托福閱讀真題Official 49 Passage 1（七）

托福閱讀真題Official 49 Passage 1（七）

Ancient Coastlines

Information on past climates is primarily of 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 archaeologists 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 glacial 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 movements.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.

Question 13 of 14

Look at the four squares[■]that indicate where the following sentence could be added to the passage.The location of these heaps of rubbish can be an accurate indicator of earlier coastlines.Where would the sentence best fit?Click on a square[■]to add the sentence to the passage.

正確答案：B

題目詳解

題型分類：插入句子題

題干分析：本題考查句子和句子之間的銜接。根據(jù)插入句中的these heaps of rubbish，可以知道前面應該有rubbish相關(guān)內(nèi)容。根據(jù)插入句中的indicator of earlier coastlines，可以知道后面應該有coastline相關(guān)內(nèi)容。

選項分析：

B位置的前一句中有piles of debris（殘骸堆）與插入句heaps of rubbish（這些成堆的垃圾）相呼應，后一句中有mark the position of the shoreline（標志出海岸線的位置）與indicator of earlier coastlines（早期海岸線的標志）相呼應。插入句放于此位置既有詞的銜接，邏輯也連貫，十分合適。

A位置之前沒有內(nèi)容可以作為these heaps of rubbish的指代物，后一句也沒有提到coastline，詞的銜接不明，邏輯不連貫，不合適。

C位置前一句已經(jīng)提到東京港的shell mounds（貝丘）可以標出海岸線的位置，插入句在C位置則heaps指代mounds，內(nèi)容與前一句重復，不合適。

D位置前一句沒有可作為heaps of rubbish指代物的內(nèi)容，從詞的銜接看不合適。

Question 14 of 14

Directions:An introductory sentence for a brief summary of the passage is provided below.Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage.Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.This question is worth 2 points.

Changes in climate have altered Earth’s coastlines and their environments.

Answer Choices:

A.

Changing coastlines affect the total amount of land available for people to live on.

B.

The expansion and contraction of glaciers caused rises and falls in sea levels all over the world and in some areas,led to radical changes in their flora and fauna.

C.

The existence of Beringia,a vast landmass that may have supported human life,is still debated by archaeologists.

D.

The climate changes that led to alterations in the coastlines of San Francisco,Scandinavia,Scotland,Alaska,and Newfoundland isolated species that had once flourished together.

E.

Raised beaches,which may contain indicators of human activity,are often the result of isostatic uplifts and tectonic movements.

F.

Because raised beaches along the Mediterranean Sea were caused by tectonic movements,they contain abundant evidence of ancient civilizations.

正確答案：ABE

題目詳解

題型分類：文章總結(jié)題

題干分析：選擇概括性的正確選項。

選項分析：

A選項講海岸線變化會影響人們賴以生存的可用陸地總量，這是第二段的重要信息，是對第二段第四句及其之后內(nèi)容的總結(jié)。第四句的Falls in sea level often exposed a number of important land bridges和第五句中的fall in sea level of only four meters would turn it into a land bridge對應選項中的Changing coastlines affect the total amount of land。第六句中的the vast plain和第七句中的it could have supported human life對應選項中的available for people to live on。

B選項講冰川的擴張與收縮在全世界范圍內(nèi)和部分區(qū)域引起了海平面的升降，這使得動植物群發(fā)生了根本的變化，這也是第二段的重要信息。選項中的The expansion…over the world用詞和意思與第二段第二句高度重合，選項中的radical changes in their flora and fauna與第二段第四句最后一分句主干the flora and fauna were radically affected意思相同。

E選項講包含了人類活動痕跡的上升海灘常常是均衡上升和構(gòu)造運動的結(jié)果，它對應的分別是第三段的第四句和第四段的首句。選項中的contain indicators of human activity對應第四段首句里的comprising shells and bones of marine animals used by humans，選項中的the result of isostatic uplifts and tectonic movements對應第三段第四句里的the land has been raised up through isostatic uplift or tectonic movements。

C選項出自第二段的最后兩句，選項中a vast landmass的信息來自倒數(shù)第二句，與原句意思相符；其他信息都來自最后一句，但與原句意思不符。選項說白令陸橋的存在與否仍在被考古學家爭論。根據(jù)原句，白令陸橋的存在是爭論的證據(jù)而不是對象，爭論的對象是人類殖民新大陸的路線和日期。爭論的主體原句沒有說明，不能確認是否只有考古學家。

D選項出自第三段倒數(shù)第二句，因為選項和原句都講到了斯堪的納維亞等地海岸線的變化，但選項句子與原句意思不符。根據(jù)原文，導致這些地區(qū)海岸線變化的是isostatic uplift均衡上升而不是選項中的climate changes氣候變化。另外，選項中的isolated species that had once flourished together在原句中沒有提及。

F選項出自第三段最后一句，選項前半句中的raised beaches…tectonic movements與原句意思相符，但后半句的contain abundant evidence of ancient civilizations（包含豐富的古文明證據(jù)）是無中生有。

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