[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.51,0:00:08.52,Default,,0000,0000,0000,,[ Music ]
Dialogue: 0,0:00:09.02,0:00:12.00,Default,,0000,0000,0000,,[ Applause ]
Dialogue: 0,0:00:12.56,0:00:12.77,Default,,0000,0000,0000,,>> Alright.
Dialogue: 0,0:00:13.46,0:00:15.64,Default,,0000,0000,0000,,Let's get up our picture of the earth.
Dialogue: 0,0:00:16.15,0:00:17.39,Default,,0000,0000,0000,,The earth is pretty awesome.
Dialogue: 0,0:00:17.52,0:00:20.18,Default,,0000,0000,0000,,I'm a geologist, so I get pretty psyched about this,
Dialogue: 0,0:00:20.39,0:00:21.38,Default,,0000,0000,0000,,but the earth is great.
Dialogue: 0,0:00:21.38,0:00:24.84,Default,,0000,0000,0000,,It's powerful, it's dynamic, it's constantly changing,
Dialogue: 0,0:00:24.84,0:00:27.45,Default,,0000,0000,0000,,it's a pretty exciting place to live.
Dialogue: 0,0:00:27.61,0:00:30.60,Default,,0000,0000,0000,,But I want to share with you guys today my perspective
Dialogue: 0,0:00:30.60,0:00:34.13,Default,,0000,0000,0000,,as a geologist and how understanding earth's past can help
Dialogue: 0,0:00:34.13,0:00:37.03,Default,,0000,0000,0000,,inform and guide decisions that we make today,
Dialogue: 0,0:00:37.27,0:00:39.98,Default,,0000,0000,0000,,about how to sustainably live on earth's surface.
Dialogue: 0,0:00:41.06,0:00:43.06,Default,,0000,0000,0000,,So, there's a lot of exciting things that go
Dialogue: 0,0:00:43.06,0:00:44.16,Default,,0000,0000,0000,,on the surface of the earth.
Dialogue: 0,0:00:44.16,0:00:46.28,Default,,0000,0000,0000,,If we zoom in here a little bit,
Dialogue: 0,0:00:46.37,0:00:48.57,Default,,0000,0000,0000,,I want to talk to you guys a little bit about one
Dialogue: 0,0:00:48.57,0:00:50.74,Default,,0000,0000,0000,,of the things that happens is material gets shuffled
Dialogue: 0,0:00:50.74,0:00:52.13,Default,,0000,0000,0000,,around earth's surface all the time,
Dialogue: 0,0:00:52.13,0:00:53.94,Default,,0000,0000,0000,,and one of the big things that happens is material
Dialogue: 0,0:00:53.94,0:00:57.33,Default,,0000,0000,0000,,from high mountains gets eroded and transported
Dialogue: 0,0:00:57.33,0:00:58.44,Default,,0000,0000,0000,,and deposited in the sea.
Dialogue: 0,0:00:58.78,0:01:00.53,Default,,0000,0000,0000,,And this process is ongoing all the time
Dialogue: 0,0:01:00.53,0:01:02.70,Default,,0000,0000,0000,,and it has huge effects on how the landscape works.
Dialogue: 0,0:01:03.51,0:01:05.12,Default,,0000,0000,0000,,So this example here in South India,
Dialogue: 0,0:01:05.28,0:01:07.65,Default,,0000,0000,0000,,we have some of the biggest mountains in the world,
Dialogue: 0,0:01:07.65,0:01:09.67,Default,,0000,0000,0000,,and you can see in this satellite photo,
Dialogue: 0,0:01:09.95,0:01:11.90,Default,,0000,0000,0000,,rivers transporting material
Dialogue: 0,0:01:11.90,0:01:13.72,Default,,0000,0000,0000,,from those mountains out to the sea.
Dialogue: 0,0:01:14.15,0:01:15.92,Default,,0000,0000,0000,,You can think of these rivers like bulldozers.
Dialogue: 0,0:01:15.92,0:01:18.11,Default,,0000,0000,0000,,They're basically taking these mountains and pushing them
Dialogue: 0,0:01:18.11,0:01:18.88,Default,,0000,0000,0000,,down towards the sea.
Dialogue: 0,0:01:19.02,0:01:24.09,Default,,0000,0000,0000,,If we zoom in a little bit, we can see that,
Dialogue: 0,0:01:25.22,0:01:26.98,Default,,0000,0000,0000,,I'll give you guys an example here, right?
