阅读词汇题：
Remarkable
Wealthy of
Devoid
Coincide with
Diffusion
Propagate
Subsequence
Initiate
Chronological
第一篇：
苏美尔人的居住地土地贫瘠，但是每年的洪水泛滥留下了肥沃的淤泥用来耕作，由此产生了统治阶层。而统治阶层在管理时为了记录则导致了楔形文字的产生，后来文字应用到了社会生活中。
解析：苏美尔人(也译作苏默)，是历史上两河流域(底格里斯河和幼发拉底河中下游)早期的定居民族，他们所建立的苏美尔文明是整个美索不达米亚文明中最早，同时也是全世界最早产生的文明。苏美尔文明主要位于美索不达米亚的南部，通过放射性碳十四的断代测试，表明苏美尔文明的开端可以追溯至公元前4000年。约结束在公元前2000年，被闪米特人(闪族人)建立的巴比伦所代替。这里发现的含有楔形文字前文字的最古老的石板(这是目前公认的最早的文字记录)可以被定期为约前36世纪。
背景知识：
Sumerian Agriculture and hunting
The Sumerians adopted an agricultural mode of life as by perhaps as early as c. 5000 - 4500 BC the region demonstrated a number of core agricultural techniques, including organized irrigation, large-scale intensive cultivation of land, mono-cropping involving the use of plough agriculture, and the use of an agriculturalspecialized labour force under bureaucratic control. The necessity to manage temple accounts with this organization led to the development of writing (c. 3500 BC).
From the royal tombs of Ur, made of lapis lazuli and shell, shows peacetime
In the early Sumerian Uruk period, the primitive pictograms suggest that sheep, goats, cattle, and pigs were domesticated. They used oxen as their primary beasts of burden and donkeys or equids as their primary transport animal and "woollen clothing as well as rugs were made from the wool or hair of the animals. ... By the side of the house was an enclosed garden planted with trees and other plants; wheat and probably other cereals were sown in the fields, and the shaduf was already employed for the purpose of irrigation. Plants were also grown in pots or vases."
An account of barley rations issued monthly to adults and children written in cuneiformon clay tablet, written in year 4 of King Urukagina, circa 2350 BC
The Sumerians practiced similar irrigation techniques as those used in Egypt. American anthropologist Robert McCormick Adams says that irrigation development was associated with urbanization, and that 89% of the population lived in the cities.
They grew barley, chickpeas, lentils, wheat, dates, onions, garlic, lettuce, leeks and mustard. Sumerians caught many fish and hunted fowl and gazelle.
Sumerian agriculture depended heavily on irrigation. The irrigation was accomplished by the use of shaduf, canals, channels,dykes, weirs, and reservoirs. The frequent violent floods of the Tigris, and less so, of the Euphrates, meant that canals required frequent repair and continual removal of silt, and survey markers and boundary stones needed to be continually replaced. The government required individuals to work on the canals in a corvee, although the rich were able to exempt themselves.
As is known from the "Sumerian Farmer's Almanac", after the flood season and after the Spring Equinox and the Akitu or New Year Festival, using the canals, farmers would flood their fields and then drain the water. Next they let oxen stomp the ground and kill weeds. They then dragged the fields with pickaxes. After drying, they plowed, harrowed, and raked the ground three times, and pulverized it with a mattock, before planting seed. Unfortunately the high evaporation rate resulted in a gradual increase in the salinity of the fields. By the Ur III period, farmers had switched from wheat to the more salt-tolerant barley as their principal crop.
Sumerians harvested during the spring in three-person teams consisting of a reaper, a binder, and a sheaf handler. The farmers would use threshing wagons, driven by oxen, to separate the cereal heads from the stalks and then use threshing sleds to disengage the grain. They then winnowed the grain/chaff mixture.
Language and writing
Main articles: Sumerian language and Cuneiform
Early writing tablet recording the allocation of beer, 3100-3000 BC
The most important archaeological discoveries in Sumer are a large number of tablets written in cuneiform. Sumerian writing is the oldest example of writing on earth. Although pictures - that is, hieroglyphs - were first used, symbols were later made to represent syllables. Triangular or wedge-shaped reeds were used to write on moist clay. A large body of hundreds of thousands of texts in the Sumerian language have survived, such as personal or business letters, receipts, lexical lists, laws, hymns, prayers, stories, daily records, and even libraries full of clay tablets. Monumental inscriptions and texts on different objects like statues or bricks are also very common. Many texts survive in multiple copies because they were repeatedly transcribed by scribes-in-training. Sumerian continued to be the language of religion and law in Mesopotamia long after Semitic speakers had become dominant.
