托福閱讀真題Official 49 Passage 1（二）

托福閱讀真題Official 49 Passage 1（二）

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 3 of 14

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

正確答案：A

題目詳解

題型分類：事實信息題

原文定位：關(guān)鍵詞：ephesus；根據(jù)關(guān)鍵詞定位到第一段最后一句話：“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.”大意是河會產(chǎn)生新的土地，就像土耳其的E一樣。

選項分析：

A選項：是原文定位句的同義改寫，故正確。

B選項：原文未提及失去土地，屬于無中生有。

C選項：原文提到的是river，不是海洋，故錯誤。

D選項：原文說的不是海岸線對內(nèi)陸城市的影響，因為E是港口城市。

Question 4 of 14

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 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.

正確答案：C

題目詳解

題型分類：推論題

原文定位：climate change，Paleolithic；根據(jù)關(guān)鍵詞可以定位到：“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”大意為：冰增長時，海平面就會下降，冰融化，海平面就會上升。下降時，會產(chǎn)生陸地橋，影響人類的殖民，同時也影響很多動植物。

選項分析：

C選項：因為寒冷的天氣所以陸地橋暴露出來。根據(jù)定位句，是因為結(jié)冰所以才有陸地橋，結(jié)冰可以推理出天氣寒冷，所以該選項正確。

A選項：和原文“when the ice melted,the sea level would rise again.”矛盾，海平面上升陸地就少了。

B選項：根據(jù)推理，氣溫高海平面上升，動植物被淹沒，所以該選項錯誤。

D選項：和原文“when the ice melted,the sea level would rise again”相悖。

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