Dialogue: 0,0:01:27.07,0:01:28.18,Default,,0000,0000,0000,,So if we zoom in a little bit,
Dialogue: 0,0:01:28.18,0:01:30.77,Default,,0000,0000,0000,,I want to talk to you guys specifically about a river.
Dialogue: 0,0:01:31.04,0:01:33.22,Default,,0000,0000,0000,,You can see these beautiful patterns that the rivers make
Dialogue: 0,0:01:33.22,0:01:35.14,Default,,0000,0000,0000,,as they're pushing material down to the sea,
Dialogue: 0,0:01:35.62,0:01:36.80,Default,,0000,0000,0000,,but these patterns are not static.
Dialogue: 0,0:01:37.09,0:01:39.54,Default,,0000,0000,0000,,These rivers are wiggling and jumping around quite a bit,
Dialogue: 0,0:01:39.54,0:01:41.52,Default,,0000,0000,0000,,and it can have big impacts on, on our lives.
Dialogue: 0,0:01:42.24,0:01:44.74,Default,,0000,0000,0000,,So an example of this is, this is the Kosi River.
Dialogue: 0,0:01:44.83,0:01:47.18,Default,,0000,0000,0000,,So the Kosi River has this nice C-shaped pathway,
Dialogue: 0,0:01:47.53,0:01:50.31,Default,,0000,0000,0000,,and it exits the big mountains of Nepal carrying
Dialogue: 0,0:01:50.31,0:01:51.94,Default,,0000,0000,0000,,with it a ton of material,
Dialogue: 0,0:01:52.18,0:01:53.70,Default,,0000,0000,0000,,a lot of sediment that's being eroded
Dialogue: 0,0:01:53.70,0:01:56.67,Default,,0000,0000,0000,,from the high mountains and it spreads out across India
Dialogue: 0,0:01:56.67,0:01:58.04,Default,,0000,0000,0000,,and moves this material.
Dialogue: 0,0:01:58.70,0:02:00.93,Default,,0000,0000,0000,,So we're going to zoom in to this area,
Dialogue: 0,0:02:00.93,0:02:02.70,Default,,0000,0000,0000,,and I'm going to tell you a little bit about what happened
Dialogue: 0,0:02:03.01,0:02:04.08,Default,,0000,0000,0000,,with the, with the Kosi.
Dialogue: 0,0:02:04.29,0:02:06.48,Default,,0000,0000,0000,,It's an example of how dynamic these systems can be.
Dialogue: 0,0:02:06.58,0:02:10.25,Default,,0000,0000,0000,,So this is a satellite image from August of 2008,
Dialogue: 0,0:02:10.31,0:02:12.85,Default,,0000,0000,0000,,and this is satellite image is colored so that vegetation
Dialogue: 0,0:02:12.85,0:02:15.79,Default,,0000,0000,0000,,or plants show up as green and water shows up as blue.
Dialogue: 0,0:02:16.27,0:02:19.55,Default,,0000,0000,0000,,So, here again, you can see that C-shaped pathway
Dialogue: 0,0:02:19.78,0:02:21.54,Default,,0000,0000,0000,,that this river takes as it exits Nepal,
Dialogue: 0,0:02:22.21,0:02:25.44,Default,,0000,0000,0000,,and now this is monsoon season, August is monsoon season
Dialogue: 0,0:02:25.44,0:02:26.65,Default,,0000,0000,0000,,in this region of the world, and,
Dialogue: 0,0:02:26.65,0:02:28.78,Default,,0000,0000,0000,,and anyone that lives near a river is no stranger
Dialogue: 0,0:02:28.78,0:02:31.93,Default,,0000,0000,0000,,to flooding and the hazards and inconveniences at minimum
Dialogue: 0,0:02:31.93,0:02:32.96,Default,,0000,0000,0000,,that are associated with that.
Dialogue: 0,0:02:33.53,0:02:35.77,Default,,0000,0000,0000,,But something interesting happened in 2008
Dialogue: 0,0:02:35.77,0:02:38.78,Default,,0000,0000,0000,,and this river moved in a way that's very different,
Dialogue: 0,0:02:38.78,0:02:40.32,Default,,0000,0000,0000,,it flooded in a way that's very different
Dialogue: 0,0:02:40.40,0:02:41.09,Default,,0000,0000,0000,,than it normally does.
