Dr. Jesse Reimink: [00:00:00] Okay. Chris Ha,

Chris Bolhuis: What? He just said my name. How you doing, Jesse?

Dr. Jesse Reimink: I'm just excited. I, I am, uh, I'm super pumped about [00:00:15] this episode, about this whole thing that we get to talk finally about the Geology of Yellowstone

Chris Bolhuis: That's right. In depth stuff. That's right.

Dr. Jesse Reimink: Uh, we're getting started on the real stuff here, the super exciting stuff. What makes Yellowstone great? I think.

Chris Bolhuis: That's right. So Jesse, [00:00:30] what is the plan for today's episode then? What have we got going on?

Dr. Jesse Reimink: So this is the overview. This is the starting point. This is the the foundation for which every other chapter that continues on. This is chapter two. Anything else after this will build on what we talk about today. [00:00:45] This is the high level geologic story of Yellowstone National Park.

Chris Bolhuis: That's right. So what we're trying to paint a picture of is hovering above Yellowstone in a hot air balloon, 30,000 feet above the [00:01:00] surface, so we get to see, we're gonna try to paint a picture of what happened in the 4.5 billion year history of Yellowstone National Park and make it as visual as we possibly can because Geology needs to be that way. Geology needs to be [00:01:15] seen. It needs to be imagined. It's, this is such an awesome story

Dr. Jesse Reimink: Yeah, Chris, and let me interrupt right there because this is a great visual you've put together here. This 30,000

foot view, hover over the land that is Yellowstone National Park today. And we're gonna start from back in [00:01:30] time, geologic time, deep time, billions of years ago. And we're gonna fast forward and we're just gonna watch what happens from 30,000 feet to the land surface and to the deep interior as well. And I love this visual. And Chris, it makes me think of when I was a young student, you [00:01:45] taught me Geology in high school, some of which was in Yellowstone National Park. So we have sort of a deep connection to this place. You and I do, uh, together and independently. But what it makes me think of is we did this class that you teach where you take, I don't know what, 25, [00:02:00] 26, I think it was 22 when I was a student. But high school students out west from Michigan, drive across all the Great Plains, all the flat boring states. And you eventually get to the Western states and you get to Yellowstone National Park, and you always would be driving this big yellow school bus. [00:02:15] And you had a little radio , you know, one of the radios in the front of the bus. So you'd be trundling along with a big steering wheel up front, and you'd get on the radio and be lecturing us about Geology on the way. And so this episode really makes me think of that. This is the 30,000 foot view of [00:02:30] Yellowstone. And we're your guides along the way here. And, and Chris has got the, the CB radio up front. . So

Chris Bolhuis: well . I'm not sure if that's a good thing. Don't ever give me a radio, but

Dr. Jesse Reimink: get a radio. A radio in 20 hours of driving where you're stuck. You're stuck listening to you [00:02:45] for 20 hours.

Chris Bolhuis: Oh, don't forget about my whiteboard. I bust out the whiteboard too. But now I, now I use window markers. I, I just do all my diagrams and stuff. I just do it right on, the outside the bus on, on the side of the bus. So when we come back to Michigan and our trip is [00:03:00] done, our bus is, It looks like a, a unicorn threw up over the, the, the side of the bus that's all, all, all kinds of different colors.

Dr. Jesse Reimink: super fun, super interesting Geology images, right?

Chris Bolhuis: That's right, that's right. There's one other twist to this though, [00:03:15] Jesse, that we're, what we're trying to do today is not only are we hovering above Yellowstone from 30,000 feet, but we also have a remote control in our hand. And we're gonna be able to push pause, we're gonna be able to rewind and fast forward at will. We're gonna be able to slow down. So [00:03:30] we're gonna get to these really important events that happen geologically and then we're gonna fast forward to the next thing. And it's kind of just this, this, it's always been a dream of mine to be able to do this; to be able to actually [00:03:45] see Geology this way. Where you get to just kind of, you know, linger on these really awesome, cool events that really define what Yellowstone National Park is.

Dr. Jesse Reimink: Yeah. And that takes us really nicely, Chris, into the first image in your [00:04:00] stack, which is a gif. And this is just an overview of the geologic timeline that we're gonna work through. And we can't belabor this point enough is that this is not linear. We can't go through this in a linear scale because the geologic [00:04:15] time is just too big. We're gonna cover, you know, 2.7 billion years of geologic time. So we have to fast forward through some of the early stuff faster. You know, we need to fast forward at 10 x speed and then we're gonna slow down and we're gonna fast forward at two x speed, [00:04:30] Um, so we're gonna go faster through the oldest parts, and then we're gonna slow down as we get closer to the more recent events. And you can see that in the timeline there. Down the middle of that image number one. You can see that this is not a linear scale with [00:04:45] time. The top half of the plot is 40 million years. The tire thing is 2.7 billion. So,

Chris Bolhuis: It's so, it's not exactly to scale, but it does a good job of showing all the events where they happened. And these are the things that we're gonna [00:05:00] talk about during this episode. They're, all of those things that are on that gif. Those are things that we're gonna emphasize. I do wanna say this, Jesse, too, before we dive into this, and we need to get going here. But to me, I mean, look, you and I both have been a lot of places [00:05:15] of geologic interest. For me, Yellowstone is one of the most, if not the most interesting place to teach field Geology. It's the, the coolest place to take students. Um, and, and just watch, watch [00:05:30] them realize what's going on. It's just a, I, I don't know how to really describe it. I've, you know, I've done this for a long time, a better part of 25 years I think.

Dr. Jesse Reimink: Yeah, you can tell it. I can tell it. Looking at you on Zoom right now. But [00:05:45]

Chris Bolhuis: Yeah. I'm pretty. I've been doing this for a long time, though, teaching students you know, I've taught students Geology in the field many places. I have to say, Yellowstone is probably my favorite place to teach.

