TOEFL | 地理相关习题精炼+词汇整理
地质时代划分 （Classification of geologic time periods）
在地质年代划分中，习惯于以生物的情况来划分，把整个46亿年划成两个大的单元，那些看不到或者很难见到生物的时代被称做隐生宙（大概在6亿年前），而将可看到一定量生命以后的时代称做是显生宙。托福目前出现的题目都集中在显生宙：
- 显生宙的开始是寒武纪，因而在此之前的隐生宙时间也被称为前寒武纪（pre-cambrain），此时也被称为冰河时期（ice-age）
- 显生宙一共可分为三个代，即：
- 古生代（Paleozoic Era，5.4-2.5亿年前），其以寒武纪（cambrain） 开始，经历奥陶纪、志留纪、泥盆纪、石炭纪，最后以二叠纪（permian） 结束
- 寒武纪的经典事件是
物种大爆发 （deverstification），出现大量的生物，其中以三叶虫（trilobire）最为著名，在随后的几个世纪里气候逐渐变暖，藻类、蕨类植物、鱼类、两栖类动物路陆续繁荣 - 二叠纪的经典事件是史上最大的
物种大灭绝 （mass extinction），其中超过95%的物种都灭绝了，其中恐龙灭绝的原因是小行星撞地球
- 寒武纪的经典事件是
- 中生代（Mesozoic Era，2.5亿-6500万年前），其中由远及近包含3个世纪，分别是三叠纪（Triassic）、侏罗纪（Jurassic）、白垩纪（Certaceous），在该时期裸子植物和爬行动物出现
- PS：恐龙（dinosaur）出现在侏罗纪，灭绝于白垩纪（和小行星撞击有关）
- 新生代（Cenozoic Era，6500万年前至今），分为早第三纪、晚第三纪和第四纪，进一步地又可以分为
古新世、始新世、渐新世 、中新世、上新世 、更新世、全新世 ，托福考试主要几种在前两世和后两世，在这一代出现了被子植物和哺乳动物- 古新世（paleocene）、始新世（eocene，5500万年前）主要发生的事件是全球变暖（warming）
- 更新世（pieistocene，250万-1.2万年前），其晚期又称为旧石器时代（paleolithic period），其主要事件有三个主题：冰川、巨型动物灭绝、人类和哺乳动物出现
- 全新世（holocene，1.2万年前至今），主要有两个时间比较重要，分别是新石器时代（neolithic period，1万-4000年前），这个时期出现了古老的人类文明——古埃及文明（ancient Egypt），以及青铜时代（Bronze Age，4000年前-公元0年），这个时期的主要文明是苏美尔人文明（sumerain）
- 自8000年前农耕行为的普及或1800年工业革命（industrial revolution），地球进入了由人类主导的新世代——人类世（anthropocene Epoch）
- 古生代（Paleozoic Era，5.4-2.5亿年前），其以寒武纪（cambrain） 开始，经历奥陶纪、志留纪、泥盆纪、石炭纪，最后以二叠纪（permian） 结束
相关TPO 篇 目 ：TPO15-L2,TPO27-L3,TPO35-L4 重点词条： Cretaceous period, Pleistocene Epoch
TPO35-L5: Permian Extinction
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What does the professor mainly discuss?
- New evidence about what happened to dinosaurs
- New methods for gathering evidence about mass extinctions
- The link between two mascons from the Permian period
- A possible cause of the Permian extinction
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According to the professor, why did researchers begin looking for evidence that an asteroid may have caused the Permian extinction?
- They discovered that macrons on the Moon were caused by asteroid impacts.
- They found rock samples in Wilkes Land that appeared to be 250 million years old.
- The theory that an asteroid caused the dinosaur extinction gained acceptance.
- The theory about a decline in seawater oxygen levels proved to be false.
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Why does the professor mention getting a bump on the head?
- To help students understand an explanation of how a mascon forms
- To illustrate a theory about how the supercontinent broke apart
- To show the relationship between an asteroid and the dinosaur extinction
- To compare the dinosaur extinction to the Permian extinction
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What did researchers notice that could be evidence of an asteroid impact in Wilkes Land?
