经济学人249:大灭绝 陨石很小不过危害却很致命

 　　Science and technology

　　科学技术

　　Mass extinctions

　　大灭绝

　　Small but deadly

　　陨石很小不过危害却很致命

　　The biggest extinction¹ in history was probably caused by a space rock that changed the climate

　　历史上规模最大的一次物种灭绝，也许是由于陨石坠落导致的气候变化而造成

　　AS EVERY schoolchild knows, the dinosaurs² were wiped out in an instant, when a rock from outer space hit what is now southern Mexico.

　　就像每个小学生知道的那样，当一块天外陨石坠落到现今的墨西哥南部地区之后，恐龙就那在一瞬间遭受了灭顶之灾。

　　That happened 66m years ago, at the end of the Cretaceous period.

　　这一切就发生在6600万年前的白垩纪末期。

　　Well-informed schoolchildren also know that this mass extinction was neither unique nor the biggest.

　　一些博学的小学生还知道这次物种大灭绝既不是历史上唯一的一次，也不是历史上最大的一次。

　　The geological record speaks of four others since animal life became complex at the beginning of the Cambrian period 541m years ago.

　　地质学档案记录了5亿4100万年前寒武纪物种多样化以来的另外四次物种大灭绝。

　　What neither these clever schoolchildren nor anyone else knows, however, is whether these extinctions had similar causes.

　　有些历史不论是那些聪明的小学生还是别的人都还不知道，比如，导致这些灭绝的原因是否相似？

　　But evidence is accumulating that the biggest extinction of all, 252.3m years back, at the end of the Permian period, was indeed also triggered by an impact.

　　不过有证据不断地证明发生在2亿5230万年前二叠纪时期的那次大灭绝也是因为陨石坠落而造成的。

　　Nevertheless, though the trigger was the same, the details are significantly different, according to of the University of Western Australia.

　　然而，按照西澳大利亚大学的埃里克·托瓦尔教授的说法，虽然两次大灭绝引发的原因是一致的，但是其中细节却大不相同。

　　When the dinosaurs vanished they were accompanied by more than 70% of the other animal species on Earth.

　　当时和恐龙一起灭绝的还有地球上超过70%的物种。

　　At the end of the Permian, the extinction figure was more than 80%.

　　在二叠纪末期，那场大灭绝带走了超过80%的物种。

　　And just as the Cretaceous slate-clearing permitted the rise of a hitherto obscure group called the mammals,

　　就如同白垩纪大灭绝成就了一个迄今为止都未被研究透彻的物种—哺乳类动物的崛起，

　　so the Permian clearance³ permitted the rise of the reptiles⁴,

　　二叠纪大灭绝也成就了爬行类生物的崛起，

　　one branch of which turned into Tyrannosaurus, Diplodocus and all the other names familiar from childhood.

　　它们的一支最后演化成了如今小学生们口中的暴龙、梁龙以及其它各种叫龙的动物。

　　The idea that an impact caused the Permian extinction has been around for a while.

　　导致二叠纪大灭绝的原因长期以来都没有一个定论。

　　As at the end of the Permian, as at the end of the Cretaceous, huge volcanic⁵ eruptions⁶ had been going on for hundreds of thousands of years.

　　在二叠纪和白垩纪末期，大量火山持续爆发了数百到数千年。

　　These may have weakened the world's ecosystems⁷, making them vulnerable to an external shock.

　　这可能破坏了地球的生态系统，使其难以抵御外来的破坏。

　　But the abruptness⁸ of both extinctions indicates that the coup⁹ de grace was administered by something else,

　　但是两次大灭绝来得如此突然，这说明了实施致命一击”的另有其人，

　　and in the case of the Permian some fragments of meteorite¹⁰ of the correct age, found in rock in Antarctica, suggest that, as with the Cretaceous, that something was an asteroid¹¹ or a comet.

　　而且在南极洲的岩石里发现的一些陨星碎片与二叠纪的年代相吻合，这说明了地球在二叠纪与在白垩纪一样，遭受了小行星或是彗星的袭击。

　　What was missing from the story, though, was a suitable crater¹².

　　只不过这个故事里还缺一个部分—一个合适的陨石坑。

　　Fracking hell!

　　如同置身地狱一般的裂解反应

　　Last year Dr Tohver and his colleagues thought they might have found it.

　　去年，托瓦尔博士和他的同事表示他们也许找到这个陨石坑了。

　　They redated a hole that straddles the border of the states of Mato Grosso and Goias in Brazil, called the Araguainha crater, to 254.7m years, with a margin¹³ of error of plus or minus 2.5m years.

