托福阅读真题Official 49 Passage 1（二）

托福阅读真题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

正确答案：A

题目详解

题型分类：事实信息题

原文定位：关键词：ephesus；根据关键词定位到第一段最后一句话：“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.”大意是河会产生新的土地，就像土耳其的E一样。

选项分析：

A选项：是原文定位句的同义改写，故正确。

B选项：原文未提及失去土地，属于无中生有。

C选项：原文提到的是river，不是海洋，故错误。

D选项：原文说的不是海岸线对内陆城市的影响，因为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.

正确答案：C

题目详解

题型分类：推论题

原文定位：climate change，Paleolithic；根据关键词可以定位到：“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”大意为：冰增长时，海平面就会下降，冰融化，海平面就会上升。下降时，会产生陆地桥，影响人类的殖民，同时也影响很多动植物。

选项分析：

C选项：因为寒冷的天气所以陆地桥暴露出来。根据定位句，是因为结冰所以才有陆地桥，结冰可以推理出天气寒冷，所以该选项正确。

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

B选项：根据推理，气温高海平面上升，动植物被淹没，所以该选项错误。

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

>> 雅思 托福 免费测试、量身规划、让英语学习不再困难<<