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托福阅读深度解析:AncientCoastlines

来源:cnchuban.com.cn    发布时间:2017-05-27 13:18   关键词:阅读

原标题:托福阅读深度解析:Ancient Coastlines

Ancient Coastlines

Information on past climates is of primary relevance to archaeology because of what it tells us about the effects on the land and on the resources that people needed to survive.The most crucial effect of climate was on the sheer quantity of land available in each period,measurable by studying ancient coastlines.These have changed constantly through time,even in relatively recent periods,as can be seen from the Neolithic stone circle of Er Lannic,in Brittany,France(once inland but now half submerged on an island)or medieval villages in east Yorkshire,England,that have tumbled into the sea in the last few centuries as the North Sea gnaws its way westward and erodes the cliffs.Conversely,silts deposited by rivers sometimes push the sea farther back,creating new land,as at Ephesus in western Turkey,a port on the coast in Roman times but today some five kilometers inland.

Nevertheless,for archeologists concerned with the long periods of time of the Paleolithic period there are variations in coastlines of much greater magnitude to consider.The expansion and contraction of the continental glaciers caused huge and uneven rises and falls in sea levels worldwide.When the ice sheets grew,the sea level would drop as water became locked up in the glaciers;when the ice melted,the sea level would rise again.Falls in sea level often exposed a number of important land bridges,such as those linking Alaska to northeast Asia and Britain to northwest Europe,a phenomenon with far-reaching effects not only on human colonization of the globe but also on the environment as a whole-the flora and fauna of isolated or insular areas were radically and often irreversibly affected.Between Alaska and Asia today lies the Bering Strait,which is so shallow that a fall in sea level of only four meters would turn it into a land bridge.When the ice sheets were at their greatest extent some 18,000 years ago (the glacier maximum),it is thought that the fall was about 120 meters,which therefore created not merely a bridge but a vast plain,1,000 kilometers from the north to the south,which has been called Beringia.The existence of Beringia(and the extent to which it could have supported human life)is one of the crucial pieces of evidence in the continuing debate about the likely route and date of human colonization of the New World.

The assessment of past rises and falls in sea level requires study of submerged land surfaces off the coast and of raised or elevated beaches on land.Raised beaches are remnants of former coastlines at higher levels relative to the present shoreline and visible,for instance,along the Californian coast north of San Francisco.The height of a raised beach above the present shoreline,however,does not generally give a straightforward indication of the height of a former sea level.In the majority of cases,the beaches lie at a higher level because the land has been raised up through isostatic uplift or tectonic movement.Isostatic uplift of the land occurs when the weight of ice is removed as temperatures rise,as at the end of an ice age;it has affected coastlines,for example,in Scandinavia,Scotland,Alaska,and Newfoundland during the postglacial period.Tectonic movements involve displacements in the plates that make up Earth’s crust.Middle and Late Pleistocene raised beaches in the Mediterranean are one instance of such movements.

Raised beaches often consist of areas of sand,pebbles,or dunes,sometimes containing seashells or piles of debris comprising shells and bones of marine animals used by humans.In Tokyo Bay,for example,shell mounds of the Jomon period(about 10,000 to 300 B.C.E.)mark the position of the shoreline at a time of maximum inundation by the sea(6,500-5,500 years ago),when, through tectonic movement,the sea was three to five meters higher in relation to the contemporary landmass of Japan than at present.Analysis of the shells themselves has confirmed the changes in marine topography,for it is only during the maximum phase that subtropical species of mollusc are present,indicating a higher water temperature.

Paragraph 1:

Information on past climates is of primary relevance to archaeology because of what it tells us about the effects on the land and on the resources that people needed to survive.The most crucial effect of climate was on the sheer quantity of land available in each period,measurable by studying ancient coastlines.These have changed constantly through time,even in relatively recent periods,as can be seen from the Neolithic stone circle of Er Lannic,in Brittany,France(once inland but now half submerged on an island)or medieval villages in east Yorkshire,England,that have tumbled into the sea in the last few centuries as the North Sea gnaws its way westward and erodes the cliffs.Conversely,silts deposited by rivers sometimes push the sea farther back,creating new land,as at Ephesus in western Turkey,a port on the coast in Roman times but today some five kilometers inland.