　　他们重测了一个位于位于巴西马托·格罗索州和戈雅斯州交界的洞穴—阿拉瓜尼亚陨石坑，并确定其形成年代为2亿5470万年前，年代误差在正负250万年左右。

　　Previous estimates had suggested Araguainha was 10m years younger,

　　早期研究所估计的阿拉瓜尼亚陨石坑的形成时间要较这个数据晚1000万年，

　　but Dr Tohver has put it within geological spitting distance of the extinction date, which itself has a margin of error of plus or minus 200,000 years.

　　不过托瓦尔博士把这个时间差归结于大灭绝发生的具体时间本身就有一个范围，大概是正负20万年的误差。

　　Which would all be fine and dandy, except most people think Araguainha is too small to be the culprit. It is a mere¹⁴ 40km across.

　　除开大部分人觉得阿拉瓜尼亚实在太小，不足以成为元凶以外，这对大灭绝来说会是个很好的解释。

　　The Chicxulub crater in Mexico, which did for the dinosaurs, is 180km in diameter, and it may have been paired with an even bigger impact in the Indian Ocean.

　　导致恐龙灭绝的墨西哥希克苏鲁伯陨石坑，其直径有180公里，而且它可能与同时期在印度洋产生的另一个更大的碰撞共同作用，从而导致白垩纪大灭绝。

　　Dr Tohver, however, has an answer to this criticism.

　　面对质疑，托瓦尔博士有着合理的解释。

　　His latest paper, just published inPalaeogeography, Palaeoclimatology, Palaeoecology, describes the rock in the area in which Araguainha resides.

　　他最近在古地理学，古气候学，古生态学”杂志上发表的一片文章详细描述了阿拉瓜尼亚附近的岩石性质。

　　After an extensive geological survey, he and his team discovered that a sizeable amount of this rock is oil shale¹⁵.

　　经过了广泛的地质学研究调查后，他和他的团队发现这些岩石很多都是油页岩，

　　Any hydrocarbons¹⁶ in the crater would certainly have been vaporised.

　　这说明所有的碳氢化合物已经被汽化。

　　More intriguingly¹⁷, the researchers calculate that the impact would have generated thousands of earthquakes of up to magnitude 9.9 for hundreds of kilometres around.

　　更有趣的是，研究人员通过计算发现撞击所产生的能量足以在附近数百公里的范围内产生几千次9.9级地震。

　　In effect, it would have been the biggest fracking operation in history, releasing oil and gas from the shattered rock in prodigious¹⁸ quantities.

　　从效果上来说，这也许是历史上最大的裂解工程，它将数量惊人的石油和天然气从岩石中释放出来。

　　The upshot, Dr Tohver believes, would have been a huge burp of methane¹⁹ into the atmosphere.

　　托瓦尔博士相信，这导致了巨量的甲烷被排向大气层。

　　Since methane is a powerful greenhouse gas, that burp would have resulted in instant global warming, making things too hot for much of the planet's animal life.

　　而甲烷是很强的温室效应气体，它就使得全球气温瞬时上升，过高的气温危及了许多物种的生存。

　　Presto²⁰! The Permian mass extinction is explained.

　　是的！这就是二叠纪物种大灭绝的解释。

　　Determining whether this was really what happened will take a lot more digging, of course.

　　当然，要确认这是不是造成这一切的真实原因还有待更多的探索研究。

　　Even now, there are those who think the formation of the Chicxulub crater was a coincidence, and that what did for the dinosaurs was actually the volcanoes, so Dr Tohver will have to work hard to convince the sceptics.

　　直到今天还有人认为希克苏鲁伯陨石坑的形成只不过是个巧合，真正让恐龙消亡的原因是火山爆发，所以托瓦尔博士还需要加把劲来证明他的假设。

　　If he does, though, he will have proved himself a great geological detective, for he will have been responsible for solving one of the biggest puzzles in palaeontology.

　　如果他做到了，他将证明他是一个伟大的地质学发现者，因为他解开了古生物学中的一个最重要的谜题。

　　1.wipe out 消灭，彻底摧毁

　　Please wipe the bottles out before you return them.

