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2.3.3 Milankovitch Cycles关于气候变化和orbit@

1讲的是M关于气候变化和orbit的假说，

第二段讲技术发达后发现这个假说有问题然后又说在一个条件下，这个假说还是有价值的，所以又被慢慢接受。

V2

第三篇讲关于地球orbit和气候的改变,两段,第二段整段highlight 作者一开始就说 , 一个人M 在以前做了研究, 好像是用化石层的分布然后发表了理论.说ice age发生是有一定的时间规律.. 第二段就说,但是呢,1950年人们用了新科技发现这个M是错的 (有考点). 用着甚么其他地方的化石还是甚么的. 但是呢作者接着说, 1970年人们又用了新科技证明M是对的!!!!! 最后说到虽然到现在M的许多理论都还没被证实 (有考点) 问题有问第二段的作用, 这篇文章的主旨, 那些1950年的人如果用更新的科技的话就不会怎样 (我选就不会不支持M的理论)

考古 2.3.3

Milankovitch Cycles Theory

Milankovitch cycles theory is about the frequency of ice age. Milankovich proposed that the temperature of earth has something to do with the position of the earth in the orbit around sun. However it did not gain acceptance until 1968 when Dr. Imbrie presented additional evidence for M theory. He meassured the isotope level in small seashell deposit and the change of isotope abundancy corresponds with the temperature change.

However, later on, a geochemist tested the samples from Devil&aposs Hole, a place in south Nevada and the results did not match with the previous results.

Even thought Dr. Imbrie still think M theory was valid, he conceded that many other factors contribute to the isotope level. It maybe why the results did not match.

OLD JJ

V1

是讲某人MM的理论，关于change in earth‘s orbit影响气候什么的，也没看懂…… V2

03/21 第二篇是change in earth orbit. 第一段讲M的理论多牛B，第二段讲50年代的什么试验证明M是错的，然后第二段的后半部分又说原来50年代的试验方法（还是数据？）是错误的，这样的话M的理论又被证明是对的了。

V1

1.先是陈述了 这个理论 然后说当时人们只能在实验条件不足的情况下 大体的承认这个理论

2.但是1950年出了个A.B 研究了一些东西 说是理论错误了。 导致一段时间内人们都不再接受M的理论了

3.随着科技的进步 新的方法（或旧的改良） 出现了 证明了AB的 证据索取是比较片面的 M再次被人们接受

V2

1.先是陈述了 这个理论 然后说当时人们只能在实验条件不足的情况下 有些人研究了一下化石一类的，大体的承认这个理论

2.但是1950年出了个A.B 研究了一些东西，carbon rating之类的，说是理论错误了。（我觉得段时间内人们都不再接受M的理论了.随着科技的进步,应该是旧的改良结合很多其它新的technology, 出现了 证明了AB的 证据索取是比较片面的 M再次被人们接受。

问题：1. A..B. 对MilankovitchCycles Theory的看法 2. 主题题：选的不同的方法对某一科学推断的研究和看法(没有一个选项提到了Milankovitch CyclesTheory,所以猜测某一科学推断指代Milankovitch CyclesTheory)。

3．Infer: 说如果第一段那些“当时人们”有accurate carbondating technologies 的时候，他们会怎样？

4. 不记得了MilankovitchCycles Theory的看法

V3

某教授在1920S研究发现冰河期和地球轨道有关，然后是通过化石做了张表来说明。第二段突然说1950S科技进不了，发觉他理论不对了。然后1980S，科技有进步了，说其实1950S是不对的，以前那个教授其实是对的。

V4

米兰先生那个冰河时期的理论，jj的考古很有用，居然4道题！ 第二段有考点，就是那个infer的题目，说以前如果也用了carbon那个方法，会怎样 还有就是新的学者（高亮了）认为米兰先生的theory的一个评价。。。

V5

关于Milankovich理论的， P1.该理论的贡献 P2。该理论受到新的基于quantative和radiocarbon方法的挑战，被数据证实有误，但后来的研究证明上述方法有问题，新的更精确的方法验证了M理论的正确性，因而M理论重新得到认可 问题：1。 如果基于quantative和radiocarbon方法得到的结果是正确的，那会有什么结果。（答案都忘了，但此题不易解，干扰项严重）