Dr. Jesse Reimink: Well, I've [00:06:00] got, uh, I might, debate you on that one a little bit, Chris. I will definitely defer to your teaching expertise when it comes to Yellowstone, but uh, the last time I was in Yellowstone, I was actually with you and your class and this was a couple years ago and I was a professor and you know, you uh, gave me the opportunity to give a little bit of a lecture and [00:06:15] we could talk about this more in chapter three cuz it's really about chapter three. But, I think I put 'em to sleep when I gave a little lecture.

Chris Bolhuis: You did, you did a great job.

Dr. Jesse Reimink: I’m not sure that yellowstone's necessarily best place to teach Geology, but that's just my own personal experience talking

Chris Bolhuis: It was [00:06:30] good. It was just a, you know, you, you got a little doctory on these 26 high school seniors, and. You did a good job though. I, you helped my interest anyway.

Dr. Jesse Reimink: We could get into that next chapter. So let's get started here, Chris. And again, we are in a hot air balloon hovering up [00:06:45] 30,000 feet above the earth, looking down on the location that is now Yellowstone National Park and we're back in time. We're starting 2.7 billion years ago. What do we see?

Chris Bolhuis: We don't see much of this, exposed in Yellowstone National Park. We're talking about, , in [00:07:00] Geology we call this the pre-Cambrian era. In other words, really old stuff. There's not a lot here, but they are here. For instance, you can see them exposed in the northeast corner of the park where Lamar Valley is. You get some glimpses of [00:07:15] super old Granite and metamorphic rocks, like gneiss and schist. And, we're gonna stop with that, Jesse, because like, I know this is your, this is your thing.

Dr. Jesse Reimink: I can't dive into the weeds here. Okay. Alright, fair enough. [00:07:30] Well,

Chris Bolhuis: You can just quickly paint a picture of what they look like.

Dr. Jesse Reimink: I just wanna say that these are really old and so they're pretty tortured. These are rocks that I work on for my job. I mean, these are the ones we study in our lab, in our research group, we analyze at Penn State and the lab. These are old, they're tortured. [00:07:45] They look it. You will see little white veins everywhere. They've been deformed multiple, multiple times. They're really…

Chris Bolhuis: Let me interrupt you. When you say tortured, what you're referring to is these are rocks that existed as something else before that and subjected them to just really [00:08:00] high heat and high pressure, and transformed them into new minerals and different looks. And so they do look like tortured rocks. Absolutely. It's a good way of putting it.

Dr. Jesse Reimink: And the last thing, Chris, is they represent mountain building events, ancient mountain building events. So these are [00:08:15] mountains that used to exist. They no longer exist and we actually have very little record of them ever existing apart from these deep roots of the continent. Deep roots of the mountain belt, which are these tortured rocks in the middle here.

Chris Bolhuis: But it would've been really cool to see.

Dr. Jesse Reimink: It would've

Chris Bolhuis: if [00:08:30] we were here, 2.7 billion years ago, hovering above this, watching this. This would've been an amazing mountain building event to be able to watch in fast forward.

Dr. Jesse Reimink: So then Chris, we're gonna hit our fast forward button a couple times and speed that baby [00:08:45] up to go really, really fast cuz we have to skip forward for about 2 billion years here, which is a big interval of time where we have very little rock record - basically no rock record in Yellowstone.

Chris Bolhuis: That's right. However, this would've [00:09:00] been cool to watch in fast forward - this 2 billion years because we saw the formation of the mountains, and then over the next 2 billion years we get to watch Weathering and Erosion do their thing. And that would've been a pretty cool [00:09:15] thing to see these mountains kind of get erased because it wouldn't have just been this, you know, there would be powerful things that happen. We'd see these immense muscular mountains being eroded flat, right? Eventually exposing these deep roots [00:09:30] that we get to see in, in Lamar Valley and so on. We would see massive earthquakes happen because of the removal of the weight and the mantle below is pushing up and pushing up. And when the pressure of that force exceeds the [00:09:45] strength of the rocks, you'd get these just really, really powerful earthquakes happen. So it would be a cool thing to watch in fast forward.

Dr. Jesse Reimink: Yeah, that's exactly right. And I think we need to sort of point to this, that [00:10:00] there's a lot of stuff that happened in this interval between 2.7 and we're gonna skip ahead to about 500 million years ago, 515 million years ago. So we're skipping ahead 1.5 billion years. A lot of stuff happens in there. We just don't have a record of that in Yellowstone. So if we, instead of just looking at [00:10:15] Yellowstone National Park from our hot air balloon, if we zoomed out and looked at the whole region, we would see different mountain building events 1.9 billion years ago. But we don't have a record of that though in Yellowstone National Park because there's no rocks of that age. So we're missing rocks, which is [00:10:30] missing time. It's missing geological history. So that, I just wanna point that out, that we're describing it as sort of not much happening, but there's a lot that happened. We just don't have a record of it in the Yellowstone area.

Chris Bolhuis: That's right. So we hit fast forward, we watched these mountains get [00:10:45] ero, we hit fast forward. We watched these mountains get eroded kind of flat, you know, not perfectly flat, but we can think of it that way. And we hit about 515 million years ago, and now we're gonna [00:11:00] slow this down because we get to see something kind of cool happening. We would see the shallow sea that covered the greater Yellowstone area and, and it was depositing immense layers of sedimentary rocks that are very common, like shales and [00:11:15] sandstones and limestones. And the, you know, the shoreline was kind of shifting back and forth. It would get deeper and shallower and so on. And we also have abundant fossils that are in this.

