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
77
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 2, Lyell’s strategy for estimation geologic dates was not very accurate for periods before the Tertiary Period party because
选项
A、Marine mollusks did not evolve until the Tertiary Period.
B、fossil records of the very distant past are incomplete.
C、there was not much agreement about how to identify or categorize earlier eras.
D、the duration of previous geologic periods was difficult to determine.
答案
B
解析
【事实信息题】倒数第2句转折“However,for older sequence of evolutionary development,only a part of the fossil record could be used.”说明之前的化石只有一部分可用,不能说明问题,因此答案为B。
转载请注明原文地址:https://kaotiyun.com/show/TrfO777K
0
托福(TOEFL)
相关试题推荐
ChooseFOURanswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions37-40.AStudentUnionBuildingBNursery
Writethecorrectletter,A-F,nexttoquestions21-26.AVideoResourceCentreBReadingRoomCFoodServiceCentreDPeriodic
Completethesentencesbelow.WriteNOMORETHANTHREEWORDSforeachanswer.Peopleinthewestwishthewatertobe______.
Choosefouranswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions27-30.AlightsBfixedcameraCmirrorD
Choosefouranswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions27-30.AlightsBfixedcameraCmirrorD
Choosefouranswersfromtheboxandwritethecorrectletter,A-G,nexttoquestions27-30.AlightsBfixedcameraCmirrorD
Completethesentencesbelow.WriteONEWORDONLYforeachanswer.FootballintheUKPeopleattemptedtostandardisetherules
Completethenotesbelow.WriteONEWORDONLYforeachanswer.EffectsofurbanenvironmentsonanimalsIntroductionRecenturba
poverty本题有关现时宿命主义者的生活态度。录音原文的religionorsocietyitself是题目中religiousbeliefs,socialconditions的同义替换。
CoursesforinternationalstudentsExampleWritinginfirsttermInsecondterm:【L1】________Throughouttheyear:【L2】_______
随机试题
心功能不全(cardiacinsufficiency)
某项目经理在一栋高层建筑的施工中,由于工程指导失误,致使施工人员伤亡并造成施工项目重大经济损失,按事故的责任分类属于()。
A、马尾丛综合征B、霍纳氏综合征C、脊髓前动脉综合征D、仰卧位综合征E、Mendelson综合征硬膜外阻滞可出现_____。
可用于治疗青光眼的药物是
下列项目应征增值税的是()。
下列关于方差的说法错误的是( )。
下列选项中,()指公司赚取利润的能力。
甲公司以一栋厂房和一项无形资产与丁公司的一项长期股权投资(对被投资方不构成控制)进行非货币性资产交换。甲公司换出厂房的账面原价为500万元,累计折旧为125万元,公允价值为390万元;换出无形资产的账面原价为60万元,累计摊销为12万元,公允价值为50万元
最近有很多人对公众事件进行调查,如云南躲猫猫事件,杭州70码事件,南京天价烟事件,并把调查结果在网络上公开,对此你有什么看法?
2012.25×2013.75-2010.25×2015.75=?
最新回复
(
0
)