有益补充1：地球轨道根数变化与第四纪冰期 Changes of the Earth&aposs Orbital Elements and the Quaternary Glacial Epoch

米兰柯维奇(Milankovitch)天文气候学理论和第四纪地质时期以来冰期的研究进展.研究结果表明,地球上的冰体积具有近10万yr的变化周期,并伴有近4万yr和2万yr的变化周期,它们是由于地球的轨道根数变化导致的气候变迁所致;不同的地球物理资料中均存在上述类似的变化周期,表明气候变迁所导致的变化是全球性效应,证实米兰柯维奇天文理论是基本正确的。 这个像不像jj里讲的mm理论？ 冰川变化 地球轨道

有益补充2 （补充1的英文）： At the recent American Geophysical Union meeting in San Francisco, the 25th anniversary of one of the great papers in paleoclimatology was celebrated. The paper, entitled “Variations in the Earth’s orbit: Pacemaker of the Ice Ages,” presented important new evidence supporting the orbital theory of glaciation. Orbital theory goes back over a century but is most closely associated with Milankovitch, who calculated the fects of gravitational perturbations on the seasonal cycle of Earth’s insolation (the radiation incident at the top of the atmosphere). Insolation varies on several time scales, including ~20,000 years (termed precession), ~40,000.

Milankovitch proposed in the early twentieth century that the ice ages were caused by variations in the Earth’s orbit around the Sun. For some time this theory was considered untestable, (5)largely because there was no sufficiently precise chronology of the ice ages with which the orbital variations could be matched. P1：M提出一个理论, 指出其缺陷 To establish such a chronology it is necessary to determine the relative amounts of land ice that (10)existed at various times in the Earth’s past. A recent discovery makes such a determination possible: relative land-ice volume for a given period can be deduced from the ratio of two oxygen isotopes, 16 and 18, found in ocean sediments. Almost (15)all the oxygen in water is oxygen 16, but a few molecules out of every thousand incorporate the heavier isotope 18. When an ice age begins, the continental ice sheets grow, steadily reducing the amount of water evaporated from the ocean that (20)will eventually return to it. Because heavier isotopes tend to be lt behind when water evaporates from the ocean surfaces, the remaining ocean water becomes progressively enriched in oxygen 18. The degree of enrichment can be determined (25)by analyzing ocean sediments of the period, because these sediments are composed of calcium carbonate (calcium carbonate: n.[化]碳酸钙) shells of marine organisms, shells that were constructed with oxygen atoms drawn from the surrounding ocean. The higher the ratio of (30)oxygen 18 to oxygen 16 in a sedimentary specimen, the more land ice there was when the sediment was laid down. P2: 一个新发现可弥补M理论的缺陷 As an indicator of shifts in the Earth’s climate, the isotope record has two advantages. First, it is (35)a global record: there is remarkably little variation in isotope ratios in sedimentary specimens taken from different continental locations. Second, it is a more continuous record than that taken from rocks on land. Because of these advantages, (40)sedimentary evidence can be dated with sufficient accuracy by radiometric methods to establish a precise chronology of the ice ages. The dated isotope record shows that the fluctuations in global ice volume over the past several hundred (45)thousand years have a pattern: an ice age occurs roughly once every 100,000 years. These data have established a strong connection between variations in the Earth’s orbit and the periodicity of the ice ages. P3：新发现的优点 However, it is important to note that other (50)factors, such as volcanic particulates or variations in the amount of sunlight received by the Earth, could potentially have affected the climate. The advantage of the Milankovitch theory is that it is testable: changes in the Earth’s orbit can be (55)calculated and dated by applying Newton’s laws of gravity to progressively earlier configurations of the bodies in the solar system. Yet the lack of information about other possible factors affecting global climate does not make them unimportant. P4：其他的理论也不容忽视 70. In the passage, the author is primarily interested in 主题题（D） suggesting an alternative to an outdated research method introducing a new research method that calls an accepted theory into question emphasizing the instability of data gathered from the application of a new scientific method presenting a theory and describing a new method to test that theory以下是澳际留学为您收集的2010年11月GMAT机经，2010年11月GMAT阅读机经，共51篇。澳际留学祝您考试顺利!