WEBVTT 00:00:00.000 --> 00:00:02.620 OK, let's get into this. When you think about 00:00:02.620 --> 00:00:07.419 truly monumental American geology, your mind 00:00:07.419 --> 00:00:09.640 usually goes to the big names, right? Absolutely. 00:00:09.939 --> 00:00:12.039 Grand Canyon, the Rockies, you know, the big 00:00:12.039 --> 00:00:14.400 explosive volcanoes of the Cascades. Sure, classics. 00:00:14.939 --> 00:00:18.750 But there is this. This massive, almost hidden 00:00:18.750 --> 00:00:21.489 giant sitting right there in the Pacific Northwest. 00:00:21.870 --> 00:00:25.670 A geographic feature so vast that its creation 00:00:25.670 --> 00:00:28.949 literally rewrote the map of three entire states. 00:00:29.269 --> 00:00:32.289 And what's more, it holds the key to understanding 00:00:32.289 --> 00:00:34.850 why one of our most famous national parks is, 00:00:34.990 --> 00:00:37.829 well, so volatile today. That is the perfect 00:00:37.829 --> 00:00:39.810 way to put it. It's a paradox. And that's what 00:00:39.810 --> 00:00:41.450 we're diving in today, the Columbia Plateau. 00:00:41.450 --> 00:00:43.969 Right. And our mission for you. listening, is 00:00:43.969 --> 00:00:46.210 to get past just the surface geography, you know, 00:00:46.250 --> 00:00:48.149 the wheat fields, the high desert, and really 00:00:48.149 --> 00:00:50.369 understand that this whole region is, in essence, 00:00:50.549 --> 00:00:54.450 one enormous solidified snapshot of deep earth 00:00:54.450 --> 00:00:56.969 history. A snapshot. I like that. Yeah. And we're 00:00:56.969 --> 00:01:00.469 going to trace its surprising and incredibly 00:01:00.469 --> 00:01:03.119 violent creation. We'll get into the physics 00:01:03.119 --> 00:01:06.480 of how 6 ,000 feet of solid rock piled up. And 00:01:06.480 --> 00:01:09.560 then we'll reveal its direct, undeniable, and 00:01:09.560 --> 00:01:12.200 frankly astonishing connection to the geysers 00:01:12.200 --> 00:01:14.560 and bubbling springs of Yellowstone. And that 00:01:14.560 --> 00:01:18.159 connection, that link between a flat, high desert 00:01:18.159 --> 00:01:21.319 in Washington and the famous thermal features 00:01:21.319 --> 00:01:24.400 of Yellowstone, that's the real aha moment. That's 00:01:24.400 --> 00:01:26.760 the one. It ties everything together. But before 00:01:26.760 --> 00:01:29.319 we get there, we really have to establish the 00:01:29.319 --> 00:01:31.120 sheer scale of this thing. I mean, it's almost 00:01:31.120 --> 00:01:33.560 impossible to comprehend. This isn't just a patch 00:01:33.560 --> 00:01:35.920 of high ground. No, not at all. It's an immense 00:01:35.920 --> 00:01:39.200 geologic and geographic region. It spans huge 00:01:39.200 --> 00:01:41.980 portions of Washington, Oregon, and Idaho. And 00:01:41.980 --> 00:01:44.680 its location is key. Right. It sits right in 00:01:44.680 --> 00:01:46.780 the middle, sandwiched between the Cascade Range 00:01:46.780 --> 00:01:49.060 to the west, which is a classic volcanic arc 00:01:49.060 --> 00:01:51.700 on a plate boundary, and then the Rocky Mountains 00:01:51.700 --> 00:01:54.980 to the east. So it's inland, way inland. Exactly. 00:01:55.400 --> 00:01:57.920 And that central inland location is what makes 00:01:57.920 --> 00:02:00.500 its very existence such a profound geological 00:02:00.500 --> 00:02:03.859 puzzle to begin with. And its fundamental identity, 00:02:04.120 --> 00:02:07.799 we have to define this. It's a wide flood basalt 00:02:07.799 --> 00:02:10.379 plateau. Right. Cut through by the Columbia River. 00:02:10.520 --> 00:02:12.699 And we should probably sit with that term flood 00:02:12.699 --> 00:02:15.020 basalt for a second because it tells you exactly 00:02:15.020 --> 00:02:18.219 what this region is not. Yes. It is the absolute 00:02:18.219 --> 00:02:22.360 antithesis of the classic volcano image. You 00:02:22.360 --> 00:02:24.629 know, you picture Mount Rainier. Mount Hood. 00:02:24.830 --> 00:02:28.610 You see a central vent, a peak, that classic 00:02:28.610 --> 00:02:31.330 cone shape. A mountain. A mountain, exactly. 00:02:31.689 --> 00:02:33.770 Flood basalts are totally different. This means 00:02:33.770 --> 00:02:36.610 the entire region wasn't formed by slow, gentle 00:02:36.610 --> 00:02:40.389 plate movement or even a singular explosive eruption. 00:02:40.550 --> 00:02:43.030 It was formed by fissures. Fissures, so just 00:02:43.030 --> 00:02:45.729 cracks in the ground. Long, massive cracks in 00:02:45.729 --> 00:02:47.870 the Earth's crust that just opened up and unleashed 00:02:47.870 --> 00:02:51.650 this overwhelming, sustained outpouring of superheated 00:02:51.650 --> 00:02:54.189 liquid rock that literally... float across the 00:02:54.189 --> 00:02:56.689 landscape like water. And outpouring is the right 00:02:56.689 --> 00:02:58.370 word. And when we talk about the size of the 00:02:58.370 --> 00:03:00.750 area that's affected, it really redefines the 00:03:00.750 --> 00:03:03.469 word massive. It does. The plateau covers the 00:03:03.469 --> 00:03:05.909 geologic region we call the Columbia River Basalt 00:03:05.909 --> 00:03:08.150 Group. And the scale of that. Well, this is the 00:03:08.150 --> 00:03:10.689 initial shock factor, always. The lava flows 00:03:10.689 --> 00:03:14.050 literally engulfed about 63 ,000 square miles. 00:03:14.539 --> 00:03:18.020 Wow. That's 160 ,000 square kilometers of the 00:03:18.020 --> 00:03:20.060 Pacific Northwest. OK, put that in perspective 00:03:20.060 --> 00:03:23.099 for me. 63 ,000 square miles is. It's roughly 00:03:23.099 --> 00:03:26.240 the size of the entire state of Georgia or a 00:03:26.240 --> 00:03:29.039 bit larger than England and Wales combined. And 00:03:29.039 --> 00:03:30.979 the important thing, the so what here is that. 00:03:31.360 --> 00:03:34.139 This land didn't rise up slowly like mountains 00:03:34.139 --> 00:03:36.860 do. Not at all. It wasn't crustal deformation. 00:03:37.259 --> 00:03:41.659 It was violently and geologically speaking very 00:03:41.659 --> 00:03:44.479 quickly inundated by liquid rock. It's one of 00:03:44.479 --> 00:03:46.560 the largest such events ever documented on the 00:03:46.560 --> 00:03:49.240 planet. It's what we call a large igneous province. 00:03:49.560 --> 00:03:52.919 L .I .P. L .I .P. Exactly. So we've got the enormous 00:03:52.919 --> 00:03:55.560 scale of the where. Now let's dig into the when 00:03:55.560 --> 00:03:57.500 and the how. This wasn't just a one and done 00:03:57.500 --> 00:03:59.719 event, was it? Not even close. It was a process 00:03:59.719 --> 00:04:02.520 that spanned deep, deep time. The time frame 00:04:02.520 --> 00:04:04.759 puts us mostly in the late Miocene and early 00:04:04.759 --> 00:04:07.099 Pliocene epochs. Now we're talking, what, around 00:04:07.099 --> 00:04:11.439 17 to 6 million years ago? Roughly, yes. We're 00:04:11.439 --> 00:04:14.180 looking at a continuous, relentless eruption 00:04:14.180 --> 00:04:17.319 cycle that happened over a span of maybe 10 to 00:04:17.319 --> 00:04:20.660 15 million years. That's, I mean, in human terms, 00:04:20.660 --> 00:04:24.240 that's an eternity. But geologically? Geologically, 00:04:24.279 --> 00:04:27.600 that is a remarkably short period for this much 00:04:27.600 --> 00:04:30.600 material to be extruded. It really wasn't a slow 00:04:30.600 --> 00:04:34.120 leak. It was a sustained gusher. 