【阅读练习】04.1.10阅读第一篇

qiaoUID: 2103572

来源： ourielts

此文是雅思04年1月10日阅读第一篇文章的原文的80%

The giant tube worms were totally unknown to science until scientists researching the deep Pacific ocean floor discovered strange hydrothermal vents on the ocean floor. Powered by volcanic heat, these vents circulate water that seeps down through cracks or faults in the rock. When the water emerges from the vent, it is rich in chemicals and minerals. Scientists were shocked to an entire ecosystem of animals around these vents. These organisms are unique because they do not depend on sunlight for their source of energy. Instead the feed on tiny bacteria that get their energy directly from the chemicals in the water in a process known as chemosynthesis. The hydrothermal vents have been called "black smokers" because of the dark color of the material they eject. The giant tube worms grow up to eight feet in length and have no mouth or gut. They depend on symbiotic bacteria that live inside them for their food. These bacteria convert the chemicals from the vents into food for the worm. When the worms are very tiny, they have a primitive mouth and gut through which the bacteria enter. As the worm grows older, the mouth and gut disappear, trapping the bacteria inside. The worm's tube is composed of a tough, natural material called chitin. Entire communities of shrimps and crabs have been found living around these giants. It is believed that these invertebrates feed by nibbling off bits of the tube worms' red plumes. Photo courtesy of the OAR/National Undersea Research Program (NURP).

From 1977 through 1979, Alvin made a series of dives to further investigate the nature of these hydrothermal vent communities. The vents were shown to be associated with the formation of new oceanic crust. Water coming from the vents had a temperature of 17 degrees C compared to 2 degrees C for the surrounding bottom water. These vents also issued a rich variety of minerals, presumably from the dissolution of chemicals in rocks deep beneath the vents. As this hot, mineral-rich water comes into contact with the cold bottom water, these minerals precipitate and form deposits on the surrounding rocks.

Some of these deposits accumulate as great mounds of material and may attain great heights. In 1979, during an expedition along the tip of Baja California, Alvin discovered 65-foot-high chimney-shaped structure spitting hot black "smoke." Hence was born the name "black smokers" for vents that emitted dark streams of particles. While their chemistry may vary, black smokers often emit particles that are rich in sulfides, lead, cobalt, zinc, copper, and silver. Other types of vents ejecting a different composition of minerals have been found and named, including "white smokers", who spit out streams of gypsum and zinc, rather than sulfides. They also contain less amounts of iron and copper.

One puzzle for scientists to figure out is why the chemistry of hydrothermal vents changes, not only among locations, but over temporal scales as well. Measurements of vent water taken from the time of a sea floor eruption indicate a change in the mineral composition being emitted. Scientists have also found that individual vents or entire vent fields can change anywhere from days to thousands of years.

Despite these puzzles, a great deal has been learned about hydrothermal vents in the past couple decades. Vents have been found at just about every type of sea floor spreading boundary (slow, intermediate, fast); they have been found at "hot spots"; and they have been found in back-arc basins. Seemingly everywhere that some type of mantle-driven activity occurs, scientists have found hydrothermal vents.

Although less than 1% of the sea floor where hydrothermal vents are suspected has been investigated, hundreds of hydrothermal vent fields have been identified around the globe in the past couple decades. Typically, vents within these regions cluster in groups, much like the geyser basins in Yellowstone. The largest vent field, called TAG, (Trans Atlantic Geotraverse, whatever that means) measures as big as a football field. Other vent fields have taken more personal names. The first fields discovered at the Galapagos site were named Rose Garden, Garden of Eden, and East of Eden, after the giant red-fleshed tube worms found there. Along the Mid-Atlantic Ridge, the American west prevails, with names like Lucky Strike, Broken Spur, and Snake Pit. Lucky Strike was named when scientists found a colony of mussels growing on a fresh mound of sulfide. The French and American scientists who found this field also named a couple of individual mounds: Statue of Liberty and Eiffel Tower. Broken Spur refers to the topography of another field, which consists of a series of "spurs" coming off the ridge. The Snake Pit was named for the profusion of white, eel-like fish that live there. One of the black smokers at Snake Pit was named Saracen's Head, after one scientist's favorite British pub.

同学们，这篇文章比原来的还要长一些，但是基本重要内容都在里面了，你们除了专业名词，人名，机构名不要去细究，其它的，都得搞懂。

[ Last edited by qiao on 2005-6-4 at 13:25 ]

蜻蜓切UID: 201589

不会是有人背下来的吧……

FanielUID: 2106691

Originally posted by qiao at 2005-6-4 13:21
来源： ourielts

此文是雅思04年1月10日阅读第一篇文章的原文的80%

The giant tube worms were totally unknown to science until scientists researching the deep Pacific ocean floo ...

那够BT的～～～:L

FanielUID: 2106691

Originally posted by 蜻蜓切 at 2005-6-4 18:16
不会是有人背下来的吧……

引用错了，对不起～～～

再加：那够BT的～～

lucy_zq2002UID: 177408

材料比较可靠，大家不要怀疑啦～～:victory:多读点没坏处的