The Sumerian language is generally regarded as a language isolate in linguistics because it belongs to no known language family; Akkadian, by contrast, belongs to the Semitic branch of the Afro-Asiatic languages. There have been many failed attempts to connect Sumerian to other language groups. It is an agglutinative language; in other words, morphemes ("units of meaning") are added together to create words, unlike analytic languages where morphemes are purely added together to create sentences.
Understanding Sumerian texts today can be problematic even for experts. Most difficult are the earliest texts, which in many cases do not give the full grammatical structure of the language.
During the 3rd millennium BC a cultural symbiosis developed between the Sumerians and the Akkadians, which included widespread bilingualism. The influences between Sumerian on Akkadian are evident in all areas including lexical borrowing on a massive scale--and syntactic, morphological, and phonological convergence. This mutual influence has prompted scholars to refer to Sumerian and Akkadian of the 3rd millennium BC as asprachbund.
Akkadian gradually replaced Sumerian as a spoken language somewhere around the turn of the 3rd and the 2nd millennium BC, but Sumerian continued to be used as a sacred, ceremonial, literary, and scientific language in Babylonia and Assyria until the 1st century AD.#p#副标题#e#
第二篇：
机经：
小行星对恐龙灭绝的影响。一个科学家发现土层中里有很多Ir元素，而Ir元素在地球上少见，因此推断是小行星导致了恐龙灭绝。后面又说了小行星使得气温降低，空气化学组成改变等等也导致恐龙的灭绝，但是一些小的啮齿类动物则存活了下来。
解析：在恐龙绝灭假说中，小行星撞击说最为流行。此说认为，小行星(后有学者认为彗星的可能性更大)才是杀死恐龙的罪魁祸首。小行星撞击说是1979年由美国物理学家阿尔瓦雷斯等人提出的。他们认为，6500万年前的一颗直径约为10公里的小行星与地球相撞，发生猛烈大爆炸，大量尘埃抛入大气层中，致使数月之内阳光被遮挡，大地一片黑暗寒冷，植物枯死，食物链中断，包括恐龙在内的很多动物绝灭。
参考文章：Meteorite Impact and Dinosaur Extinction
Extinction of the Dinosaurs
Mass Extinctions
背景知识：
Impact event
Biospheric effects
The effect of impact events on the biosphere has been the subject of scientific debate. Several theories of impact related mass extinction have been developed. In the past 500 million years there have been five generally accepted, major mass extinctions that on average extinguished half of all species. One of the largest mass extinction to have affected life on Earth was in the Permian-Triassic, which ended the Permian period 250 million years ago and killed off 90% of all species; life on Earth took 30 million years to recover. The cause of the Permian-Triassic extinction is still matter of debate with the age and origin of proposed impact craters, i.e. the Bedout High structure, hypothesized to be associated with it are still controversial. The last such mass extinction led to the demise of the dinosaurs and coincided with a large meteorite impact; this is the Cretaceous–Paleogene extinction event (also known as the K–T or K–Pg extinction event); This occurred 66 million years ago. There is no definitive evidence of impacts leading to the three other major mass extinctions.
In 1980, physicist Luis Alvarez; his son, geologist Walter Alvarez; and nuclear chemists Frank Asaro and Helen V. Michael from the University of California, Berkeley discovered unusually high concentrations of iridium in a specific layer of rock strata in the Earth's crust. Iridium is an element that is rare on Earth but relatively abundant in many meteorites. From the amount and distribution of iridium present in the 65-million-year-old "iridium layer", the Alvarez team later estimated that an asteroid of 10 to 14 km (6 to 9 mi) must have collided with the earth. This iridium layer at the Cretaceous–Paleogene boundary has been found worldwide at 100 different sites. Multidirectionally shocked quartz (coesite), which is only known to form as the result of large impacts or atomic bomb explosions, has also been found in the same layer at more than 30 sites. Soot and ash at levels tens of thousands times normal levels were found with the above.