10 to 15 million 00:04:34.120 --> 00:04:37.160 years of these huge fissure eruptions just flowing 00:04:37.160 --> 00:04:39.339 over the landscape, one layer on top of the next. 00:04:39.459 --> 00:04:42.480 It's just, it's hard to visualize that much sustained 00:04:42.480 --> 00:04:45.300 activity. And remember, the lava wasn't coming 00:04:45.300 --> 00:04:47.899 from a single point like a volcano. It was coming 00:04:47.899 --> 00:04:50.540 from these immense... fissure systems. Imagine 00:04:50.540 --> 00:04:53.000 cracks in the earth that are tens, maybe even 00:04:53.000 --> 00:04:55.100 hundreds of miles long, just pouring out this 00:04:55.100 --> 00:04:57.939 very low viscosity, incredibly liquid basalt 00:04:57.939 --> 00:05:00.519 lava. Low viscosity, meaning it's really runny. 00:05:00.519 --> 00:05:02.259 Super runny. It could travel massive distances 00:05:02.259 --> 00:05:04.779 before it finally cooled and hardened so it didn't 00:05:04.779 --> 00:05:07.079 pile up in a cone. Right. It spread out like 00:05:07.079 --> 00:05:09.540 pancake batter on a giant griddle. That's a great 00:05:09.540 --> 00:05:12.139 analogy. It spread out and covered pretty much 00:05:12.139 --> 00:05:14.620 everything. And the cumulative effect of all 00:05:14.620 --> 00:05:17.420 those flows is just staggering. If you were to 00:05:17.420 --> 00:05:20.240 drill down today, The final thickness of all 00:05:20.240 --> 00:05:22.920 that solidified lava reaches a maximum of more 00:05:22.920 --> 00:05:25.720 than 6 ,000 feet. 6 ,000 feet. That's over a 00:05:25.720 --> 00:05:29.540 mile deep. Over a mile of solid rock. And that's 00:05:29.540 --> 00:05:33.180 1 .8 kilometers. In some of the deepest parts 00:05:33.180 --> 00:05:35.839 of the basin, geologists think it could be closer 00:05:35.839 --> 00:05:39.300 to 10 ,000 feet. 10 ,000 feet deep. OK, to give 00:05:39.300 --> 00:05:41.540 you another analogy, if you took the Willis Tower 00:05:41.540 --> 00:05:44.220 in Chicago, the Sears Tower, which is over 1 00:05:44.220 --> 00:05:48.079 ,400 feet tall. You'd have to stack four, maybe 00:05:48.079 --> 00:05:50.360 five of them on top of each other just to reach 00:05:50.360 --> 00:05:52.519 the depth of the rock foundation under parts 00:05:52.519 --> 00:05:54.720 of Washington and Oregon. That really drives 00:05:54.720 --> 00:05:56.660 it home, doesn't it? It's not a feature on the 00:05:56.660 --> 00:05:58.759 landscape. It is the landscape. It's the foundation. 00:05:59.339 --> 00:06:01.800 Exactly. And this is where it gets really interesting 00:06:01.800 --> 00:06:04.500 because we move from just one simple massive 00:06:04.500 --> 00:06:08.560 flow to a highly complex, readable geological 00:06:08.560 --> 00:06:10.500 record. You mean it's not just one big block 00:06:10.500 --> 00:06:13.500 of rock? Not at all. Because the eruptions happened 00:06:13.500 --> 00:06:16.759 episodically over millions of years, it created 00:06:16.759 --> 00:06:19.360 this meticulously structured record. It's made 00:06:19.360 --> 00:06:22.120 up of seven major formations. So like layers 00:06:22.120 --> 00:06:24.800 in a cake. And these formations, I assume they 00:06:24.800 --> 00:06:26.519 tell a story. They're not just about different 00:06:26.519 --> 00:06:29.100 ages, but maybe different chemistries, different 00:06:29.100 --> 00:06:31.920 eruption styles. You've got it. The sequencing 00:06:31.920 --> 00:06:36.199 gives us the precise history of how this... this 00:06:36.199 --> 00:06:38.540 heat source behaved as the continent moved over 00:06:38.540 --> 00:06:41.500 it. These are the layers geologists use to date 00:06:41.500 --> 00:06:44.540 and correlate rock across the entire region. 00:06:44.680 --> 00:06:46.339 Okay, so let's walk through them. What are these 00:06:46.339 --> 00:06:48.839 seven layers? All right, so generally from the 00:06:48.839 --> 00:06:51.519 oldest and deepest layer up to the youngest and 00:06:51.519 --> 00:06:54.199 shallowest. Number one is the Steens Basalt. 00:06:54.300 --> 00:06:56.160 Steens. This is often considered the initial, 00:06:56.259 --> 00:06:58.930 the first big outpouring. These flows are critical 00:06:58.930 --> 00:07:00.990 because they represent the very first moment 00:07:00.990 --> 00:07:03.790 that plume of hot rock reached the base of the 00:07:03.790 --> 00:07:05.949 lithosphere. And where do you find those? Mostly 00:07:05.949 --> 00:07:08.810 in southern Oregon. Yeah. And their sheer volume 00:07:08.810 --> 00:07:12.029 points to an immediate dramatic start to all 00:07:12.029 --> 00:07:13.990 this activity. It's like the initial crack in 00:07:13.990 --> 00:07:16.029 the continental crust. Okay, what's next? After 00:07:16.029 --> 00:07:18.949 that, we have the Imnaha Basalt. It's named for 00:07:18.949 --> 00:07:21.670 flows you can see near the Imnaha River. And 00:07:21.670 --> 00:07:24.230 it represents a subsequent major pulse of volcanism. 00:07:24.620 --> 00:07:26.240 You can tell it apart from the Steen's flows 00:07:26.240 --> 00:07:28.579 by slightly different chemical signatures. So 00:07:28.579 --> 00:07:30.959 geologists can fingerprint these different layers. 00:07:31.399 --> 00:07:34.420 They can. And that brings us to number three, 00:07:34.459 --> 00:07:37.279 which is really the main event, the Grande Ronde 00:07:37.279 --> 00:07:39.720 Basalt. Grande Ronde. That one sounds important. 00:07:40.000 --> 00:07:43.060 Oh, it is. The Grande Ronde Basalt is the single 00:07:43.060 --> 00:07:45.620 largest volume of basalt in the entire group. 00:07:45.939 --> 00:07:48.899 It accounts for an estimated 85 % of the total 00:07:48.899 --> 00:07:53.250 rock volume. 85 % in one formation. 85%. This 00:07:53.250 --> 00:07:55.529 formation alone is thought to have poured out 00:07:55.529 --> 00:07:57.870 over just a few million years, which points to 00:07:57.870 --> 00:08:00.550 a period of just unimaginable heat and productivity 00:08:00.550 --> 00:08:03.670 from the mantle plume below. Wow. Okay, so that's 00:08:03.670 --> 00:08:05.529 the big one. What follows that? Then you get 00:08:05.529 --> 00:08:07.370 the picture of Gorch Basalt. You find this more 00:08:07.370 --> 00:08:09.870 in central Oregon, and it shows that even while 00:08:09.870 --> 00:08:11.990 the massive Grand Ronde flows were happening, 00:08:12.149 --> 00:08:16.129 there were other localized, chemically distinct 00:08:16.129 --> 00:08:18.709 eruptions going on. So multiple fissures were 00:08:18.709 --> 00:08:21.509 active. Right. Then there's the Prineville Basalt, 00:08:21.610 --> 00:08:23.629 another layer named for a location in Oregon. 