Dialogue: 0,0:02:41.42,0:02:44.06,Default,,0000,0000,0000,,So the Kosi River is flowing down here,
Dialogue: 0,0:02:44.53,0:02:47.13,Default,,0000,0000,0000,,but sometimes as these rivers are bulldozing sediment they
Dialogue: 0,0:02:47.20,0:02:49.82,Default,,0000,0000,0000,,kind of get clogged, and these clogs can actually cause the
Dialogue: 0,0:02:49.82,0:02:51.64,Default,,0000,0000,0000,,rivers to shift their course dramatically.
Dialogue: 0,0:02:51.82,0:02:54.75,Default,,0000,0000,0000,,So this satellite image is from just two weeks later.
Dialogue: 0,0:02:55.15,0:02:58.47,Default,,0000,0000,0000,,Here's the previous pathway, that C-shaped pathway,
Dialogue: 0,0:02:58.77,0:03:00.13,Default,,0000,0000,0000,,and you notice it's not blue anymore,
Dialogue: 0,0:03:00.89,0:03:02.95,Default,,0000,0000,0000,,but now what we have is this blue pathway that cuts
Dialogue: 0,0:03:03.03,0:03:04.43,Default,,0000,0000,0000,,down the middle of the field of view here.
Dialogue: 0,0:03:04.89,0:03:07.09,Default,,0000,0000,0000,,What happened is the Kosi River jumped its banks,
Dialogue: 0,0:03:07.75,0:03:10.43,Default,,0000,0000,0000,,and for reference, this scale bar here is 40 miles.
Dialogue: 0,0:03:10.43,0:03:13.74,Default,,0000,0000,0000,,This river moved over 30 miles very abruptly.
Dialogue: 0,0:03:14.63,0:03:17.46,Default,,0000,0000,0000,,So this river got clogged and it jumped its banks.
Dialogue: 0,0:03:17.82,0:03:19.94,Default,,0000,0000,0000,,Here's an image from an, about a week later,
Dialogue: 0,0:03:19.94,0:03:21.86,Default,,0000,0000,0000,,and you can see these are the previous pathways,
Dialogue: 0,0:03:21.91,0:03:24.55,Default,,0000,0000,0000,,and you can see this process of river jumping continues
Dialogue: 0,0:03:24.95,0:03:27.14,Default,,0000,0000,0000,,as this river moves father away from its major course.
Dialogue: 0,0:03:27.61,0:03:31.32,Default,,0000,0000,0000,,So you can imagine in landscapes like this where rivers move
Dialogue: 0,0:03:31.39,0:03:34.94,Default,,0000,0000,0000,,around frequently, it's really important to understand when,
Dialogue: 0,0:03:34.94,0:03:36.36,Default,,0000,0000,0000,,where, and how they're going to jump.
Dialogue: 0,0:03:37.22,0:03:40.11,Default,,0000,0000,0000,,But these kinds of processes also happen a lot closer
Dialogue: 0,0:03:40.11,0:03:40.92,Default,,0000,0000,0000,,to home as well.
Dialogue: 0,0:03:41.74,0:03:44.100,Default,,0000,0000,0000,,So, in the United States we have the Mississippi River
Dialogue: 0,0:03:44.100,0:03:49.02,Default,,0000,0000,0000,,that drains most of the Continental U.S. It pushes material
Dialogue: 0,0:03:49.02,0:03:51.14,Default,,0000,0000,0000,,from the Rocky Mountains and from the Great Plains,
Dialogue: 0,0:03:51.33,0:03:54.62,Default,,0000,0000,0000,,it drains and it moves it all the way across America
Dialogue: 0,0:03:54.62,0:03:56.61,Default,,0000,0000,0000,,and dumps it out in the Gulf of Mexico.
Dialogue: 0,0:03:57.31,0:04:00.04,Default,,0000,0000,0000,,So this is the course of the Mississippi that we're familiar
Dialogue: 0,0:04:00.04,0:04:02.58,Default,,0000,0000,0000,,with today, but it didn't always flow in this direction.
Dialogue: 0,0:04:02.92,0:04:04.67,Default,,0000,0000,0000,,If we use the geologic record,
Dialogue: 0,0:04:04.67,0:04:07.71,Default,,0000,0000,0000,,we can reconstruct where it went in the past.
Dialogue: 0,0:04:08.26,0:04:10.73,Default,,0000,0000,0000,,So, for example, this red area here is
Dialogue: 0,0:04:10.73,0:04:14.08,Default,,0000,0000,0000,,where know the Mississippi flowed and deposited material
Dialogue: 0,0:04:14.08,0:04:15.55,Default,,0000,0000,0000,,about 4,600 years ago.