- A ring of ice containing a high concentration of oxygen
- A portion of Earth’s crust that is less dense than normal
- Extraterrestrial rock fragments lying below the ice
- Relatively high gravity measurements in the center of a circular ridge
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What does the professor emphasize about some of the rock samples taken from the Bedout High near Australia? Click on 2 answers.
- They are similar to the samples from the Yucatán peninsula in Mexico.
- They are from the same time period as the Permian extinction.
- They have been exposed to extreme temperatures and pressure.
- They contain fossils of many species that are now extinct.
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What does the professor imply when he says this: But don’t forget, the textbook makes it very clear—that’s only a theory.
- The student should read the assignments before coming to class.
- The student has not fully understood a statement in the textbook.
- The student has not provided sufficient evidence to disprove the theory in the textbook.
- The only reasonable explanation is the theory that the student suggests.
TPO35-L5: Permian Extinction
Listen to part of a lecture in an Earth science class.
| Professor: | Let’s review something from last week. We talked about an event that happened 65 million years ago… Anyone? |
| Student: | An |
| Professor: | Right, uh, I wouldn’t say that we’ve got 100 percent proof, but there’s very strong evidence that this is why that mass extinction occurred. OK, but did you know there was an earlier extinction – far greater than the one that killed off the dinosaurs? It was what we call the |
| Professor: | Now, way back about 290 million years ago-at the beginning of the Permian period, there was just one big continent, a |
| Professor: | But about 250 million years ago, the Permian period ended with a rapid mass extinction. Something happened that wiped out 75 percent of the land animals and over 95 percent of ocean life. |
| Professor: | So what was it? What could have caused this? Well, with all the evidence that it was an asteroid that led to the dinosaur extinction, we began asking ourselves: Is it possible that another asteroid… much earlier… caused the Permian extinction? And so researchers have been looking for an impact |
| Student: | I thought the Permian extinction was caused by a decline in |
| Professor: | But don’t forget, the textbook makes it very clear-that’s only a theory. |
| Student: | And it mentions something about |
| Professor: | It does. But now, this new theory has led to a search for evidence of an asteroid impact. And one place of interest is a region called Wilkes Land in eastern |
| Professor: | A few years ago, a researcher reported a strange |
| Professor: | When an asteroid hits Earth, when it slams into Earth’s crust, we think that causes molten rock from deep below the surface to rise up into the impact area – sort of like if you bump your head, you get a big lump under the skin… fluid makes the area swell. |
| Professor: | Anyway, the material flowing up from below the crust is more dense than the crust itself. So that’s how we get a mascon – a spot in the crust with newer crust material that’s more dense than the material all around it. |
| Professor: | There are lots of mascons on the Moon too, where a mascon’s density causes a small increase in the local gravity that can be measured and mapped by orbiting spacecraft. And where do these mascons tend to be found? In the centers of impact |
| Professor: | But back to Wilkes Land…We’re not certain that the mascon there… what might be a mascon… was actually caused by the impact of an asteroid, but there does seem to be evidence: researchers noticed a gravity anomaly similar to those on the Moon. And the spot where the gravity readings are especially high- this is right in the middle of a 500-kilometer-wide circular |