00:08:23.910 --> 00:08:26.949 Then number six is the Wannapum Basalt. These 00:08:26.949 --> 00:08:29.149 flows are spread broadly across the plateau, 00:08:29.430 --> 00:08:32.129 and they often have distinct physical features, 00:08:32.250 --> 00:08:34.850 which give geologists really critical visual 00:08:34.850 --> 00:08:37.529 markers when they're mapping. And the final one, 00:08:37.629 --> 00:08:40.389 the top layer. And finally, number seven, the 00:08:40.389 --> 00:08:42.909 Saddle Mountains Asphalt. These are generally 00:08:42.909 --> 00:08:44.409 some of the younger flows. You find them at the 00:08:44.409 --> 00:08:46.429 very top of the stack. And what's really cool 00:08:46.429 --> 00:08:48.090 is they're sometimes interbedded with sediments. 00:08:48.330 --> 00:08:50.750 Sediments like from rivers or lakes. Exactly. 00:08:50.809 --> 00:08:53.629 And those sediments give us clues about what 00:08:53.629 --> 00:08:55.629 the climate was like right before the volcanism 00:08:55.629 --> 00:08:58.009 finally started to die down. Let's go back to 00:08:58.009 --> 00:09:01.009 the Grand Ronde for a second. If that one formation 00:09:01.009 --> 00:09:06.120 is 85 percent of the entire volume. What does 00:09:06.120 --> 00:09:08.240 that tell you about the plume underneath? Was 00:09:08.240 --> 00:09:10.720 it just like an initial super gush that then 00:09:10.720 --> 00:09:12.799 tapered off? That's a great question. And yes, 00:09:12.879 --> 00:09:16.039 that is absolutely the interpretation. The enormous 00:09:16.039 --> 00:09:18.899 volume of the Grand Evrand suggests that when 00:09:18.899 --> 00:09:21.820 the plume had, you can think of it as this vast 00:09:21.820 --> 00:09:24.960 mushroom -shaped top of the mantle plume, when 00:09:24.960 --> 00:09:28.200 it first slammed into the cold, rigid North American 00:09:28.200 --> 00:09:32.480 plate. The melting was just instantaneous and 00:09:32.480 --> 00:09:35.179 incredibly productive. It's like opening a massive 00:09:35.179 --> 00:09:37.759 valve all at once. So that first deluge just 00:09:37.759 --> 00:09:40.980 created the bulk of that 6 ,000 foot thick stack. 00:09:41.200 --> 00:09:43.720 In a nutshell, yes. It quickly covered thousands 00:09:43.720 --> 00:09:46.360 of square miles. The flows that came after it, 00:09:46.399 --> 00:09:48.240 like the Wannapum and Saddle Mountains, were 00:09:48.240 --> 00:09:50.440 still massive by any normal standard, but they 00:09:50.440 --> 00:09:53.539 represented the activity. tapering off or maybe 00:09:53.539 --> 00:09:55.159 the heat source shifting as the plate moved. 00:09:55.320 --> 00:09:57.080 So it goes from being a geological catastrophe 00:09:57.080 --> 00:10:01.039 to a complex layered history book. A very, very 00:10:01.039 --> 00:10:02.860 thick history book. And remember, even these 00:10:02.860 --> 00:10:05.460 seven major formations are broken down even further 00:10:05.460 --> 00:10:08.620 by geologists into formal, informal members and 00:10:08.620 --> 00:10:11.120 literally hundreds, if not thousands, of individual 00:10:11.120 --> 00:10:13.320 flows. Every single flow representing its own 00:10:13.320 --> 00:10:16.480 eruption event. Its own moment in time. It means 00:10:16.480 --> 00:10:18.960 for about 10 million years, the Pacific Northwest 00:10:18.960 --> 00:10:21.820 was just continually being repaved by molten 00:10:21.820 --> 00:10:24.720 rock. Okay, so that structure is now clear. 6 00:10:24.720 --> 00:10:28.419 ,000 feet deep, 63 ,000 square miles, seven major 00:10:28.419 --> 00:10:31.299 layers, all dominated by that incredible Grand 00:10:31.299 --> 00:10:34.320 Ronde basalt. But now we have to talk about the... 00:10:35.200 --> 00:10:37.440 The immediate mechanical consequence of all this. 00:10:37.539 --> 00:10:40.600 You're pouring trillions of tons of new rock 00:10:40.600 --> 00:10:43.240 onto the surface. How did the Earth's crust even 00:10:43.240 --> 00:10:45.320 handle that? This is where we get into the mechanism 00:10:45.320 --> 00:10:48.519 of subsidence. And it's a bit counterintuitive, 00:10:48.519 --> 00:10:50.759 but it's a fascinating tradeoff driven by mass 00:10:50.759 --> 00:10:53.440 displacement. A tradeoff. Think about it. As 00:10:53.440 --> 00:10:56.620 that huge volume of molten rock, the magma, came 00:10:56.620 --> 00:10:58.679 to the surface, it didn't just appear out of 00:10:58.679 --> 00:11:00.820 nowhere. It came from the mantle below. Right. 00:11:00.899 --> 00:11:03.139 It had to leave a space behind. It left a relative 00:11:03.139 --> 00:11:06.179 void. This rapid evacuation of material from 00:11:06.179 --> 00:11:09.139 beneath the lithosphere created a space. So instead 00:11:09.139 --> 00:11:11.019 of the surface being pushed up, which is what 00:11:11.019 --> 00:11:13.220 happens when mountains form. The opposite happened. 00:11:13.480 --> 00:11:16.179 The opposite happened. The very movement of mass 00:11:16.179 --> 00:11:19.080 from deep underground to the surface meant the 00:11:19.080 --> 00:11:22.340 crust above had its foundational support literally 00:11:22.340 --> 00:11:24.639 pulled out from under it. And at the same time, 00:11:24.639 --> 00:11:27.320 you've got the incredible weight of the new basalt 00:11:27.320 --> 00:11:30.240 flows pushing down. Precisely. That tremendous 00:11:30.240 --> 00:11:33.059 load, combined with the evacuation of the material 00:11:33.059 --> 00:11:35.860 underneath, caused the Earth's crust to gradually 00:11:35.860 --> 00:11:38.379 sink into the space left by the rising lava. 00:11:38.580 --> 00:11:41.179 So the plateau is actually a depression. It is. 00:11:41.279 --> 00:11:44.259 It's a large, slightly depressed lava plateau. 00:11:44.460 --> 00:11:47.919 It created this broad basin. The plateau is literally 00:11:47.919 --> 00:11:50.100 a depression because of the sheer volume and 00:11:50.100 --> 00:11:52.519 weight of its own creation. It's a wonderful 00:11:52.519 --> 00:11:55.090 piece of geological irony. Which means the center 00:11:55.090 --> 00:11:57.490 of the Columbia Plateau is actually a bit lower 00:11:57.490 --> 00:11:59.610 in elevation than the mountain ranges around 00:11:59.610 --> 00:12:01.990 it, even though it's covered by miles of rock. 00:12:02.230 --> 00:12:04.690 That's exactly right. It defined the entire regional 00:12:04.690 --> 00:12:07.809 topography. Now, this massive event didn't happen 00:12:07.809 --> 00:12:10.549 in a vacuum. It was interacting, often violently, 00:12:10.750 --> 00:12:12.629 with the geography that was already there. And 00:12:12.629 --> 00:12:14.309 nothing would have been more affected than the 00:12:14.309 --> 00:12:16.850 biggest feature of all the ancient Columbia River. 00:12:17.110 --> 00:12:19.970 Absolutely. The river was directly confronted 00:12:19.970 --> 00:12:22.649 by these northwesterly advancing lava flows. 00:12:23.600 --> 00:12:26.000 Remember, this basalt was incredibly liquid. 