Permian Extinction托福听力原文翻译及问题答案

Permian Extinction托福听力原文翻译及问题答案

一、Permian Extinction托福听力原文：

Narrator:Listen to part of a lecture in an Earth science class.

MALE PROFESSOR:Let's review something from last week.We talked about an event that happened 65 million years ago.Anyone?FEMALE STUDENT:An asteroid hit Earth.Um...well,we think an asteroid hit Earth,near the Yucatan Peninsula,in Mexico,and that wiped out all the dinosaurs.MALE PROFESSOR:Right.I wouldn't say that we've got 100%proof,but there's very strong evidence that this is why that mass extinction occurred.Okay.But did you know there was an earlier extinction far greater than the one that killed off the dinosaurs?It was what we call the Permian Extinction.Now,way back about 290 million years ago,at the beginning of the Permian Period,there was just one big continent,a super continent.And as the climate warmed up,plant and animal species began to diversify profusely.So life during the Permian Period was abundant and diverse.But about 250 million years ago,the Permian Period ended with a rapid mass extinction,something happened that wiped out 75%of the land animals and over 95%of ocean life.So what was it?What could have caused this.Well,with the all the evidence that it was an asteroid that led to the dinosaur extinction,we began asking ourselves:is it possible that another asteroid much earlier caused the Permian Extinction?And so researchers have been looking for an impact crater.FEMALE STUDENT:I thought the Permian Extinction was caused by a decline in sea water oxygen levels.Isn't that what's in the textbook?MALE PROFESSOR:But don't forget the textbook makes it very clear that's only a theory.FEMALE STUDENT:And it mentions something about volcanic eruptions too.MALE PROFESSOR:It does,but now this new theory has led to a search for evidence of an asteroid impact.And one place of interest is a region called Wilkes Land in eastern Antarctica.A few years ago,a researcher reported a strange anomaly beneath the ice in Wilkes Land.Evidence of what may be a mascon.That's just short for mass concentration.When an asteroid hits Earth,when it slams into Earth's crust,we think that causes molten rock from deep below the surface to rise up into the impact area.Sort of like if you bump your head,you get a big lump under the skin.Fluid makes the area swell.Anyway,the material flowing up from below the crust is more dense than the crust itself.So that's how we get a mascon,a spot in the crust with newer crust material that's more dense than the material all around it.There're lots of mascons on the moon too,where a mascon's density causes a small increase in the local gravity that can be measured and mapped by orbiting spacecraft.And where do these mascons tend to be found?In the centers of impact craters on the moon's surface.But back to Wilkes Land.We're not certain that the mascon there...what might be a mascon...was actually caused by the impact of an asteroid,but there does seem to be evidence.Researchers notice a gravity anomaly similar to those on the moon.And the spot where the gravity readings are especially high...this is right in the middle of a 500-kilometer wide,circular ridge,what could be part of an old impact crater.And if there was an asteroid impact there in Wilkes Land,the next question is:did it happen 250 million years ago?Because that would put it when in geologic history?

FEMALE STUDENT:At the end of the Permian Period?Right when those animals went extinct.MALE PROFESSOR:Exactly.

FEMALE STUDENT:But can't researchers figure that out by studying the rocks there in Wilkes Land...where this impact supposedly took place?MALE PROFESSOR:Well,to get to anything from that long ago,we would have to drill down to about a mile,about 1.6 kilometers of solid ice that covers the area today.And that's not likely to happen.But speaking of rocks,I should mention that Wilkes Land is not the only place of interest here.There's another called the Bedout High off the coast of Australia.And we have rock samples from the Bedout High.Some apparently have extraterrestrial origin.I mean,they show the effects of extreme temperatures and pressures,the level of extremes produced only by an impact.And as for their age,well,they do in fact,date back to about 250 million years ago.

