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有益补充1：地球轨道根数变化与第四纪冰期 Changes of the Earth's 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 effects 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 left 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（D）
initiating a debate about a widely accepted theory
71. The author of the passage would be most likely to agree with which of the following statements about the Milankovitch theory?
应用题（D）
It is the only possible explanation for the ice ages.
It is too limited to provide a plausible explanation for the ice ages, despite recent research findings.
It cannot be tested and confirmed until further research on volcanic activity is done.
It is one plausible explanation, though not the only one, for the ice ages. （D）
It is not a plausible explanation for the ice ages, although it has opened up promising possibilities for future research.
72. It can be inferred from the passage that the isotope record taken from ocean sediments would be less useful to researchers if which of the following were true?
推导题（B）
the isotope record has two advantages. First, it is
(35)a global record；Second, it is
a more continuous record than that taken from
rocks on land
It indicated that lighter isotopes of oxygen predominated at certain times.
It had far more gaps in its sequence than the record taken from rocks on land.否定了第二点
It indicated that climate shifts did not occur every 100,000 years.削弱M理论，而不是方法
It indicated that the ratios of oxygen 16 and oxygen 18 in ocean water were not consistent with those found in fresh water. （B）
It stretched back for only a million years.
73. According to the passage, which of the following is true of the ratios of oxygen isotopes in ocean sediments?
观点题（C）
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.
They indicate that sediments found during an ice age contain more calcium carbonate than sediments formed at other times.
They are less reliable than the evidence from rocks on land in determining the volume of land ice.
They can be used to deduce the relative volume of land ice that was present when the sediment was laid down.
They are more unpredictable during an ice age than in other climatic conditions. （C）
They can be used to determine atmospheric conditions at various times in the past.
74. It can be inferred from the passage that precipitation formed from evaporated ocean water has
推导题（B）
Because heavier isotopes
tend to be left behind when water evaporates
from the ocean surfaces, the remaining ocean
water becomes progressively enriched in oxygen
18.
the same isotopic ratio as ocean water
less oxygen 18 than does ocean water
less oxygen 18 than has the ice contained in continental ice sheets
a different isotopic composition than has precipitation formed from water on land（B）
more oxygen 16 than has precipitation formed from fresh water
75. It can be inferred from the passage that calcium carbonate shells
推导题（E）
shells that
were constructed with oxygen atoms drawn from
the surrounding ocean.
are not as susceptible to deterioration as rocks
are less common in sediments formed during an ice age
are found only in areas that were once covered by land ice
contain radioactive material that can be used to determine a sediment’s isotopic composition
reflect the isotopic composition of the water at the time the shells were formed |
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DBCBCEAB