All right, let's get up our picture of the earth. The earth is pretty awesome. I'm a geologist, so I get pretty psyched about this, but the earth is great. It's powerful, it's dynamic, it's constantly changing. It's a pretty exciting place to live. But I want to share with you guys today my perspective as a geologist in how understanding earth's past can help inform and guide decisions that we make today about how to sustainably live on earth's surface.
好,我們先來看一下地球的圖片。 地球是很了不起的。 我是地質學家, 所以我對這點十分亢奮。 但地球很棒, 它很強大、它是動態的、 它不斷在改變, 住在地球是很讓人興奮的。 但我今天想和大家分享的, 是我身為地質學家的觀點, 來談談了解地球的過去, 如何能提供我們資訊和導引, 協助我們在現今做出關於 如何在地球表面永續居住的決策。
So there's a lot of exciting things that go on on the surface of the earth. If we zoom in here a little bit, I want to talk to you guys a little bit about one of the things that happens. Material get shuffled around earth's surface all the time, and one of the big thing that happens is material from high mountains gets eroded and transported and deposited in the sea. And this process is ongoing all the time, and it has huge effects on how the landscape works. So this example here in south India -- we have some of the biggest mountains in the world, and you can see in this satellite photo rivers transporting material from those mountains out to the sea. You can think of these rivers like bulldozers. They're basically taking these mountains and pushing them down towards the sea.
在地球表面上, 有許多讓人興奮的事物在發生。 如果我們把這裡放大一點, 我想要跟大家談一下, 其中一件正在發生的事: 物質隨時在地球表面上移來移去, 其中一件在發生的大事, 就是來自高山的物質 會被侵蝕、運送、沉澱到大海中。 這個過程一直在進行中, 它對於地景有很大的影響。 這裡的例子是南印度, 這裡有一些世界最大的山。 從衛星照片可以看見, 河流將物質從那些山 向外運送到大海。 你可以把這些河流想像成推土機, 基本上,它們是在 將這些山推移向大海。
We'll give you guys an example here. So we zoom in a little bit. I want to talk to you guys specifically about a river. We can see these beautiful patterns that the rivers make as they're pushing material down to the sea, but these patterns aren't static. These rivers are wiggling and jumping around quite a bit, and it can have big impacts on our lives.
我會給大家看一個例子。 再放大一點來看。 我想要跟你們談的是一條河。 你們可以看見河流 在把物質推向大海的同時, 構成了很漂亮的圖案, 但這些圖案不是靜態不變的, 這些河流挺會擺動和跳動的, 這對我們的生活有很大的影響。
So an example of this is this is the Kosi River. So the Kosi River has this nice c-shaped pathway, and it exits the big mountains of Nepal carrying with it a ton of material, a lot of sediments that's being eroded from the high mountains, and it spreads out across India and moves this material. So we're going to zoom in to this area and I'm going to tell you a little bit about what happened with the Kosi. It's an example of how dynamic these systems can be. So this is a satellite image from August of 2008, and this satellite image is colored so that vegetations or plants show up as green and water shows up as blue. So here again you can see that c-shaped pathway that this river takes as it exits Nepal. And now this is monsoon season. August is monsoon season in this region of the world, and anyone that lives near a river is no stranger to flooding and the hazards and inconveniences at minimum that are associated with that. But something interesting happened in 2008, and this river moved in a way that's very different. It flooded in a way that's very different than it normally does. So the Kosi River is flowing down here, but sometimes as these rivers are bulldozing sediment, they kind of get clogged, and these clogs can actually cause the rivers to shift their course dramatically. So this satellite image is from just two weeks later. Here's the previous pathway, that c-shaped pathway, and you notice it's not blue anymore. But now what we have is this blue pathway that cuts down the middle of the field of view here. What happened is the Kosi River jumped its banks, and for reference, the scale bar here is 40 miles. This river moved over 30 miles very abruptly. So this river got clogged and it jumped its banks. Here's an image from about a week later, and you can see these are the previous pathways, and you can see this process of river-jumping continues as this river moves farther away from its major course.