二、Permian Extinction托福听力中文翻译：

旁白：听地球科学课上的一部分讲座。

男教授：让我们复习一下上周的内容。我们讨论了6500万年前发生的一件事。任何人女学生：小行星撞击地球。嗯…嗯，我们认为一颗小行星撞击了地球，在墨西哥尤卡坦半岛附近，并消灭了所有的恐龙。男教授：对。我不会说我们有100%的证据，但有非常有力的证据表明，这就是大灭绝发生的原因。可以但是你知道吗，有一次比杀死恐龙的那次更为早期的灭绝？这就是我们所说的二叠纪灭绝。现在，回到大约2.9亿年前，在二叠纪初期，只有一个大大陆，一个超级大陆。随着气候变暖，动植物物种开始大量多样化。因此，二叠纪时期的生命是丰富多样的。但大约2.5亿年前，二叠纪时期以一次快速的大规模灭绝而结束，发生了一件事，使75%的陆地动物和95%以上的海洋生物灭绝。那是什么？是什么导致了这一切。好吧，有了所有的证据表明是一颗小行星导致了恐龙灭绝，我们开始问自己：有可能是另一颗小行星更早地导致了二叠纪灭绝吗？因此，研究人员一直在寻找撞击坑。女学生：我认为二叠纪灭绝是由海水含氧量下降引起的。这不是课本上的内容吗？男教授：但别忘了教科书很清楚这只是一个理论。女学生：它也提到了火山爆发。男教授：是的，但现在这一新理论导致了对小行星撞击证据的研究。一个有趣的地方是南极洲东部的威尔克斯岛。几年前，一位研究人员报告了威尔克斯岛冰层下的一个奇怪异常。可能是mascon的证据。这只是质量浓度的缩写。当小行星撞击地球时，当它撞击地壳时，我们认为这会导致地表深处的熔融岩石上升到撞击区域。有点像如果你撞到你的头，你的皮肤下会有一个大肿块。流体使该区域膨胀。不管怎样，从地壳下面向上流动的物质比地壳本身密度更大。这就是我们如何得到一个mascon，地壳中的一个点，有较新的地壳材料，比周围的材料密度更高。月球上也有很多mascon，mascon的密度会导致局部重力的小幅度增加，这可以通过轨道航天器测量和绘制。而这些Mascon往往在哪里找到？在月球表面撞击坑的中心。但回到威尔克斯庄园。我们不确定那里的黑子…可能是黑子…实际上是小行星撞击造成的，但似乎有证据。研究人员注意到了一个类似于月球上的重力异常。重力读数特别高的地方……这正是一个500公里宽的圆形山脊的中间，可能是一个古老的撞击坑的一部分。如果威尔克斯岛上有小行星撞击，下一个问题是：它发生在2.5亿年前吗？因为这会把它放在地质史上？

女学生：在二叠纪末期？就在那些动物灭绝的时候。男教授：没错。

女学生：但研究人员难道不能通过研究威尔克斯岛上的岩石得出这个结论吗……这一撞击应该发生在哪里？男教授：好吧，要想从很久以前找到任何东西，我们必须钻到大约一英里，大约1.6公里的固体冰，覆盖今天的区域。这不太可能发生。但说到岩石，我应该提到威尔克斯庄园不是这里唯一的名胜。在澳大利亚海岸有另一个叫贝多特高地的地方。我们有贝多特高地的岩石样本。有些显然是地外起源的。我的意思是，它们显示了极端温度和压力的影响，只有冲击才会产生极端水平。至于它们的年龄，事实上，它们可以追溯到大约2.5亿年前。

三、Permian Extinction托福听力问题：

Q1:1.What does the professor mainly discuss?

A.New evidence about what happened to dinosaurs

B.New methods for gathering evidence about mass extinctions

C.The link between two mascons from the Permian period

D.A possible cause of the Permian extinction

Q2:2.According to the professor,why did researchers begin looking for evidence that an asteroid may have caused the Permian extinction?

A.They discovery that mascons on the Moon were caused by asteroid impacts.

B.They found rock samples in Wilkes Land that appeared to be 250 million years old.

C.The theory that an asteroid caused the dinosaur extinction gained acceptance.

D.The theory about a decline in seawater oxygen levels proved to be false.

Q3:3.Why does the professor mention getting a bump on the head?

A.To help students understand an explanation of how a mascon forms

B.To illustrate a theory about how the supercontinent broke apart

C.To show the relationship between an asteroid and the dinosaur extinction

D.To compare the dinosaur extinction to the Permian extinction

Q4:4.What did researchers notice that could be evidence of an asteroid impact in Wilkes Land?

A.A ring of ice containing a high concentration of oxygen

B.A portion of Earth's crust that is less dense than normal

C.Extraterrestrial rock fragments lying below the ice

D.Relatively high gravity measurements in the center of a circular ridge

Q5:5.What does the professor emphasize about some of the rock samples taken from the Bedout High near Australia?[Click on 2 answers.]

A.They are similar to the samples from the Yucatán peninsula in Mexico.

B.They are from the same time period as the Permian extinction.

C.They have been exposed to extreme temperatures and pressure.

D.They contain fossils of many species that are now extinct.

Q6:6.What does the professor imply when he says this:

A.The student should read the assignments before coming to class.

B.The student has not fully understood a statement in the textbook.

C.The student has not provided sufficient evidence to disprove the theory in the textbook.

D.The only reasonable explanation is the theory that the student suggests.

四、Permian Extinction托福听力答案：

A1:正确答案：D

A2:正确答案：C

A3:正确答案：A

A4:正确答案：D

A5:正确答案：BC

A6:正确答案：B

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