1. The wordcrucialin the passage is closest in meaning to

A: Interesting

B: Important

C: Established

D: Understood

2. Which of the sentencesbelow best expresses the essential information in the highlighted sentence in the passage?Incorrect choices change the meaning in important ways or leave out essential information.

A: In the last few centuries,the erosion of coastline created the Neolithic stone circle in Brittany,France,at the same time that it destroyed the medieval villages in Yorkshire,England.

B: Coastlines have changed even in recent times as shown by the current locations of certain Neolithic monuments and medieval villages.

C: Recent changes in the coastlines near the Neolithic stone circle of Er Lannic in Brittany,France,and the medieval villages in Yorkshire,England,suggest that ancient coastlines changed in similar ways.

D: Changes in coastlines can lead to the creation of islands such as Er Lannic in France or the total erosion of the cliffs as in Yorkshire in England,though no considerable changes have occurred in recent periods.

3. According to paragraph 1,the city of Ephesus in western Turkey is an example of which of the following?

A: Recent changes in the shoreline that have resulted in the creation of new land.

B: Port cities that have lost shoreline due to the erosion of land.

C: The ocean's role in the formation of new land.

D: The importance of changes in shoreline to cities located inland.

Paragraph 2:

Nevertheless,for archeologists concerned with the long periods of time of the Paleolithic period there are variations in coastlines of much greater magnitude to consider.The expansion and contraction of the continental glaciers caused huge and uneven rises and falls in sea levels worldwide.When the ice sheets grew,the sea level would drop as water became locked up in the glaciers;when the ice melted,the sea level would rise again.Falls in sea level often exposed a number of important land bridges,such as those linking Alaska to northeast Asia and Britain to northwest Europe,a phenomenon with far-reaching effects not only on human colonization of the globe but also on the environment as a whole-the flora and fauna of isolated or insular areas were radically and often irreversibly affected.Between Alaska and Asia today lies the Bering Strait,which is so shallow that a fall in sea level of only four meters would turn it into a land bridge.When the ice sheets were at their greatest extent some 18,000 years ago (the glacier maximum),it is thought that the fall was about 120 meters,which therefore created not merely a bridge but a vast plain,1,000 kilometers from the north to the south,which has been called Beringia.The existence of Beringia(and the extent to which it could have supported human life)is one of the crucial pieces of evidence in the continuing debate about the likely route and date of human colonization of the New World.

4. Which of the following can be inferred from paragraph 2 about the effects of climate change during the Paleolithic period?

A: The amount of land not covered by water was a greater during warmer periods.

B: Warmer weather encouraged the expansion of the range of flora and fauna.

C: As a result of colder weather,land bridges became exposed.

D: The rise of sea level occurred during periods of cold weather.

5. By indicating that flora and fauna of isolated or insular areaswere often irreversibly affectedby the changes due to the Ice Age,theauthor means that the flora and fauna were

A: Unableto return to their previous conditions.

B: Ina constant state of change.

C: Completelydestroyed by human colonization

D: Unevenly distributed across the area.

6. According to paragraph 2,all of the following are true ofBeringia EXCEPT:

A: Itmay have been used by the people who first colonized North America.

B: Itmay have been large enough to support life.

C: Itwas probably still four meters under water during the glacier maximum.

D: It was probably a vast plain.

7. What purpose does the discussion about the Bering Strait inparagraph 2 serve in the passage?

A: Itexplains the idea that changes in coastlines do not necessarily result insignificant alternations to existing marine life.

B: Itillustrates the kind of impact that variations in land availability caused byclimate change can have.

C: Itprovides a large amount of archaeological evidence that casts doubt on changesin sea level during the Paleolithic period.

D: Itshows how ancient coastlines can serve as useful models in understanding recentchanges in coastlines.

