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
46
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 is the main thesis of the article?
选项
A、Volcanic eruptions are not always deadly.
B、Older volcanic eruptions are more destructive.
C、Carbon dioxide emissions often give rise to global warming.
D、It is not easy to calculate the killing power of a volcanic eruption.
答案
B
解析
文章第一段直接点明了文章的主要论点。“Volcanoes were more destructive in ancienthistory…”(古代火山喷发更具破坏力)。故选B。
转载请注明原文地址:https://kaotiyun.com/show/DvUd777K
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
FreezingtoDeathforBeautyPeopleinBeijingwearalotofclothingduringwintertofendoffthecold.IntheUnitedStates,
Itislogicalthatadetailedlearningofplantsandtheirpropertiesmustbeextremelyancient.Todaypeopleusuallyacquirea
PlantsandMankindBotany,thestudyofplants,occupiesapeculiarpositioninthehistoryofhumanknowledge.Wedon’tknowwh
WhydoestheauthorthinktheEiffelToweristransformedintosymbolofaworldonthemove?WhichstatementisNOTtrueofHu
FinancialRisksSeveraltypesoffinancialriskareencounteredininternationalmarketing;themajorproblemsincludecommercia
TheFatProblemthatMenFaceItisapleasuretoseemenofacertainageworryingabouttheirweight.Listeningtothemi
随机试题
A.黄色B.红色C.黑色D.绿色E.蓝色硫化氢试验阳性结果是
一名患急性喉炎的小儿,安静时可听到喉呜,并有吸气性呼吸困难,听诊可闻管状呼吸音,患儿心率加快,约130次/分,该患儿喉梗阻程度为
患者,男,54岁。症见足膝红肿、筋骨疼痛。中医辨为湿热下注所致的痹病,处以四妙丸,其药物组成为盐黄柏、苍术、薏苡仁、牛膝。下列关于处方中盐黄柏炮制方法、炮制作用的说法,错误的是
A.第一类医疗器械产品B.第二类医疗器械产品C.第三类医疗器械产品D.第四类医疗器械产品E.第五类医疗器械产品
背景资料:某电力建设公司承接2×1000MW电厂建设工程的总承包任务。考虑工期和专业特长的要求,辅助工程采用分包的方式组织建设。在工程建设中发生如下事件:事件一:在发电机转子安装时,施工单位进行了发电机转子安装前单独气密性试验,在试验
关于SWOT分析中机会和威胁的说法正确的有()。
下列有关定金的说法中,正确的是()。
我国著名乐曲《万马奔腾》是以()为主奏乐器的蒙古族作品。
Usingtheinformationinthetext,completeeachsentence14-18withanexpressionfromthelistbelow.Foreachsentence(14
A、It’sme.B、It’sus.C、It’smine.C
最新回复
(
0
)