| Professor: | And if there was an asteroid impact there in Wilkes Land, the next question is- Did it happen 250 million years ago? Because that would put it when in geologic history? |
| Student: | At the end of the Permian period, right when all those animals went extinct. |
| Professor: | Exactly. |
| Student: | But… can’t researchers figure that out by studying the rocks there in Wilkes Land… where this impact |
| Professor: | Well, to get to anything from that long ago, we’d have to drill down through about a mile… about 1.6 kilometers… of solid ice that covers the area today. And that’s not likely to happen. |
| Professor: | But speaking of rocks, I should mention that Wilkes Land is not the only place of interest here. There’s another called the Bedout High…off the coast of Australia. |
| Professor: | And we have rock samples from the Bedout High- some apparently of |
地形地貌（Landscape）
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冻原（tundra）：冻原是植被（vegetation）覆盖甚少的平坦地面，主要分布在北极（arctic）的阿拉斯加（Alaska）。冻原包括两层：表层为活土层（active layer），下层为永久冻土层（permafrost）。活土层春、冬两季结冰，夏天解冻（thaw）;永久冻土层全年冰冻，植物的根和水都无法渗透（penetrate）进永久冻土层。随着北极地区的温度升高，冻原上的植被开始增加，主要增加的是灌木（shrub）。
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沙漠湖泊（desert lake）：阿拉伯半岛（Arabian Peninsula）上的沙漠（desert）区域曾经在季风（monsoon）的影响下形成绿洲（grassland）和星罗棋布的湖泊。在干旱的沙漠中形成湖泊需要两个条件：
- 这个地方有倾盆大雨（torrential），这样所有的雨水不会都渗入地下，给之后的湖泊提供水。
- 沙丘（sand dune）中除了沙子还有粘土（clay）和泥沙（silt）。雨水形成地表径流（runoff）带走粘土和泥沙，粘土和泥沙一旦沉降下来，就会形成水无法渗透的地层（layer），最终形成一个湖泊。
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湿地（wetland）：湿地是一层充满沼泽（marsh）的湿软土地，一年四季都有水覆盖着土壤表层。湿地有独特的生态系统，适宜多种植物、动物居住，而动物会释放出甲烷（methane）。人们尝试通过将水从湿地中引出，把湿地改造成适宜耕种的土地。但是，水的减少会降低当地的气温，带来霜冻（frost），不利于农作物生长。
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融沉湖（thaw lake）：阿拉斯加北部有大量融沉湖，湖的形状是椭圆形。融沉湖由冰楔（ice wedge）发展而来。当水流进地面裂缝，遇冷后产生冰楔，形成冻土。冻土在冬天会进一步收缩，加深裂缝。到了夏天，活土层开始融化，水流进裂缝。到了冬天水结成冰，由于水变成冰会膨胀，所以裂缝就像滚雪球般越变越大，越变越深。当冰楔大到一定程度时，在夏天冰融化后，活土层顶部形成湖泊，也就是融沉湖。
相关TPO篇目： TPO9-L2, TPO9-L3, TPO11-L3, TPO49-L1 重点词条： permafrost, runoff, ice wedge, thaw lake
TPO49-L2: Alaska Geologists
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What is the main purpose of the lecture? Click on 2 answers.
- To contrast how different kinds of thaw lakes grow
- To explain why a new theory of thaw lakes is gaining acceptance
- To explain how processes in permafrost lead to the formation of thaw lakes
- To describe two competing theories about the growth of thaw lakes
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The professor explains thaw lake formation as a cycle of events that occur repeatedly.Summarize this cycle, starting with the eventflled in below.
- A. Meltwater flows into cracks in permafrost.
- B. Ice wedges inside permafrost completely melt.
- C. Freezing water expands cracks in permafrost.
- D. Ice in the active layer melts as temperatures rise.
- E. Permafrost shrinks and cracks as temperatures drop.
参考答案：EDABC
PS：答案的分析参考原文中蓝线部分的内容，有三个需要注意的点，
- B选项和D选项很相像，其区别在于前者是completely，而后者强调了active layer，根据原文active layer是指代冰面的表层，是在融沉湖形成初期所观察到的情形
- 另一个误导点在于题目中两次出现了D选项的内容，一开始说是表层融化，但很快教授就意识到自己没有从一开始说，于是说了should I back up?所以D选项不应该是事件的起始
- 第三个误导点在于B和C选项的前后顺序，原文中虽然在同一句话中且C先于B出现，但根据因果关系，B事件（冰融化）应该发生C（裂缝扩大）之前
PS：最后的顺序应该是E->D->(A->B->C)->(A->B->C)->(A->B->C)…
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What is the significance of the ‘protective shelf’ discussed by the professor?
- It prevents the slumping of lake banks.
- It shields the lake surface from strong winds.
- It redirects the waves to lake banks that do not face the wind.
- It allows the lakes to grow in the same direction as the wind blows.
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According to the thaw slumping model, which side of a thaw lake grows fastest?
