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Narrator:Listen to part of a lecture in a geology class.
獨白:聽下面一段地質學課堂演講
Professor:As geologists, we examine layers of sediment on the Earth's surface to approximate the dates of past geologic time periods.
教授:作為地質學家，我們檢查地球表面的沉積層來評估過去地質時期的年代。
Ah sediment as you know i s material like sand, gravel, fossil fragments that is transported by natural processes like wind, water flow or the movement of glaciers.
呃，沉淀物就是一些像沙子、碎石、化石脆片等物質，由自然過程如風、流水或者冰川移動等進行轉移。
So sediment is transported and then deposited and it forms layers on the Earth's surface over time.
沉淀物被轉移然后沉積，并隨著時間的流逝在地球表層形成層。
We examine these layers to learn about different geologic time periods including when they began and ended.
我們研究這些層來得知不同地質時期的信息，包括它們的起止時間。
For example, from about 1.8 million years ago to around 11 thousand years ago was the Pleistocene epic.
比如，從大約 180 萬年前到 11,000 年前左右是更新世時期。
The Pleistocene epic was an ice age.
更新世時期是冰河時期。
During this epic, sediment was made by the kind of erosion and we athering that happens when the climate is colder, and part of those sediments are fossils of plants and animals that lived at that time.
在這個時期，沉淀物是由腐蝕物構成，我們推斷當時氣候更加寒冷，沉淀物中的一部分是當時動植物的化石。
The Holocene epic followed the Pleistocene epic when the Earth's climate warmed up around 11 thousand years ago.
全新世時期在更新世之后，是在大約11,000 年前氣候開始變暖的階段。
The Holocene epic is characterized by different sediments, ones that form when the climate is warmer.
全新世沉積物的特征是各種各樣，都是在氣候變暖后形成的。
Because the climate changed, the types of plants and animals changed also.
由于氣候變化，動植物的類型也有所變化。
Holocene sediments contain remnants of more recent plants and animals, so it's pretty easy to differentiate geologically between these two epics.
全新世沉淀物包含了更接近現代的動植物的殘骸，因此在地質上也很好區分這兩個時期。
Now there is growing evidence that the presence of humans has altered the earth so much that a new epic of geologic history has begun-the Anthropocene epic, a new human-influenced epic.
現在有越來越多的證據顯示人類的存在已經很大程度上的改變了地球，以至于開始了地質歷史的一個新紀元-人類世，一個全新的人類主導的時期。
This idea that we've entered a new Anthropocene epic was first proposed in 2002.
我們進入人類世的這種說法第一次是在 2002 年提出。
The idea is that around the year 1800 CE the human population became large enough, around a billion people, that its activities started altering the environment.
這種說法是說在大約 1800 年人類人口已經足夠多，達到 10 億左右，人類的活動已經改變了環境。
This was also the time of the industrial revolution, which brought a tremendous increase in the use of fossil fuels such as coal.
這也是工業革命時期，人類使用煤等化石燃料也大幅度上升。
The exploitation of fossil fuels has brought planet wide developments:industrialization, construction, uh, mass transport.
對化石燃料的開發給地球帶來了廣泛的發展，工業、建筑，還有大宗運輸。
And these developments have caused major changes like additional erosion of the Earth's surface and deforestation.
而這些發展就引發了巨大的變化，如地球表面額外的腐蝕以及森林采伐。
Also, things like the damming of rivers, has caused increased sediment production, not to mention the addition of more carbon dioxide and methane in the atmosphere.
同樣，像給河筑壩，也會導致沉積物的增加，更不要說大氣層中更多的二氧化碳和甲烷了。
Naturally all these changes show up in recent sediments.
很自然的這些變化就會在近期的沉淀物中展現出來。
And these sediments are quite different from pre year 1800 sediment layers.
這些沉淀物與 1800 年前的沉積層有很大不同。
Interestingly there's some speculation that humans started having a major impact on Earth much earlier, about 8000 years ago.
有趣的是，還有一種猜測是人類早在 8000 年前就對地球產生了巨大的影響,
That's when agriculture was becoming widespread.
也就是農業開始廣泛開展的時期。
Early farmers started clearing forests and livestock produced a lot of extra methane.
早期的農民開始清除森林和家畜來生產出大量額外的甲烷。
But I want to stress this is just a hypothesis.
但是我想強調一下這只是一個猜想。
The idea that early humans could have had such a major effect, well I'm just not sure we can compare it with the industrial age.
這種早期人類造成的巨大影響的說法，我只是不確定能否將它與工業時期來相比。
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:
未來的地質學家將能檢查今天的沉積物，然而現在我想說的是，人類對地球的影響是顯而易見的，
It'll be future researchers who have better perspective and will be able to really draw a line between the Holocene and the Anthropocene epics.
但是將來的研究人員會有更好的視角并能將全新世與人類世劃分開來。