這裡是一個例子:戈西河。 戈西河有個很完好的 C 形路徑, 它從尼泊爾的大型山岳出海, 帶著一大堆的物質, 很多從高山侵蝕下來的沉積物。 它佈及整個印度, 移動著這些物質。 我們再把這個區域放大, 我要告訴各位戈西河的狀況。 這個例子可以說明 這些系統有多動態。 這是一張衛星影像, 於 2008 年 8 月拍攝。 這張衛星影像是彩色的, 植被和植物會以綠色呈現, 水會用藍色呈現。 你可以再次看到 C 形路徑, 這條河流從尼泊爾出海。 這時期是季風季, 在這個區域,八月是季風季。 住在河流附近的人, 對於洪水絕對不陌生, 且肯定也很熟悉洪水 帶來的危險以及不便。 但在 2008 年發生了 一件很有意思的事, 這條河流的移動方式變得非常不同, 它泛濫的方式也和平時非常不同。 戈西河在這裡向下流, 但有時,當這些河流 在推動沉積物時, 它們會像是塞住了。 這些堵塞會造成河流 顯著轉變它們的路線。 這張衛星影像是兩週後拍的, 這是先前的路徑, C 形的路徑。 你可以注意到,它不再是藍色的了。 現在我們多了這條藍色路徑, 從畫面的中間切下來。 發生的事是: 戈西河躍過了它的堤岸。 供大家參考,這條比例尺的 長度是 40 英哩。 這條河流非常突然地 移動了超過 30 英哩。 這條河流被堵塞, 接著躍過了它的堤岸。 這是大約一週後的影像。 可以看見這些是先前的路徑, 且可以看見這個 河流跳躍的過程還在持續著, 這條河流離它的主河道越來越遠。
So you can imagine in landscapes like this, where rivers move around frequently, it's really important to understand when, where and how they're going to jump. But these kinds of processes also happen a lot closer to home as well. So in the United States, we have the Mississippi River that drains most of the continental US. It pushes material from the Rocky Mountains and from the Great Plains. It drains it and moves it all the way across America and dumps it out in the Gulf of Mexico. So this is the course of the Mississippi that we're familiar with today, but it didn't always flow in this direction. If we use the geologic record, we can reconstruct where it went in the past. So for example, this red area here is where we know the Mississippi River flowed and deposited material about 4,600 years ago. Then about 3,500 years ago it moved to follow the course outlined here in orange. And it kept moving and it keeps moving. So here's about 2,000 years ago, a thousand years ago, 700 years ago. And it was only as recently as 500 years ago that it occupied the pathway that we're familiar with today. So these processes are really important, and especially here, this delta area, where these river-jumping events in the Mississippi are building land at the interface of the land and the sea. This is really valuable real estate, and deltas like this are some of the most densely populated areas on our planet. So understanding the dynamics of these landscapes, how they formed and how they will continue to change in the future is really important for the people that live there.
你可以想像,在這種河流 常會到處移動的地景中, 知道它們何時、在哪兒、 以及如何跳躍是非常重要的。 但這類過程也會在離家 更近的地方常常發生, 在美國, 我們有密西西比河, 流過幾乎整個美國大陸, 它把物質從洛磯山脈, 以及北美大平原推走。 它帶著物質,一路穿越美國, 然後將物質倒在墨西哥灣。 這是我們現今很熟悉的 密西西比河路線, 但它之前並非都是流向這個方向的。 如果我們使用地理記錄, 我們可以重新建造出 它過去流過的路線。 比如,這裡的紅色區域 是據我們所知在 4600 年前密西西比河 流過並將物質沉積的地方。 接著,約 3500 年前,它移動了, 延著這裡用橘色標出的路線流動。 它不斷、不斷地移動。 這是約 2000 年前、 1000 年前、 700 年前。 一直要到 500 年前 這麼近期的時候, 它才移到了我們現今熟悉的路徑。 這些過程非常重要, 特別是這裡,這個三角區域, 在這裡,這些 密西西比河的跳躍事件 在土地和海洋的接介處建立了土地。 這是非常珍貴的不動產, 地球上有許多人口密度最高的 區域都是像這樣的三角洲。 所以,了解這些地景的動態、 它們如何形成、 以及它們未來會如何持續改變, 對於居住在那兒的人而言, 是非常重要的。
So rivers also wiggle. These are sort of bigger jumps that we've been talking about. I want to show you guys some river wiggles here. So we're going to fly down to the Amazon River basin, and here again we have a big river system that is draining and moving and plowing material from the Andean Mountains, transporting it across South America and dumping it out into the Atlantic Ocean. So if we zoom in here, you guys can see these nice, curvy river pathways. Again, they're really beautiful, but again, they're not static. These rivers wiggle around. We can use satellite imagery over the last 30 or so years to actually monitor how these change. So take a minute and just watch any bend or curve in this river, and you'll see it doesn't stay in the same place for very long. It changes and evolves and warps its pattern. If you look in this area in particular, I want you guys to notice there's a sort of a loop in the river that gets completely cut off. It's almost like a whip cracking and snaps off the pathway of the river at a certain spot. So just for reference, again, in this location, that river changed its course over four miles over the course of a season or two.