Dialogue: 0,0:04:16.37,0:04:17.96,Default,,0000,0000,0000,,Then about 3,500 years ago,
Dialogue: 0,0:04:17.96,0:04:20.40,Default,,0000,0000,0000,,it moved to follow the course outlined here in orange,
Dialogue: 0,0:04:20.89,0:04:22.89,Default,,0000,0000,0000,,and it kept moving, and it keeps moving,
Dialogue: 0,0:04:22.94,0:04:27.77,Default,,0000,0000,0000,,so here's about 2,000 years ago, 1,000 years, 700 years ago,
Dialogue: 0,0:04:27.77,0:04:30.19,Default,,0000,0000,0000,,and it was only as recently as 500 years ago
Dialogue: 0,0:04:30.19,0:04:32.66,Default,,0000,0000,0000,,that it occupied the pathway that we're familiar with today.
Dialogue: 0,0:04:34.17,0:04:37.28,Default,,0000,0000,0000,,So these processes are really important and especially here,
Dialogue: 0,0:04:37.38,0:04:41.36,Default,,0000,0000,0000,,this delta area, where these river-jumping events
Dialogue: 0,0:04:41.63,0:04:44.74,Default,,0000,0000,0000,,in the Mississippi are building land at the interface
Dialogue: 0,0:04:44.78,0:04:45.52,Default,,0000,0000,0000,,of the land and the sea.
Dialogue: 0,0:04:45.52,0:04:47.41,Default,,0000,0000,0000,,This is really valuable real estate,
Dialogue: 0,0:04:47.41,0:04:49.43,Default,,0000,0000,0000,,and they're some of the most, deltas, like this,
Dialogue: 0,0:04:49.43,0:04:52.50,Default,,0000,0000,0000,,are some of the most densely populated areas on our planet.
Dialogue: 0,0:04:52.77,0:04:55.25,Default,,0000,0000,0000,,So understanding the dynamics of these landscapes,
Dialogue: 0,0:04:55.31,0:04:57.63,Default,,0000,0000,0000,,how they formed and how they will continue to change
Dialogue: 0,0:04:57.63,0:04:59.11,Default,,0000,0000,0000,,in the future is really important
Dialogue: 0,0:04:59.11,0:05:01.45,Default,,0000,0000,0000,,for the people that live there.
Dialogue: 0,0:05:01.69,0:05:03.15,Default,,0000,0000,0000,,So rivers also wiggle.
Dialogue: 0,0:05:03.15,0:05:04.32,Default,,0000,0000,0000,,These are sort of bigger jumps
Dialogue: 0,0:05:04.36,0:05:05.22,Default,,0000,0000,0000,,that we've been talking about,
Dialogue: 0,0:05:05.22,0:05:06.88,Default,,0000,0000,0000,,I want to show you guys some river wiggles here.
Dialogue: 0,0:05:07.46,0:05:10.34,Default,,0000,0000,0000,,So we're going to fly down to the Amazon River basin,
Dialogue: 0,0:05:10.62,0:05:13.89,Default,,0000,0000,0000,,and here, again, we have a big river system that is draining
Dialogue: 0,0:05:13.89,0:05:16.80,Default,,0000,0000,0000,,and moving and plowing material from the Andes Mountains,
Dialogue: 0,0:05:17.33,0:05:19.09,Default,,0000,0000,0000,,transporting it across South America,
Dialogue: 0,0:05:19.09,0:05:21.80,Default,,0000,0000,0000,,and dumping it out into the Atlantic Ocean.
Dialogue: 0,0:05:22.71,0:05:24.73,Default,,0000,0000,0000,,So if we zoom in here, you guys can see these nice,
Dialogue: 0,0:05:25.29,0:05:27.24,Default,,0000,0000,0000,,curvy river pathways, right?
Dialogue: 0,0:05:27.33,0:05:28.59,Default,,0000,0000,0000,,Again, they're really beautiful, but,
Dialogue: 0,0:05:28.59,0:05:29.64,Default,,0000,0000,0000,,again, they're not static.
Dialogue: 0,0:05:30.21,0:05:31.65,Default,,0000,0000,0000,,These rivers wiggle around.