00:12:26.120 --> 00:12:29.000 It moved fast. So it didn't just go around the 00:12:29.000 --> 00:12:30.580 river valley. It didn't care about the river 00:12:30.580 --> 00:12:32.259 valley. The flow was so overwhelming it just 00:12:32.259 --> 00:12:34.399 poured right into the existing stream valleys, 00:12:34.539 --> 00:12:37.759 filling them up completely. This often forced 00:12:37.759 --> 00:12:40.100 the river to just stop flowing for a while or 00:12:40.100 --> 00:12:42.460 scramble to find entirely new channels. It's 00:12:42.460 --> 00:12:45.179 the ultimate geological obstruction. Just imagine 00:12:45.179 --> 00:12:48.110 a river valley. and then a mile -thick layer 00:12:48.110 --> 00:12:50.850 of liquid rock pouring across it. You can imagine 00:12:50.850 --> 00:12:54.450 the steam, the explosions, as the water flashed 00:12:54.450 --> 00:12:57.379 to vapor. But that filling action wasn't just 00:12:57.379 --> 00:12:59.659 destructive. It was also critically constructive. 00:13:00.019 --> 00:13:02.320 How so? Well, when the lava finally hardened, 00:13:02.480 --> 00:13:05.019 often creating those huge distinctive columnar 00:13:05.019 --> 00:13:07.320 basalt patterns you can see today, it formed 00:13:07.320 --> 00:13:10.259 natural dams. Oh, of course. Dams hundreds of 00:13:10.259 --> 00:13:12.639 feet high. And these natural dams backed up the 00:13:12.639 --> 00:13:15.340 water, causing these massive impoundments. They 00:13:15.340 --> 00:13:17.679 created temporary but often really extensive 00:13:17.679 --> 00:13:20.799 lakes all across the landscape. So the flow had 00:13:20.799 --> 00:13:24.389 this incredible two -sided power. It didn't just 00:13:24.389 --> 00:13:27.850 pave over old land, it forcibly rerouted one 00:13:27.850 --> 00:13:30.529 of the continent's major water systems. And the 00:13:30.529 --> 00:13:32.309 current course of the Columbia River, especially 00:13:32.309 --> 00:13:35.129 where it cuts through the gorge, is largely a 00:13:35.129 --> 00:13:37.009 result of the river being repeatedly blocked 00:13:37.009 --> 00:13:40.629 and then forced into new, deeper channels by 00:13:40.629 --> 00:13:43.289 the relentless movement of that lava. It had 00:13:43.289 --> 00:13:45.029 to carve its way through some of the hardest 00:13:45.029 --> 00:13:47.490 rock imaginable. And you mentioned those temporary 00:13:47.490 --> 00:13:49.549 lakes. It's in those impoundment sites, right? 00:13:49.980 --> 00:13:52.419 the ones created by the hardened basalt dams, 00:13:52.419 --> 00:13:54.679 that we find something almost paradoxical. It 00:13:54.679 --> 00:13:56.700 is. We find one of the most exciting parts of 00:13:56.700 --> 00:13:59.700 the plateau's formation. The paleontological 00:13:59.700 --> 00:14:02.519 fossil record. I just find this transition phenomenal. 00:14:02.820 --> 00:14:05.879 You have this massive, destructive volcanic event 00:14:05.879 --> 00:14:09.059 that, by complete chance, creates the perfect 00:14:09.059 --> 00:14:11.820 conditions for preserving the tiny details of 00:14:11.820 --> 00:14:13.940 the life it was displacing. It's all about the 00:14:13.940 --> 00:14:16.039 conditions. When you have a calm, deep, still 00:14:16.039 --> 00:14:18.820 body of water, like a lake, and you have fine, 00:14:18.899 --> 00:14:21.259 sediment -like volcanic ash or silt building 00:14:21.259 --> 00:14:23.320 up very quickly. You get a low -oxygen environment. 00:14:23.679 --> 00:14:25.799 You get an anaerobic, low -energy environment. 00:14:26.330 --> 00:14:29.289 It's a perfect laboratory for preservation. The 00:14:29.289 --> 00:14:31.889 lake beds became these incredible time capsules 00:14:31.889 --> 00:14:34.850 entombed between layers of hardened basalt. So 00:14:34.850 --> 00:14:38.009 what are we actually finding in these Miocene 00:14:38.009 --> 00:14:41.289 -era lake beds? The detail is just astonishing. 00:14:41.470 --> 00:14:44.529 We find beautiful, incredibly detailed fossil 00:14:44.529 --> 00:14:47.250 leaf impressions. From what kinds of trees? We're 00:14:47.250 --> 00:14:48.889 talking about capturing the whole flora of the 00:14:48.889 --> 00:14:52.259 Miocene. Sycamores, oaks. Other trees that tell 00:14:52.259 --> 00:14:54.879 us the climate was much warmer and wetter than 00:14:54.879 --> 00:14:57.679 the semi -arid plateau we know today. These leaves 00:14:57.679 --> 00:14:59.279 would just settle to the bottom, get trapped 00:14:59.279 --> 00:15:02.200 in fine silt, and then instantly get covered 00:15:02.200 --> 00:15:05.139 by the next eruption's fine ash or the next flood's 00:15:05.139 --> 00:15:07.600 sediment, perfectly preserved. So you can literally 00:15:07.600 --> 00:15:10.200 reconstruct the ancient forests that were there 00:15:10.200 --> 00:15:12.379 right before or even during the eruption cycles. 00:15:12.679 --> 00:15:15.320 That's the goal. We also find vast quantities 00:15:15.320 --> 00:15:18.019 of petrified wood, sometimes in logs. hundreds 00:15:18.019 --> 00:15:20.580 of feet long, which speaks to just how extensive 00:15:20.580 --> 00:15:23.000 these ancient forests were. And what about smaller 00:15:23.000 --> 00:15:26.240 things? Critically, we find exquisitely preserved 00:15:26.240 --> 00:15:30.139 fossil insects. They're tiny, but they are crucial 00:15:30.139 --> 00:15:32.620 data points for understanding the precise temperature 00:15:32.620 --> 00:15:36.059 and ecology of the Miocene era. Insects? Wow. 00:15:36.509 --> 00:15:38.870 And larger life. Does any animals get preserved? 00:15:39.210 --> 00:15:41.149 Yes. And this is perhaps the most compelling 00:15:41.149 --> 00:15:44.929 part. The bones of vertebrate animals. Researchers 00:15:44.929 --> 00:15:47.470 have uncovered remains of large mammals, including 00:15:47.470 --> 00:15:50.889 ancient rhinos, horses, even early camels, which 00:15:50.889 --> 00:15:53.230 were once abundant in North America. So the remains 00:15:53.230 --> 00:15:55.570 got trapped in the lake mud. Trapped in the soft 00:15:55.570 --> 00:15:58.529 mud, quickly buried, and then sealed off by the 00:15:58.529 --> 00:16:01.070 surrounding basalt. It gives us this amazing 00:16:01.070 --> 00:16:03.690 window into the fauna of the Northwest before 00:16:03.690 --> 00:16:06.990 it became a 6 ,000 foot deep slab of rock. The 00:16:06.990 --> 00:16:08.929 destruction literally created the preservation. 00:16:09.269 --> 00:16:11.570 That is just remarkable, moving from the scale 00:16:11.570 --> 00:16:13.870 of a planetary upheaval to the microscopic detail 00:16:13.870 --> 00:16:16.669 of an ancient insect wing. But now we have to 00:16:16.669 --> 00:16:18.809 get back to the central, most challenging puzzle 00:16:18.809 --> 00:16:21.129 here. The big one. Everything we've talked about, 00:16:21.230 --> 00:16:23.570 the volume, the scale, the 10 million year time 00:16:23.570 --> 00:16:25.929 frame, it all points to a process that should 00:16:25.929 --> 00:16:27.960 be happening at a... plate boundary, where the 00:16:27.960 --> 00:16:31.220 crust is being stretched or subducted. But the 00:16:31.220 --> 00:16:34.519 Columbia Plateau is far inland. Hundreds of miles 00:16:34.519 --> 00:16:37.399 from the Pacific plate boundary. So how could 00:16:37.399 --> 00:16:39.659 an area so far from a plate boundary experience 00:16:39.659 --> 00:16:42.679 such an enormous outpouring of lava? That is 00:16:42.679 --> 00:16:45.879 the core geological question. It challenged scientists 00:16:45.879 --> 00:16:49.019 for decades. Tectonic theory, as it was first 00:16:49.019 --> 00:16:51.080 understood, just didn't have a clean answer for 00:16:51.080 --> 00:16:54.399 this kind of massive inland volcanism. It required 00:16:54.399 --> 00:16:57.990 thinking outside the box. or rather outside the 00:16:57.990 --> 00:17:00.389 movement of the plates themselves, the evidence 00:17:00.389 --> 00:17:03.159 was clearly suggesting some kind of concentrated 00:17:03.159 --> 00:17:06.099 non -traditional heat source was melting rock 00:17:06.099 --> 00:17:07.960 right at the base of the lithosphere. It had 00:17:07.960 --> 00:17:09.960 to be concentrated and it had to be persistent. 