Anomalies in chromium isotopic ratios found within the K-T boundary layer strongly support the impact theory. Chromium isotopic ratios are homogeneous within the earth, therefore these isotopic anomalies exclude a volcanic origin which was also proposed as a cause for the iridium enrichment. Furthermore the chromium isotopic ratios measured in the K-T boundary are similar to the chromium isotopic ratios found in carbonaceous chondrites. Thus a probable candidate for the impactor is a carbonaceous asteroid but also a comet is possible because comets are assumed to consist of material similar to carbonaceous chondrites.
Probably the most convincing evidence for a worldwide catastrophe was the discovery of the crater which has since been named Chicxulub Crater. This crater is centered on the Yucatán Peninsula of Mexico and was discovered by Tony Camargo and Glen Pentfield while working as geophysicists for the Mexican oil companyPEMEX. What they reported as a circular feature later turned out to be a crater estimated to be 180 km (110 mi) in diameter. Other researchers would later find that the end-Cretaceous extinction event that wiped out the dinosaurs had lasted for thousands of years instead of millions of years as had previously been thought. This convinced the vast majority of scientists that this extinction resulted from a point event that is most probably an extraterrestrial impact and not from increased volcanism and climate change (which would spread its main effect over a much longer time period).
Recently, several proposed craters around the world have been dated to approximately the same age as Chicxulub — for example, the Silverpit crater in the United Kingdom, the Boltysh crater in Ukraine and the Shiva crater near India. This has led to the suggestion that the Chicxulub impact was one of several that occurred almost simultaneously, perhaps due to a disrupted comet impacting the Earth in a similar manner to the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994; however, the uncertain age and provenance of these structures leaves the hypothesis without widespread support.
It was the lack of high concentrations of iridium and shocked quartz which has prevented the acceptance of the idea that the Permian extinction was also caused by an impact. During the late Permian all the continents were combined into one supercontinent named Pangaea and all the oceans formed one superocean,Panthalassa. If an impact occurred in the ocean and not on land at all, then there would be little shocked quartz released (since oceanic crust has relatively little silica) and much less material.
Although there is now general agreement that there was a huge impact at the end of the Cretaceous that led to the iridium enrichment of the K-T boundary layer, remnants have been found of other, smaller impacts, some nearing half the size of the Chicxulub crater, which did not result in any mass extinctions, and there is no clear linkage between an impact and any other incident of mass extinction.
Paleontologists David M. Raup and Jack Sepkoski have proposed that an excess of extinction events occurs roughly every 26 million years (though many are relatively minor). This led physicist Richard A. Muller to suggest that these extinctions could be due to a hypothetical companion star to the Sun calledNemesis periodically disrupting the orbits of comets in the Oort cloud, and leading to a large increase in the number of comets reaching the inner solar system where they might hit Earth. Physicist Adrian Melott and paleontologist Richard Bambach have more recently verified the Raup and Sepkoski finding, but argue that it is not consistent with the characteristics expected of a Nemesis-style periodicity.#p#副标题#e#
第三篇：
机经：
冰河时期形成原因
第一段：地球周期一直被人们观测。但直到科学家M，才提出是地球的orbit三个因素共同发生造成的。Eccentric, tilt and orbit.。
第二段：三个理论。【好长一段】
第三段：三个角度变化要好多年。周期不能解释。
第四段：还有好多其他解释，有人说火山，有人说…有人说…
