Great Smoky Mountain National Park

Great Smoky Mountain National Park

Jesse Reimink: [00:00:00] Welcome to PlanetGeo the podcast where we talk about our amazing planet, how it works

Jesse Reimink: and why it matters to you.

Chris Bolhuis: How are we doing Jesse?

Jesse Reimink: Good. Chris, how about you?

Chris Bolhuis: I'm I'm great. feeling I'm feeling especially

Jesse Reimink: especially smart. That's good. Cause you were telling me how I should be so lucky to get the chance to work with you before we hit record. You're just, you know, I'm feeling lucky.

Chris Bolhuis: Well, you should, and I need to do a better job of reminding you of

Jesse Reimink: Yeah. I mean, look at you sitting in there with your hoodie flannel, mean, what is the weather in Michigan right now? Is this super cold or what's going

Jesse Reimink: on?

Chris Bolhuis: it is, oh man. It's cold. Yeah. And not, not liking this very much so it's but I'm I'm I'm in my, in the basement, in the

Jesse Reimink: In the case and the recording cave.

Chris Bolhuis: good to go.

Jesse Reimink: All right, today, this is a you one, man. This is a, this is something you put together. You've [00:01:00] been to Great Smoky Mountain National Park how many times now?

Chris Bolhuis: Oh, I don't know. I have absolutely no idea.

Jesse Reimink: time, right?

Jesse Reimink: Yeah.

Chris Bolhuis: we do. Yeah. Yeah, we do. Yup. Um, and so, yeah, we've been kind of neglectful, right?

Chris Bolhuis: we've we've done a lot a lot of episodes on the Western mountains and the S you know, we've done some things in the Southwest and we've kind neglected, uh, the Eastern mountains in the United

Jesse Reimink: No, we can't be doing that. No, definitely not. and I live now in the Appalachians, the central Appalachians, which is different geology, different rocks, but broadly similar tectonics, we just don't get the exposure of the great smoky mountains. So I agree. We've completely been missing the east coast. Cool east coast parks and rocks so far in PlanetGeo

Chris Bolhuis: Well, it's why I keep em They're they're, it's, It's, uh, not very far away, you know, it's like a 10 hour drive in I love That's doable

Chris Bolhuis: thing, you know? Um, cause to get out west is much, much further, so yeah, [00:02:00] we go there a lot and I absolutely

Jesse Reimink: so we're going to chunk this up into kind of three general parts. We're going to talk about the bedrock geology, the deformation in mountain building, and then erosion, which kind of sets the Smoky Mountains or the Appalachians apart from other more modern mountain belts, but we need to start out, unfortunately, talking about biology a little bit and why the Smokies why they smoky. So, Chris, why are the Smoky Mountains smoky?

Jesse Reimink: Uh,

Chris Bolhuis: Uh, yeah. If you've ever seen the smokey mountains, they have this kind of, they have a hue to Um, A lot of people think the smoky mountains are called this because it's got this kind of like smog look to it, but it's actually not, it has a bluish hue to it, which is what sets it apart from a human problem versus like this natural kind of that's w that's that's what is happening in the Smokies It co it comes down to a biological thing

Jesse Reimink: There's [00:03:00] one time. I remember. It wasn't in the smoky mountain national park, but it was in the, in the blue Ridge. And we were sitting, I was with a couple of friends and we're in a national park in Shenandoah national park. And we were like facing west and it was that sunset. And we went out and had kind of been raining for a lot of the day. And we had a whiskey sitting on this rock ledge, looking out over the valleys. And you know what I'm talking about, Chris, you have many experiences with Jenny I'm sure. But the clouds were just rolling over the hill. The mountains and it was just the, you see these clouds, these really blue clouds, but then there's this haze to it. I mean, distances look huge in this region. Like it looks like you can see forever when it's really not that far. I think because of this kind of blue haziness to it.

Chris Bolhuis: Yeah. Yeah. so you've, you've

Jesse Reimink: Oh yeah. W I just have this really distinct memory we're sitting on this rock ledge. It's kind of cold. It had been raining like the water's dripping down from the leaves and there's just like blue fog rolling over the mountains. It's just stunningly [00:04:00] beautiful as a sunset.

