Memorial Bridge. Mike O’Callaghan was governor²¹ of Nevada in the nineteen seventies. Pat Tillman was a football player who quit the Arizona Cardinals²² to join the Army. He died in Afghanistan in two thousand four.

SHIRLEY GRIFFITH: The bridge is about five hundred eighty meters long. It is the largest single-span concrete arch²³ bridge in the Western Hemisphere²⁴. Each of the one hundred six cast concrete pieces of the bridge was built in mid-air with the support of huge steel cables²⁵. Building took place on both sides of the river. For the curve²⁶ to be perfect, the two sides had to meet within two and a half centimeters of each other.

Before this new bridge, the only way to cross the river in this area was on a small two-lane highway extending²⁷ across the dam. This road was too small for the amount of traffic in the area. The new bridge keeps the majority of vehicles further away from the dam. So experts hope to protect it from possible attack or harm.

The new bridge is also giving visitors to Hoover Dam a fresh view of this important structure.

(MUSIC)

STEVE EMBER: This program was written by Paul Thompson and Dana Demange, who was also the producer. I’m Steve Ember.

SHIRLEY GRIFFITH: And I’m Shirley Griffith. You can comment on this program on our website, voaspecialenglish.com. Join us again next week for EXPLORATIONS in VOA Special English
 

1 bypass   

n.旁道；分流术；vt.绕过，越过...于不顾

参考例句：

• If we take the bypass we'll avoid the town centre.我们走旁道就能绕过镇中心。
• You cannot bypass this question.你不能回避这个问题。

2 engineering   

n.工程，工程学，管理，操纵

参考例句：

• The science of engineering began as soon as man learned to use tools. 人类一学会使用工具,工程科学就开始了。
• It was the first great engineering works in the world. 这是世界上第一家大型的工程工厂。

3 virgin   

n.处女，未婚女子；adj.未经使用的；未经开发的

参考例句：

• Have you ever been to a virgin forest?你去过原始森林吗？
• There are vast expanses of virgin land in the remote regions.在边远地区有大片大片未开垦的土地。

4 canyon   

n.峡谷，溪谷

参考例句：

• The Grand Canyon in the USA is 1900 metres deep.美国的大峡谷1900米深。
• The canyon is famous for producing echoes.这个峡谷以回声而闻名。

5 demonstrated   

举行示威游行（或集会）( demonstrate的过去式和过去分词 )； 示范。展示； 显示； 论证

参考例句：

• All of those demonstrated the correctness of his analysis. 这一切都证明了他分析的正确性。
• The fireman demonstrated great courage in saving the child. 那位消防队员在抢救孩子的过程中，表现了极大的勇气。

6 proposed   

被提议的

参考例句：

• There is widespread discontent among the staff at the proposed changes to pay and conditions. 员工对改变工资和工作环境的建议普遍不满。
• an outcry over the proposed change 对拟议的改革所发出的强烈抗议

7 boulder   

n.巨砾；卵石，圆石

参考例句：

• We all heaved together and removed the boulder.大家一齐用劲，把大石头搬开了。
• He stepped clear of the boulder.他从大石头后面走了出来。

8 compact   

adj.紧密的，简明的，紧凑的；v.使紧凑，压缩

参考例句：

• It was a compact package.这是个捆得很紧的包裹。
• The article is compact and well organized.文章严密，又很有章法。

9 volcano   

n.火山

参考例句：

• The volcano unexpectedly blew up early in the morning.火山一早突然爆发了。
• It is most risky to go and examine an active volcano.去探察活火山是非常危险的。

10 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

11 railroad   

n.铁路；vi.由铁路运输

参考例句：

• The railroad connects two cities,namely,New York and Chicago.这条铁路连接两个城市，即纽约与芝加哥。
• My brother is working on the railroad.我兄弟在铁路系统工作。