Dialogue: 0,0:05:32.15,0:05:35.77,Default,,0000,0000,0000,,We can use satellite imagery, over the last 30 or so years,
Dialogue: 0,0:05:35.77,0:05:37.50,Default,,0000,0000,0000,,to actually monitor how these changed.
Dialogue: 0,0:05:37.93,0:05:40.84,Default,,0000,0000,0000,,So take a minute and just watch any bend
Dialogue: 0,0:05:40.84,0:05:42.100,Default,,0000,0000,0000,,or curve in this river, and you'll see it doesn't stay
Dialogue: 0,0:05:42.100,0:05:45.73,Default,,0000,0000,0000,,in the same place for very long, it changes and evolves,
Dialogue: 0,0:05:46.25,0:05:47.29,Default,,0000,0000,0000,,and warps its pattern.
Dialogue: 0,0:05:48.60,0:05:51.17,Default,,0000,0000,0000,,If you look in this area, in particular,
Dialogue: 0,0:05:51.26,0:05:53.31,Default,,0000,0000,0000,,I want you guys to notice there's a sort of a loop
Dialogue: 0,0:05:53.31,0:05:55.55,Default,,0000,0000,0000,,in the river that gets completely cutoff.
Dialogue: 0,0:05:55.78,0:05:58.54,Default,,0000,0000,0000,,It's almost like a whip cracking and snaps off the pathway
Dialogue: 0,0:05:58.54,0:05:59.61,Default,,0000,0000,0000,,of the river at a certain spot.
Dialogue: 0,0:06:00.49,0:06:03.36,Default,,0000,0000,0000,,So, just for reference, again, so in this location,
Dialogue: 0,0:06:03.55,0:06:06.57,Default,,0000,0000,0000,,that river changed its course over 4 miles
Dialogue: 0,0:06:07.05,0:06:08.49,Default,,0000,0000,0000,,over the course of a season or two.
Dialogue: 0,0:06:09.24,0:06:11.88,Default,,0000,0000,0000,,So, the landscapes that we live in, on earth,
Dialogue: 0,0:06:12.14,0:06:14.20,Default,,0000,0000,0000,,as this material is being eroded from mountains
Dialogue: 0,0:06:14.20,0:06:16.85,Default,,0000,0000,0000,,and transported to sea, are wiggling around all the time,
Dialogue: 0,0:06:16.85,0:06:17.80,Default,,0000,0000,0000,,they're changing all the time,
Dialogue: 0,0:06:17.80,0:06:20.09,Default,,0000,0000,0000,,and we need to be able to understand these processes
Dialogue: 0,0:06:20.52,0:06:23.62,Default,,0000,0000,0000,,so we can manage and live sustainably on these landscapes.
Dialogue: 0,0:06:24.10,0:06:27.48,Default,,0000,0000,0000,,But it's hard to do if the only information we have is
Dialogue: 0,0:06:27.54,0:06:29.13,Default,,0000,0000,0000,,what's going on today at earth's surface.
Dialogue: 0,0:06:29.63,0:06:32.39,Default,,0000,0000,0000,,Alright, we don't have a lot of observations, we only hear,
Dialogue: 0,0:06:32.47,0:06:34.02,Default,,0000,0000,0000,,only have 30, you know,
Dialogue: 0,0:06:34.02,0:06:36.10,Default,,0000,0000,0000,,30 years' worth of satellite photos for example.
Dialogue: 0,0:06:36.64,0:06:37.75,Default,,0000,0000,0000,,We need more observations
Dialogue: 0,0:06:37.75,0:06:38.94,Default,,0000,0000,0000,,to understand these processes more.
Dialogue: 0,0:06:39.33,0:06:40.74,Default,,0000,0000,0000,,And additionally, we need
Dialogue: 0,0:06:40.74,0:06:43.12,Default,,0000,0000,0000,,to know how these landscapes are going to respond
Dialogue: 0,0:06:43.25,0:06:46.65,Default,,0000,0000,0000,,to changing climate and to changing land use as we continue
Dialogue: 0,0:06:46.65,0:06:48.32,Default,,0000,0000,0000,,to occupy and modify earth's surface.
Dialogue: 0,0:06:49.27,0:06:51.31,Default,,0000,0000,0000,,So this, this is where the rocks come in.
