 So about a hundred years ago, scientists were making a lot of discoveries that now allow us to connect turbidity currents on the ocean floor and turbidites, the rocks that show a characteristic flowing flow through time. So about a hundred years ago, geologists were describing turbidite rocks and suggesting that there were actually very fast flows on the bottom of the ocean floor, even though dynamically it's very difficult to sort out how to do that. Oceanographers were mapping the bathymetry of the sea floor and discovering that there were these giant canyons on the sea floor. And they were trying to understand what processes could actually form those canyons and suggested, well, maybe when sea level was low, rivers caused them or there are all sorts of different processes. And then at the same time, engineers were starting to put telegraph cables between the continents on the ocean floor. So for example, there were a lot of telegraph cables that were going from Newfoundland and Canada across to Europe to aid intercontinental communications. And then finally, there were also people doing experiments with flumes, and they discovered that when you mix sediment with water, if you get enough sediment and it's dense enough that it will flow along a slope under standing water that doesn't have as much sediment. And so all of these things eventually came together into the idea of turbidites and turbidity currents, but not until the 1950s. So it's a really interesting story about how different pieces of evidence of science come together for a specific interpretation. And so I want to use an example of a flow in 1929, which was not understood at the time, to show how those pieces of evidence came together. So in November 1929, there was a magnitude 7.2 earthquake off the coast of Newfoundland. And immediately after the earthquake hit, about six telegraph cables broke. And the timing, the break of the cables is known instantly because the telegraphs stopped getting transmitted. And then over the next 13 hours, plus a little bit more, more and more cables broke going south from the epicenter of the earthquake. And each one of those cables that broke was also in deeper water. And interesting, none of the cables in the shallow water on the continental shelf itself broke. So there had to have been a process going on in the deep ocean, along as you went away from the coast. And in 1952, Hazen and Ewing recognized, two geologists recognized, that what was probably happening was that the earthquake had triggered a landslide that generated a turbidity current. And that current was flowing down the slope and breaking the cables one after the other. People had proposed turbidity currents before, but there wasn't a real understanding about how they worked and how fast they actually went. So by looking at the sequence of cable breaks, they were able to calculate that the flow speed was initially 90 kilometers an hour. And then it was breaking cables until it was flowing as it slowed down to 20 kilometers an hour. So still very, very fast. And they could also track the slope of the area where the cables broke. And what they saw was that it was a very steep slope initially, and then the turbidity current would have slowed down as the slope decreased, which is very consistent with the dynamics. Finally, there's one more point of evidence that suggests that it really was a turbidity current is that the ships, when they went out to repair the cables, dredged up a lot of sediment, and they were finding pebbles and mud clasks and sharp sand, sharp sand, meaning it's hard on the equipment, so coarse sand, when they were dredging things up. And so that suggested that there was a fast flow, it was fast enough to transport those large grains, but it was also slowing down through time, so it was actually depositing those grains. So if the flow keeps going fast, it will keep transporting the grains themselves. So this is a really nice example of how all different types of science and observations can feed into discovering a new process, and in this particular case, it fits really well with the turbidites that we can see in the rock record. Thanks for watching.