托福阅读真题Official 49 Passage 1（六）

托福阅读真题Official 49 Passage 1（六）

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 11 of 14

The word“comprising”in the passage is closest in meaning to

A.taken from

B.made up of

C.suggesting

D.covering

正确答案：B

题目详解

题型分类：词汇题

选项分析：

词汇位于最后一段第一句，原句说上升沙滩常常由沙地、卵石或沙丘区域组成，有时还包含海贝或者残骸堆，残骸堆comprising人类用过的海洋动物的贝壳和骨头。根据常识，comprising前面的残骸堆和后面人类用过的贝壳骨头应是包含关系，所以推测comprising是包含的意思，也可以说是made up of由……组成，B选项正确。

A选项：从……拿；

C选项：认为是；

D选项：覆盖，带入原文均不符合语境。

Question 12 of 14

Which of the following can be inferred from paragraph 4 about Tokyo Bay?

A.The coastal land currently available is smaller than it was during the Jomon period.

B.The height of raised beaches around Tokyo Bay is a poor indicator of ancient sea levels.

C.The water temperature in Tokyo Bay is lower at present than it was during the Jomon period.

D.Tectonic movement during the Jomon period was not responsible for the formation of Tokyo Bay’s raised beaches.

正确答案：C

题目详解

题型分类：推论题

原文定位：根据Tokyo Bay定位到最后一段第二句（原文高亮），这句讲的是日本新石器时代的贝丘标出了海水最高期海岸线的位置。当时，经过构造运动，海洋与当今的日本大陆相比要高出三到五米。文章最后一句讲对东京港贝壳的分析，分析证实了海洋地形的变化，因为只有在最高期软体动物的亚热带物种才会出现，这表明当时的水温更高。

选项分析：

C选项说现在的水温与日本新石器时代相比更低is lower at present than it was…这与原文最后一句说那个时代有一个a higher water temperature是一致的。

A选项说与日本新石器时代相比，现有可用的海岸陆地is smaller与原文第二句新石器时代the sea was three to five meters higher海水更高矛盾。

B选项The height of raised beaches around Tokyo Bay属于无中生有。最后一段只提到东京港shell mounds贝丘的位置和analysis of the shells对贝壳的分析，并没有提到东京港附近上升沙滩的高度。

D选项说新石器时代的Tectonic movement构造运动不是东京港上升沙滩形成的原因。原文第二句只提到构造运动使得当时海水比当今日本大陆高，但没有提到这与东京港上升沙滩形成的关系，属于无中生有。