Chris Bolhuis: Yeah, this, I mean, this actually goes back native Americans with the with them. It was, You know, these mountains to, to the Cherokee and they refer to them as the “Shaconage” means, um, the land of blue smoke. it's it's, really, uh, an obvious apparent thing. So what is going on with this is actually because of biology, the

Jesse Reimink: Oh, shucks biology actually serves a purpose here.

Chris Bolhuis: Yeah, and it has to do with And, you know, I think like on a very general level, most people think of photosynthesis as it takes in carbon dioxide uses water and these compounds to create oxygen and sugar. Right. Um, one of the things that is also given off due to photosynthesis are what are called these volatile organic compounds, or what we refer to all the time is V O CS. And. natural. it's the S you're smelling it when you smell the scent of a pine forest, [00:05:00] for I mean, you're, that scent is the volatile organic compounds. Um, and that's kind of a, it's an interesting thing, right? Volatile, organic compounds sounds horrible,

Jesse Reimink: And in many ways, they are kind of bad to breathe in. And,

Chris Bolhuis: like

Jesse Reimink: I mean, in the lab, we talk about VOC and they're given off with chemical reactions that you really don't want to breathe in VOC, but in this case they're natural and not harmful to humans. They're relatively low proportion.

Chris Bolhuis: Right. Um, and these VOC, these volatile organic they have, um, a very high vapor pressure, means that they can they can form vapors at room temperature. Um, and happens essentially? I'm just going to kind of boil this down real quick. it's, it's a lot like why our sky is blue.

Chris Bolhuis: It's the same Um, When sunlight comes The particles that are in the, our atmosphere, the molecules, and so on. They scatter blue light more than the other wavelengths of the visible And so, because they're [00:06:00] they're scattered in random directions, they're scattered towards our eyes. That's what we see is blue. W throw into this, then all these volatile organic compounds and they do the same thing. They scatter the blue light preferentially, which makes it hazy. And it's bluish because of the blue light, getting scattered more than like the reds and the oranges and the yellows, the Roy part of the visible spectrum. So it really comes down to the fact that the Smokies have a lot

Jesse Reimink: Absolutely. And, you know, I was thinking about this as we were putting this script together, I was driving back across the Appalachians in Pennsylvania from state college to York. And yeah, it was this blue haze kind of around, and it was beautiful. I mean, it's stunningly beautiful to see, You know, we have to note that the Great Smoky Mountains are actually the most biodiverse national park in the United States national park system. And depending on your definition could be defined as a temperate rainforest. there's a lot of plants, so many trees, a lot [00:07:00] of different animal life over 19,000 species have been documented there. And way more, probably live there that have been undocumented, but it's a really biodiverse place which plays into this. Why are they smoky as you've been talking about Chris,

Chris Bolhuis: And I think also it's important to note that they're not the only mountains that are smoky this. Um, You and I have both been to Acadia. We, we went on a rock collecting trip, not in Acadia, but we were in the vicinity. And so we took a day and just, oh man, we did a ton of hiking on that day in Acadia. They are known for that too. They have extensive pine And for the same reason, they give off these volatile organic compounds and often gives them this kind of bluish haze as well. So it's not exclusive to Great Smoky Mountain National Park, but that's what it's known for, for sure. If you've ever been there, then you know exactly what we're talking about. And I think it's also important to note that like 80% of this. that smoke. We get that give the Smokies, their name [00:08:00] comes from this natural thing. This photosynthesis and volatile organic Um, 20% of it is coming from burning of like um, and the induced, uh, emissions. to It It changes the hue from a bluish to a white kind of thing. But yeah, the vast majority of the Smokies being smoky

Jesse Reimink: And typically the natural one tends to give this blue hue, as you mentioned before, whereas unnatural or human induced or sort of burning coal, those sulfate particles is what they typically are. give it like a wider grayish haze and not really this blue tinge to it. this blueness is, definitely entrenched in great smoky mountain national park. Yeah.