Dialogue: 0,0:06:51.87,0:06:55.68,Default,,0000,0000,0000,,So, as rivers flow, as they're bulldozing material
Dialogue: 0,0:06:55.68,0:06:58.53,Default,,0000,0000,0000,,from the mountains to the sea, sometimes bits of sand
Dialogue: 0,0:06:58.53,0:07:00.30,Default,,0000,0000,0000,,and clay and rock get stuck in the ground,
Dialogue: 0,0:07:00.76,0:07:02.79,Default,,0000,0000,0000,,and that stuff that gets stuck in the ground gets buried,
Dialogue: 0,0:07:03.10,0:07:05.44,Default,,0000,0000,0000,,and through time, we get big,
Dialogue: 0,0:07:05.44,0:07:07.04,Default,,0000,0000,0000,,thick accumulations of sediments
Dialogue: 0,0:07:07.20,0:07:08.57,Default,,0000,0000,0000,,that eventually turn into rocks.
Dialogue: 0,0:07:09.26,0:07:11.86,Default,,0000,0000,0000,,What this means is that we can go to places like this
Dialogue: 0,0:07:11.86,0:07:14.15,Default,,0000,0000,0000,,where we see big, thick stacks of sedimentary rocks,
Dialogue: 0,0:07:14.55,0:07:17.47,Default,,0000,0000,0000,,and go back in time and see what the landscapes look
Dialogue: 0,0:07:17.47,0:07:18.71,Default,,0000,0000,0000,,like in the past.
Dialogue: 0,0:07:18.84,0:07:22.55,Default,,0000,0000,0000,,We can do this to help reconstruct and understand how,
Dialogue: 0,0:07:23.65,0:07:25.12,Default,,0000,0000,0000,,how earth landscapes evolve.
Dialogue: 0,0:07:26.24,0:07:28.17,Default,,0000,0000,0000,,This is pretty convenient too,
Dialogue: 0,0:07:28.21,0:07:30.83,Default,,0000,0000,0000,,because the earth has had sort of an epic history, right?
Dialogue: 0,0:07:30.90,0:07:35.43,Default,,0000,0000,0000,,So, this video here is a reconstruction of paleogeography
Dialogue: 0,0:07:35.74,0:07:38.56,Default,,0000,0000,0000,,for the first, just the first 600 million years
Dialogue: 0,0:07:38.56,0:07:41.07,Default,,0000,0000,0000,,of earth's history, so, just a little bit of time here.
Dialogue: 0,0:07:41.14,0:07:44.13,Default,,0000,0000,0000,,So as, as the plates move around,
Dialogue: 0,0:07:44.13,0:07:47.04,Default,,0000,0000,0000,,we know climate has changed, sea level has changed,
Dialogue: 0,0:07:47.29,0:07:50.94,Default,,0000,0000,0000,,we have a lot of different types of landscapes
Dialogue: 0,0:07:50.94,0:07:53.12,Default,,0000,0000,0000,,and different types of environment that we can go back,
Dialogue: 0,0:07:53.41,0:07:55.85,Default,,0000,0000,0000,,if we have a time machine, we can go back and look at.
Dialogue: 0,0:07:56.12,0:07:57.88,Default,,0000,0000,0000,,And we do, indeed, have a time machine,
Dialogue: 0,0:07:57.88,0:07:59.62,Default,,0000,0000,0000,,because we can look at the rocks
Dialogue: 0,0:07:59.62,0:08:00.96,Default,,0000,0000,0000,,that were deposited at these times.
Dialogue: 0,0:08:01.36,0:08:02.74,Default,,0000,0000,0000,,So I'm going to give you an example of this,
Dialogue: 0,0:08:02.74,0:08:04.37,Default,,0000,0000,0000,,I'm going to take you to a special time in earth's past,
Dialogue: 0,0:08:04.74,0:08:06.42,Default,,0000,0000,0000,,about 55 million years ago,
Dialogue: 0,0:08:06.66,0:08:08.34,Default,,0000,0000,0000,,there was a really abrupt warming event,
Dialogue: 0,0:08:08.63,0:08:09.97,Default,,0000,0000,0000,,and what happened was a whole bunch
Dialogue: 0,0:08:09.97,0:08:12.20,Default,,0000,0000,0000,,of carbon dioxide was released into earth's atmosphere
Dialogue: 0,0:08:12.20,0:08:14.76,Default,,0000,0000,0000,,and it caused a rapid, and,
Dialogue: 0,0:08:14.76,0:08:17.36,Default,,0000,0000,0000,,and pretty extreme global warming event, and,
Dialogue: 0,0:08:17.36,0:08:20.08,Default,,0000,0000,0000,,and when I say warm, I mean pretty warm.