00:17:10.240 --> 00:17:12.940 So the detective work began. What is feeding 00:17:12.940 --> 00:17:15.740 this giant furnace and why is its influence visible 00:17:15.740 --> 00:17:18.480 across such a vast linear distance? And to solve 00:17:18.480 --> 00:17:20.799 this, scientists undertook this incredible feat 00:17:20.799 --> 00:17:23.759 of geological detective work, right? Using radiometric 00:17:23.759 --> 00:17:26.700 dating. Sophisticated radiometric dating techniques. 00:17:27.000 --> 00:17:29.819 They established precise hardening dates for 00:17:29.819 --> 00:17:32.440 thousands of individual lava flows. and volcanic 00:17:32.440 --> 00:17:35.839 rocks across the entire Pacific Northwest. They 00:17:35.839 --> 00:17:37.319 were just looking at the big picture anymore. 00:17:37.599 --> 00:17:40.660 They were looking for a pattern, a trail of evidence. 00:17:40.920 --> 00:17:43.240 And what they found was the ultimate clue. It 00:17:43.240 --> 00:17:46.160 was a temporal -spatial correlation that links 00:17:46.160 --> 00:17:49.099 this inland flow to the biggest thermal anomaly 00:17:49.099 --> 00:17:51.900 in North America today. So walk us through that 00:17:51.900 --> 00:17:54.240 key discovery. What was the pattern? The key 00:17:54.240 --> 00:17:57.599 finding was just startlingly elegant. When they 00:17:57.599 --> 00:18:00.299 mapped out all the ages of the rocks, the youngest 00:18:00.299 --> 00:18:02.660 volcanic rocks, the most recently active ones, 00:18:02.799 --> 00:18:04.940 they were all clustered right near the Yellowstone 00:18:04.940 --> 00:18:07.750 Plateau in the east. Okay. Conversely, the farther 00:18:07.750 --> 00:18:10.789 west they went, back into the massive flood basalts 00:18:10.789 --> 00:18:13.009 of Washington and Oregon. The older the lavas 00:18:13.009 --> 00:18:15.289 were. The older and older they got. This wasn't 00:18:15.289 --> 00:18:17.230 a random scattering. It was a perfect linear 00:18:17.230 --> 00:18:20.809 timeline, a continuous chronological track stretching 00:18:20.809 --> 00:18:23.670 nearly 500 miles across the continent. The rocks 00:18:23.670 --> 00:18:25.769 were essentially dating themselves, creating 00:18:25.769 --> 00:18:28.609 a perfect geological breadcrumb trail. Exactly. 00:18:29.039 --> 00:18:31.420 The entire Columbia Plateau was revealed to be 00:18:31.420 --> 00:18:35.380 the older, solidified part of a continuous ongoing 00:18:35.380 --> 00:18:38.200 event that is currently culminating in the intense 00:18:38.200 --> 00:18:40.720 activity we see at Yellowstone today. And this 00:18:40.720 --> 00:18:43.539 unmistakable pattern led directly to the dominant 00:18:43.539 --> 00:18:47.039 theory. The most probable explanation, the deep 00:18:47.039 --> 00:18:50.539 mantle plume, or hotspot theory. This theory 00:18:50.539 --> 00:18:53.319 says that an extremely hot plume of deep metal 00:18:53.319 --> 00:18:55.619 material is rising all the way to the surface 00:18:55.619 --> 00:18:57.880 right beneath the Columbia Plateau province. 00:18:58.160 --> 00:19:00.400 Now, we've heard this theory applied elsewhere. 00:19:00.519 --> 00:19:03.339 Hawaii is the classic example. Hawaii, Iceland, 00:19:03.460 --> 00:19:05.859 they're the prime examples. Massive volcanic 00:19:05.859 --> 00:19:08.460 systems that are nowhere near a major plate boundary. 00:19:09.470 --> 00:19:10.910 But let's talk about the physics here because 00:19:10.910 --> 00:19:13.130 it's immense. Where is this heat coming from? 00:19:13.269 --> 00:19:15.210 Right. What's the source? The source is at the 00:19:15.210 --> 00:19:17.049 deepest layer of the Earth we can really access. 00:19:17.329 --> 00:19:19.789 The concentrated heat originates from a temperature 00:19:19.789 --> 00:19:22.269 instability that develops. Well, for reasons 00:19:22.269 --> 00:19:24.289 we don't fully understand, but it's at the boundary 00:19:24.289 --> 00:19:26.690 between the Earth's core and its mantle. The 00:19:26.690 --> 00:19:29.049 core -mantle boundary. How deep is that? It's 00:19:29.049 --> 00:19:32.329 roughly 2 ,900 kilometers or 1 ,800 miles beneath 00:19:32.329 --> 00:19:35.430 our feet. This is the deepest, most sustained 00:19:35.430 --> 00:19:38.849 furnace we can conceptualize. That is truly mind 00:19:38.849 --> 00:19:41.509 -boggling depth. We are talking about a heat 00:19:41.509 --> 00:19:43.849 source that originates almost halfway to the 00:19:43.849 --> 00:19:47.190 center of the Earth. Precisely. And this tremendous 00:19:47.190 --> 00:19:51.609 heat triggers a plume, a buoyant column of superheated 00:19:51.609 --> 00:19:54.130 rock that could be hundreds of kilometers in 00:19:54.130 --> 00:19:57.400 diameter. Because it's hotter, and less dense 00:19:57.400 --> 00:19:59.559 than the rock around it, it just ascends directly 00:19:59.559 --> 00:20:01.680 up through the mantle. All the way to the base 00:20:01.680 --> 00:20:03.920 of our tectonic plate. All the way. And when 00:20:03.920 --> 00:20:06.059 it hits the bottom of that cold, rigid continental 00:20:06.059 --> 00:20:09.119 plate, it causes massive decompression melting, 00:20:09.259 --> 00:20:11.559 which then erupts as the flood basalt we've been 00:20:11.559 --> 00:20:14.079 talking about. And here it is, the core revolutionary 00:20:14.079 --> 00:20:17.359 concept that connects the entire story. The mechanism 00:20:17.359 --> 00:20:19.119 that allows this to happen in the middle of a 00:20:19.119 --> 00:20:21.640 continent is that the hotspot itself, that deep 00:20:21.640 --> 00:20:24.769 mantle plume, is stationary. It's anchored. Deep 00:20:24.769 --> 00:20:27.329 below the crust, completely indifferent to what's 00:20:27.329 --> 00:20:29.569 happening on the surface. Correct. So the elegance 00:20:29.569 --> 00:20:32.869 of this theory is its simplicity. The North American 00:20:32.869 --> 00:20:36.490 plate is moving over it. Yes. Think of the hotspot 00:20:36.490 --> 00:20:39.509 as a stationary, high -intensity industrial torch 00:20:39.509 --> 00:20:42.589 just anchored deep inside the Earth. In the North 00:20:42.589 --> 00:20:44.970 American continent is this immense conveyor belt 00:20:44.970 --> 00:20:48.130 just passing slowly over the flame. That's the 00:20:48.130 --> 00:20:52.309 perfect analogy. The hotspot burns a long, sequential 00:20:52.309 --> 00:20:54.730 track onto the bottom of the plate. So those 00:20:54.730 --> 00:20:58.230 massive 6 ,000 -foot deep flows we talked about 00:20:58.230 --> 00:21:01.000 in Washington and Oregon. They're