Dr. Jesse Reimink: So, and I think it's important Chris, to, to note that these sedimentary rocks [00:11:30] huge, like you said, huge stack of them. Thousands of feet high are being deposited on top of the old deep cold roots, the ancient mountain belt. So this is what we call the great unconformity. And again, that's missing time. There's a one and a half billionaire gap in time there. [00:11:45] These also, I think to paint this visual, we have to imagine how are we getting thousands of feet of sediments here? Is that the, the ocean is, is sort of depositing sediments and the weight is kind of bearing it down and the weight of the sediments kind of makes the land [00:12:00] subside. But if we could look down into the water, we would see that these oceans are starting to have life. And, and 515 million years ago, the life is a little bit rudimentary, but an image number two in our stack shows one example of this. This is a [00:12:15] trilobite fossil. And these are weird creatures, Chris. I mean, there's some similarities to, uh, these horseshoe crabs that you find sometimes in the Atlantic Ocean on the east coast. They're totally weird creatures though, these trilobites. And you sort of start to see this sea life [00:12:30] form and take over the area and it'll change through time.

Chris Bolhuis: That's right, because if you look at image number three in your stack, this is an image of an ichthyosaur fossil, which

is much younger [00:12:45] than the Trilobite. This is about 250 million years ago. Is that right, Jesse? 250. Okay. Yeah. So yeah, so this Ichthyosaur fossil is about 250 million years old. So this just shows the, the dramatic change in life. This [00:13:00] ocean was teaming with life. The rocks that we see have abundant fossils. Um, and so it would just be awesome to watch this shifting shoreline back and forth as, as the, you know, as the sea got [00:13:15] deeper and then shallower and so on, and be able to watch how the life changed as you're hovering above watching this in fast forward

Dr. Jesse Reimink: And so let me interrupt Chris. I just wanna highlight this again, that we're fast forwarding, pretty fast still. Those two images, the difference between those images is like 250 [00:13:30] million years between those fossils. Trilobites exist for a long time, but trilobites are the sort of early representation and then the Ichthyosaurs later. So we're still fast forwarding pretty fast, but you're watching this sea shift back and forth. And the life is evolving in that sea [00:13:45] as well as we progress forward in time.

Chris Bolhuis: Now we move on to the next major event, which is a mountain building event. And in Geology we often refer to these as orogenies. And so what we see is what's called the Sevier orogeny, and it's [00:14:00] spelled s e v i e r, but it's pronounced severe. This is a mountain building event that begins to encroach upon the Yellowstone area from the west. And what this does to the sea, [00:14:15] it results in the thickening of the crust. And so the sea goes away. This, this event is gonna drain the oceans and we now get to re, we get to see off to the west of the greater Yellowstone area, these kind [00:14:30] of thin skinned mountains that are beginning to, to pop up.

Dr. Jesse Reimink: And this really affected regions like Glacier National Park. The Sevier Orogeny, you can go and see the geological implications of the Sevier orogeny in Glacier National Park, which is [00:14:45] quite a ways west and northwest of Yellowstone. But into the east towards Yellowstone, basically what you get, Chris, and this is the analogy that you use to teach me when, uh, you were teaching me Geology is a, a rumbling of a carpet. If you, you know, have a carpet and it's not nailed down and you push against [00:15:00] the edge of it, it kind of rumbles. And right where you're pushing it, it rumbles pretty big. That's the severe orogeny part out there, uh, near Glacier National Park. But in, in Burt. But in further into the room, away from the edge, you get these sort of broader rumbles and it kind [00:15:15] of bends up. And that's what's happening in Yellowstone is basically the land is rising slightly. It's draining the sea to the east now. And so the sea gets drained to the east because there's this mountain building event, the Sevier Orogeny on the west.

Chris Bolhuis: But this mountain building event, we're kind of on [00:15:30] the edge of it. We're on the eastern edge of this mountain building event. And so you have these mountains that are being lifted up, which whenever that happens, that means weather and erosion are accelerated to. And so as they're being uplifted, they're also being [00:15:45] vigorously eroded. So this sediment being eroded off the mountains, dumping it into the greater Yellowstone area, and further east results in this kind of sinking - this down warping. And what this does is it enables [00:16:00] another very important shallow ocean to invade the area. And this brings us to image number four. This is called the Western Interior Seaway. This went from where the Gulf of Mexico is currently all the way up [00:16:15] through the western part of the United States up into Canada. So this was a very warm, very shallow seaway that went basically north to south across the entire western United States.

Dr. Jesse Reimink: And let's go back to our visual here, Chris. We're gonna look down and the [00:16:30] climate is very different in this environment. There's gonna be magnolia trees and cypress trees, and huge sequoias ash, cedar, pine, spruce it. It looks very different from today is the point. It's a lot warmer, it's a lot wetter. There's a big shallow ocean there. So there's [00:16:45] lots of life in here. We got plesiosaurs and dinosaurs roaming around. Imagine a warm kind of coastal forest. I always kind of think of like, you know, Caribbean with mangroves and things like that. Like kind of imagine that sort of dynamic, warm, shallow water. [00:17:00] Lots of life on the margins in the marshlands and stuff like that. So that's kind of what I view. And this is what you see looking down on this Western interior Seaway area and Yellowstone National Park specifically.

Chris Bolhuis: And again, this is very, very different from what the [00:17:15] climate is like today in Yellowstone. You're describing something that doesn't exist there today. But we know that it was at the time because of the fossils that we see in the rocks, the kind of trees that got petrified and so on that we'll talk about here in a little bit. The other thing that I wanna [00:17:30] mention about the Western interior seaway is Yellowstone is kind of right, near the edge of that sea. It's not right in the middle of it. So we would see, roaming dinosaurs and, and when sea level would transgress and get deeper, we'd see plesiosaurs [00:17:45] patrolling the oceans and just very, very awesome life existing in this area.

