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  3. Ten thousand years ago, as the last ice age drew to a close, sea levels arou

Ten thousand years ago, as the last ice age drew to a close, sea levels arou

游客2023-12-24  51
问题     Ten thousand years ago, as the last ice age drew to a close, sea levels around the world were far lower than they are today. Much of the land under the North Sea and the English Channel was part of a huge region of forests and grassy plains. Then the climate gradually became warmer and the water trapped in glaciers and ice caps was released. This ancient land was submerged in the resulting deluge and all that remains to tell us that it was once lush and verdant— and inhabited — is the occasional stone tool, harpoon or mammoth tusk brought up from the sea bed by fishing boats.
    Now the development of advanced sonar technology, known as bathymetry, is making it possible to study this flooded landscape in extraordinary detail. While previous devices have only been able to produce two-dimensional images, bathymetry makes use of computers, satellite positioning devices and special software to create accurate and remarkably detailed maps. For the first time an ancient river bed leaps out of the three-dimensional image, complete with rocky ledges rising up from the bottom of the valley. The sites of pre-historic settlements can now be pinpointed, and it is also possible to see in stunning detail the sunken shipwrecks that litter this part of the sea bed.
    According to archaeologist Dr Linda Andrews, this technological development is of huge significance. "We now have the ability to map the sea bed as accurately as we can map dry land," she says. She is, however, scathing about the scale of government funding for such projects. "We have better images of Mars and Venus than of two-thirds of our own planet! In view of the fact that Britain is a maritime nation, and the sea has had such a massive influence on us, it’s an absolute scandal that we know so little about the area just off our shores!"
    Once bathymetric techniques have identified sites where people might have built their homes and villages, divers could be sent down to investigate further. The idea of Britain as a natural island kingdom will be challenged by these findings: Britain has been inhabited for about 500,000 years, and for much of this time it has been linked on and off to continental Europe. It remains to be seen how far this new awareness is taken on board among our "island" people.
    In fact, the use of bathymetry scanners will not be limited to the study of lost landscapes and ancient settlements. It will also be vital in finding shipwrecks. Records show that there are about 44,000 shipwrecks off the shores of Britain, but there is good reason to believe that the real figure is much higher. In addition, commercial applications are a real possibility. Aggregates for the construction industry are becoming increasingly expensive, and bathymetry scanners could be used to identify suitable sites for quarrying this material. However, mapping the sea bed will also identify places where rare plants and shellfish have their homes. Government legislation may prevent digging at such sites, either to extract material for a profit or to make the water deeper: there are plans to dredge parts of the English Channel to provide deeper waterways for massive container ships.  [br] What is the most important aspect of the new scanning technique?
选项 A、It can attract more government funding for mapping.
B、It only requires the use of an echo sounder.
C、It can measure the depth of the sea bed with accuracy.
D、It reveals important details of underwater topography.
答案 D
解析 这是道细节题。文章中第二段一开始就介绍了一种新的技术，而提到这个技术时就指出它使得非常详细的勘探被淹没的地貌成为可能。这和第四个选项它可以非常详细的显示出地下水的地貌是一样的。这道题需要注意的是第三个选项。有考生会认为第三段的“We now have the ability to map the sea bed as accurately as we can map dry land，”(我们现在有能力测量河床非常精确，可以和干地相同)就应该选第三个答案，所以考生做题目的时候需要注意本题问的是最重要的方面是什么，故选D。
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