Paragraph 3:

The assessment of past rises and falls in sea level requires study of submerged land surfaces off the coast and of raised or elevated beaches on land.Raised beaches areremnantsof former coastlines at higher levels relative to the present shoreline and visible,for instance,along the Californian coast north of San Francisco.The height of a raised beach above the present shoreline,however,does not generally give a straightforward indication of the height of a former sea level.In the majority of cases,the beaches lie at a higher level because the land has been raised up through isostatic uplift or tectonic movement.Isostatic uplift of the land occurs when the weight of ice is removed as temperatures rise,as at the end of an ice age;it has affected coastlines,for example,in Scandinavia,Scotland,Alaska,and Newfoundland during the postglacial period.Tectonic movements involve displacements in the plates that make up Earth’s crust.Middle and Late Pleistocene raised beaches in the Mediterranean are one instance of such movements.

8. The word remnantsin the passage is closest meaning to

A: Remains

B: Regions

C: Points

D: Origins

9. According to paragraph 3,why is the height of a raised beach nota straightforward indicator of past sea level?

A: Theheight of the beach may have been raised or altered by human interventions inthe shore environment.

B: Theheight of the beach may be the result of erosion over a brief period of time.

C: Itis difficult to assess if the sea actually existed at that level for anysignificant period of time.

D: Thesurface of Earth may have shifted,moving the beach from its original positron.

10. According to paragraph 3,which of following causes an isostaticuplift?

A: Shiftsin Earth's crust.

B: Adecrease in the pressure of thick ice sheets.

C: Adecrease in temperature.

D:Changes in sea level.

Paragraph 4:

■Raised beaches often consist of areas of sand,pebbles,or dunes,sometimes containing seashells or piles of debriscomprisingshells and bones of marine animals used by humans. ■In Tokyo Bay,for example,shell mounds of the Jomon period(about 10,000 to 300 B.C.E.)mark the position of the shoreline at a time of maximum inundation by the sea(6,500-5,500 years ago),when, through tectonic movement,the sea was three to five meters higher in relation to the contemporary landmass of Japan than at present. ■Analysis of the shells themselves has confirmed the changes in marine topography,for it is only during the maximum phase that subtropical species of mollusc are present,indicating a higher water temperature. ■

11. The word comprisingin the passage 4 is closest in meaningto

A: Takenfrom

B: Madeup of

C: Suggesting

D:Covering

12. Which of the following can be inferred from paragraph 4 aboutTokyo Bay?

A: Thecoastal land currently available is smaller than it was during the Japanperiod.

B: Theheight of raised beaches around Tokyo Bay is a poor indicator of ancient sealevels.

C: Thewater temperature in Tokyo Bay is lower at present than it was during the Jomonperiod.

D: Tectonicmovement during the Jomon period was not responsible for the formation of TokyoBay's raised beaches.

13. Look at thefour squares [■] that indicate where the following sentencecould be added to the passage.Where would the sentence best fit?

The location of these heaps of rubbish can bean accurate indicator of earlier coastlines.

Answer Choices

A:Changing coastlines affect the total amountof land available for people to live on.

B:The existence of Beringia,a vast landmassthat may have supported human life,is still debated by archaeologists.

C:Raised beaches,which may contain indicatorsof human activity,are often the result of isotactic uplifts and tectonicmovements.

D:The expansion and contraction of glacierscaused rises and falls in sea levels all over the world and in some areas,ledto radical changes in their flora and fauna.

E:The climate changes that led to alternationsin the coastlines of San Francisco,Scandinavia,Scotland,Alaska,and Newfoundlandisolated species that had once flourished together.

F:Because raised beaches along the MediterraneanSea were caused by tectonic movements,they contain abundant evidence of ancientcivilizations.

