托福 新托福 45 - Microscopes The Beringia Landscape
题目
1 2 3 4 5 6 7 8 9 10
1.The word "remnants" in the passage is closest in meaning
  • A. remains
  • B.evidence
  • C.results
  • D. reminders
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    During the peak of the last ice age, northeast Asia (Siberia) and Alaska were connected by a broad land mass called the Bering Land Bridge. This land bridge existed because so much of Earth’s water was frozen in the great ice sheets that sea levels were over 100 meters lower than they are today. Between 25,000 and 10,000 years ago, Siberia, the Bering Land Bndge, and Alaska shared many environmental characteristics. These included a common mammalian fauna of large mammals, a common flora composed of broad grasslands as well as wind-swept dunes and tundra, and a common climate with cold, dry winters and somewhat warmer summers. The recognition that many aspects of the modem flora and fauna were present on both sides of the Bering Sea as remnants of the ice-age landscape led to this region being named Beringia.

    It is through Beringia that small groups of large mammal hunters, slowly expanding their hunting territories, eventually colonized North and South America. On this archaeologists generally agree, but that is where the agreement stops. One broad area of disagreement in explaining the peopling of the Americas is the domain of paleoecologists, but it is critical to understanding human history: what was Beringia like?

    The Beringian landscape was very different from what it is today. Broad, windswept valleys; glaciated mountains; sparse vegetation; and less moisture created a rather forbidding land mass. This land mass supported herds of now-extinct species of mammoth, bison, and horse and somewhat modern versions of caribou, musk ox, elk, and saiga antelope. These grazers supported in turn a number of impressive carnivores, including the giant short-faced bear, the saber-tooth cat, and a large species of lion.

    The presence of mammal species that require grassland vegetation has led Arctic biologist Dale Guthrie to argue that while cold and dry, there must have been broad areas of dense vegetation to support herds of mammoth, horse, and bison. Further, nearly all of the ice-age fauna had teeth that indicate an adaptation to grasses and sedges; they could not have been supported by a modern flora of mosses and lichens. Guthrie has also demonstrated that the landscape must have been subject to intense and continuous winds, especially in winter. He makes this argument based on the anatomy of horse and bison, which do not have the ability to search for food through deep snow cover. They need landscapes with strong winds that remove the winter snows, exposing the dry grasses beneath. Guthrie applied the term “ mammoth steppe" to characterize this landscape.

    In contrast, Paul Colinvaux has offered a counterargument based on the analysis of pollen in lake sediments dating to the last ice age. He found that the amount of pollen recovered in these sediments is so low that the Beringian landscape during the peak of the last glaciation was more likely to have been what he termed a "polar desert," with little or only sparse vegetation, in no way was it possible that this region could have supported large herds of mammals and thus, human hunters. Guthrie has argued against this view by pointing out that radiocarbon analysis of mammoth, horse, and bison bones from Beringian deposits revealed that the bones date to the period of most intense glaciation.

    The argument seemed to be at a standstill until a number of recent studies resulted in a spectacular suite of new finds. The first was the discovery of a 1,000-square-kilometer preserved patch of Beringian vegetation dating to just over 17,000 years ago—the peak of the last ice age The plants were preserved under a thick ash fall from a volcanic eruption. Investigations of the plants found grasses, sedges, mosses, and many other varieties in a nearly continuous cover, as was predicted by Guthrie. But this vegetation had a thin root mat with no soil formation, demonstrating that there was little long-term stability in plant cover, a finding supporting some of the arguments of Colinvaux. A mixture of continuous but thin vegetation supporting herds of large mammals is one that seems plausible and realistic with the available data.

    上一次冰期高峰,东北亚(西伯利亚)和阿拉斯加被一名为白令陆桥的广阔大陆块连接起来。这座大陆桥的出现是因为,那时候地球上大量的水被冻结成巨大的冰盖,所以海平面比现在低100米(即大陆桥就露出来了)。在10000年到25000年之前,西伯利亚、白令大陆桥和阿拉斯加有许多共同的环境特征。其中包括,这三个地方都有常见的由大型哺乳动物组成的哺乳动物群和由广袤的草地、寒风凌厉的沙丘和冻原组成的植物群,以及冬季寒冷干燥、夏季校暖和的气候。人们认为现在白令海两岸的植物群和动物群在许多方面都可以被认为是冰河时代的残存者,所以这个地区被命名为白令陆桥。 正是通过白令陆桥,一些捕捉大型哺乳动物的猎人小团体慢慢地扩大了他们的狩猎领地,最终占领了美洲的北部和南部。在这一点上考古学家普遍表示认同,但是在其他方面大家就产生了分歧。在解释美洲印第安人的居住情况时产生的一个比较大的分歧在于古生物学的范畴,但这关键是要理解人类历史:那时候的白令陆桥是什么样的? 彼时白令陆桥的景观与如今大不相同。那时山谷宽广,海风吹拂,山脉被冰覆盖,植被稀疏;降水稀少,令人望而生畏。这个陆块中生存着成群的现今已灭绝的猛犸象、野牛、马,以及现代版的驯鹿、麝牛、麋鹿和赛加羚羊。以这些食草动物为食的是大型食肉动物,包括巨型短面熊、剑齿猫、和大型狮子。 哺乳动物的存在需要草地植被,这使得北极生物学家戴尔·古思莱认为虽然白令陆桥地区寒冷干燥,但是应该有大面积的茂密植被来养活庞大的猛犸群、马群和野牛群。此外,几乎所有冰河时代动物的牙齿都表明它们适应了禾草和莎草;他们不可能只吃现代植物苔藓和地衣。古思莱还表明,陆桥地区应该时常持续刮强风,特别是在冬季。对野马和野牛的解剖可以发现它们没有穿过深雪寻找食物的能力,这就证明了他的论点。野马和野牛需要大风吹走积雪,使得下面的干草显露出来。古思莱用了“猛犸草原”一词来描述陆桥地区。 与这个论点相反,保罗.柯林沃斯基于对湖泊沉积物中发现的可追溯至冰河时期的花粉的研究,提出了反对论据。他发现,在这些沉积物中的花粉是如此之少,以至于他认为末次冰河时代高峰期的白令陆桥很可能是“极地荒漠”,由于植被稀疏,所以这个地区不可能养活那么大群的大型哺乳动物,因此也不会有那么多猎人。古思莱表示反对,他指出,对白令陆桥地区猛犸象、马、草原野牛的骨头沉积物进行放射性碳定年分析发现这些骨头可以追溯到冰川作用最强烈的时期。 两种观点一直以来处于僵持状态,直到最近才有了一些重大的新发现。首先是发现了一个保存下来的1000平方公里的白令陆桥植被区,该植被区可以追溯到17000多年前,也就是上一次冰期高峰。植被区被火山喷发出来的厚厚的灰烬覆盖,故而得以保存。对其调查发现,正如古思莱预测的那样,在这几乎不断的灰层覆盖之下,这个地区生长着包括禾草、莎草、苔藓在内的多种植物。不过这个植被区有一层细细的根系,但是并没有土壤形成,说明本地区的植被不具备长期稳定性,这与柯林沃斯的一些观点吻合。以现有的数据来看,目前看似合理和现实的解释是,大型哺乳动物群是以这些连续生长的、薄薄的植被层为食的。