所以,河流也會曲行。 這些是我們先前談到的大跳躍。 我想讓大家看一些河流的曲行, 所以我們要飛去亞瑪遜河盆地, 在這裡我們也有很大的河流系統, 將物質從安地斯山脈取下, 運輸到南美的另一端, 將它丟在大西洋中。 我們把這裡放大, 讓大家能看見這些彎曲的路徑。 同樣地,它們也很漂亮, 但也同樣地,它們不是靜態的。 這些河流會到處曲行。 我們可以用 過去 30 年的衛星影像, 來監看這些改變。 花一點時間,看著這條河的彎曲處, 你會發現它並不會在同一處 停留很長的時間。 它會改變、會演化、 會扭曲它的路線。 我們可以特別看一下這個區域, 請大家注意,河流的這裡 有一個像是迴圈的狀況, 是完全切割開來的。 幾乎就像是鞭子猛擊過去, 在某個點把河流的路徑給打斷。 這比例尺同樣也是參考用, 在這個地方,河流路徑改變了 4 英哩, 且只花了一到兩季的時間。
So the landscapes that we live in on earth, as this material is being eroded from the mountains and transported to the sea, are wiggling around all the time. They're changing all the time, and we need to be able to understand these processes so we can manage and live sustainably on these landscapes. But it's hard to do if the only information we have is what's going on today at earth's surface. Right? We don't have a lot of observations. We only have 30 years' worth of satellite photos, for example. We need more observations to understand these processes more. And additionally, we need to know how these landscapes are going to respond to changing climate and to changing land use as we continue to occupy and modify earth's surface.
所以在地球上我們所居住的地景, 隨著這些物質從山上被侵蝕下來 並運送到海洋, 隨時隨地都在移動。 它們無時無刻不在改變, 而我們必須要了解這些過程, 才能在這些地景中 以永續的方式生活下去。 但是,如果我們手上只有 關於現今地球表面 發生什麼狀況的資訊, 就很難做到。 對吧?我們並沒有很多觀察資料。 比如,我們的衛星照片 就只有近 30 年的。 我們需要更多的觀察 才能更了解這些過程。 此外,我們得要知道 這些地景對於氣候變遷、 以及因我們持續佔領和改變地球表面 而造成的土地使用改變, 將會有什麼反應。
So this is where the rocks come in. So as rivers flow, as they're bulldozing material from the mountains to the sea, sometimes bits of sand and clay and rock get stuck in the ground. And that stuff that gets stuck in the ground gets buried, and through time, we get big, thick accumulations of sediments that eventually turn into rocks. What this means is that we can go to places like this, where we see big, thick stacks of sedimentary rocks, and go back in time and see what the landscapes looked like in the past. We can do this to help reconstruct and understand how earth landscapes evolve. This is pretty convenient, too, because the earth has had sort of an epic history. Right? So this video here is a reconstruction of paleogeography for just the first 600 million years of earth's history. So just a little bit of time here. So as the plates move around, we know climate has changed, sea level has changed, we have a lot of different types of landscapes and different types of environments that we can go back -- if we have a time machine -- we can go back and look at, and we do indeed have a time machine because we can look at the rocks that were deposited at these times.
這就是要來談岩石的地方了。 隨著河流流動, 隨著它們把物質從山上推到海中, 有些沙、泥、石頭會卡在地上, 卡在地上的這些東西就會被埋掉, 隨著時間,會讓沉積物更多更厚, 最終變成岩石。 這意味著,我們可以到 圖上的這種地方, 在這裡會看到厚實的 層層大型沉積岩, 再回到過去, 看看過去的地景是什麼樣子的。 我們可以這樣做,來重新建造 並了解地球地景是如何演化的。 這也挺方便的, 因為地球的歷史還蠻壯觀的,對吧? 這段影片是古地理學的重建, 它僅呈現了地球歷史的前六億年。 只是一點點時間而已。 隨著板塊移動, 我們知道氣候改變了、 海平面改變了, 我們有許多不同的地景, 及不同型的環境, 如果我們有時光機, 就可以回到過去, 我們可以回去看看, 且我們的確有時光機, 因為我們可以去看 這些時代所沉積的岩石。
So I'm going to give you an example of this and take you to a special time in earth's past. About 55 million years ago, there was a really abrupt warming event, and what happened was a whole bunch of carbon dioxide was released into earth's atmosphere, and it caused a rapid and pretty extreme global warming event. And when I say warm, I mean pretty warm, that there were things like crocodiles and palm trees as far north as Canada and as far south as Patagonia. So this was a pretty warm time and it happened really abruptly. So what we can do is we can go back and find rocks that were deposited at this time and reconstruct how the landscape changed in response to this warming event.
