首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Older Volcanic Eruptions Volcanoes were more destructive in ancient history, not because they were bigger, but because the c
Older Volcanic Eruptions Volcanoes were more destructive in ancient history, not because they were bigger, but because the c
admin
2014-09-13
75
问题
Older Volcanic Eruptions
Volcanoes were more destructive in ancient history, not because they were bigger, but because the carbon dioxide they released wiped out life with greater ease.
Paul Wignall from the University of Leeds was investigating the link between volcanic eruptions and mass extinctions. Not all volcanic eruptions killed off large numbers of animals, but all the mass extinctions over the past 300 million years coincided with huge formations of volcanic rock. To his surprise, the older the massive volcanic eruptions were, the more damage they seemed to do. He calculated the "killing efficiency" for these volcanoes by comparing the proportion of life they killed off with the volume of lava(熔岩)that they produced. He found that size for size, older eruptions were at least 10 times as effective at wiping out life as their more recent rivals.
The Permian(二叠纪)extinction, for example, which happened 250 million years ago, is marked by floods of volcanic rock in Siberia that cover an area roughly the size of western Europe. Those volcanoes are thought to have pumped out about 10 gigatonnes of carbon as carbon dioxide. The global warming that followed wiped out 80 percent of all marine genera(种类)at the time, and it took 5 million years for the planet to recover. Yet 60 million years ago, there was another huge amount of volcanic activity and global warming but no mass extinction. Some animals did disappear but things returned to normal within ten thousand of years. "The most recent ones hardly have an effect at all, " Wignall says. He ignored the extinction which wiped out the dinosaurs 65 million years ago, because many scientists believe it was primarily caused by the impact of an asteroid(小行星). He thinks that older volcanoes had more killing power because more recent life forms were better adapted to dealing with increased levels of CO
2
.
Vincent Courtillot, director of the Paris Geophysical Institute in France, says that Wignall’ s idea is provocative. But he says it is incredibly hard to do these sorts of calculations. He points out that the killing power of volcanic eruptions depends on how long they lasted. And it is impossible to tell whether the huge blasts lasted for thousands or millions of years. He also adds that it is difficult to estimate how much lava prehistoric volcanoes produced, and that lava volume may not necessarily correspond to carbon dioxide emissions.
What can be inferred from Paragraph 3 concerning dinosaurs?
选项
A、They were killed off by an asteroid.
B、They died of drastic climate change.
C、They were wiped off by a volcanic eruption.
D、The cause of their extinction has remained a controversial issue.
答案
D
解析
由文章第三段倒数第二句话“…because many scientists believe it was primarily caused bythe impact of an asteroid.”可知,Wignall没有提6 500万年前恐龙的灭绝是否跟火山爆发有关是因为许多科学家认为恐龙的灭绝是由一颗小行星的影响造成的。由此可推断出关于恐龙灭绝的原因在科学家之间是有分歧的。故选D。
转载请注明原文地址:https://www.kaotiyun.com/show/xvUd777K
本试题收录于:
职称英语综合类A级题库职称英语分类
0
职称英语综合类A级
职称英语
相关试题推荐
SharksPerformaServiceforEarth’sWatersItishardtogetpeopletothinkofsharksasanythingbutadeadlyenemy.They
SharksPerformaServiceforEarth’sWatersItishardtogetpeopletothinkofsharksasanythingbutadeadlyenemy.They
SharksPerformaServiceforEarth’sWatersItishardtogetpeopletothinkofsharksasanythingbutadeadlyenemy.They
SharksPerformaServiceforEarth’sWatersItishardtogetpeopletothinkofsharksasanythingbutadeadlyenemy.They
SharksPerformaServiceforEarth’sWatersItishardtogetpeopletothinkofsharksasanythingbutadeadlyenemy.They
FinancialRisksSeveraltypesoffinancialriskareencounteredininternationalmarketing;themajorproblemsincludecommercia
"HappyBirthdaytoYou"ThemainproblemindiscussingAmericanpopularcultureisalsooneofitsmaincharacteristics:itwon’
TheFatProblemthatMenFaceItisapleasuretoseemenofacertainageworryingabouttheirweight.Listeningtothemi
TheFatProblemthatMenFaceItisapleasuretoseemenofacertainageworryingabouttheirweight.Listeningtothemi
随机试题
政策问题一般都能顺利地进入正式议程的模型是()
禁婚亲
风险应对计划制定过程的依据不包括()
金属与石材幕墙工程采用的密封胶应掌握的原则有()。
蒸汽状态污染物,指在常温常压下易挥发的物质,以蒸汽状态进入大气,下列属于蒸汽状态污染物的是( )。
当给定利率及终值时,取得终值的时间越长,该终值的现值就越低。( )
银行从业操守和法律的区别有()。
(2012年)关于市场细分的说法,错误的是()。
A、 B、 C、 D、 B每行图形中分割空间数递减,小图形种类及数量轮换变化。
工作中你难以和同事、上司相处,你该怎么办?
最新回复
(
0
)