just the old 00:21:01.000 --> 00:21:03.700 scars. They are the ancient scarring left by 00:21:03.700 --> 00:21:06.420 that initial powerful thermal event. They were 00:21:06.420 --> 00:21:08.319 created when that part of the North American 00:21:08.319 --> 00:21:10.680 plate was sitting directly over the most intense 00:21:10.680 --> 00:21:13.339 part of the heat source 10 to 15 million years 00:21:13.339 --> 00:21:15.680 ago. And as the plate continued its steady journey 00:21:15.680 --> 00:21:18.420 to the northeast. It carried the solidified Columbia 00:21:18.420 --> 00:21:21.079 basalts with it away from the heat source. And 00:21:21.079 --> 00:21:24.119 today, millions of years later. The North American 00:21:24.119 --> 00:21:26.359 plate is positioned so that the hot spot is now 00:21:26.359 --> 00:21:28.519 sitting directly beneath the Yellowstone National 00:21:28.519 --> 00:21:31.829 Park region. That's the whole story. The track 00:21:31.829 --> 00:21:34.390 starts in the far west with the oldest flows, 00:21:34.609 --> 00:21:37.690 the Steens and Grand Ronde forming the vast basalt 00:21:37.690 --> 00:21:40.549 plateau, and it just sweeps up to the Yellowstone 00:21:40.549 --> 00:21:43.509 Plateau, which is the current location of the 00:21:43.509 --> 00:21:46.109 youngest, most powerful volcanic activity. So 00:21:46.109 --> 00:21:48.750 the whole thing provides this superb record of 00:21:48.750 --> 00:21:51.509 the rate and direction of plate motion. It's 00:21:51.509 --> 00:21:54.269 a geological tape measure stamped right onto 00:21:54.269 --> 00:21:56.970 the continent. It is the ultimate aha moment. 00:21:57.190 --> 00:21:59.809 The Columbia Plateau isn't just a place, it's 00:21:59.809 --> 00:22:01.910 a history. book recording our continent's physical 00:22:01.910 --> 00:22:04.730 journey across the globe. But just to be thorough, 00:22:04.910 --> 00:22:06.890 while this hotspot theory is widely accepted, 00:22:07.170 --> 00:22:10.150 are there any credible counter -arguments? For 00:22:10.150 --> 00:22:11.829 the listener who follows this stuff, it's important 00:22:11.829 --> 00:22:13.990 to acknowledge where the scientific debate is. 00:22:14.150 --> 00:22:16.630 That's a crucial point. While the deep plume 00:22:16.630 --> 00:22:18.970 model is dominant because it just so elegantly 00:22:18.970 --> 00:22:21.289 explains the linearity and the sheer scale of 00:22:21.289 --> 00:22:24.190 it all, some geologists have proposed alternatives. 00:22:24.569 --> 00:22:27.009 Okay, like what? Often involving shallower mantle 00:22:27.009 --> 00:22:30.230 processes. For instance, some models suggest 00:22:30.230 --> 00:22:32.349 that maybe the initial rifting and extension 00:22:32.349 --> 00:22:35.150 caused by the Cascade's subduction zone far to 00:22:35.150 --> 00:22:37.890 the west might have allowed a more passive upwelling 00:22:37.890 --> 00:22:39.630 of the mantle. Which would mean you wouldn't 00:22:39.630 --> 00:22:42.990 need a deep, core -anchored plume. The heat source 00:22:42.990 --> 00:22:45.130 would be a result of the plate itself ripping 00:22:45.130 --> 00:22:48.210 apart and letting the ambient heat escape. Exactly. 00:22:48.230 --> 00:22:51.269 But the problem with that is the timing of the 00:22:51.269 --> 00:22:54.049 eruptions, the incredible volume, and that clear 00:22:54.049 --> 00:22:56.609 chronological track leading directly to Yellowstone. 00:22:56.960 --> 00:22:59.599 At the end of the day, the evidence is just overwhelming 00:22:59.599 --> 00:23:03.799 in favor of a fixed deep heat source. The deep 00:23:03.799 --> 00:23:05.859 bloom theory is by far the strongest candidate. 00:23:06.240 --> 00:23:08.599 And of course, the modern visible evidence of 00:23:08.599 --> 00:23:11.039 this active process is just impossible to miss 00:23:11.039 --> 00:23:13.359 if you go to Yellowstone. Oh, absolutely. Yellowstone 00:23:13.359 --> 00:23:15.839 with its iconic geysers like Old Faithful, the 00:23:15.839 --> 00:23:18.240 mud pots, the steaming fumaroles. It provides 00:23:18.240 --> 00:23:20.380 all the visible evidence you could ever want 00:23:20.380 --> 00:23:23.079 of the concentration of heat right beneath the 00:23:23.079 --> 00:23:24.720 surface where that hotspot currently resides. 00:23:25.039 --> 00:23:28.240 All that bubbling, all that heat. It's the current 00:23:28.240 --> 00:23:30.799 manifestation of the exact same mantle plume 00:23:30.799 --> 00:23:33.299 that caused the Grand Ronde basalts to erupt 00:23:33.299 --> 00:23:36.019 millions of years ago. It's the current. active, 00:23:36.160 --> 00:23:39.859 and highly visible end of that 63 ,000 square 00:23:39.859 --> 00:23:42.400 mile trail of ancient lava. It really makes you 00:23:42.400 --> 00:23:44.400 look at the entire topography of the Pacific 00:23:44.400 --> 00:23:47.099 Northwest completely differently. You go from 00:23:47.099 --> 00:23:50.099 seeing a flat, high desert region to recognizing 00:23:50.099 --> 00:23:54.579 it as this giant solidified wound left by a planetary 00:23:54.579 --> 00:23:56.680 heating element moving beneath the continent. 00:23:56.920 --> 00:23:59.220 A wound is a good word for it. So let's move 00:23:59.220 --> 00:24:01.519 from that deep time geology to the world we actually 00:24:01.519 --> 00:24:04.740 live in. We need to ground this enormous geological... 00:24:04.779 --> 00:24:08.019 formation in our modern reality. We need to connect 00:24:08.019 --> 00:24:10.980 the 6 ,000 feet of basalt to the ecology, the 00:24:10.980 --> 00:24:13.819 resources, and the human communities that live 00:24:13.819 --> 00:24:15.859 on its surface today. Right. And that transition 00:24:15.859 --> 00:24:18.400 is fascinating because the geology really does 00:24:18.400 --> 00:24:21.579 dictate the biology. The plateau's surface terrain 00:24:21.579 --> 00:24:24.880 is globally classified by ecologists as the Columbia 00:24:24.880 --> 00:24:27.220 Plateau Eco -Region. And what category does that 00:24:27.220 --> 00:24:29.940 fall into? It sits within a massive global category. 00:24:30.460 --> 00:24:34.000 the near -arctic temperate and subtropical grasslands, 00:24:34.119 --> 00:24:37.359 savannas, and shrublands ichor region. So even 00:24:37.359 --> 00:24:40.519 though the foundation is volcanic rock, the environment 00:24:40.519 --> 00:24:44.680 itself is defined by being dry, by aridity. Yes, 00:24:44.700 --> 00:24:46.880 and that aridity is also a result of the geology, 00:24:47.119 --> 00:24:49.279 isn't it? The sheer height of the Cascade Range 00:24:49.279 --> 00:24:51.839 to the west creates a monumental rain shadow. 00:24:52.119 --> 00:24:55.180 Oh, of course. The Cascades block all the moist 00:24:55.180 --> 00:24:57.940 air coming off the Pacific. Exactly. And that 00:24:57.940 --> 00:25:00.500 leaves the inland plateau dry and semi -arid. 00:25:01.000 --> 00:25:03.660 But the basalt foundation defines more than just 00:25:03.660 --> 00:25:06.000 the climate. It defines the soil. Right, because 00:25:06.000 --> 00:25:08.220 the plateau is famous for its agriculture, but 00:25:08.220 --> 00:25:10.420 you can't be planting wheat directly into 10 00:25:10.420 --> 00:25:12.319 million year old basalt. You certainly cannot. 