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
Attempts at Determining Earth’s Age P1: Since the dawn of civilization, people have been curious about the age of Earth. What’s
Attempts at Determining Earth’s Age P1: Since the dawn of civilization, people have been curious about the age of Earth. What’s
admin
2018-10-18
43
问题
Attempts at Determining Earth’s Age
P1: Since the dawn of civilization, people have been curious about the age of Earth. What’s more, we have not been satisfied in being able to state merely the relative geologic age of a rock or fossil—human curiosity demands that we know the actual age in years. Generally speaking, scientists have developed three different methods of determining the age of the earth. Using these methods, or a combination of them, the age of geological formations and even fossilized bones of prehistoric animals left behind by past events can be determined.
P2: As geologists endeavored to reconstruct the earth’s geologic history in the 1700s and early 1800s, they quickly recognized that the distribution of fossils within this history was not random—fossils occurred in a consistent order. This was true on a regional and even a global scale. The natural processes that continue at a constant rate also leave a tangible record in rocks. Evolution is one such process, and geologist Charles Lyell (1797-1875) recognized this. By using empirical observations of fossil succession, he was able to propose a fine subdivision of the rocks and map out the formations of southern England in one of the earliest geological maps. Furthermore, fossil organisms were both more unique than rock types and much more varied, offering the potential for a much more precise subdivision of the stratigraphy and events within it. By comparing the amount of evolution exhibited by marine mollusks then, Lyell estimated that 80 million years had elapsed since the beginning of the Tertiary Period. He came astonishingly close to the mark, since it was actually about 65 million years. However, for older sequence of evolutionary development, only a part of the fossil record could be used. Rates of evolution for many orders of plants and animals were not well understood.
P3: In another attempt, geologists suggested that they might be able to estimate the time required for deposition of a given thickness of strata, or rock layers, because each layer represented a specific interval of geologic time. Similar reasoning argued that rock layers were originally deposited more or less evenly, and each layer should therefore continue laterally unless there was a material or structural impediment to prevent its extension. Thus, one could estimate the total elapsed geologic time by dividing the average thickness of sediment deposited in the past and transported annually to the oceans. Unfortunately, such estimates did not adequately account for the precise sedimentation rates of most strata losses during extreme weather conditions like episodes of erosion. Also, some extremely ancient sediment deposits were no longer recognizable, having been converted to igneous and metamorphic rocks during the formation of mountains. Today, such a proposal would appear to be quite elementary, but nearly 200 years ago, it amounted to a major breakthrough in scientific reasoning by establishing a rational basis for relative time measurements.
P4: Yet another scheme for approximating Earth’s age had been proposed in 1715. Sir Edmund Halley (1656-1742), an astronomer and the first real proponent of using the salt clock to calculate the age of the Earth, surmised that the original ocean was not salty and that subsequently salt must have derived from the weathering of rocks was brought to the sea by streams. Theoretically, in a closed system, measuring the salt content of a body of water would work to calculate an approximate age. If a somewhat constant rate of accumulation of the salt is known, and the present amount of salt in the water is given, then a simple algebraic calculation would render the age of that particular body of water. In 1899, Irish geologist John Joly (1857-1933) attempted the calculation. From information provided by gauges placed at the mouths of streams, Joly was able to estimate the annual increment of salt to the oceans. Then, knowing the salinity of ocean water and the approximate volume of water, he calculated the amount of salt already held in solution in the oceans. According to Joly, it would take 99.4 million years for the sulfates of calcium and magnesium to reach their present concentrations in the oceans. The dates calculated by all who attempted this method were wrong because of several fundamental flaws in the system. First of all, to use the salt clock as an actual clock, you must assume that the starting point would be 0% salinity. This, of course, could never be known because no one was around to measure the salinity of the oceans right when they formed. Also, people assumed that the ocean is an eternal reservoir, and when the salt is dumped in the ocean, it stays there permanently. This assumption is false as it has been later proven that elements of the ocean are being constantly recycled and leave the water. Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years. The belief in Earth’s immense antiquity was also supported by Darwin, Huxley, and other evolutionary biologists, who saw the need for time in the hundreds of millions of years to accomplish the organic evolution apparent in the fossil record.