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    最新提问
    • wx_6697
      觉得B C 意思一样,不知道选哪个
    • wx_5576
      这道题C为什么对,E为什么不对?
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      B为什么不能选啊?
    • wx_6697
      TPO30 passage 2 Q5我选的 D,不明白为啥不对?
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      鑫哥,TPO6passage3Q5 答案是给错了吗?好多人都选A
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      这题也很容易选错选成了D
    • wx_6697
      这道题A为什么错了
    • 芊儿
      为什么这道题不选c??a中的variety不是应该对应文中的differentiating 吗??求解!
    • wx_1000
      这道题不选E是因为太细节了吗
    • 王金阁
      这个题为什么不选C啊。。。
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      这道题的D选项不是和文中的better able to reproduce in open settings相对应么??
    • 风荨火
      有大佬解释一下这个为啥选D嘛?
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      鑫哥,这道题D是从哪里看出来的
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      这题我选的是C依据是into a new habitat outside of its natural range, it may adapt to the new environment and leave its enemies behind.C为啥错了呢?鑫哥
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      F选项的weather-related destruction在哪里体现了呢?原文最后一段的开头Among the costs里的costs是不是打错了?应该是coast?
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      这题为什么选C?
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B哪里错了
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B为啥不对
    • 李浩然
      B选项错误,是因为残缺么?
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    • wx xxxxx
      请问鑫哥,这段开头有写As one pesticide replaces another为什么不是对应a new pesticide is developed?
    • wx_7695
      鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
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      @鑫哥,这题the damage will continue 不应该对应前面的 the target species evolves resistance to it,然后As one pesticide replaces another,不应该是结束了time cycle 吗
    • wx_2065
      鑫哥,想知道E错在哪里?
    • wx_7695
      鑫哥,B选项 cannot extended to earlier geological periods. 原文说的意思是后来的进化无法估计吧
    • wx_2163
      B为什么不选
    • wx_7780
      鑫哥,这个哪里看不use了。BD是修饰错,C是无中生有,怎么能直接选出A?
    • 100
      看到第一句话,以为是中心句就选了A... 为什么不能选A呢
    • 100
      为什么选b?
    • gu33
      请问下 这里选D的原因是 因为 evolutionary approach 对应着 原文的 Rates of evolution 嘛? 这里我选了C。。不是很懂 插入句和 D的关系 求解答
    • 我是啦啦啦
      我是啦啦啦 去解答 去解答
      这个题A哪里错了?是因为主语不对吗?这个C比A多一步推理啊
    • haiyuqiao
      鑫哥,D选项里的19世纪出现了很多假设,原文中并没有提到啊
    • wx_7060
      为什么选a 呢。我觉得a是细节。F哪错了?
    • wx_1105
      我想问一下,这道题为什么不能选A呢?
    • wx_8122
      D为什么不选
    • wx_1655
      f选项哪里说了
    • chaulaw
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    • chaulaw
      interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
    • wx_6697
      鑫哥,这道题答案是不是错了,好多人选D 我也选的D求解答
    • wx_6697
      这道题应该是一道易错题,每个选项的都有,然而我选的A错了,求解
    • wx_6697
      鑫哥,这题的C是怎么得到的?B也没有找到啊?难道不是应该选B
    • wx_6697
      鑫哥,还有这个,好多人选A答案是不是错了
    • wx_6697
      求问D是从哪里得出来的,我选的B呀哎呀
    • wx_4185
      it is difficult to say how far they were intended to be portraits rather than generalized images 这句话怎么理解呢
    • 此楠楠
      请问下这个插入题怎么选的呢?
    • 此楠楠
      求鑫哥讲解下A选项。。。 Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.