你知道地球上的山川河流是怎么形成的吗？它们的形成可以比喻成一篇非常华丽的乐章。Liz Hajek博士向我们展示了堆积的岩石如何可以研究地球山川河流的形成历史，让我们了解在今天的自然环境中人类是怎样持续生存发展的。
演讲者：Liz Hajek
演说题目：山川大河的形成历史是如此美妙
TED视频
TED演讲稿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. 好的，我们来看看地球的照片，地球确实令人惊叹。我是名地质学家，所以对这很着迷，地球很伟大。它充满力量、充满活力，时时刻刻都在变化。
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.确实是个令人兴奋的居住地。但我今天想从一个地质学家的视角和你们分享，了解地球的过去将如何帮助并指导我们在地球上可持续的生存下去。
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. 地球表面有着许多令人兴奋的事物。如果我们在这里放大一点，我想和你们谈谈一个现象。物质在地球的表面不断被冲刷，其中一个重要的影响是，高山上的东西也会被冲刷掉，被搬运并最终沉淀于海底。这一过程一直发生着，并且深刻的影响了地形的形成。
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.举个例子，在印度南部有着世界上最高的山峰，你可以从这张卫星图像上看到，河流运输着这些山上的东西直至海洋。你可以把这些河流想象成推土机。它们基本上就是在拽着这些山峰，将它们向海的方向推移。
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.给你们举个例子。我们放大一点。我想和你们具体谈谈其中一条河。我们可以看到河流 运输物质到海洋的过程中， 描绘出的美丽图案， 但是这些图案不是一成不变的。这些河流这里绕一绕，那里绕一绕， 就会对我们的生活产生很大的影响。
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. 其中一个例子是戈西河。戈西河有着漂亮的C形河道，它从尼泊尔的高山流出，带着成吨的矿物，通过侵蚀高山得到的沉积物，穿过印度，并且运输着它们。我们将放大这一块区域，而我将告诉你们戈西河发生的事情。这个例子告诉了我们这些系统的动态程度。
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. 这是2008年八月的一张卫星图像，已经被着色了，所以植物或植被都是绿色的，水是蓝色的。你可以看到当它离开尼泊尔时是呈C形的河道。现在是季风季节。
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. 八月是这个地区的季风季节，任何住在河流旁边的人都对洪水以及洪水带来的危害和不便不感到陌生。但是2008年发生了有趣的事情， 这条河流以十分不同的方式变化了。
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. 它以与平常不同的方式造成了洪水。戈西河流到这里， 但是有时随着这些河流 运输的沉积物越来越多， 河道开始堵塞了， 而这些堵塞实际上可以导致河流走向的巨大变动。 这是仅仅两周后的卫星图像。这是之前的河道， 那C形的河道， 你会发现它不再是蓝的了。
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. 现在蓝色的河道， 在图中央纵切了一刀。现实中，戈西河漫上了它的河堤， 还有这里的比例尺是40英里。这条河十分突然的移动了超过30英里。
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.这条河堵住了，然后漫过了河堤。这是一周后的一张图片， 你可以看到这些是之前的河道， 而且漫堤的过程仍在继续， 这条河离它的主道越来越远。
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.所以你可以想象，在这种河流经常改道的地形里，理解河流何时、何地以及如何改道是十分重要的。但是这种过程同样也发生在我们身边。在美国， 密西西比河流经大部分的美洲大陆。
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. 它推动着来自落基山脉和大平原的物质。它夹带着这些物质贯穿美国， 然后把它们倒入墨西哥湾。这是我们今天熟悉的密西西比河河道， 但是它并非一直是按这个方向流动的。如果我们利用地质记录， 就可以重建它过去的走向。
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. 举个例子，这里红色的区域 据我们目前所知，是大约4600年前密西西比河流过并且沉积物质的地方。然后大约在3500年前，它移动到了橘色标注的河道流动。它一直移动，不停移动。
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. 这是约2000年前， 1000年前， 700年前。直到500年前，它才移动到了我们今天熟悉的河道。
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. 这些过程十分重要，特别是这里，这个三角洲，在这个三角洲里密西西比河不断漫堤和改道，于是在陆地和海洋的交界处形成了（新的）陆地。这是非常宝贵的资产，像这样的三角洲是我们星球上人口最稠密的地区。
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.所以了解这些地形的动态变化，它们如何形成，在未来将如何继续演化对于生活在那里的人们十分重要。
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. 河流也会轻微摆动。我们刚才谈到的是更大的漫堤过程。我想向你们展示这里的一些河流摆动。我们转移到亚马逊河流域，类似的，这里有一个巨大的河流系统，不断冲刷，转移着安第斯山脉上的物质，携带着它们穿越南美大陆，最终它们被倾入大西洋。