Chris Bolhuis: But note, they think it's getting better time, um, you know, with the burning of less coal for primarily, the human induced side of the Smokies is getting better. So that's good.

Jesse Reimink: All right, Chris, uh, I don't know that's enough about biology for me. I'm

Jesse Reimink: kind of, [00:09:00] I've had my daily allotment of biology stuff now, so let's get into some rocks.

Chris Bolhuis: Okay,

Jesse Reimink: like you said, three chunks. This is the bedrock geology we're talking about. Really the basement rocks. We term these metamorphic and igneous rocks at the deep roots of the continent bedrock or basement rocks typically. So the Smokies are some of, one of the oldest mountain chains in the world. And we'll kind of end talking about this aspect as well, because it shapes how we see the landscape, what the landscape looks like. But the oldest rocks in the Smokies are really old, over a billion years old. The earth again is 4.5 billion years old, 4.5682 billion years old. And the oldest rocks here are dated back to ancient, super continents or ancient continental collision zones where crust was buried really deeply and heated up and metamorphosed high pressures, high temperatures, and was buried [00:10:00] in these ancient mountain belts. Even more ancient than the Smokies. The Smokies are ancient, but we're talking about one step further back than the Smokies.

Chris Bolhuis: about. No. I want to ask you a Okay. Something with something that you said said that these are one of the mountain chains and the rocks, some of the rocks are super old. However, they're not as old as the rocks that are exposed in the core of the Tetons, for instance, or the rocks that are exposed uh, parts of the Rockies. All right. So. What we're talking about is really two different We talk about these. This is the oldest mountain chain. What we're referring to is, uh, that the actual like mountain building events that took place are super, super old. The rocks that are exposed are not necessarily the that you know, that we've discussed in

Jesse Reimink: Exactly we're talking about. When did the mountains, the topographic feature of the mountains form. And when did the rocks form, and those are two distinct events, right? And so. [00:11:00] We're talking right now about the rocks that are exposed, which could be, have been formed and metamorphose during their most recent mountain building event. But in this case, they were formed during a prior mountain building event. So before the Smoky Mountains were formed before the topographic feature of the smoky mountains was formed. I think another way to .Explain it, which hopefully makes a little bit more sense is that there have been several continental collision throughout earth history,

Jesse Reimink: meaning we

Chris Bolhuis: Well, I think what you mean is right continents,

Jesse Reimink: exactly

Jesse Reimink: meaning we.

Chris Bolhuis: Most most of of our audience is familiar with the term Pangea. Which is the last time that the world, the earth had a supercontinent on it. Right. But what a lot of people don't realize is that that's just the last time that happened. And in order to talk about the Smokies, we have to talk about an earlier supercontinent and I want to throw this back to you, Jesse, [00:12:00] because this is kind of right up your alley because you deal with all things old. what, w w what are we talking about? What's the supercontinent and when

Jesse Reimink: Well, so super continents are times in earth history when most of the continental landmasses, we're all one single unit, they were all aggregated together into one package. Hence supercontinent. Do you have one or two super continents on earth during a supercontinent cycle. So basically you take north America, you take Africa. Europe, you smash them together. That's a super continent, and that has happened multiple times. You said Pangea. Pangea existed the last couple of hundred million years. So 330 million years to about 170 million years ago. That was Pangea that's prior to the Atlantic ocean opening up. So Europe, Africa, the Americas north and south America smashed them together. Supercontinent Pangea. There have been older ones. There's some like Gondwana, there's some like Rodinia and that's the one that we're going to [00:13:00] talk about. Rodinia R O D I N I a. That is a supercontinent that existed between 1.1 billion years ago and 750 million years ago. So between that time interval for that 400 million year cycle, the continents were grouped together. So I think to kind of bring it back to mountain building events, when you smash continents together, when you aggregate continents, that is a very violent event that builds mountains. And that creates metamorphism, that metamorphoses rocks, rocks caught up in that collision or that aggregation of continents together get deformed altered metamorphosed. And that's what we are seeing. Basement of the great smoky mountains is 1.1 billion year old rocks that were formed and metamorphose during the formation of Rodinia this ancient supercontinent