答案精析

1. 词汇题

解析:crucial是“重要的”意思,故选B选项。

2. 句子简化题

解析:these指代前一句的ancient coastlines。主干信息是海岸线持续改变。跟上一个时间状语,甚至在最近时间段中。再跟上一个as引导的非限制性定语从句,as指代主句的内容,as can be seen from…表示from后面的内容是海岸线持续改变的证据(Neolithic stone circle或者 medieval villages)。

正确选项:

B. coastlines发生改变,甚至在最近的时间段,这可以从Neolithic stone circle 和 medieval villages目前的位置得到证实。此选项与原文主干信息一致,省略了原文Neolithic stone circle 和medieval villages分别的后置修饰。

错误选项:

coastlines的侵蚀作用创造了Neolithic stone circle,与此同时毁坏了medieval villages。缺少原文主干信息海岸线持续改变。

主句的谓语是suggest,此选项的主干信息是coastlines最近的改变表明了古代coastlines以相似的方式变化,与原文主干信息不一致。

此选项的主干信息是coastlines的变化能导致小岛的生成和对悬崖的侵蚀作用,虽然最近coastlines没有发生显著的变化。主干信息与原文不一致,并且原文未出现让步逻辑。

3. 细节题

解析:题干问E城市是什么的例子。对应第一段最后一句,主语是silts,谓语是push,讲淤泥有时将大海往回推,产生出新的土地,正如E这个城市。这里的as后跟介词短语,作副词,译成“正如,就像”,表明E城市是此现象的例子。A选项讲海岸线最近的变化导致新土地的产生,recent changes in shorelines对应原文淤泥使海岸线后退的现象。

4. 推理题

解析:题干问及旧石器时代气候变化的影响。第二段第一句是段落主旨句:对于关注旧石器时代的考古学家来说,他们需要考虑更大规模的海岸线变化。接下来具体解释这样一个更大规模的变化:大陆冰川的扩张和收缩引起海平面的上升和下降,当冰盖增长时,海平面就会下降,当冰川融化时,海平面就会上升,海平面的下降会暴露许多land bridges。因此据原文可知以下因果关系:气候变冷导致冰盖增长,又导致海平面下降,再导致陆地桥被暴露,故C选项是正确答案。

错误选项:

根据原文:气候变暖导致冰川融化,又导致海平面上升,再导致更大面积的陆地被水覆盖。故此选项信息与原文相反。

考点是flora and fauna,第四句有提到。海平面的下降会暴露许多land bridges,这是一个对人类定居和环境都有深远影响的现象,破折号之后具体解释海岸线的变化对环境的影响,即会对动植物产生不可逆的影响。因此原文未提及温暖气候导致动植物范围扩张这一关系。

与原文信息相反,气候变冷,海平面应下降。

5. 词汇题

解析: irreversibly affected是“不可逆转”的意思,因此选A,即无法回到以前的状态。

6. 排除题

解析:原文第二段从第五句到段尾第七句都是举例子:由于Bering strait很浅,海平面下降4米就可以将其变成land bridge。当冰川达到最大化时,海平面下降120米,因此就产生了Beringia平原。此平原的存在为人类占领新大陆的可能路径和日期之争论提供了重要证据。说明人类有可能通过此平原到达了新大陆。A选项的North America对应该段最后一句的the New World。B选项对应最后一句小括号内容,可支持人类生命。D选项对应倒数第二句a vast plain。C选项的考点是four meters或者是glacier maximum,这两个考点分别在第五句和第六句,比如第六句讲glacier maximum不仅使strait成为bridge,还产生了plain,说明当时Beringia完全在水之上,故C选项与原文不一致,是正确答案。

7. 修辞目的题

解析:第二段前四句话都在论述气候变化即大陆冰川的生长和收缩对海平面的影响,继而对大陆面积的影响,从第五句开始提到Bering Strait,它在冰川最大化时被暴露出来成为平原,例证前四句气候变化对陆地面积的影响,故B选项是正确答案。

Bering strait例子中未提及marine life。

Beringia的存在是人类到达新大陆的可能证据,而不是质疑海平面变化的证据。

选项讲凭借古代海岸线变化可了解最近的海岸线变化。但第二段都是在讲古石器时代的海岸线变化,未提及最近的。

8. 词汇题

解析:remnant是“残余”的意思,故选A选项。

9. 细节题

解析:题干问为什么a raised beach 不能直接表明past sea level?第三段第一句讲通过研究下沉的陆地(submerged land surface)和上升的海滩(raised or elevated beaches),来评估过去海平面的上升和下降。第二句讲被抬升的海滩是是之前高海拔海岸线的遗迹。第三句提到了题干关键词,a raised beach不能直接表明past sea level。第四句讲出了原因,海滩被抬升是由于isostatic uplift(均衡隆升)或者tectonic movement(地壳运动),即不是由于海岸线下降导致海滩被抬升,所以被抬升的海滩无法表明过去海平面的高度。正确答案是D选项。