P2: As geologists endeavored to reconstruct the earth’s geologic history in the 1700s and early 1800s, they quickly recognized that the distribution of fossils within this history was not random—fossils occurred in a consistent order. This was true on a regional and even a global scale. The natural processes that continue at a constant rate also leave a tangible record in rocks. Evolution is one such process, and geologist Charles Lyell (1797-1875) recognized this. ■ By using empirical observations of fossil succession, he was able to propose a fine subdivision of the rocks and map out the formations of southern England in one of the earliest geological maps. Furthermore, fossil organisms were both more unique than rock types and much more varied, offering the potential for a much more precise subdivision of the stratigraphy and events within it. By comparing the amount of evolution exhibited by marine mollusks then, Lyell estimated that 80 million years had elapsed since the beginning of the Tertiary Period. He came astonishingly close to the mark, since it was actually about 65 million years. ■ However, for older sequence of evolutionary development, only a part of the fossil record could be used. ■ Rates of evolution for many orders of plants and animals were not well understood. ■
According to paragraph 4, in which of the following ways could Joly’s estimate of Earth’s age be considered significant?
选项
A、It proved that Halley’s idea about the age of the ocean was fairly accurate.
B、It indicated that Earth was much older than some scientists had claimed.
C、It was favored by the majority of scientists at the end of the nineteenth century.
D、It was the basis for much modern research into the salinity of the ocean.
答案
B
解析
【事实信息题】倒数第2句在提到测量方法的缺陷后补充“Even though in error,…”说明他的贡献在与证实地球的年龄比我们以为的更古老,所以答案是B。C选项的majority和19世纪在原文未提及。
转载请注明原文地址:https://jikaoti.com/ti/gVhYFFFM
0
托福(TOEFL)
相关试题推荐
Wheredoesthespeakerdecidetoputitemsin?Writethecorrectletter,A,BorC,nexttoquestions7-10.Ainemergencypack
Listentothedirectionsandmatchtheplacesinquestions11-15totheappropriateplaceamongA-Eonthemap.Cafe
Listentothedirectionsandmatchtheplacesinquestions11-15totheappropriateplaceamongA-Eonthemap.HealthCentre
Choosefouranswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions27-30.AlightsBfixedcameraCmirrorD
Choosefouranswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions27-30.AlightsBfixedcameraCmirrorD
Whichattitudeisassociatedwiththefollowingpeopleduringtheconversation?ChooseSIXanswersfromtheboxandwritetheco
Whichattitudeisassociatedwiththefollowingpeopleduringtheconversation?ChooseSIXanswersfromtheboxandwritetheco
ChooseTWOletters,A-E.WhichTWOthingsmakethemuseumunusual?AtheguidesBtheeventsCtheanimalsDthebuildingsEthe
Completethenotesbelow.WriteONEWORDONLYforeachanswer.EffectsofurbanenvironmentsonanimalsIntroductionRecenturba
TheDinee,aNativeAmerican(people)ofthesouthwesternUnitedStates,were(once)seminomadichunterswho(practiced)a(few)
随机试题
合理用药基本原则中“经济”的含义,是指在用药安全、有效的前提下,必须做到
公司一次配股发行股份总数不得超过该公司前一次发行并募集股份后其股份总数的()
下列项目中属于土地增值税扣除项目且可据实扣除的是()。
采用账龄分析法计提坏账准备时,收到债务单位当期偿还的部分债务后,剩余的应收账款的账龄应按原账龄加上本期应增加的账龄确定。()
某企业生产甲、乙两种产品。该企业的单位电价为每度0.75元。各产品的电费按生产工时比例分配。甲、乙两种产品本月用电合计20000度;生产工时共计1500小时,其中甲产品的生产工时为900小时。据此计算的乙产品本月负担的电费是()元。
投资银行的主要业务有()。①证券发行与交易②企业并购③基金管理④项目融资⑤银团贷款
以下说法中正确的是()。
改革开放以来,我国出现了一些新的社会阶层,这些阶层归纳起来主要是民营科技企业的创业人员和技术人员、受聘于外资企业的管理技术人员、个体户、私营企业主、中介组织从业人员、自由职业人员等。这些阶层出现的原因在于
为进一步提升北京旅游行业整体队伍素质,打造高水平、懂业务的旅游景区建设与管理队伍,北京旅游局将为工作人员进行一次业务培训,主要围绕“北京主要景点”进行介绍,包括文字、图片、音频等内容。请根据考生文件夹下的素材文档“北京主要景点介绍.文字.docx”,帮
Readthearticleaboutthecashbasicofaccounting.Choosethebestwordtofilleachgap,fromA,B,CorD.Foreachquestion
最新回复
(
0
)