Chris Bolhuis: Yep. Right. And so we refer to that as a continent to continent, convergent boundary. We have a modern day analogy of that. Actually we can point to, you know, the Himalaya. [00:14:00] Where the sub-continent of India is colliding with Eurasia have this, what what happens with continent to continent? Convergence is a little bit different than what happens when let's say an oceanic plate collides with a continental plate or converges with it. Right? What is the main

Jesse Reimink: Well, the main difference is that, an oceanic plate is more dense and thinner. So it's subducted. It gets recycled into the mantle. Continents are too buoyant and too thick to be subducted. So they just smashed together and you create doubly thick continental crust, which causes a lot of metamorphism. The Himalayas are. About 70 kilometers thick the continental crust is whereas in most continental crust it's more like 35 or 40 kilometers thick. And so, these super continents as we go back in time, there has been more supercontinent cycles proposed or rocks that I study that are about 2.7 billion years old, which you mentioned at the base of the Tetons. There's a supercontinent proposed, that would have been Kenorland or there's various other [00:15:00] proposals for a possible supercontinent that long ago back in Earth history. But we just have less information from that far back in time.

Chris Bolhuis: Okay, so let's get back on track then Rodinia this supercontinent that began happening about 1.1 billion years ago. Why is that okay. We have That's what happened, but how does that play into or the beginning anyway, of the story of the Great Smoky Mountain

Jesse Reimink: Well, so we have to consider that the rocks themselves, these deep rooted rocks were metamorphosed during that mountain building event. So those rocks contain a record of the supercontinent cycle. And then after that, at some point that supercontinent broke up. And formed another ocean. So you imagine, when about 175 million years ago, the Atlantic ocean started forming when you had a supercontinent you had Africa and south America and [00:16:00] Europe and north America all smashed together. The continent started to break apart and you formed a big ocean basin in there, and it's still getting bigger and bigger and bigger today. That process has happened before. And so this breakup of Rodinia formed this ocean basin and that formed a lot of the younger rocks that we see in the smoky mountains. So that's kind of why we have to worry about this event.

Chris Bolhuis: So this continental convergence created these massive mountains. And then it began to break apart. And what happens when you take these continental convergence and then begin to split them apart, as you have the Highlands, you also have these immense basins that are created by this divergence, right? So you have the sediment then from the Highland. These rocks that are being weathered and eroded and carried down into this newly created basin that is just continuing to open up and get bigger and bigger and bigger and more and [00:17:00] more sedimentary rocks are being deposited there. And there's this one basin that's important in Great Smoky Mountain National Park because the Ocoee basin is where Great. Smoky mountain national park sits today. In what was going on in the

Jesse Reimink: Well in this time period, this supercontinent is breaking apart and there's a few modern analogies for this one is the east African rift in Africa, where you have segments of continental crust that are separating. There's a lot of volcanic activity. There's actually sediments being deposited. Because if you think, if you pull apart something, you stretch it and you pull it apart, you're going to get cracks, forming in it. In the stuff that's being pulled apart is thinned, which means that you have a topographic relief generated. Now you have thick crust on the edges. You have thin crust in the middle where it's being stretched and broken apart, which means that erosion starts to happen. And you pull sediments from the high parts, from the thick parts. And you rode those [00:18:00] into the basin that you're forming. So. That's still ongoing right now, the Appalachian mountains are being eroded into the Atlantic ocean and being deposited there because that's a thinner area. We have topography so erosion happens. So this basin that's been forming it's formed as you stretch apart continental crust and, you break it, you get sedimentation, you get sediments being formed. And that eventually forms, rocks, which we see today. And they're forming the rocks that we see now in the Great Smoky Mountain National Park.

Chris Bolhuis: So rivers were carrying massive amounts of sediment to this basin were the Smokies sit today. And this is an amazing thing to me. Anyway, there are nine miles of vertically accumulated sedimentary rocks in this.