Dr. Jesse Reimink: I'd be happy to be in my hot air balloon. 30,000 feet above this one though, so, um. Okay, Chris, now we're gonna again hit the fast forward [00:18:00] button and we're gonna move forward here. And we're gonna hit about 80 million years ago. And again, we're gonna drain this ocean. And what happens here is, this is the famous Laramide Orogeny. Another orogenic event, another [00:18:15] mountain building event that lifts up the Rockies that forms the Rocky Mountains. And image number five is a gif of how this happens - how the Laramide orogeny happens. So, Chris, all right. Get back on your radio in the front of the bus here,

Dr. Jesse Reimink: And give us, [00:18:30] give us

Chris Bolhuis: Okay.

Dr. Jesse Reimink: the view of the Laramide Orogeny.

Chris Bolhuis: Well, all right. Image number five shows these events. It begins with subduction at the western part of the North American continent, and it, it's a normal subduction zone. It's rather steep and so on. What [00:18:45] happens then is sediment is getting scraped off from the subducting slab and plastered onto the overriding plate, and that's the Sevier orogeny. But then something happens. The subduction angle changes. It goes from being a normal subduction zone [00:19:00] to just this, it flattens out. It's kind of like, um, a sliver being jammed up underneath the finger. I know that's a crude analogy, but it, but it works. I mean, that's, it's exactly what's going on. You have this subducting plate that [00:19:15] is not doing what normal subduction zones do anymore. It's just jamming up underneath the continental plate and it's causing then these really young muscular mountains to get [00:19:30] shoved up skyward. I mean, this is what we're able to see. I think this would be so cool to be able to watch this really thin skinned mountain building event happen. Lots of thrust faulting and pretty cool stuff, right? And then all of a sudden we see [00:19:45] that it, becomes more than that. It, it's different Now. This is deep seeded mountain building stuff that's shoving old deep rocks up towards the sky, up closer to us in our hotter balloon

Dr. Jesse Reimink: Uh, Chris, it's, it's like I'm back in, you know, [00:20:00] 2004, sitting in the back of the bus right there. I mean, it is a great visual. We've got the rock, the entire Rocky Mountain range, uplifting, and this is cool. We're basically the entire western third of North America get pushed up. This is a huge event [00:20:15] and a really, really, really cool visual to watch. And so Chris, we've got this huge event going on, but we're gonna zoom in on Yellowstone National Park and start zooming down in on this region. And this is the event that forms a bunch of the mountain ranges that basically you almost have to [00:20:30] see when you're driving into Yellowstone National Park. Uh, so what are those ranges? We're gonna walk through the different ones here and image number six, and our stack goes through these and shows the images really nicely in a little gif. So, uh, where do you wanna start with these Chris?

Chris Bolhuis: I don't know, I guess I'll [00:20:45] start on the west and work my way clockwise. So this gif begins by showing the Madison range, which is west of Yellowstone. It's a, you know, a little bit west and a little bit north of where Yellowstone is. And then you have the Gallatin range[00:21:00] that does actually cross through the northwest part of the park. And so that's again, west and north. And then to the north of Yellowstone, you have the famous Beartooth Mountains. These are very like young [00:21:15] muscular mountains. They're awesome. I mean, you get some white knuckle driving if you drive through the Beartooths into Yellowstone through Cook City and so on. I mean, it's, it's really . It's - I enjoy it. Other people, not so much. Um, and then you have the very [00:21:30] famous Absaroka Mountains on the eastern part of the park. So if you were coming into Yellowstone from Cody from the east, you're gonna drive up and over the Absarokas and they're amazing. And then lastly, in the southern part of the park, you have this small [00:21:45] mountain range that's called the Red Mountains. The thing is about all of these mountain ranges, the Madison, Gallatin, Beartooth Absarokas, and Red Mountains, these were all volcanic. They acted a lot like the Cascades do in the northwestern part of the United States [00:22:00] today. If we're hovering above this right, we would get to see some spectacular volcanism. We would see these violent volcanic eruptions where ashes spewed out. We might have to, go up a little higher in the hot air balloon to, to stay safe. And then we [00:22:15] would see, you know, lava flows that would pour out and, and build up these destroyed mountains and so on. We would see lahars, these spectacular mud flows that would follow these volcanic eruptions and they would come roaring down the valleys and [00:22:30] knocking down these trees that you described. These, very different climate trees that don't exist or grow in Yellowstone anymore today. And those lahars would petrify the wood. And we're gonna talk about that a lot in [00:22:45] chapter seven and what this looks like. It's a very, very cool part of Yellowstone's story. But the point is, Jesse, all these mountains, these are Yellowstone's other volcanoes. Now, why do I say that? What do we mean “other volcanoes”? What's going on with Yellowstone now? What do we have [00:23:00] to do now?

Dr. Jesse Reimink: Well, so now, Chris, we're around about 40 million years, 35 million years ago or so. And when we look down, we see all mountains everywhere. Very different from what you would see if you were in a hotter balloon above Yellowstone National Park today. Those mountain ranges [00:23:15] go back to image number six in the stack and you see that there are mountain ranges that go kind of all around Yellowstone National Park. And this is a really key part of the story. We're gonna move forward about 20 million years now, so we're gonna skip fast forward and we're gonna see a lot of weathering going on. There's mountain [00:23:30] ranges everywhere. They're being weathered down gradually. Then we hit 17 million years ago, and then this really dramatic and interesting and very cool thing starts to happen. If we look west. If we turned in our hot air balloon and looked pretty far to the west -[00:23:45] kind of where Oregon, Nevada, Idaho intersect, we start to see the birth of a mantle plume. And we're really gonna hit this in chapter three. So we've gotta, you and I, Chris, are gonna have to work hard to stay out of the weeds here right now. We're gonna move through this a [00:24:00] little bit quickly, but we're gonna hammer it in chapter three, so, stay tuned to learn more here. But basically this is a hotspot with massive volcanoes and it's going to start marching towards our hot air balloon from the west 17 million [00:24:15] years ago, moving towards us in Yellowstone National Park.

