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
Blasts from the Past 1.Volcanoes were destructive in ancient history. Not because they were bigger, but because the carbon di
Blasts from the Past 1.Volcanoes were destructive in ancient history. Not because they were bigger, but because the carbon di
admin
2010-01-13
40
问题
Blasts from the Past
1.Volcanoes were destructive in ancient history. Not because they were bigger, but because the carbon dioxide they released wiped out life with greater ease.
2.Paul Wignall from the University of Leeds was investigating the link between volcanic eruptions and mass extinctions. Not all volcanic eruptions killed off large number of animals, but all the mass extinction cover 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.
3.Wignall calculated the "killing efficiency" for these volcanoes by comparing the proportion of life they killed off with the volume of lava 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.
4.The Permian 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 per cent of all marine genera at the time, and it took 5 million years for the planet to recover.
5.Yet 60 million years ago in the late Palaeocene 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 thousands of years. "The most recent ones hardly have an effect at all," Wignall says. He ignored the extinction which wiped out the dinosaurs at the end of the Cretaceous, 265 million years ago, because many scientists believe it was primarily caused by the impact of an asteroid.
6.Wignall thinks that older volcanoes had more killing power because more recent life forms were better adapted to dealing with increased levels of CO2. Ocean chemistry may also have played a role. As the supercontinents broke up and exposed more coastline there may have been more weathering of silica rocks. This would have encouraged the growth of phytoplankton in the oceans, increasing the amount of CO2absorbed from the atmosphere.
7.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.
8.Courtillot 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 or sulphur dioxide emissions.
*
选项
答案
C
解析
第三段的第一句话是这么说的:Wignall calculated the“killing efficiency" for these volcanoes…Wignall计算了这些火山的“灭种效率”……killing power与“killing efficiency”意思差不多。killing power:灭种力。
转载请注明原文地址:https://kaotiyun.com/show/7RGd777K
本试题收录于:
职称英语综合类基础题库职称英语分类
0
职称英语综合类基础
职称英语
相关试题推荐
AccordingtoRobertBell,ifmobilephonesprovetobedangeroustopeople’shealth,Manytransmittertowerswerebuilt
Ordinaryplantsareunabletosurviveinthedesertmainlybecauseofthechangeableweather.Winteristhetoughestseasonfor
NASAplanstodesignthenewspacecrafttoAccordingtothepassage,the1billionfunds,ifgranted,would
Accordingtothepassage,inbuyingasecond-handvehicleitismostimportanttoknow______.Accordingtothepassage,fromw
LivewithComputerAftertoolongonthenet,evenaphonecallcanbeashock.Myboyfriend’sLiverpudlian(利物浦的)accentsu
Ford1Ford’sgreatstrengthwasthemanufacturingprocess—notinvention.Longbeforehestartedacarcompany,hewasawor
WhatisChineseNewYear?InmanypartsofAsia,nationsfollowthelunarcalendarratherthantheGregoriancalendarusedb
TheFirstFourMinutesWhendopeopledecidewhetherornottheywanttobecomefriends?Duringtheirfirstfourminutestogethe
Theygotinquiteabrawl.
随机试题
利用分度头在工件的圆周上划出均匀分布的15个孔的中心,试求每划完一个孔中心时,手柄应转过多少转?
下列选项中,属于配伍禁忌的有
A.眩晕欲仆B.目睛上吊C.手足蠕动D.手足拘挛不伸E.咳嗽咽痒肝阳化风可见
土坝清基开挖线的放样方法有()。
面层下基层的水泥混凝土抗压强度达到( )MPa以上时,方可进行面层混凝土拌合料的铺设。
按公司股票是否上市流通为标准,可将公司分为上市公司和非上市公司,证券投资分析中公司分析的对象主要指上市公司,所以证券分析师应主要分析上市公司,非上市公司不在分析的考虑范围。()
新加坡国立大学社会学家波林.斯特劳恩副教授对当地已婚者和离婚者展开的调查发现.恋爱时间较长的夫妻,婚后闹分手的几率会比那些恋爱时间较短的夫妻低。于是有人得出结论.要想以后的婚姻更稳固,必须延长恋爱时问。下列哪项为真,最能削弱上述结论?
生搬硬套:效仿
A
A、enteredtheGazaStripB、receivedordertoattackPalestinianmilitantsC、beenorderedtomakepreparationforpossiblemilita
最新回复
(
0
)