Jesse Reimink: Yes,

Chris Bolhuis: Nine miles, Jesse. , it is. So how does that happen? Like, I think we need to talk about this a second and paint a picture of, wait a minute. [00:19:00] How can you get nine miles of vertically accumulated rocks? Because you know, I'm looking outside right now. It's kind of cloudy out the clouds or maybe a

Jesse Reimink: Yeah, I know. Nine miles is incredible.

Chris Bolhuis: how does that

Jesse Reimink: Yeah. So there's this term called isostacy. And isostacy is how high does the crust float? You can think of it like floating on the mantle. So the crust is floating on the mantle and thicker crust. You have this analogy, Chris of a shipping container, a cargo ship with shipping containers on it. If you load it. Shipping containers, heavy, full shipping containers on the ship. The bottom of the ship is going to sink down. The top is still gonna float high though. But as you put your first layer on the ships floating pretty high, it's you don't have a deep draft in the ship. put your second layer of shipping container ships on it, it's going to sink down third layer, sink down, fourth layer. I mean maybe these things go up 15 layers. I don't really know how high do shipping [00:20:00] container layers go 15. Let's say. Huge. And so as you layer these things on the ship sinks down, that's, what's going on here to accumulate nine miles of sediments is that as you pile sediments into the basin, the basin sinks down and you can put more sediments in there. You're creating

Chris Bolhuis: Right, right. It allows for more deposition. And that's exactly what's going on. You said you referred to it earlier about, the sediment getting shed off from the Appalachians today is getting carried to the Mississippi, Delta. Well, it's the exact same process, If you don't have this process going on, then the deposition gets spread out over this vast area. But instead what happens is it deposits sediment that sediment weighs a lot, it causes it to sink, which allows for more sediment to be deposited, which sinks. And it just repeats again and again and again,

Jesse Reimink: and this term is called accommodation space. How much sediment can you pack in there before it fills up? Because once it fills up, you can't put [00:21:00] any more sediments in there and there's no more erosion, but the subsidence creates more accommodation space. So The weight of the sediments causes it to sink down. It creates more space to put more sediments in

Chris Bolhuis: That's cool. Now we got nine miles of sediment, which is an amazing, like scientific fact. But what does it look like? Well, it's relatively flat, vertically accumulated. Sedimentary rocks. so it looks nothing like the mountains we see today, we're going to get to that point, but we need other steps in there, but there's one other thing happened with this host rocks, too, right? That we have much younger sedimentary rocks, you know, 540 to ish, 450 million years old. That's much younger than these rocks we just got done talking about. And this was a little bit different in the sense that it transitioned to this shallow continental margin kind of deposition, where we had rocks, like limestones being deposited then and [00:22:00] other, you know, shallow Marine, typical shallow

Jesse Reimink: Yep. Absolutely. And So it basically transitions from a lot of sedimentation, a lot of deposition, a lot of this, isostatic, sinking and accommodation space, build up to a more passive environment where there's not a lot of erosion happening. There's not a lot of topography that creates this accommodation space. So it becomes a little more passive, but it continues forming rocks. You're exactly right, Chris. And these early phases are very active. There's a lot of copper deposits formed in this Ocoee basin. But it kind of call everything kind of calms down and becomes a passive margin, which deposits these background sediments.

Chris Bolhuis: And some of these younger rocks have some really cool fossils in them. The fossils, they they're like from burrowing organisms, filter feeders, things like this. And so you have fossils in and of themselves, but you also have trace fossils where you have these like burrows where these organisms were going and it's super,

Jesse Reimink: time period is the, this sort of 570 to 450 million year [00:23:00] time period is really the onset of multicellular life on earth. So there's this big explosion in biodiversity for the first time in earth history. And so the trace fossils are crazy in here sometimes.

Chris Bolhuis: Yeah. All right. Let's move on Jesse to the next phase then, which is the defamation and mountain building. We're going to get closer then to, do we get to these mountains? Looking like they look.