Chris Bolhuis: Wouldn't that be cool to see Jesse? We, uh, we would, it would be unmistakable. We would see this, and that's 500 miles away to the west, but these eruptions were [00:24:30] so big, so explosive. We would certainly see them in our hot air balloon. We would

Dr. Jesse Reimink: We,

Chris Bolhuis: probably be affected by them in, in like a not good way,

Dr. Jesse Reimink: we'd have to move our hot air balloon a couple times

Chris Bolhuis: We, we would. But the other really [00:24:45] cool thing about this, as the North American plate continues to move over this hotspot. We would see these eruptions getting closer, and closer and closer to where we are because the hotspot is gonna [00:25:00] stay in a relatively fixed position. The plate is moving over top of it. So we saw these eruptions begin, and then as they happen, and then I'll keep in mind, these didn't happen very often. Over the 17 million years, there [00:25:15] were maybe a hundred Caldera forming eruptions.

Dr. Jesse Reimink: Yeah. And this, Chris, I want to, the visual here is kind of a buzzsaw. We're kind of marching very slowly at the rate your fingernail grows, we're marching towards a buzz saw here. The mantle plum is a buzz [00:25:30] saw, and this is why the mountains ring Yellowstone and are not in the middle of Yellowstone. And so basically what this buzzsaw did this mantle plume buzzsaw, is it just blew a hole through the continental crust and blew apart the mountain ranges all the [00:25:45] way along that 500 mile track. And so these eruptions…

Chris Bolhuis: Now I want to, can I interrupt you a second here? First of all, let's point everybody to image number seven. This gifified image here shows the track of the plate moving over the hotspot. And [00:26:00] so you can see in the lower left-hand part of that gif where it all began about 17 million years ago. Now, I do wanna say, I said that there are over a hundred Caldera forming eruptions, but not all of these are super eruptions. We think there were only maybe [00:26:15] a dozen super eruptions that happened over that 17 million years. So we really have to, as we're hovering in our balloon, we have to hit the fast forward button and then let's watch the show and then hit the fast forward button, you know, and so on. Because in order for something to be [00:26:30] classified as a super eruption, it has to be over a thousand cubic kilometers of material that was ejected out. So there were a lot of eruptions that just didn't meet that standard. They were still caldera, forming eruptions, but [00:26:45] about a dozen or so, qualified. And so I like your analogy of the buzzsaw, because that's really what it must have, what it would've looked like if we were able to do what we're, what we're trying to describe here.

Dr. Jesse Reimink: Okay, Chris. So, uh, this buzzsaw [00:27:00] kind of gets concentrated into about seven volcanic centers that are highlighted again on that image number seven, that gift there. And what we're gonna move towards, and what we're gonna talk about now is the actual Yellowstone one, the last one, the one that's there now underneath of Yellowstone National Park. And this story really [00:27:15] begins about 2.1 million years ago, where an eruption, the scale, rarely ever seen on earth occurred 2.1 million years ago. This thing is huge! And it began [00:27:30] this series of eruptions that occurs every 600 to 700,000 years ago. There's been three major eruptions in the Yellowstone area, but this thing, Chris, we would've to get our hot air balloon out of there, or go out into space and move to the moon

Chris Bolhuis: That's right.

Dr. Jesse Reimink: and watch for a little [00:27:45] while to watch this happening from the moon

Chris Bolhuis: Yeah, this is probably better viewed from space for sure. Let's, let's talk about these. If we can turn you to image number eight. This gi shows certain landmark eruptions that I think most people are familiar with.[00:28:00] It starts with Mount St. Helen's, that little tiny cube there, and then there's Mount Mazama, and that's where Crater Lake is in Oregon. That was about 10 times larger than Mount St. Helen's. And then you have the three big Yellowstone eruptions. You have…

Dr. Jesse Reimink: Chris, let me, [00:28:15] let me interrupt you there real quick cuz I want to calibrate this gif a minute because you said before that a super eruption is over a thousand cubic kilometers and, a thousand cubic kilometers is around about 240 cubic miles. So only the two biggest ones are super eruptions on this [00:28:30] scale. But, regardless, these

Chris Bolhuis: That's right.

Dr. Jesse Reimink: things are huge. So I just wanted to

Chris Bolhuis: Well, yeah, I mean I can run through the numbers a second, right? So you have 2.1 million years ago. That's the first eruption that happened where Yellowstone is today. That was 2,500 times [00:28:45] larger than the Mount St. Helen's eruption of 1980. The second eruption that happened in Yellowstone is 1.3 million years ago. This one was only 280 times larger than Mount St. Helen's. I'm saying that sarcastically, you know, so it didn't meet [00:29:00] the criteria for a super eruption. The one, 1.3 million years ago. And then we have this other one, 630,000 years ago that was a thousand times larger than Mount St. Helen's. So that qualified as a super eruption. So the first [00:29:15] one and the third one all qualify. But like you said, this is probably better off viewed - all three of these - from space because these are unbelievable earth events.