- The side where the bank is shortest
- The side least exposed to wind
- The side that is at the highest elevation
- The side opposite the protective shelf
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What is the professor’s opinion of the thaw slumping model?
- He thinks it was urgently needed.
- He is not convinced that it has a firm basis.
- He thinks it would be better if it were simplified.
- He does not think it is very different from the old model.
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Why does the professor say this: You ever see mud after it dries?
- He wants some information from the students.
- He thinks that the students may find an example helpful.
- He realizes that he forgot to mention an important topic.
- He wants to point out an important difference between frozen ground and dry ground.
TPO49-L2: Alaska Geologists
Listen to part of a lecture in a geology class.
| Professor: | Alaska is fascinating to geologists because of its incredible landscapes. Uh, |
| Professor: | The northern part of Alaska is covered in lakes—thousands of them—and most of these are what we call |
| Professor: | So, how these thaw lakes are formed has to do with…OK, it starts with |
| Professor: | You ever see mud after it dries? Dried mud has cracks, because when it dries, it contracts, it shrinks. Well, in winter, permafrost behaves similarly. |
| Professor: | Then in the summer, when |
| Professor: | |
| Professor: | Then in winter, the permafrost starts contracting again and the cracks open up even wider. So the next summer, when the active layer melts again and flows into the widened cracks…and…freezes… it makes the cracks even wider. So it’s sort of a cycle through which the cracks and the wedges grow wider and wider. |
| Professor: | So when the ice wedge reaches a certain size, its top part—in the active layer—turns into a little pond when it melts in the summer. And that’s the beginning of your thaw lake. |
| Professor: | There are thousands of them in northern Alaska. One of the most fascinating things about these lakes—and this is important—is that |
| Professor: | And what’s more, |
| Professor: | There’s been considerable research done to try to figure out what causes them to be shaped and oriented this way. We know that the shape and orientation are caused by the way the lakes grow once they’re formed, but the question is, what makes them grow this way? |
| Professor: | One theory sees winds as the cause. This region of Alaska has strong winds that blow |
| Professor: | Now, wouldn’t that erode the lake bank in that direction? The same direction as the wind? Well…no. |
| Professor: | Actually, what happens is that the |
| Professor: | The bank straight ahead is protected, but the lake currents–the waves– erode the banks to the sides. |
| Professor: | That’s the current model, um, |
| Professor: | Thaw slumping, um…OK. Sometimes, in the summer, the temperature rises pretty quickly. So the active layer of permafrost thaws faster than the water can drain from the soil. So the sides of the thaw lakes get, like, mushy, and slump, or slide, into the lake. |