Dialogue: 0,0:08:20.08,0:08:22.74,Default,,0000,0000,0000,,That there were things like crocodiles and palm trees
Dialogue: 0,0:08:23.06,0:08:25.98,Default,,0000,0000,0000,,as far north as Canada and as far south as Patagonia.
Dialogue: 0,0:08:26.15,0:08:27.39,Default,,0000,0000,0000,,So this is a pretty warm time,
Dialogue: 0,0:08:27.44,0:08:28.57,Default,,0000,0000,0000,,and it happened really abruptly.
Dialogue: 0,0:08:29.33,0:08:31.52,Default,,0000,0000,0000,,So what we can do is we can go back and find rocks
Dialogue: 0,0:08:31.52,0:08:32.78,Default,,0000,0000,0000,,that were deposited at this time
Dialogue: 0,0:08:32.78,0:08:35.48,Default,,0000,0000,0000,,and we reconstruct how the landscape changed in response
Dialogue: 0,0:08:35.48,0:08:36.34,Default,,0000,0000,0000,,to this warming event.
Dialogue: 0,0:08:37.70,0:08:40.26,Default,,0000,0000,0000,,So, here, yay, rocks! So [laughter], here,
Dialogue: 0,0:08:40.67,0:08:43.35,Default,,0000,0000,0000,,here's a pile of rocks.
Dialogue: 0,0:08:43.72,0:08:46.82,Default,,0000,0000,0000,,This yellow blob here, this is actually a fossil river.
Dialogue: 0,0:08:47.13,0:08:48.65,Default,,0000,0000,0000,,So just like this cartoon I showed,
Dialogue: 0,0:08:48.76,0:08:51.68,Default,,0000,0000,0000,,these are deposits that were laid down 55 million years ago.
Dialogue: 0,0:08:52.10,0:08:55.15,Default,,0000,0000,0000,,As geologists, we can go and look at these up close
Dialogue: 0,0:08:55.23,0:08:56.56,Default,,0000,0000,0000,,and reconstruct the landscape.
Dialogue: 0,0:08:56.97,0:08:58.81,Default,,0000,0000,0000,,So here's another example
Dialogue: 0,0:08:58.81,0:09:01.15,Default,,0000,0000,0000,,of the yellow blob here is a, is a fossil river.
Dialogue: 0,0:09:01.35,0:09:02.32,Default,,0000,0000,0000,,Here's another one above it.
Dialogue: 0,0:09:02.89,0:09:05.30,Default,,0000,0000,0000,,We can go and look in detail and make measurements
Dialogue: 0,0:09:05.30,0:09:08.10,Default,,0000,0000,0000,,and observations, and we can measure features, for example,
Dialogue: 0,0:09:08.10,0:09:10.07,Default,,0000,0000,0000,,the features I just highlighted there tell us
Dialogue: 0,0:09:10.07,0:09:12.21,Default,,0000,0000,0000,,that this particular river was probably
Dialogue: 0,0:09:12.27,0:09:13.43,Default,,0000,0000,0000,,about three feet deep.
Dialogue: 0,0:09:13.55,0:09:15.05,Default,,0000,0000,0000,,You could wade across this cute,
Dialogue: 0,0:09:15.05,0:09:16.25,Default,,0000,0000,0000,,little stream if you were walking
Dialogue: 0,0:09:16.25,0:09:18.42,Default,,0000,0000,0000,,around 55 million years ago.
Dialogue: 0,0:09:18.62,0:09:21.39,Default,,0000,0000,0000,,The reddish stuff that's above and below those channels,
Dialogue: 0,0:09:21.49,0:09:22.94,Default,,0000,0000,0000,,those are ancient soil deposits.
Dialogue: 0,0:09:23.31,0:09:25.28,Default,,0000,0000,0000,,So we can look at those to tell us what lived
Dialogue: 0,0:09:25.39,0:09:26.90,Default,,0000,0000,0000,,and grew on the landscape,
Dialogue: 0,0:09:27.19,0:09:29.59,Default,,0000,0000,0000,,and to understand how these rivers were interacting
Dialogue: 0,0:09:29.59,0:09:31.71,Default,,0000,0000,0000,,with their flood plains.
Dialogue: 0,0:09:31.85,0:09:34.34,Default,,0000,0000,0000,,So we can look in detail and we can reconstruct with some,
Dialogue: 0,0:09:34.74,0:09:37.42,Default,,0000,0000,0000,,some specificity how these rivers flowed
Dialogue: 0,0:09:37.42,0:09:38.67,Default,,0000,0000,0000,,and what the landscapes looked like.