Dr. Jesse Reimink: These are massive, massive events. And [00:29:30] it's important to point out, Chris, that these are probably not three individual massive eruptions. These are more like episodes of volcanism that last for a long time. And you know these last to tens of years, to many decades, the sun is blotted out many [00:29:45] times. In the area, life is incinerated. I mean, you, likened it to Mount St. Helen's or you know, something a thousand or 2500 times bigger than Mount St. Helen's. So these things are huge. Ash flows are sweeping out. The whole area is turned gray. And really [00:30:00] what happens if we kind of bring it back to the map view, this 30,000 foot view, we're destroying the central part of Yellowstone's other ancient - the more ancient volcanoes that were formed in the region. And so we're really blasting a hole through these other [00:30:15] volcanic centers. And Chris, again, we're gonna talk more about this in chapter three, but we're forming Calderas. So these magma chambers are so large that when they get emptied out, they create space in the earth and the land around them [00:30:30] collapses down into it. So it's very different from a crater. A caldera is a much larger, much more dynamic thing, but the land is collapsing into the leftover dregs of an empty magma chamber is what's going on. And so that's what we're watching is [00:30:45] all this trauma, you know, stuff being thrown up in the air, life being obliterated in a region. And then when it's empty, the land collapses down in and subsides down into it. And that's why Yellowstone is ringed by mountain ranges at the moment.

Chris Bolhuis: Yellowstone's. Other volcanoes, the [00:31:00] Madison range, the Gallatin, the Beartooths, the Absarokas, and the Red Mountains. It almost looks like there's a huge apple bite right out of those mountains. They're just gone. And that's because of what you just described. What [00:31:15] wasn't destroyed by these three cataclysmic eruptions, collapsed down into the magma chambers. So Yellowstone is kind of cannibalistic, you know, because now it's gonna take that material and it's gonna begin to melt that material and [00:31:30] assimilate those rocks into its newly forming magma chamber. Yeah. Good, good description.

Dr. Jesse Reimink: And so now we're at this third eruption, we're 640,000 years ago. And we see this calera having collapsed down into itself. But we do see more lava [00:31:45] flows coming out. It's this kind of sticky, really oozing magma that kind of oozes up through the surface and spreads out on the surface.

Chris Bolhuis: These are way more common than these explosive eruptions. . So [00:32:00] after it collapses down in, you kind of get this, like rising bread dough is, is maybe a, good description of how thick these lava flows are. They're really, really viscous stuff. It forms the rock Rhyolite, which is all over the place inside the Caldera of Yellowstone. [00:32:15] And so, Yellowstone has had since the last eruption, dozens of these things, of these lava flow eruptions that just kind of fills everything in. So you have these volcanoes that were, obliterated or swallowed [00:32:30] by the Yellowstone Caldera, and then everything in there just gets covered up with these rhyolitic lava flows. So there's no sign of those other volcanoes that we got to watch form beginning 80 million years ago.

Dr. Jesse Reimink: [00:32:45] And, elephant Back Mountain is one place where you can see this. Often these, things kind of occur in rings around the Caldera, again, we're kind of oozing out and filling back in this Caldera volume with this sticky rhyolitic lava that's coming out onto the surface and oozing out onto [00:33:00] the surface. So, Chris, we're gonna hit fast forward again a couple times here, right? And we're gonna move to 175,000 years ago. Is that okay to do at this juncture?

Chris Bolhuis: It it is. But I do want to just reiterate and put a pin in what you just said. Elephant [00:33:15] back mountain. Highly, highly recommended hike. It is. It's, it's a steep hike. It's, it's four miles long round trip, but it gives you spectacular views of Yellowstone Lake - it's awesome. So highly, highly recommended that[00:33:30]

Dr. Jesse Reimink: so, so 174,000 years ago, we kind of get a “smaller” eruption that occurs. The Caldera is now. only 10 miles across. And so again, if we're up watching this from our 30,000 foot view, [00:33:45] kind of viewing this parasitic caldera that's inside of the larger Yellowstone Caldera, which is 30 by 45 miles across. And this is what formed again, the West thumb of Yellowstone Lake. Or at least it formed the depression that would later be filled in [00:34:00] to form the west thumb of Yellowstone Lake. So where are we at now, Chris? What's going on in the landscape after this eruption?

Chris Bolhuis: Um, we're getting cold. We're getting cold now. And so what we're starting to see shortly after this West Thumb [00:34:15] explosion 174,000 years ago, we're gonna see glaciers begin to move into the Yellowstone area. Massive glaciers. These things covered Canada. They covered a lot of the northern US, but Yellowstone has the ripe [00:34:30] conditions to make this a zone of accumulation. So let's describe that, Jesse. Why is Yellowstone ripe for more snow than anywhere else around?

Dr. Jesse Reimink: Yeah, well, I mean it's, it's high, but it's not as high as [00:34:45] the surrounding mountains, but really what's happening is there's an air funnel that's coming up, this Snake River plane, which is this track that the buzz saw went through that you just described so aptly. and so the air is kind of funneled up there. It cools as it rises higher and [00:35:00] as it cools, it dumps precipitation. And a zone of accumulation is just where there's more snow and ice accumulated than is melted. And that's a recipe for a glacier forming. So we have this kind of glacial cap on Yellowstone surrounding it. And the, [00:35:15] the view that we're seeing as we're looking down is that Yellowstone has a bunch of glaciers around it. Uh, there are glaciers moving, as you said, from the north. So if we turned and looked up north, there's continental scale glaciers everywhere up north, and they come down and they're eroding. And as a glacier [00:35:30] flows across the landscape, it is scraping off all of these rocks. It's cutting big U-shaped valleys into the region. Cirques, aretes… all these really cool things that make mountains look badass. I think like, you know, a mountain range that has been glaciated looks [00:35:45] freaking cool, and glaciers are doing this, scraping through it. And so that's kind of what's going on. And we'll touch on this a little bit. Later on in some other chapters as well, more about this glaciation event. But the ice would retreat as the earth [00:36:00] warmed over a thousand years, and then it would come back as the earth cooled. And so our 30,000 foot view, we're looking down on this, the glaciers are getting bigger and smaller. They're extending in certain directions and retreating. Sometimes some of the mountains around Yellowstone or [00:36:15] in Yellowstone are exposed above the glacier cap. Sometimes they're buried down under it. And if we point to image number nine, this is what's called Avalanche Peak, which is a great hike. I mean, I love the Avalanche Peak hike. Anywhere you go on that is is totally cool. [00:36:30]

Chris Bolhuis: It is the best.