解析：冰期 地球表面覆盖有大规模冰川的地质时期。又称为冰川时期。两次冰期之间唯一相对温暖时期，称为间冰期。地球历史上曾发生过多次冰期，最近一次是第四纪冰期。 地球在40多亿年的历史中，曾出现过多次显著降温变冷，形成冰期。特别是在前寒武纪晚期、石炭纪至二叠纪和新生代的冰期都是持续时间很长的地质事件，通常称为大冰期。大冰期的时间尺度至少数百万年。大冰期内又有多次大幅度的气候冷暖交替和冰盖规模的扩展或退缩时期，这种扩展和退缩时期即为冰期和间冰期。
学者们提出过种种解释，但至今没有得到令人感到满意的答案。归纳起来，主要有天文学和地球物理学成因说。
天文学成因说
天文学成因说主要考虑太阳、其他行星与地球间的相互关系。①太阳光度的周期变化影响地球的气候。太阳光度处于弱变化时，辐射量减少，地球变冷，乃至出现冰期气候。米兰科维奇认为，夏半年太阳辐射量的减少是导致冰期发生的可能因素。②地球黄赤交角的周期变化导致气温的变化。黄赤交角指黄道与天赤道的交角，它的变化主要受行星摄动的影响。当黄赤交角大时，冬夏差别增大，年平均日射率最小，使低纬地区处于寒冷时期，有利于冰川生成。
地球物理学成因说
地球物理学成因说影响因素较多，有大气物理方面的，也有地理地质方面的。①大气透明度的影响。频繁的火山活动等使大气层饱含着火山灰，透明度低，减少了太阳辐射量，导致地球变冷。②构造运动的影响。构造运动造成陆地升降、陆块位移、视极移动，改变了海陆分布和环流型式，可使地球变冷。云量、蒸发和冰雪反射的反馈作用，进一步使地球变冷，促使冰期来临。③大气中CO2的屏蔽作用。CO2能阻止或减低地表热量的损失。如果大气中CO2含量增加到今天的2~3倍，则极地气温将上升8~9℃;如果今日大气中的CO2含量减少55~60%，则中纬地带气温将下降4~5℃。在地质时期火山活动和生物活动使大气圈中CO2含量有很大变化，当CO2屏蔽作用减少到一定程度，则可能出现冰期。
背景知识：
An ice age is a period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Within a long-term ice age, individual pulses of cold climate are termed "glacial periods" (or alternatively "glacials" or "glaciations" or colloquially as "ice age"), and intermittent warm periods are called "interglacials".Glaciologically, ice age implies the presence of extensive ice sheets in the northern and southern hemispheres. By this definition, we are in an interglacial period - the holocene, of the ice age that began 2.6 million years ago at the start of the Pleistocene epoch, because the Greenland, Arctic, and Antarctic ice sheets still exist.
Variations in Earth's orbit (Milankovitch cycles)
The Milankovitch cycles are a set of cyclic variations in characteristics of the Earth's orbit around the Sun. Each cycle has a different length, so at some times their effects reinforce each other and at other times they (partially) cancel each other.
Past and future of daily average insolation at top of the atmosphere on the day of the summer solstice, at 65 N latitude.
There is strong evidence that the Milankovitch cycles affect the occurrence of glacial and interglacial periods within an ice age. The present ice age is the most studied and best understood, particularly the last 400,000 years, since this is the period covered by ice cores that record atmospheric composition and proxies for temperature and ice volume. Within this period, the match of glacial/interglacial frequencies to the Milanković orbital forcing periods is so close that orbital forcing is generally accepted. The combined effects of the changing distance to the Sun, the precession of the Earth's axis, and the changing tilt of the Earth's axis redistribute the sunlight received by the Earth. Of particular importance are changes in the tilt of the Earth's axis, which affect the intensity of seasons. For example, the amount of solar influx in July at 65 degrees north latitude varies by as much as 22% (from 450 W/m² to 550 W/m²). It is widely believed that ice sheets advance when summers become too cool to melt all of the accumulated snowfall from the previous winter. Some workers believe that the strength of the orbital forcing is too small to trigger glaciations, but feedback mechanisms like CO
2 may explain this mismatch.
While Milankovitch forcing predicts that cyclic changes in the Earth's orbital elements can be expressed in the glaciation record, additional explanations are necessary to explain which cycles are observed to be most important in the timing of glacial–interglacial periods. In particular, during the last 800,000 years, the dominant period of glacial–interglacial oscillation has been 100,000 years, which corresponds to changes in Earth's orbital eccentricity and orbitalinclination. Yet this is by far the weakest of the three frequencies predicted by Milankovitch. During the period 3.0–0.8 million years ago, the dominant pattern of glaciation corresponded to the 41,000-year period of changes in Earth's obliquity (tilt of the axis). The reasons for dominance of one frequency versus another are poorly understood and an active area of current research, but the answer probably relates to some form of resonance in the Earth's climate system.