Dialogue: 0,0:09:38.99,0:09:42.97,Default,,0000,0000,0000,,So when we do this, for this particular place, at this time,
Dialogue: 0,0:09:42.97,0:09:45.71,Default,,0000,0000,0000,,if we look what happened before this abrupt warming event,
Dialogue: 0,0:09:46.25,0:09:48.94,Default,,0000,0000,0000,,the rivers kind of carved their way down from the mountains
Dialogue: 0,0:09:48.100,0:09:51.96,Default,,0000,0000,0000,,to the sea and they did so, they looked maybe similar
Dialogue: 0,0:09:51.96,0:09:54.54,Default,,0000,0000,0000,,to what we, what I showed you in the Amazon River basin,
Dialogue: 0,0:09:55.04,0:09:57.41,Default,,0000,0000,0000,,but right at the onset of this climate change event,
Dialogue: 0,0:09:57.47,0:09:58.97,Default,,0000,0000,0000,,the rivers changed dramatically.
Dialogue: 0,0:09:59.57,0:10:01.18,Default,,0000,0000,0000,,All of a sudden they got much broader,
Dialogue: 0,0:10:01.46,0:10:02.83,Default,,0000,0000,0000,,and they started to slide back
Dialogue: 0,0:10:02.92,0:10:04.76,Default,,0000,0000,0000,,and forth across the landscape more readily.
Dialogue: 0,0:10:05.97,0:10:08.46,Default,,0000,0000,0000,,Eventually, the rivers reverted back to a state
Dialogue: 0,0:10:08.46,0:10:11.29,Default,,0000,0000,0000,,that was more similar to what they would have looked
Dialogue: 0,0:10:11.64,0:10:13.03,Default,,0000,0000,0000,,like before this climate event,
Dialogue: 0,0:10:13.63,0:10:15.27,Default,,0000,0000,0000,,but it took a long, long time.
Dialogue: 0,0:10:16.33,0:10:19.37,Default,,0000,0000,0000,,So we can go back in earth's time and do these kinds
Dialogue: 0,0:10:19.37,0:10:22.35,Default,,0000,0000,0000,,of reconstructions and understand how earth's landscape has
Dialogue: 0,0:10:22.35,0:10:25.11,Default,,0000,0000,0000,,changed in response to a climate event like this
Dialogue: 0,0:10:25.52,0:10:26.44,Default,,0000,0000,0000,,or a land use event.
Dialogue: 0,0:10:26.69,0:10:28.79,Default,,0000,0000,0000,,So some of the ways that rivers that change,
Dialogue: 0,0:10:28.79,0:10:32.02,Default,,0000,0000,0000,,or the reasons that rivers change their pattern and their,
Dialogue: 0,0:10:32.41,0:10:34.42,Default,,0000,0000,0000,,and their movements, is because of things
Dialogue: 0,0:10:34.42,0:10:37.81,Default,,0000,0000,0000,,like with extra water falling on the land's surface, when,
Dialogue: 0,0:10:37.87,0:10:40.92,Default,,0000,0000,0000,,when climate is hotter, we can move more sediment
Dialogue: 0,0:10:40.92,0:10:43.59,Default,,0000,0000,0000,,and erode more sediment and that changes how rivers behave.
Dialogue: 0,0:10:44.89,0:10:49.01,Default,,0000,0000,0000,,So, ultimately, as long as earth's surface is our home,
Dialogue: 0,0:10:49.55,0:10:52.41,Default,,0000,0000,0000,,we need to carefully manage the resources
Dialogue: 0,0:10:52.41,0:10:55.26,Default,,0000,0000,0000,,and risks associated with living in dynamic environments.
Dialogue: 0,0:10:55.93,0:10:58.80,Default,,0000,0000,0000,,And I think the only way we can really do
Dialogue: 0,0:10:58.80,0:11:01.86,Default,,0000,0000,0000,,that sustainably is if we include information
Dialogue: 0,0:11:02.16,0:11:05.50,Default,,0000,0000,0000,,about how landscapes evolved and behaved in earth's past.
Dialogue: 0,0:11:06.24,0:11:06.54,Default,,0000,0000,0000,,Thank you.
Dialogue: 0,0:11:07.52,0:11:10.50,Default,,0000,0000,0000,,[ Applause ]