托福阅读真题Official 49 Passage 1（七）

托福阅读真题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.

正确答案：B

题目详解

题型分类：插入句子题

题干分析：本题考查句子和句子之间的衔接。根据插入句中的these heaps of rubbish，可以知道前面应该有rubbish相关内容。根据插入句中的indicator of earlier coastlines，可以知道后面应该有coastline相关内容。

选项分析：

B位置的前一句中有piles of debris（残骸堆）与插入句heaps of rubbish（这些成堆的垃圾）相呼应，后一句中有mark the position of the shoreline（标志出海岸线的位置）与indicator of earlier coastlines（早期海岸线的标志）相呼应。插入句放于此位置既有词的衔接，逻辑也连贯，十分合适。

A位置之前没有内容可以作为these heaps of rubbish的指代物，后一句也没有提到coastline，词的衔接不明，逻辑不连贯，不合适。

C位置前一句已经提到东京港的shell mounds（贝丘）可以标出海岸线的位置，插入句在C位置则heaps指代mounds，内容与前一句重复，不合适。

D位置前一句没有可作为heaps of rubbish指代物的内容，从词的衔接看不合适。

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.

正确答案：ABE

题目详解

题型分类：文章总结题

题干分析：选择概括性的正确选项。

选项分析：

A选项讲海岸线变化会影响人们赖以生存的可用陆地总量，这是第二段的重要信息，是对第二段第四句及其之后内容的总结。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对应选项中的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对应选项中的available for people to live on。

B选项讲冰川的扩张与收缩在全世界范围内和部分区域引起了海平面的升降，这使得动植物群发生了根本的变化，这也是第二段的重要信息。选项中的The expansion…over the world用词和意思与第二段第二句高度重合，选项中的radical changes in their flora and fauna与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选项讲包含了人类活动痕迹的上升海滩常常是均衡上升和构造运动的结果，它对应的分别是第三段的第四句和第四段的首句。选项中的contain indicators of human activity对应第四段首句里的comprising shells and bones of marine animals used by humans，选项中的the result of isostatic uplifts and tectonic movements对应第三段第四句里的the land has been raised up through isostatic uplift or tectonic movements。

C选项出自第二段的最后两句，选项中a vast landmass的信息来自倒数第二句，与原句意思相符；其他信息都来自最后一句，但与原句意思不符。选项说白令陆桥的存在与否仍在被考古学家争论。根据原句，白令陆桥的存在是争论的证据而不是对象，争论的对象是人类殖民新大陆的路线和日期。争论的主体原句没有说明，不能确认是否只有考古学家。

D选项出自第三段倒数第二句，因为选项和原句都讲到了斯堪的纳维亚等地海岸线的变化，但选项句子与原句意思不符。根据原文，导致这些地区海岸线变化的是isostatic uplift均衡上升而不是选项中的climate changes气候变化。另外，选项中的isolated species that had once flourished together在原句中没有提及。

F选项出自第三段最后一句，选项前半句中的raised beaches…tectonic movements与原句意思相符，但后半句的contain abundant evidence of ancient civilizations（包含丰富的古文明证据）是无中生有。

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