Jesse Reimink: Let's do it. So we've arrived at the point where these continents are spreading apart. We have this passive margin, sedimentation is happening, but eventually they start to come back together. We talked about the supercontinent cycle and how we have multiple super continents in history. We need to build Pangea now. So. What happens is these continents start to come back together and there's multiple collisional events that happen during this process. It takes a while to add a bunch of stuff to the continents,

Chris Bolhuis: this is just a random process, right? I mean, continents coming together. It's totally around.

Jesse Reimink: that's up for debate, whether it's a random thing or not. I mean, where they occur, but it basically, if you imagine [00:24:00] continents

Chris Bolhuis: Really? I always thought that it was just a given that when super continents form, it's kind of just this random thing that happened.

Jesse Reimink: I think it's a little bit up for debate. There's this old idea named after Tuzo Wilson of plate tectonics fame, uh, that is called the Wilson cycle, which is

Chris Bolhuis: jumpin Tuzo wilson.

Jesse Reimink: just, uh, oh my God. I need a new podcast partner. Uh, so, so there's a, this is idea that. super continents have existed on kind of a 400, 450 year cycle throughout history. If you compare Pangea to Rodinia, it's about 450 million years apart, and that goes back further in time into the thinking is that if you break apart a continent, a supercontinent, as it spreads out, it only has a certain amount of distance to go till it gets all the way around the earth. And they run back into each other. That's a gross oversimplification, but basically like continental drift apart, and then they'll hit each other. On the other [00:25:00] side, that cycle is roundabout 450 million years. Again, very oversimplified, but that's a good way to kind of picture it. I think this time period.

Chris Bolhuis: awesome. I, yeah, I'm going to look into this then more I've got, I've got work to

Jesse Reimink: It's not quite right, that they drift around and hit each other, but they kind of spread apart until they don't spread anymore. And then they come back together. So ocean basins, open up, and close and see. That's what's happening now, we're starting the continents kind of drift back towards each other. They're moving via plate tectonics and they eventually run into each other. There's some island arc accretionary events that happen that are relatively minor, they create little mountains, but not on the scale of continent, continent collision. That's a big event. And so Chris what happens to the rocks when that happens?

Chris Bolhuis: So before the continents come together, we have nine miles of rather boring, flat, vertically accumulated sedimentary rocks. And I would say boring. It's amazing that there's that much, but that's what we have when you take them. These, these [00:26:00] continental landmasses and they collide together then to form Pangea. So we're talking about north America collided with Europe and Africa. So this continent to continent convergent boundary, takes these flat lying sedimentary rocks, and it throws them into massive folds like anticlines and synclines, and there were earthquakes and faults and things like this going on because if you bend rocks too far, too fast. they break. Okay. And so some of these earthquakes were violent earthquakes. it began to now really get interesting.

Jesse Reimink: And it deforms the rocks that we see. So the pressures and temperatures are pretty high, in the smoky mountain national park. Too. I've seen numbers that are around 700 degrees and nine kilo bars, which is basically about 27 kilometers deep, so pretty thick and pretty deep the metamorphism. So you're taking these sediments and putting them down, not just nine miles deep, but 27 kilometers deep. That's a [00:27:00] big difference. So we're burying them even further heating them up and metamorphosing them during this

Chris Bolhuis: And we're talking about the entire Appalachian mountain region that's being uplifted and effected this way. So that we're not just talking about the Smokies here. We're talking about the entire range that goes through the, you know, the blue Ridge Parkway is Shenandoah national park, great Smokies up to Acadia. It's this entire mountain range that's being affected and it didn't all happen at the same time. It was kind of like a. know, a swinging door

Jesse Reimink: that's a perfect analogy. Chris. I love the swinging gate swinging door kind of analogy that that's great. So, Chris. During this phenonmenon you take sandstones, you turn them into quartzites you take shales, you turn them into slates or schists or something, even higher grade.

Chris Bolhuis: I want to just say Jesse, that, these mountains, they were much larger during this time. At the peak of this mountain building event, they were bigger than the Rockies [00:28:00] today. I mean, these were mountains that were more like the Himalayas. Then the Rockies, right? I mean, these, these were massive mountains at the time. So where did this heat. And pressure, obviously the pressure, I think, but where did this all come from? What's the source of this what's going on?