12 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

13 provided   

conj.假如，若是；adj.预备好的，由...供给的

参考例句：

• Provided it's fine we will have a pleasant holiday.如果天气良好，我们的假日将过得非常愉快。
• I will come provided that it's not raining tomorrow.如果明天不下雨，我就来。

14 newly   

adv.新近，最近；重新，再度；以新的方式

参考例句：

• Have you reviewed for this newly published novel?你给这本新出版的小说写书评了吗？
• It is a newly planted tree and it has not established yet.这是一颗新栽的树，还没有扎下根来。

15 pat   

n.轻拍，拍打声；vt.轻拍，拍打；vi.轻跑，轻击；adv.适时，彻底；adj.油腔滑调的，恰好的，合适的

参考例句：

• Could you hear the pat?你能听到轻轻的拍击声吗？
• He gave her a reassuring pat on the shoulder. 他轻拍了一下她的肩膀让她放心。

16 suspended   

a.被暂时搁置的

参考例句：

• A lamp was suspended from the ceiling. 一盏吊灯悬在天花板上。
• The British government has now suspended humanitarian aid to the area. 英国政府现已暂停对这一地区的人道主义援助。

17 dynamite   

n./vt.(用)炸药(爆破)

参考例句：

• The workmen detonated the dynamite.工人们把炸药引爆了。
• The philosopher was still political dynamite.那位哲学家仍旧是政治上的爆炸性人物。

18 dedicated   

adj.一心一意的；献身的；热诚的

参考例句：

• He dedicated his life to the cause of education.他献身于教育事业。
• His whole energies are dedicated to improve the design.他的全部精力都放在改进这项设计上了。

19 turbine   

n.涡轮机，叶轮机，透平机

参考例句：

• A disadvantage of the turbine is that it is not reversible.涡轮机的一个缺点就是它不可以反转。
• Before the air enters the turbine，fuel is sprayed into it.在空气进入涡轮之前，燃料就喷进了。

20 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

21 governor   

n.统治者，地方长官(如省长，州长，总督等)

参考例句：

• The governor was an expert at fencing with reporters.这位州长是搪塞新闻记者的能手。
• He was elected governor of the state of California.他当选为加州州长。

22 cardinals   

红衣主教( cardinal的名词复数 )； 红衣凤头鸟（见于北美，雄鸟为鲜红色）； 基数

参考例句：

• cardinals in scarlet robes 身披红袍的枢机主教
• A conclave of cardinals was held to elect the new Pope. 红衣主教团举行了秘密会议来选举新教皇。

23 arch   

n.拱门，桥洞；v.拱起，成为弓形

参考例句：

• Dip your head under the low arch.在低矮的门拱下要低头。
• The trees arch overhead.树木在头顶上弯成拱形。

24 hemisphere   

n.半球，半球地图

参考例句：

• This animal is to be found only in the Southern Hemisphere.这种动物只有在南半球才能找到。
• In most people,the left hemisphere is bigger than the right.多数人的左脑比右脑大。

25 cables   

n.电报( cable的名词复数 )；电缆；（系船用的）缆绳；（船只、桥梁等上的）巨缆

参考例句：

• Use the crocodile clips to attach the cables to the battery. 用鳄鱼嘴夹把电缆接到蓄电池上。
• Please don't touch these metal cables inside a plastic sleeve. 请不要碰那些套着塑料管的金属电缆。 来自《简明英汉词典》

26 curve   

n.曲线，弯曲，曲球；v.弯，使...弯曲

参考例句：

• The train slowed its speed as it went around the curve.火车在弯道行驶时放慢了速度。
• The path of an arrow is a curve.箭的轨迹是一条曲线。

27 extending   

v.（空间、时间等）延伸，延续( extend的现在分词 )；伸展；给予；延长

参考例句：

• We are extending the radio network. 我们正在扩大广播网。 来自《简明英汉词典》
• A romance extending over several years was culminated. 一场数年之久的恋爱就此圆满告终。 来自《简明英汉词典》