您IP所在的地区,暂不支持官方真题素材

建议使用其他功能进行听力练习

返回
小站备考
托福
托福听力
Official15听力真题

托福official15听力lecture2 Geologic Time Periods原文解析+翻译音频

展开
Tip:单击查看句义;划选/双击查生词

[00:00.00]Narrator: Listen to part of a lecture in a geology class.[00:04.94]MALE PROFESSOR: As geologists, we examine layers of sediment on the Earth's surface to approximate the dates of past geologic time periods. [00:13.92]Uh, sediment, as you know, is material like sand, gravel ⋯ fossil fragments ⋯ that is transported by natural processes, like wind, water flow, or the movement of glaciers. [00:26.80]So, uh, sediment is transported, and then deposited, and it forms layers on the Earth's surface over time. [00:35.38]We examine these layers to learn about different geologic time periods, including when they began and ended.[00:42.58]Uh, for example, from about 1.8 million years ago to around 11,000 years ago was the Pleistocene epoch.[00:53.41]The Pleistocene epoch was an ice age. [00:58.96]Uh, during this epoch, sediment was made by the kind of erosion and weathering that happens when the climate is colder. [01:05.89]And part of those sediments are fossils of plants and animals that lived at that time.
[01:11.94]The Holocene epoch followed the Pleistocene epoch when the Earth's climate warmed up around 11,000 years ago.[01:20.58]The Holocene epoch is characterized by different sediments ⋯ ones that form when the climate is warmer. [01:29.34]Because the climate changed, the types of plants and animals changed also. [01:35.44]Holocene sediments contain remnants of more recent plants and animals. [01:40.28]So it’s pretty easy to differentiate, geologically, between these two epochs.[01:46.51]Now there’s growing evidence that the presence of humans has altered the Earth so much that a new epoch of geologic history has begun ⋯ the Anthropocene epoch, a new, human-influenced epoch.[02:03.43]This idea, that we've entered a new, Anthropocene epoch, was first proposed in 2002. [02:12.29]The idea is that around the year eighteen hundred C.E., the human population became large enough, around a billion people, that its activities started altering the environment.
[02:25.85]This was also the time of the Industrial Revolution, which brought a tremendous increase in the use of fossil fuels, such as coal. [02:34.83]The exploitation of fossil fuels has brought planetwide developments—industrialization, construction, uh, mass transport. And these developments have caused major changes, like additional erosion of the Earth's surface and deforestation.
[02:53.40]Also, things like the damming of rivers has caused increased sediment production. Not to mention uh, the addition of more carbon dioxide and methane in the atmosphere. [03:04.53]Naturally, all these changes show up in recent sediments. And these sediments are quite different from pre-year eighteen hundred sediment layers.
[03:15.68]Interestingly, there's some speculation that humans started having a major impact on Earth much earlier, about 8,000 years ago. That's when agriculture was becoming widespread. [03:29.19]Early farmers started clearing forests, and livestock produced a lot of extra methane. [03:35.25]But I want to stress that this is just a hypothesis. [03:39.66]The idea that early humans could’ve had such a major effect, well ⋯ I'm just not sure we can compare it with the Industrial Age.[03:48.96]Geologists in the far future will be able to examine the sediment being laid down today. Whereas right now we can say that yes, human impact on the Earth is clear, [04:01.71]it'll be future researchers who'll have a better perspective and will be able to really draw a line between the Holocene and the Anthropocene epochs.

1.What is the lecture mainly about?

你的答案:
正确答案:A
题目解析:
 后才能查看题目解析,还没有账号? 马上注册
We examine these layers to learn about different geologic time periods including when they began and ended. 开头一定要认真听的,总起句。而后则是三个时期的确定。B,D文章没提,C不是主旨,是其中一个重要细节。

学习页面

Medi

terr

anean

加强 + 政府 + 名词后缀

加强的政府——管理

原文例句

加入生词

本文生词 0

色块区域是你收藏过的生词;

查询次数越多,颜色越深哦~

显示文中生词

登录后才能收藏生词哦,现在登录注册>

本文重点词 45

文中加粗单词为本文重点词;

根据词频与核心词范围精心挑选,托福考试必掌握词汇。

显示文中重点词
学习本文词汇

文中划选/双击的生词、加粗重点词已收纳至词盒

可随时点击词盒查看哦~

只有在词句精学模式下才能开启词盒功能哦~

我知道了

词盒
收藏
笔记
我的笔记
5000
保存
反馈