Dr. Jesse Reimink: views,

Chris Bolhuis: It's the best hike in the park. I, uh, hands down Avalanche Peak is amazing. It is a tough hike. It's a five mile round trip. Uh, it's steep, but it is awesome.

Dr. Jesse Reimink: But this visual on image number nine kind of. It gives you a view of what this [00:36:45] looks like. This is a glaciated region, and so sometimes Avalanche Peak would be exposed above the glaciers. Sometimes the glaciers would be on top of it, and there's a lot of erosion going on.

Chris Bolhuis: But to be able to hover above this, Jesse and right above it, cuz we could get close to this then, and, and [00:37:00] then watch it fast forward and let it slow down. I mean, it would be just incredible to see this ice come and go and, listening to it, moving ice is not a quiet thing. I mean, the groans and the creeks of cracking and [00:37:15] snapping ice and the, the process of erosion as it scours out these valleys in the Absarokas and, and just, I would love to be able to do what we're describing to be able to see it this way. So,

Dr. Jesse Reimink: So, [00:37:30] just somebody, just build Chris a time machine so we can do this. Well, yeah, I mean, get on it. So as the glaciers start to melt, though, we don't have glaciers there now. And, and so the earth has warmed since this time, and all this melting ice produces water. And the water brings us to the [00:37:45] history of Yellowstone Lake. So we're gonna go through the history of this again from the 30,000 foot view. Chris an, where are we? What's, what's happening as the glaciers are melting.?

Chris Bolhuis: Jesse. Let's refer to image number 10 - Yellowstone Lake. We can see then the effect of these glaciers. [00:38:00] These glaciers were melting and you'd get depositional features associated with that. And they're filling this natural basin in, which is now Yellowstone Lake. They are also eroding, and we see this, if you look at Yellowstone Lake from above, image number 10. [00:38:15] We see the Yellowstone Lake resembles a very contorted, gnarled hand. West thumb is the thumb. You have the main body of the northern part of the lake, that's the palm, and you have these three gnarled fingers that kind of extend out [00:38:30] to the south and southeast. Those fingers were created by glacial erosion. They're what we refer to as finger lakes. Now. There are other things going on with them, faulting and things like this too - that controlled… That's why the glaciers [00:38:45] exploited those more than others. But yeah, the basin then was filled in with glacial meltwater, and there's Yellowstone Lake.

Dr. Jesse Reimink: So Chris, let's focus again on image number 10, because image number 10 shows that Yellowstone Lake was actually bigger at this time, than it is today.

Chris Bolhuis: [00:39:00] Good point.

Dr. Jesse Reimink: and all of what is now Hayden Valley and Pelican Valley, they're largely treeless today, but they were underwater because this lake was flooded more than it is today. And the, the highlight in the gif there shows the former extent of Yellowstone [00:39:15] Lake, back at this time, several thousand years ago.

Chris Bolhuis: That's right. That's right. There was so much more water in the lake and the part because we had these ice dams where Canyon is today.

Dr. Jesse Reimink: Hold on. Chris, let me before you get into that, [00:39:30] we're kind of coming to the end here, but I just, this is a common misconception and something I always personally struggle with is we're gonna talk about river flowing here and I work a lot in northern Canada and, rivers always flow to the north, mostly up to the Arctic [00:39:45] ocean. And that's like uncomfortable for me being from the Midwest where, you know, the Mississippi River flows, we think of our maps down as south and rivers flowing south in the Mississippi. We're gonna talk about rivers flowing to the north, right? And so we're, this is to the north, just so everybody's [00:40:00] on the same page when we talk about the next thing we're talking about stuff going up to the north. So stuff's flowing to the north. Anyway. I find that hard, hard concept always, and I think many people might. So anyway,

Chris Bolhuis: Such a good point. A lot of my students struggle with that too, because they think [00:40:15] of, north as being up right - up literal in the literal sense of the word. And everybody knows water doesn't flow uphill, so water can't flow north. Uh, no, uh, not, not quite that way. So yeah, we had these ice dams that blocked [00:40:30] the drainage of Yellowstone Lake and so Yellowstone Lake swelled and buried what is now Pelican Valley and Hayden Valley in a lot of water.

Dr. Jesse Reimink: And Chris, if you were gonna build a dam and you told me you were gonna build it out of [00:40:45] ice, I would say, please don't do that. That's a bad idea. Right? That's a stupid idea. And so, uh, we're gonna talk about why that's a stupid idea, but it's pretty obvious. Why is that a stupid idea? And what happens when you build a dam out of ice?

Chris Bolhuis: Okay. I can answer that. Um, [00:41:00] they break and so we would get to see this though. What an amazing, powerful thing we would get to witness - these ice dams would break. It would then release the water out what is now the Yellowstone River through [00:41:15] Hayden Valley. We would get to see these just unbelievable flash floods going on that are scouring away what is now the Grand Canyon and forming the Grand Canyon in short order. So we're talking [00:41:30] about creating these unbelievable landscapes in a timeframe that's closer to weeks and months than hundreds or thousands of years.

Dr. Jesse Reimink: Chris, I think, again, let's go back to our visual here cuz we can get pretty close to this, right? We can move our [00:41:45] hot air balloon down and get kind of closer to the land's surface and watch this. This is incredibly powerful though. Think of, you know, your nearest river that you've seen in flood stage near your home. This is that times a thousand. Way more powerful than any [00:42:00] river and flood stage in like a normal flood stage. This is a really traumatic thing. This is scouring the landscape. And let's point to image number 11 in the stack, which is the lower falls and it's scouring through this. This is an image looking to the south, cuz remember that [00:42:15] river is flowing to the north, so this image is looking south. And you would see this huge amount of water rushing down that valley and scouring out the edges.