Jesse Reimink: Well, the heat. Well, the pressure. Yeah, you're right. It's, It's, just burial. So it's higher pressure. The heat is the same kind of thing. Basically, you know, as you bury stuff, the interior of the earth is hotter. And so you're both putting rocks down deep and it's also harder to get that heat out. So the rocks have this internal radiogenic heat production. We've talked about uranium in rocks before. They're producing heat internally. And so if you bury them, it's harder to get that heat out. It's like putting them under a big blanket. And so they kind of internally heat up as well. So there's kind of two sources of heat. Uh, but, but really it comes down to this radiogenic heating. So it's thick. The heat is under this blanket, so they heat up and they get pretty hot.

Chris Bolhuis: One thing I love about like that burial metamorphism, that process is that if there were any sedimentary [00:29:00] structures in the rocks, trace fossils, ripple marks, mud cracks, things like this, burial metamorphism preserves, those, it changes the rocks to a different rock. You know, core sandstone gets changed into courtside and things like that, but it'll preserve those structures, which I think is, is super, super cool. This massive amount of folding that we're talking about and faulting going on, you see this, these are no longer flat-lying sedimentary rocks. You drive through any part of the Appalachian region and, you look out the window and these road cuts and you see rocks that are sometimes folded to the point where they're straight up and down. That's just, I never get tired of that. Looking at the amount of the power behind this kind of deformation is mind boggling to me.

Jesse Reimink: Yeah, it's a, super powerful event, super aggressive, really? liked the way you said that Chris sends stones were turned into court sites, shales were turned into slates and even higher grade rocks during this metamorphism. And so [00:30:00] some of the structures are preserved and some of them are overprinted because of higher temperature, higher grade metamorphism. So Chris, then we have to move on. We've got this big, high, really high mountain belt. We're not yet at the current version of the smoky mountains we have to get there. And so that's erosion. That's the third part of what we're going to talk about is erosion. What happens to this mountain belt after the last 250 million years?

Chris Bolhuis: right. And I like the saying erosion happens, you know, like shit happens. Erosion happens.

Jesse Reimink: That's good. It, it does.

Chris Bolhuis: it should be a t-shirt

Jesse Reimink: It should be a t-shirt. Why don't you make that? You could make a

Chris Bolhuis: I should.

Jesse Reimink: happens and put a little plate of geo logo on it. That'd be good.

Chris Bolhuis: That's a good idea. I know I

Jesse Reimink: So chris, what happens? You know, that we're talking about erosion breaking things down. what happens during this process? Where are we at?

Chris Bolhuis: Where we're at now is that , the continental convergence, this [00:31:00] massive mountain range that was formed by this, transitions now to break it apart. Now we're going to take Pangea and we're going to begin to split it apart into. Something that, well, eventually it looks like where we're at today. Cause that's, that's what happens. So around 240 million years ago, Pangea began to break apart. the Atlantic ocean is a result of that, uh, divergence and it's still going on today. The Atlantic ocean is getting bigger and bigger and bigger from this same event. Okay, that broke apart. Pangea so there are, I like this in geology. There are patterns in geology. I think that's helpful to recognize that kind of thing and to, to point that out. So we have this mountain building event, right. And when the mountain building event ends and when any mountain building event ends, what takes over well,

Jesse Reimink: erosion happens. I think

Chris Bolhuis: that's right. Erosion happens my new shirt idea. And so that's a pattern, right? If you want to boil geology [00:32:00] down, really, really to simple terms, you have two forces at play forces that lift the. That's plate tectonics and forces that where things down and that's whether an erosion. And so the mountain building event is now done. And now divergence pulling apart begins to take over and erosion then begins to be the dominant process. And so, the mountains we see today is the core that existed a hundred million years ago from this mountain building. So we're exposing as erosion happens, you're exposing older and older and older rocks. And so the sediment gets carried away. It's now being deposited in the Gulf of Mexico. all these rivers, bring it to the Mississippi and down it goes. I think of it this way. I got, I got a little joke here. Okay. I think, cause I'm proud of myself. You have this, like what used to be this really muscular mountain, right? Okay. And now it's losing his [00:33:00] physique and it's developing a bit of a paunch it's. It's kinda like you you know, like

Jesse Reimink: Okay.