00:25:12.599 --> 00:25:15.400 So how does that deep hard rock layer support 00:25:15.400 --> 00:25:18.019 the famous agriculture of the region? The wheat 00:25:18.019 --> 00:25:20.279 fields around Pullman, the potato fields in the 00:25:20.279 --> 00:25:21.880 Tri -Cities. That must be what's on top of the 00:25:21.880 --> 00:25:23.660 basalt. It is. The critical link is laga soil. 00:25:23.880 --> 00:25:26.480 After the basalt's cooled and we're... covered 00:25:26.480 --> 00:25:29.160 by ice age sediments, massive continental winds, 00:25:29.279 --> 00:25:32.119 blue fine, glacial silt that's lawless from the 00:25:32.119 --> 00:25:35.720 now dry lake beds and river floodplains. So windblown 00:25:35.720 --> 00:25:39.640 soil. Exactly. This silt settled on top of the 00:25:39.640 --> 00:25:42.200 basalt, often accumulating into these thick, 00:25:42.200 --> 00:25:45.359 fertile, windblown drifts that are incredibly 00:25:45.359 --> 00:25:47.700 rich in minerals and deep enough to sustain massive 00:25:47.700 --> 00:25:51.299 crops. The basalt is just the solid waterproof 00:25:51.299 --> 00:25:54.539 container for that rich soil. So the 6 ,000 feet 00:25:54.539 --> 00:25:56.640 of basalt is the container in the base, and the 00:25:56.640 --> 00:25:59.339 fertile top layer, the loess, is the result of 00:25:59.339 --> 00:26:02.259 post -volcanic glacial processes, a two -stage 00:26:02.259 --> 00:26:04.559 process. And that foundation dictates the soil, 00:26:04.660 --> 00:26:06.980 the hydrology, and fundamentally how communities 00:26:06.980 --> 00:26:09.380 developed. It's helpful for you listening to 00:26:09.380 --> 00:26:11.539 realize that so many major population centers 00:26:11.539 --> 00:26:14.160 of the inland Northwest are literally built right 00:26:14.160 --> 00:26:17.059 on top of this dense feature, relying on its 00:26:17.059 --> 00:26:19.019 characteristics for survival. Let's make this 00:26:19.019 --> 00:26:21.259 tangible. Let's use that list of specific cities 00:26:21.259 --> 00:26:24.049 we compiled. Looking at Washington, the cities 00:26:24.049 --> 00:26:26.170 on the plateau really show the diversity of the 00:26:26.170 --> 00:26:28.410 region, but they're all tied together by that 00:26:28.410 --> 00:26:31.190 basalt foundation. Absolutely. In the eastern 00:26:31.190 --> 00:26:33.269 half of the state, you have a major urban center 00:26:33.269 --> 00:26:35.809 like Spokane, which sits on the northern fringe 00:26:35.809 --> 00:26:38.490 where the basalt meets glacial deposits. You 00:26:38.490 --> 00:26:41.789 got Yakima, known for its fruit and hops, which 00:26:41.789 --> 00:26:44.109 relies on irrigation from the plateau's resources. 00:26:44.549 --> 00:26:46.869 And then there are the Tri -Cities Pasco, Kennewick, 00:26:46.990 --> 00:26:49.190 and Richland, a crucial point where the Snake 00:26:49.190 --> 00:26:51.789 and Columbia Rivers meet, where the hydrology... 00:26:51.789 --> 00:26:54.710 is entirely controlled by those deep basalt layers. 00:26:55.049 --> 00:26:57.049 And don't forget the agricultural and university 00:26:57.049 --> 00:27:00.609 towns. Moses Lake, Pullman, which is famous for 00:27:00.609 --> 00:27:02.589 the Palouse Hills covered in that thick loess. 00:27:03.230 --> 00:27:05.970 Walla Walla, a famous wine region whose soil 00:27:05.970 --> 00:27:08.950 is heavily influenced by the basalt. Then Ellensburg. 00:27:10.269 --> 00:27:12.650 Colfax, Goldendale, the list goes on. And if 00:27:12.650 --> 00:27:15.269 we move south into Oregon. It's a direct extension 00:27:15.269 --> 00:27:18.049 of that same basaltic landscape. You find Pendleton, 00:27:18.250 --> 00:27:20.630 famous for its wheat, Hermiston, Hood River, 00:27:20.769 --> 00:27:23.049 where the Columbia River Gorge cuts deep into 00:27:23.049 --> 00:27:26.150 the basalt, the Dallas, Athena, and Milton Freewater. 00:27:26.349 --> 00:27:28.829 And finally, extending into Idaho, the plateau's 00:27:28.829 --> 00:27:31.529 influence is clear there too. It is. Coeur d 00:27:31.529 --> 00:27:33.349 'Alene, though it's nestled near the Rockies, 00:27:33.490 --> 00:27:36.990 it sits adjacent to the basalt flows. You have 00:27:36.990 --> 00:27:40.029 Lewiston. which is situated in a deep, lava -carved 00:27:40.029 --> 00:27:42.190 canyon at the confluence of the Snake and Clearwater 00:27:42.190 --> 00:27:45.450 Rivers, and Moscow, home to the University of 00:27:45.450 --> 00:27:48.130 Idaho, sitting on those same rich, palouse lower 00:27:48.130 --> 00:27:50.869 soils as Pullman. The takeaway here is that when 00:27:50.869 --> 00:27:52.509 you drive between any of these cities, you're 00:27:52.509 --> 00:27:55.190 not just crossing flat land. You're driving over 00:27:55.190 --> 00:27:58.009 an ancient, complex, 6 ,000 -foot -deep history 00:27:58.009 --> 00:28:01.009 book. The land might look flat or gently rolling, 00:28:01.109 --> 00:28:03.869 but that rolling topography is just the surface 00:28:03.869 --> 00:28:06.490 of what is essentially an enormous solidified 00:28:06.490 --> 00:28:09.410 oceanic style crust sitting hundreds of miles 00:28:09.410 --> 00:28:12.009 inland. And the existence of this massive block 00:28:12.009 --> 00:28:14.490 of hard rock has created several other related 00:28:14.490 --> 00:28:17.269 regional features, especially how water has tried 00:28:17.269 --> 00:28:20.069 to, well, destroy and then utilize the work of 00:28:20.069 --> 00:28:22.309 the lava. Indeed. And the first related feature 00:28:22.309 --> 00:28:24.869 is absolutely crucial. It's the antithesis of 00:28:24.869 --> 00:28:28.099 the smooth lava flow. The channeled scablands. 00:28:28.200 --> 00:28:30.440 Sablands. These are intricately carved, often 00:28:30.440 --> 00:28:33.319 bare rock channels and deep gorges, right? Etched 00:28:33.319 --> 00:28:36.039 into the basalt surface by catastrophic glacial 00:28:36.039 --> 00:28:39.740 meltwater floods, specifically the Missoula floods. 00:28:40.119 --> 00:28:42.579 So this must have been an incredible battle between 00:28:42.579 --> 00:28:45.920 ice and fire, geologically speaking. The basalt 00:28:45.920 --> 00:28:48.440 was the immovable object, and the Missoula floods 00:28:48.440 --> 00:28:50.940 were the unstoppable force. That's a perfect 00:28:50.940 --> 00:28:53.579 way to put it. And the floods happened long after 00:28:53.579 --> 00:28:56.299 the basalt had cooled. The sheer hardness and 00:28:56.299 --> 00:28:58.660 thickness of the basalt provided this formidable 00:28:58.660 --> 00:29:01.819 canvas. So when the gigantic ice dams broke, 00:29:02.079 --> 00:29:04.980 unleashing volumes of water equal to all the 00:29:04.980 --> 00:29:08.059 world's current rivers combined, the water couldn't 00:29:08.059 --> 00:29:10.799 easily penetrate the basalt. Instead, it just 00:29:10.799 --> 00:29:13.579 stripped away the lowest soil on top and carved 00:29:13.579 --> 00:29:16.259 those huge, stark, channelized landscapes right 00:29:16.259 --> 00:29:18.849 into the solid rock below. The scablands exist 00:29:18.849 --> 00:29:21.089 because the underlying rock was so unbelievably 00:29:21.089 --> 00:29:23.690 hard. So the plateau provided the hard canvas 00:29:23.690 --> 00:29:26.730 and the Ice Age floods were the geological chisel. 