The "traditional" Milankovitch explanation struggles to explain the dominance of the 100,000-year cycle over the last 8 cycles. Richard A. Muller, Gordon J. F. MacDonald, and others have pointed out that those calculations are for a two-dimensional orbit of Earth but the three-dimensional orbit also has a 100,000-year cycle of orbital inclination. They proposed that these variations in orbital inclination lead to variations in insolation, as the Earth moves in and out of known dust bands in the solar system. Although this is a different mechanism to the traditional view, the "predicted" periods over the last 400,000 years are nearly the same. The Muller and MacDonald theory, in turn, has been challenged by Jose Antonio Rial.
Another worker, William Ruddiman, has suggested a model that explains the 100,000-year cycle by the modulating effect of eccentricity (weak 100,000-year cycle) on precession (26,000-year cycle) combined with greenhouse gas feedbacks in the 41,000- and 26,000-year cycles. Yet another theory has been advanced by Peter Huybers who argued that the 41,000-year cycle has always been dominant, but that the Earth has entered a mode of climate behavior where only the second or third cycle triggers an ice age. This would imply that the 100,000-year periodicity is really an illusion created by averaging together cycles lasting 80,000 and 120,000 years. This theory is consistent with a simple empirical multi-state model proposed by Didier Paillard. Paillard suggests that the late Pleistocene glacial cycles can be seen as jumps between three quasi-stable climate states. The jumps are induced by the orbital forcing, while in the early Pleistocene the 41,000-year glacial cycles resulted from jumps between only two climate states. A dynamical model explaining this behavior was proposed by Peter Ditlevsen. This is in support of the suggestion that the late Pleistocene glacial cycles are not due to the weak 100,000-year eccentricity cycle, but a non-linear response to mainly the 41,000-year obliquity cycle.
Changes in Earth's atmosphere
There is considerable evidence that over the very recent period of the last 100–1000 years, the sharp increases in human activity, especially the burning of fossil fuels, has caused the parallel sharp and accelerating increase in atmospheric greenhouse gases which trap the sun's heat. The consensus theory of the scientific community is that the resulting greenhouse effect is a principal cause of the increase in global warming which has occurred over the same period, and a chief contributor to the accelerated melting of the remaining glaciers and polar ice. A 2012 investigation finds that dinosaurs released methane through digestion in a similar amount to humanity's current methane release, which "could have been a key factor" to the very warm climate 150 million years ago.
There is evidence that greenhouse gas levels fell at the start of ice ages and rose during the retreat of the ice sheets, but it is difficult to establish cause and effect (see the notes above on the role of weathering). Greenhouse gas levels may also have been affected by other factors which have been proposed as causes of ice ages, such as the movement of continents and volcanism.
The Snowball Earth hypothesis maintains that the severe freezing in the late Proterozoic was ended by an increase in CO2 levels in the atmosphere, and some supporters of Snowball Earth argue that it was caused by a reduction in atmospheric CO2. The hypothesis also warns of future Snowball Earths.
In 2009, further evidence was provided that changes in solar insolation provide the initial trigger for the Earth to warm after an Ice Age, with secondary factors like increases in greenhouse gases accounting for the magnitude of the change.
William Ruddiman has proposed the early anthropocene hypothesis, according to which the anthropocene era, as some people call the most recent period in the Earth's history when the activities of the human species first began to have a significant global impact on the Earth's climate and ecosystems, did not begin in the 18th century with the advent of the Industrial Era, but dates back to 8,000 years ago, due to intense farming activities of our early agrarian ancestors. It was at that time that atmospheric greenhouse gas concentrations stopped following the periodic pattern of the Milankovitch cycles. In his overdue-glaciationhypothesis Ruddiman states that an incipient glacial would probably have begun several thousand years ago, but the arrival of that scheduled glacial was forestalled by the activities of early farmers.
At a meeting of the American Geophysical Union (December 17, 2008), scientists detailed evidence in support of the controversial idea that the introduction of large-scale rice agriculture in Asia, coupled with extensive deforestation in Europe began to alter world climate by pumping significant amounts of greenhouse gases into the atmosphere over the last 1,000 years. In turn, a warmer atmosphere heated the oceans making them much less efficient storehouses of carbon dioxide and reinforcing global warming, possibly forestalling the onset of a new glacial age.