| Professor: | Then, the lake water spreads out more, and the lake gets bigger, OK? Also, in that part of Alaska, the |
| Professor: | Now, this is an exaggeration of the angle—the hill isn’t this steep—but see how with the lake’s banks, the side that is farther downhill…it’s smaller, lower. This short bank thaws faster than the tall one does, so it falls into the lake—it slumps, much more and much faster than the other bank. |
| Professor: | When the short banks of many lakes slump, they move farther downhill and the lakes grow—all in the same downhill direction. This is a new theory, so it hasn’t been tested much yet. |
| Professor: | In field studies, when we’ve looked at the banks of these thaw lakes, there’s not much evidence of slumping. We’d expect to see cliff-like formations there, from the slumping, but we haven’t really found many of those. |
板块和火山（Plate and Volcano）
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板块（plate）：地球的地壳（crust）由板块构成，板块包括大陆（continent）板块和大洋（ocean）板块。当大陆、大洋板块相撞（collide），大洋板块会俯冲到大陆板块的下面，进入到上地幔。两个板块的交界处形成俯冲带（subduction zone），板块会不断受到岩板拉力（slab pull）的影响。板块之间的相互碰撞、挤压，会形成火山、地震、地热（geothermal energy）。
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火山主要分为两种：
- 地层火山（strata volcano）：地球上的火山大多是地层火山，源于板块（tectonic plates）运动。它在地球板块边界（boundary）受到挤压形成。地球的陆地和海洋里都有火山，水下火山（underwater volcano）的运动会抬升海底岩层，形成新的岛屿。
- 盾形火山（shield volcano）：地球上还有一些火山不在板块边界处，而在大陆或大洋板块的中心，例如：太平洋（the Pacific Ocean）中夏威夷岛（Hawaii islands）上的火山，美国黄石国家公园的火山，冰岛的火山。这一类火山叫做盾形火山，形状像盾牌（shield）。盾形火山由热点（hotspot）产生，而热点的形成一种存在争议，主流说法认为热点下方存在一股岩浆，导致热点形成。这种猜想被称之为plume hypothesis。值得一提的是，金星（Venus）上也有火山，而且金星上的火山是盾形火山（shield volcano）。
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岩浆（magma）和熔岩（lava）：岩浆和熔岩都是火山活动的产物。当熔融岩石（molten rock）还在地下没有喷发时，被称作岩浆；当它喷射出来，到达地表后，被称为熔岩。火山的喷发还会伴随释放出二氧化硫。
相关TPO 篇目： TPO10-L3,TPO24-L4,TPO31-2,TPO48-L2 重点词条： hotspot, magma
地表物质的沉积（Sediment）与移动
- 沉积物 （sediment） 是地表的沙石、经由风，河流，冰川 （glaciers） 所移动，日积月累，最后堆叠在地表所留下的物质。 通过研究沉积物以及其中的化石，可以帮助人类了解不同的地质时期的开始与结束。但水中的沉积物会导致水变浑浊，影响诸如珊瑚 （coral）, 鱼类的生存。例如，大马哈鱼（salmon） 产卵时对水的清澈度要求高，不能在充满沉积物的河床 （streambed）上产卵。
- 地表物质的移动主要有两类：
- 冰川（Glacier）：冰川在重力（gravity）的作用下会移动，有2种原因：
- 基面滑移（basal slip）：因为上方冰川的压力，导致底部冰川融点（melting temperature）降低，在0℃以下依然没有冻结，而是形成一层水。这层水减少了冰川与地面之间的摩擦（reduce friction），从而使得冰川可以滑动。
- 变形（deformation）：冰具有可塑性（plastic），在冰川的压力下，冰晶（ice crystals）会发生重组（reorganize）。在重组的过程中， 冰川发生移动，但这一过程非常缓慢。
- 岩石（Rock）：加州Death Valley的沙漠平原上，一些巨石发生了移动，并留下了明显的痕迹。强风（ powerful windstorm）、降雨或者冰，这些都无法解释这些巨石移动的原因。而且因为法律约束和自然条件限制，我们至今无法找到这些巨石移动的成因。
- 冰川（Glacier）：冰川在重力（gravity）的作用下会移动，有2种原因：
相关TPO篇目： TPO15-2,TPO52-L2 重点词条 ：sediment,glacier, salmon
相关TPO 篇目： TPO7-4,TPO4-L3 重点词条： glacier, basal slip
石灰岩洞（Limestone cave）
石灰岩洞（limestone cave)，又称作钟乳石洞、溶洞。依据其形成的方式，主要有两类石灰岩洞：
- 90%的石灰岩洞都是由流动的水（flowing water），如小溪（stream）、瀑布（waterfall）腐蚀形成的。这些流水中含有的碳酸（carbonic acid），作为弱酸，也具有腐蚀作用。
- 另一种石灰岩洞是由硫酸（sulfuric acid）腐蚀形成的。地下油藏（oil deposit）中的细菌在分解石油的过程中会释放硫化氢（hydrogen sulfide）气体，硫化氢和油藏上层的水以及氧气反应，形成硫酸。硫酸会迅速腐蚀石灰岩，最终形成溶洞。美国新墨西哥州的Lechuguilla Cave，就是典型的由硫酸形成的溶洞。
相关TPO 篇目： TPO16-L1 *该篇目在介绍Lechuguilla Cave形成的机理部分，因为术语过多，难度较高，属于TPO排名前12的高难度篇章。但是同学们用课上的方法处理，会非常简单。 重点词条： limestone cave, carbonic acid, sulfuric acid