错误选项:

“人类干预”未提及。

“短时间的侵蚀作用”未提及。

“无法评估那个高度的海平面是否真正存在”未提及。

10. 细节题

解析:题干问isostatic uplift的原因。紧接着上一道题的考点,这道题在第三段第五句即可读到答案,isostatic uplift发生的条件是温度增加,冰块重量减轻(the weight of ice is removed),对应B选项。

11. 词汇题

解析:comprise是“由…组成”的意思,故选B选项。

12. 推理题

解析:第一句讲被抬升的海滩经常包含沙地、卵石或沙丘,有时还包含贝壳和碎片堆。第二句举了个例子,绳纹时代(Jomon period)的贝冢(shell mounds)表明了最大化漫滩时(at a time of maximum inundation by the sea)海岸线的位置,当时由于地壳运动,海岸线比现在高出3到5米。第三句讲对于此贝冢的分析,证实了海洋地势的变化,因为只有海平面达到最高水平时(the maximum phase),亚热带的软体动物才会出现,这表明了当时较高的水温。暗示现在水温比绳纹时代的水温更低,对应C选项。

错误选项:

此比较关系与原文不一致,该段第二句讲绳纹时代的海水漫滩作用达到了最大化,表明当时暴露出来的陆地面积要比现在小,而A选项说现在更小。

该段例子讲的是Tokyo Bay的shell mounds 证实了海洋地势的变化,没有提及Tokyo Bay的raised beaches。

选项讲地壳运动不是海滩被抬升的原因,考点是tectonic movement,带回到该段第二句讲地壳运动导致海岸线上升,与选项论述的信息不一致,再者该段也并未论述东京湾海滩被抬升的原因。

13. 句子插入题

解析:待插入句的线索是代词指代these heaps of rubbish,根据此线索,应首先重点关注每个黑方框之前的信息。其指代的是B选项之前的seashells or piles of debris,前一句讲被抬升的海滩里包含这些东西,接着待插入句讲这些东西能表明过去的海岸线位置,B选项之后是对这两句的具体举例,讲东京湾的贝冢就证实了海洋地势的变化。

14. 主旨题

解析:(Changing coastlines…)选项讲海岸线的变化会影响暴露出的地表的面积,暴露出地表可供人类生存。对应第二段第四句,海平面的下降会暴露许多land bridges,这是一个对人类定居(human colonization)和环境都有深远影响的现象。

(Raised beaches…)选项讲被抬升的海滩可能包含了人类活动的迹象,其被抬升是由于均衡隆升和地壳运动。对应第三段的第四句和第四段的第一句(被抬升的海滩上包含了人类吃剩下的海洋动物的骨头)。

(The expansion…)选项讲冰川的扩张和收缩导致海平面的上升和下降,并且在某些地区导致动植物群的极度变化。对应第二段第二句至第四句,讲大陆冰川的扩张和收缩引起海平面的上升和下降,第四句的破折号之后具体解释海岸线的变化对环境的影响,即会对动植物产生不可逆的影响。

错误选项:

选项讲Beringia的存在,作为可能支撑人类生存的大片陆地,仍然被考古学家争论。虽然在第二段有讲Beringia,但写作此例子的目的是论证海岸线的变化所产生的影响,该选项未提全文主题即海岸线。

选项讲气候变化导致Scandinavia等地海岸线的变化,这一气候变化将曾经聚集在一起的物种隔离开来。第三段中Scandinavia等地是地质活动影响海岸线的举例,而不是气候因素导致了其海岸线的变化,并且原文未提及这些地方的物种。

选项讲因为地中海沿岸被抬升的海滩是由于地壳运动形成的,所以被抬升的海滩包含大量人类文明的证据。第三段最后一句讲到地中海被抬升的海滩是地质活动导致海岸地势变化的例子,未提及其是人类文明的证据。

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