00:29:26.849 --> 00:29:28.769 Exactly. And that leads directly to the Grand 00:29:28.769 --> 00:29:30.470 Coulee, one of the most famous features of the 00:29:30.470 --> 00:29:33.369 scablands. This is a massive ancient riverbed 00:29:33.369 --> 00:29:36.049 carved deep into the basalt by those same floodwaters. 00:29:36.170 --> 00:29:38.710 It's an enormous trench, hundreds of feet deep 00:29:38.710 --> 00:29:41.210 and miles wide. Which now defines the irrigation 00:29:41.210 --> 00:29:43.609 and water systems for the whole region, including 00:29:43.609 --> 00:29:46.890 the Grand Coulee Dam. The very same. And finally. 00:29:47.230 --> 00:29:49.529 Beneath all of this hard rock that resisted erosion, 00:29:49.869 --> 00:29:53.289 we find the one resource that sustains all those 00:29:53.289 --> 00:29:56.450 cities and farms, the Columbia Plateau aquifer 00:29:56.450 --> 00:29:58.869 system. This connects perfectly back to the layering 00:29:58.869 --> 00:30:01.049 you were talking about earlier. It does. Water 00:30:01.049 --> 00:30:03.670 can't flow through solid rock. Yeah. But it can 00:30:03.670 --> 00:30:06.390 flow through fractures, joints, and critically, 00:30:06.490 --> 00:30:09.190 between the separate layers of those seven basalt 00:30:09.190 --> 00:30:12.410 formations. The way the water interacts with 00:30:12.410 --> 00:30:14.329 the cooling fractures in the sedimentary layers 00:30:14.329 --> 00:30:16.609 within the basalt determines the availability 00:30:16.609 --> 00:30:20.029 of groundwater for everyone. So the basalt is 00:30:20.029 --> 00:30:22.490 both the container and the filter for the water. 00:30:22.650 --> 00:30:25.049 Making it directly linked to modern human survival 00:30:25.049 --> 00:30:28.039 and agriculture. So we have a region forged by 00:30:28.039 --> 00:30:30.859 internal heat from the Earth's core, solidified 00:30:30.859 --> 00:30:33.619 into a deep layered structure, then sculpted 00:30:33.619 --> 00:30:36.480 by massive Ice Age floods, and now sustaining 00:30:36.480 --> 00:30:38.619 civilization through the water trapped within 00:30:38.619 --> 00:30:40.920 its own solidified layers. It's a geological 00:30:40.920 --> 00:30:43.920 legacy that is complex far beyond what you just 00:30:43.920 --> 00:30:46.160 see on the surface. Which brings us to our final 00:30:46.160 --> 00:30:48.579 moment. We've covered the ground, literally and 00:30:48.579 --> 00:30:51.400 figuratively. Let's do a quick deep dive summary. 00:30:51.759 --> 00:30:55.839 Okay. We established the staggering scale. The 00:30:55.839 --> 00:30:59.519 Columbia Plateau is a vast, large igneous province 00:30:59.519 --> 00:31:03.940 covering 63 ,000 square miles. It's built from 00:31:03.940 --> 00:31:06.000 multiple formations, like the dominant Grand 00:31:06.000 --> 00:31:08.380 Rhone Basalt, reaching a depth of more than 6 00:31:08.380 --> 00:31:11.660 ,000 feet, all piled up over a rapid 10 to 15 00:31:11.660 --> 00:31:14.740 million years. We detailed the mechanics, the 00:31:14.740 --> 00:31:17.269 incredible weight of the lava. caused the crust 00:31:17.269 --> 00:31:19.349 to subside, creating that depressed plateau. 00:31:19.630 --> 00:31:22.289 And it simultaneously rerouted the mighty Columbia 00:31:22.289 --> 00:31:25.029 River. And those resulting lava dams created 00:31:25.029 --> 00:31:27.369 temporarily lakes that acted as perfect time 00:31:27.369 --> 00:31:29.730 capsules, preserving invaluable fossil records. 00:31:29.970 --> 00:31:32.309 And we reveal the scientific astonishment that 00:31:32.309 --> 00:31:34.910 this massive volcanism happened far from a plate 00:31:34.910 --> 00:31:37.460 boundary. Because the plateau is the historical 00:31:37.460 --> 00:31:39.880 track left by the North American plate moving 00:31:39.880 --> 00:31:42.160 over a stationary deep earth hotspot, which is 00:31:42.160 --> 00:31:43.700 currently centered right beneath Yellowstone 00:31:43.700 --> 00:31:46.819 National Park. The entire basalt field is astonishingly 00:31:46.819 --> 00:31:49.339 a physical tape measure documenting the rate 00:31:49.339 --> 00:31:50.980 and direction of continental drift. That's the 00:31:50.980 --> 00:31:54.019 core of it. So we understand the past and we 00:31:54.019 --> 00:31:55.920 understand the present activity in Yellowstone. 00:31:56.500 --> 00:31:59.440 But what does this all mean for the future? We 00:31:59.440 --> 00:32:01.460 always like to end with something to mull over, 00:32:01.579 --> 00:32:05.329 a final provocative thought. Well. If we accept 00:32:05.329 --> 00:32:07.269 the evidence that the mantle plume is stationary 00:32:07.269 --> 00:32:10.130 anchored near the core mantle boundary and that 00:32:10.130 --> 00:32:12.410 the North American plate is moving over it at 00:32:12.410 --> 00:32:16.130 a measurable clip, then the concentration of 00:32:16.130 --> 00:32:18.890 heat currently visible as the spectacular geysers 00:32:18.890 --> 00:32:21.509 and fumaroles of Yellowstone National Park is 00:32:21.509 --> 00:32:23.990 actively migrating away from its current location. 00:32:24.309 --> 00:32:26.710 It's not a question of if the activity will cease 00:32:26.710 --> 00:32:29.380 in the Yellowstone region, but when. Exactly. 00:32:29.400 --> 00:32:32.099 The current dramatic thermal activity will eventually 00:32:32.099 --> 00:32:34.539 wane and die out as the North American plate 00:32:34.539 --> 00:32:37.140 slides off that stationary plume, just as the 00:32:37.140 --> 00:32:39.720 land that is now the Columbia Plateau flowed 00:32:39.720 --> 00:32:42.200 past it 10 million years ago. So the history 00:32:42.200 --> 00:32:44.500 of the plateau isn't just a record of the past. 00:32:44.779 --> 00:32:48.180 It's a clear prediction of the future. The hotspot 00:32:48.180 --> 00:32:51.039 will inevitably begin to affect new regions farther 00:32:51.039 --> 00:32:54.160 to the east or northeast. If this geological 00:32:54.160 --> 00:32:56.099 process continues on its current trajectory, 00:32:56.480 --> 00:32:58.819 the question isn't whether the geological record 00:32:58.819 --> 00:33:01.119 will continue to be written, but what part of 00:33:01.119 --> 00:33:03.140 the continent will be next to experience the 00:33:03.140 --> 00:33:05.400 surface expression of that immense, unmoving 00:33:05.400 --> 00:33:08.119 furnace thousands of miles below? Will we see 00:33:08.119 --> 00:33:11.119 new flood basalts erupting in, say, Montana? 00:33:11.380 --> 00:33:13.319 Or maybe even farther east millions of years 00:33:13.319 --> 00:33:15.279 from now, starting the entire process all over 00:33:15.279 --> 00:33:17.880 again? The legacy of heat continues to write 00:33:17.880 --> 00:33:19.940 its story across the continent, reminding us 00:33:19.940 --> 00:33:22.500 that no landscape, no matter how settled, is 00:33:22.500 --> 00:33:23.480 truly fixed in time.