　　退回瓶子前请把里边擦干净。

　　2.Cretaceous period 白垩纪

　　源于德文的白垩纪名（Kreidezeit）的缩写。“白垩纪”一词由法国地质学家达洛瓦（Jean Baptiste Julien d′Omalius d′Halloy）于1822年创用。位于侏罗纪和古近纪之间，约1亿4550万年（误差值为400万年）前至6550万年前（误差值为30万年）。

　　3.neither nor 既不…也不…

　　She seemed neither surprised nor worried.

　　她似乎既不惊讶也不担心。

　　4.too...to... 太...以致于不能...

　　He is too young to go to school.

　　他年纪太小,还不能上学。

1 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

2 dinosaurs   

n.恐龙( dinosaur的名词复数 )；守旧落伍的人，过时落后的东西

参考例句：

• The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
• Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》

3 clearance   

n.净空；许可(证)；清算；清除，清理

参考例句：

• There was a clearance of only ten centimetres between the two walls.两堵墙之间只有十厘米的空隙。
• The ship sailed as soon as it got clearance. 那艘船一办好离港手续立刻启航了。

4 reptiles   

n.爬行动物，爬虫( reptile的名词复数 )

参考例句：

• Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
• Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》

5 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

6 eruptions   

n.喷发，爆发( eruption的名词复数 )

参考例句：

• There have been several volcanic eruptions this year. 今年火山爆发了好几次。 来自《简明英汉词典》
• Over 200 people have been killed by volcanic eruptions. 火山喷发已导致200多人丧生。 来自辞典例句

7 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

8 abruptness   

n. 突然，唐突

参考例句：

• He hid his feelings behind a gruff abruptness. 他把自己的感情隐藏在生硬鲁莽之中。
• Suddenly Vanamee returned to himself with the abruptness of a blow. 伐那米猛地清醒过来，象挨到了当头一拳似的。

9 coup   

n.政变；突然而成功的行动

参考例句：

• The monarch was ousted by a military coup.那君主被军事政变者废黜了。
• That government was overthrown in a military coup three years ago.那个政府在3年前的军事政变中被推翻。

10 meteorite   

n.陨石；流星

参考例句：

• The meteorite in Jilin Exhibition Hall is believed to be the largest in the world.吉林展览馆的陨石被认为是世界上最大的。
• The famous Murchison meteorite smashed into the Australian ground in 1969.1969年著名的默奇森陨石轰然坠落在澳大利亚。

11 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

12 crater   

n.火山口，弹坑

参考例句：

• With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
• They came to the lip of a dead crater.他们来到了一个死火山口。

13 margin   

n.页边空白；差额；余地，余裕；边，边缘

参考例句：

• We allowed a margin of 20 minutes in catching the train.我们有20分钟的余地赶火车。
• The village is situated at the margin of a forest.村子位于森林的边缘。

14 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

15 shale   

n.页岩，泥板岩

参考例句：

• We can extract oil from shale.我们可以从页岩中提取石油。
• Most of the rock in this mountain is shale.这座山上大部分的岩石都是页岩。

16 hydrocarbons   

n.碳氢化合物，烃( hydrocarbon的名词复数 )

参考例句：

• Hydrocarbons (HC), like carbon monoxide, represent unburned and wasted fuel. 碳氢化合物(HC)像一氧化碳一样，为未燃尽的和被浪费掉的燃料。 来自英汉非文学 - 环境法 - 环境法
• With this restricted frequency range it is not applicable to hydrocarbons. 这个较紧缩的频率范围不适用于烃类。 来自辞典例句

17 intriguingly   

参考例句：

• Intriguingly, she gave to the music a developed although oddly malleable personality. 最神奇的是，她的音乐具有成熟却又很奇怪地极富可塑性。 来自互联网
• Intriguingly, the patients brains were riddled with tangles, but not amyloid plaques. 有趣的是，患者的大脑中充满了各缠结，但并没有粉斑。 来自互联网

18 prodigious   

adj.惊人的，奇妙的；异常的；巨大的；庞大的

参考例句：

• This business generates cash in prodigious amounts.这种业务收益丰厚。
• He impressed all who met him with his prodigious memory.他惊人的记忆力让所有见过他的人都印象深刻。

19 methane   

n.甲烷，沼气

参考例句：

• The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
• Methane may have extraterrestrial significance.甲烷具有星际意义。

20 presto   

adv.急速地；n.急板乐段；adj.急板的

参考例句：

• With something so important,you can't just wave a wand and presto!在这么重大的问题上，你想挥动一下指挥棒，转眼就变过来,办不到！
• I just turned the piece of wire in the lock and hey presto,the door opened.我把金属丝伸到锁孔里一拧，嘿，那门就开了。