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
35
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.
When did dinosaurs become extinct?
选项
A、300 million years ago.
B、250 million years ago.
C、60 million years ago.
D、65 million years ago.
答案
D
解析
由文章第三段倒数第二句话“He ignored the extinction which wiped out the dinosaurs 65million years ago…”可知,恐龙是在6 500万年前灭绝的。故选D。
转载请注明原文地址:https://kaotiyun.com/show/RvUd777K
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
OlderVolcanicEruptionsVolcanoesweremoredestructiveinancienthistory,notbecausetheywerebigger,butbecausetheca
OlderVolcanicEruptionsVolcanoesweremoredestructiveinancienthistory,notbecausetheywerebigger,butbecausetheca
IrarelyweararaincoatbecauseIspendmostofmytimeinacar.
ARichResourcesoftheStateBConnectionswiththeOutsideWorldCTransportationProblemDTheNativesoftheLandEColdCli
Itislogicalthatadetailedlearningofplantsandtheirpropertiesmustbeextremelyancient.Oncemankindbeganfarming,th
FinancialRisksSeveraltypesoffinancialriskareencounteredininternationalmarketing;themajorproblemsincludecommercia
ABuildingMaterialsBNeedofGreaterBuildingVarietiesinModemLifeCRestorationofAncientCivilizationsDEvolutioni
TheFatProblemthatMenFaceItisapleasuretoseemenofacertainageworryingabouttheirweight.Listeningtothemi
随机试题
输尿管损伤的病因为________、________、________和________。
小儿由于久病体弱,营养不良等因素,感染邪毒后发生鹅口疮,本病的发生与哪些脏腑关系最密切
张先生,55岁,有2型糖尿病病史10年,经饮食控制、运动、口服降糖药治疗,效果不理想,今日开始加用胰岛素治疗。进行健康教育时,不正确的指导是
甲公司在食品上注册“乡巴佬”商标后,与乙公司签订转让合同,获五万元转让费。合同履行后,乙公司起诉丙公司在食品上使用“乡巴佬”商标的侵权行为。法院作出侵权认定的判决书刚生效,“乡巴佬”注册商标就因有“不良影响”被依法撤销。下列哪些说法是错误的?(2009年卷
近年来剧场、电影院、礼堂成了火灾发生的频繁区域,当这些建筑设置在耐火等级为一、二级的多层民用建筑内时,应采用耐火极限不低于()h的防火隔墙和甲级防火门与其他区域分隔。
首次公开发行股票时,发行人应在发行前二至五个工作日内刊登招股说明书摘要。()
下列各项关于财务报表列报的表述中,正确的有()。
对于各种模拟演示。读理想大陆分布图(如图),回答问题。该小组在模拟演示中发现,当黄赤交角为0。时,M地气候类型在地球上无法再找到,M地所在的半球及其气候类型分别是()。
启蒙主义戏剧
Directions:Forthispart,youareallowed30minutestowriteanessaycommentingonthetopicofstudents’studyingoversells.
最新回复
(
0
)