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 ca
Older Volcanic Eruptions Volcanoes were more destructive in ancient history, not because they were bigger,but because the ca
admin
2016-08-16
63
问题
Older Volcanic Eruptions
Volcanoes were more destructive in ancient history, not because they were bigger,but because the carbon dioxide(二氧化碳)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 eruption skilled 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(十亿吨)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 tens of thousands of years. "The most recent ones hardly have an effect at all," Wignall says. He ignored the extinction which wiped out the dinosaurs(恐龙)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 is the main thesis of the article?
选项
A、Volcanic eruptions are not always deadly.
B、Carbon dioxide emissions often give rise to global warming.
C、Older volcanic eruptions are more destructive.
D、It is not easy to calculate the killing power of a volcanic eruption.
答案
C
解析
文章开篇就讲火山在远古时代的破坏力更强,然后讲火山喷发导致生物的灭绝,以及现代科学家怎么计算火山的杀伤力,故本文的主旨就是说远古火山喷发的破坏性更大。故选C。
转载请注明原文地址:https://www.kaotiyun.com/show/KmGd777K
本试题收录于:
职称英语理工类A级题库职称英语分类
0
职称英语理工类A级
职称英语
相关试题推荐
BecauseofDelaware’slenientlawsregardingbusinessincorporation,manycompanieshavetheirheadquartersinthestate’slarge
AncientWaterFromAfarItstreakedacrosstheskyonawarmMarcheveninglastyear,thencrashedintoastreetinthesma
AncientWaterFromAfarItstreakedacrosstheskyonawarmMarcheveninglastyear,thencrashedintoastreetinthesma
Themegaphonemakesthevoicesoundlouderbecauseitpointssoundwavesinonedirectionandkeepsthemfromspreadingoutina
TheHyper-XbroketherecordbecauseWhatdoesNASAplantodo?
TheHyper-XbroketherecordbecauseWhatdoesWernerJ,A.DahmsayabouttheHyper-Xtestflight?
TheHyper-XbroketherecordbecauseWhichofthefollowingisNOTtrueofthescramjetengine?
随机试题
文化强国是指一个国家具有强大的文化力量,这种力量的表现为()
求∫eaxsinbxdx.
患者,男,59岁,身高170cm,体重85kg,患高血压病10余年,未规律服用降压药,血压波动在90~100/140~160mmHg,未予重视,每于头晕、头痛明显时服药,症状消失后停药。吸烟40年,每日20支,饮酒20年,每日2两,近日由于工作劳累,情绪紧
以下关于客户至上的表述中,错误的是()。[2017年11月真题]
2016年10月20日,甲向乙购买一批原材料,价款为30万元,因乙欠丙30万元,故甲与乙约定由乙签发一张甲为付款人、丙为收款人的商业汇票,丁在汇票上签章作了保证,但未记载被保证人名称。乙于当日依约签发汇票并交付给丙,该汇票上未记载付款日期,丙取得汇票后背书
制约商业银行创造派生存款能力的主要因素包括()。
ReformingtheSocialSecurityretirementprogramisanissueofenormouspracticalimportance.Yetitremainsthemissingpiece
请在“答题”菜单中选择相应的命令,并按照题目要求完成下面的操作。注意:以下的文件必须保存在考生文件夹下。【背景素材】校摄影社团在今年的摄影比赛结束后,希望可以借助PowerPoint将优秀作品在社团活动中进行展示。这些优秀的摄影作品保存在考试文件夹中
Humansnotonlyloveeatingicecream,theyenjoy【21】ittotheirpets.Marketstudiesshowthattwothirdsofalldogownersgi
DivorceForevery1,000marriedcouplesintheUK,13endupdivorcedaccordingtostatistics.Divorceisoftenacomplicate
最新回复
(
0
)