讓我來舉個例子, 帶大家回到地球 過去的一個特殊時點, 大約五千五百萬年前, 當時的狀況是有大量的二氧化碳 被排放到地球的大氣層, 造成了快速且極端的全球暖化事件。 我說的暖化,是非常暖的暖化, 當時甚至會有鱷魚和棕櫚樹, 出現在很北方如加拿大、 以及很南方如巴塔哥尼亞的地方。 這是相當溫暖的時期, 且發生的非常突然。 我們能做的是, 回到過去,找出 在這個時期沉積的岩石, 然後重建出因應這暖化事件 而改變的地景。
So here, yay, rocks.
所以,這裡是──太棒了,岩石。
(Laughter)
(笑聲)
Here's a pile of rocks. This yellow blob here, this is actually a fossil river, so just like this cartoon I showed, these are deposits that were laid down 55 million years ago. As geologists, we can go and look at these up close and reconstruct the landscape. So here's another example. The yellow blob here is a fossil river. Here's another one above it. We can go and look in detail and make measurements and observations, and we can measure features. For example, the features I just highlighted there tell us that this particular river was probably about three feet deep. You could wade across this cute little stream if you were walking around 55 million years ago. The reddish stuff that's above and below those channels, those are ancient soil deposits. So we can look at those to tell us what lived and grew on the landscape and to understand how these rivers were interacting with their floodplains. So we can look in detail and reconstruct with some specificity how these rivers flowed and what the landscapes looked like. So when we do this for this particular place at this time, if we look what happened before this abrupt warming event, the rivers kind of carved their way down from the mountains to the sea, and they looked maybe similar to what I showed you in the Amazon River basin. But right at the onset of this climate change event, the rivers change dramatically. All of a sudden they got much broader, and they started to slide back and forth across the landscape more readily. Eventually, the rivers reverted back to a state that was more similar to what they would have looked like before this climate event, but it took a long, long time.
這裡有一堆岩石。 這裡黃色的部份, 其實是古河流, 就像我剛剛展示的連環圖, 這些沉積是五千五百萬年前發生的。 身為地質學家, 我們可以更近距離去看, 並重建出地景來。 這裡還有另一個例子。 這裡的黃色部份是古河流。 上面還有一條。 我們可以更細部去看, 並做些測量與觀察, 我們可以去測量特徵。 比如,我剛剛強調出來的特徵, 告訴我們這條河流可能有三英呎深。 如果五千五百萬年前你在這裡行走, 你可以徒步跋涉通過這條小溪。 這些河床上面和下面的紅色部份, 是古時的土壤沉積。 看著這些,我們就可以知道 在這地景上住著或生長著什麼, 並了解這些河流如何 與它們的泛濫平原互動。 我們可以去看細節, 並更明確地重建出 這些河流如何流動、 以及當時地景是什麼樣子。 當我們針對這個時期的特定地點 這麼做時, 如果我們去探究在突發暖化事件 之前發生了什麼事, 河流有點像是從 山上切下一條路通往海洋, 看起來會有點像是我先前展示的 亞瑪遜盆地的狀況。 但就在這氣候變遷甚至開始時, 河流有了戲劇性的改變, 突然間它們變寬許多, 且它們開始更快速地 在地景上前後滑動。 最終,河流回復到類似 氣候事件發生之前的狀態, 但這花了非常長的時間。
So we can go back in earth's time and do these kinds of reconstructions and understand how earth's landscape has changed in response to a climate event like this or a land use event. So some of the ways that rivers change or the reasons that rivers change their pattern and their movements is because of things like with extra water falling on the land's surface when climate is hotter, we can move more sediment and erode more sediment, and that changes how rivers behave.
我們可以回到地球的過去 並做這種重建, 以了解地球的地景如何改變, 來因應像這樣的氣候事件 或土地使用事件。 河流改變的方式、 或河流改變的原因以及移動, 要歸因於像是當氣候變熱時 有額外的水落在 地球表面的這類狀況。 更多沉積物被搬移、 更多沉積物被侵蝕, 就會改變河流的行為。
So ultimately, as long as earth's surface is our home, we need to carefully manage the resources and risks associated with living in dynamic environments. And I think the only way we can really do that sustainably is if we include information about how landscapes evolved and behaved in earth's past.
所以,最終, 只要地球表面還是我們的家園, 我們就需要小心管理與居住在 動態環境相關的資源與風險。 我認為,要做到這一點的 永續方法只有一個, 就是我們要能納入 關於地景如何演化 以及過去行為的資訊。
Thank you.
謝謝大家。
(Applause)
(鼓掌)