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. 如果我们在这里放大，你们可以看到这些蜿蜒曲折的河道。同样的，它们十分美丽，但又不稳定。这些河流的走向不停扭曲变动。
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. 我们可以利用最近30年的卫星图像来实际观察这是如何变化的。花点时间看看这条河任何地方的弯曲，你会发现它并不会在一个地方呆很久。它会不断变化，演变，改变图案。
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.如果你再仔细看看这块区域，我想让你们关注到河流中有一个类似圆圈的地方，完完全全的被分隔开来了。它就像个马鞭， 从河流的某个位置被分开了。方便大家参考， 在这个地方，河流在一到两个季节里将它的河道移动了将近四英里。
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. 所以我们所居住的这个地球上的地形其实是不断在变化的：随着高山上的物质被不断侵蚀，不断被运输到海洋，地形也在不断地发生变化，它们时时刻刻都在变化着，而我们需要理解这些过程以便于可持续的生存在这些地形之中。但如果仅仅知道地表发生了什么，仍不足以为可持续的生存指明方向。我们的观测还不够。
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.例如，我们只有近30年的卫星数据。我们需要更多的观测来更加深入地了解这些过程。此外，我们需要了解随着人类不断占据和改造地表，这些地形对气候的变化和人类对土地的使用将会呈现怎样的反应。
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. 这就是为什么我们接下来会提到岩石。随着河流流动， 随着它们不断将物质 从高山运送到海洋， 有的时候一些泥沙和石块会滞留在地面。这些留在地面的沙石逐渐被掩埋， 随着时间的流逝， 便形成了又大又厚的堆积， 最终变成了岩石。
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? 这意味着，我们可以去到拥有大量沉积岩的地方， 回到过去，了解过去的地形是什么样子的。从而我们可以重构并理解地球的地形演化过程。这也非常方便，因为地球有着宏伟的历史，对吧？
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.这个视频重构的是地球历史中最开始的那6亿年的地表演变。我们花了短短几秒就看完了（笑）。随着板块移动，我们知道气候变化了，海平面变化了，不同的地形和环境形成了，我们可以回到过去——如果有时间机器的话——我们可以回到过去进行观察， 而我们确实拥有一台时间机器， 我们可以观察这段时间内堆积的岩石。
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. 举个例子，带你们到地球历史上的一个特殊时期。大约5500万年前，地球骤暖。当时大量的二氧化碳被释放到了地球的大气中，这导致了快速并且极端的全球变暖。
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.我说的“暖和”是指超级暖和，那时北至加拿大，南至巴塔哥尼亚，都能找到鳄鱼和棕榈树。所以这的确是非常暖和的时期，而且发生得非常突然。我们能做的， 就是回到过去，找到当时沉积的岩石， 并且重构这些地形是 如何随全球变暖变化的。
So here, yay, rocks.这里，太好了，有岩石。
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. 这是一堆岩石。这里黄色圈出的一片，其实是一条古河道，就像我刚才展示的卡通一样，这些是5500万年前留下的沉积物。作为地质学家，我们可以近距离的观测它们，并且重构地形。还有一个例子。这黄色范围内的一片是古河道。在它上面还有一片。我们可以到实地仔细考察、测量，还可以观测它们的特征。
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. 例如，我刚刚标注的地方告诉我们这条河大约3英尺深。如果你生活在5500万年前， 你可以涉水通过这条萌萌的小溪。在这些渠道之上和之下的红色物质，是古代的土壤沉积。
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. 我们可以通过它们知道在这片土地生活和生长着什么样的生物，并且了解这些河流是如何和冲积平原相互影响的。我们可以仔细的观测，准确的重构这些河流的走向，以及地形的样貌。
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. 现在当我们为这个地区重构过去的地形时， 如果我们看看在这次突然变暖之前发生了什么，这些河流从高山到海洋开辟了一条道路，看上去和我向你们展示的亚马逊流域很像。
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.但是气候变化刚一开始，这些河流就发生了剧变。首先它们一下子就变宽了许多，其次它们在地表上的改道活动更加频繁。最终，这些河流变回了气候变暖之前的样子，但这花了很长很长的时间。
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.我们可以回到地球的过去，做类似的重构，了解地表是如何随着气候变化，如之前提到的地球骤暖 或土地使用的变化而变化的。河流产生变化一些方式，或是改变走向和水文活动的原因，有一些是因为当地表有了更多的水，再加上气候变暖，沉积物会被更加频繁地被运送或侵蚀，这些都会对河流产生影响。
So ultimately, as long as earth's surface is our home, we need to carefully manage the resources and risksassociated 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.总而言之，只要地球是我们的家园，我们就需要小心的管理资源，警惕生活在这种动态环境中的风险。我认为我们能真正持续这么做的唯一途径是充分考虑在地球历史的慢慢长河中，地形的演变和走向。
Thank you.谢谢。