Chris Bolhuis: Yeah. And we would get to see this canyon form right before our eyes. We would get to see the colors of the [00:42:30] canyon walls be exposed right before our eyes. Just amazing. Beautiful, powerful stuff going on here. And so this would happen periodically, more ice dams would form, the ice dams would break, and you have another flash flood, just [00:42:45] rushing down the, what is now the Yellowstone River. and so that's what we would get to see now if we fast forward a little bit more beyond this. And after this, so the glaciers have now left, left for [00:43:00] good. Now we get to witness Yellowstone's other stuff, right? We're now we get to witness the most common explosions that Yellowstone has, these hydrothermal explosions. Hydro means water, thermal means hot. So this [00:43:15] is super heated water. And you know what, Jesse, these two can be related to the breaking of the ice dams. Imagine that you have all this water. On top of this really like hot, super heated groundwater [00:43:30] below Yellowstone Lake or below Hayden Valley, and all of a sudden with these ice dams break, the water is drained very quickly. That weight is gone, which causes the groundwater to flash into steam and, [00:43:45] and you have these just unbelievable hydrothermal explosions that took place. And you'd get these huge craters like Indian Pond, Mary Bay, Sedge Bay, many, many more. They're all over the place in Yellowstone National [00:44:00] Park.

Dr. Jesse Reimink: and so Chris, uh, go back to our view here. You're seeing these things kind of pop off around the park in different regions, and we're getting to the point where Yellowstone's looking quite similar to the way it does today. And we wouldn't see many other massive events, [00:44:15] but we'd kind of see these little what look to be little now cuz we're calibrated to these massive events, these massive floods, these massive volcanic eruptions. They'd look small to us today, but they're still pretty violent. If we were on the ground they'd be pretty violent. Big steam explosions.

Chris Bolhuis: your day would be ruined. Yeah. If you were [00:44:30] standing anywhere, if you were standing near Indian Pond or Mary Bay during one of these hydrothermal explosions, um, your day just got ruined.

Dr. Jesse Reimink: Yeah, that's exactly right. And so I we're kind of slowing down, you know, we're not fast forwarding very fast at all here [00:44:45] compared to what we did earlier in this episode. We're slowing down the last 10,000 years to present. We would kind of see, uh, you know, relatively consistent Geology happening. And really what is happening is we would get to see if we kind of got closer [00:45:00] to the land service. We'd get to see all the things we talked about in episode one. Humans moving around and discovering this place and looking around and living in this region. And so, That's kind of where we will end this episode - I think this 30,000 foot view, right, [00:45:15] Chris, And say that we are gonna cover all of this stuff in more detail in the coming chapters. So chapter four, we're gonna really get into these hydrothermal features and we have an episode on, you know, old Faithful. And so go to those episodes where we get into more [00:45:30] detail about this. Chris, as is tradition, we're gonna end with a couple of frequently asked questions. Sound good to go there now?

Chris Bolhuis: Yep. Let's go. Let's do it.

Dr. Jesse Reimink: So Chris, you, uh, come across these a lot more than I do because you teach [00:45:45] 25 students here every summer for a week, at least in Yellowstone. And I was with you recently in 2019, I think it was, and a student group wandering around Yellowstone National Park attracts attention from people there, let's say. And so there's always like, [00:46:00] you know, random people that come up and they hear you lecturing and they just kind of stand, they just kind of join the group of students. So there's always like people

Chris Bolhuis: they'll migrate with us. They'll follow us.

Dr. Jesse Reimink: Yeah, exactly. Cuz they're like, oh wait, this is a great tour guide we're getting here. What's going on? So you, you get a lot [00:46:15] of these questions, so I'm gonna pass 'em to you today. The first one Chris, we have is, is Yellowstone the largest national park?

Chris Bolhuis: Yellowstone is huge. It takes a long time to get anywhere in Yellowstone and then throw in the traffic that

Yellowstone.[00:46:30] It's a big place, but the answer is no. Alaska, over half of Alaska's national parks are bigger than Yellowstone. So no - it’s not.

Dr. Jesse Reimink: Yeah, it's a huge place. Lots to see, but it's not the biggest one. Uh, the next question, and I think this kind of ends [00:46:45] our FAQs for this episode. What is the highest peak in Yellowstone National Park? It's hard to tell this actually, like many mountain ranges, you can kind of point to one and say, oh, that's clearly the big one. it's not that way in Yellowstone, in the region. So what is the tallest one?

Chris Bolhuis: it's called Eagle [00:47:00] Peak. It's in the southeastern part of the park. Uh, it's 11,358 feet tall, and it is in a very remote area. So not a lot of people get to the top of the Eagle Peak. It is safe to say that for sure.

Dr. Jesse Reimink: Yeah, but Yellowstone itself is, is quite [00:47:15] high. Like most of the park is pretty high, and the, the winters can be kind of extreme. It's, yeah, so you're pretty high already at baseline. Um, and so, uh, that's partially why it's hard to tell what the biggest peak around you is when you're standing there in the park. [00:47:30] All right, Chris. Hey, that's a wrap on chapter two, our overview, our 30,000 foot view with Chris on the radio in the front of the bus. And we're gonna start talking about more of these geological features in more detail, in coming chapters.

Chris Bolhuis: That's right. Chapter [00:47:45] three, coming your way. Next is on Hotspot Volcanism.

Dr. Jesse Reimink: Ooh, a fun one.

Chris Bolhuis: For sure. Cheers.