Chris Bolhuis: not that you were not that you were ever, not that you were ever muscular or anything

Jesse Reimink: That's a good one. That's one of your better jokes That's one of your better jokes there, christopher. Well done. I applaud you for that one. That was a good one. That was a good one. And may you know, not far off, uh, not far off, you know, this lack of going to the gym during COVID. I was actually, I've tried to, I think I was talking to you about this before. I've been, you know, playing basketball and mountain biking again and. God, I am so out of shape. So unfit. It's unbelievable, It goes away pretty quick.

Chris Bolhuis: know I, well, Jesse, I have to look at you when we record this. We're looking at each other and like, I,

Jesse Reimink: looked at a bit. Am I

Chris Bolhuis: I don't know.

Jesse Reimink: right now? Ah, that's no good. All right. I got it. I got to get back out on it. That's a good, that's a funny joke. And, uh, uh, quite a good analogy, actually. Yeah. the mountains lose their physique and develop a punch. That's a good one. I like that. [00:34:00] So I, but you're absolutely right. I mean, this is, this is a great analogy and you look at the Rockies, you look at the Himalayas, you look at any of these more modern, active mountain belts and they look aggressive, right? They look like, whoa, that's a dangerous mountain belt. You look at the Appalachians. Uh, it's not quite that way, right? It just doesn't have that raw power behind it that you just don't have that raw power and aggression in the mountain belt. And the weathering process happens differently too. Right? There's way more time for what we call differential weathering and erosion to take place, which means that some rocks are harder to weather than others. That's all that means. And so over time, hard rocks will remain as Hills and peaks and mountains and soft rocks will be made into valleys. And we can see this all throughout the Eastern United States where I'm at in York is this really rolling countryside and the Hills are all resistant, rock layers. That are slightly more [00:35:00] resistant than the valley layers. And so all the ridges and valleys formed by this differential weather and erosion where ridges are tough stuff, valleys are weak stuff, usually tough stuff like quartzite or metamorphic rocks, and the weak stuff is shale or slates. And those things get knocked down eroded it into deeper valleys. And this also forms a lot of the water features that you see in Smoky Mountain National Park. Right? Chris?

Chris Bolhuis: That's right. lots of waterfalls, this gives us an opportunity then to talk a little bit about how well, how do waterfalls often develop? Right? Well is as a river is down cutting through, let's say a resistant rock type and it down cuts it down cuts. But below that resistant rock type is a softer weaker kind of a wimpy rock. Okay. When it gets down to the point that erodes through the hard rock and starts to encounter the soft rock beneath it, Italy road, the soft rock much faster at that point. And that's, what's going to begin to develop into than a [00:36:00] waterfall that forms this, what we call in geology in nick point, where you go from hard rock to soft rock. The nick point is where the soft rock gets exploited. Much faster than the hard rock does And, it forms a waterfall. and, so

Jesse Reimink: and, uh, you've got a couple, I have not actually been to Smoky Mountain National Park. You've been there, like we said, many times. And so our GeoShort, next week, we're going to talk about. Various places you can go to see this really cool geology, many of them waterfalls in the Great Smoky Mountain National Park. And so tune in next week for some specific places, when you're planning your summer trip to Smoky Mountain National Park to go see the cool geology there. Right Chris. So I think that's kind of a wrap, right? I know we've covered our three things here and you want to just quickly summarize them and, and, uh, we can call it, uh,

Chris Bolhuis: Yeah, sure. Uh, so we started with the basement rocks, the bad rock geology of the old core of the mountain range. And then we [00:37:00] got into this massive accumulation of sedimentary rocks. That then got deformed when Pangea formed, when Pangea came together, took these rocks and folded them and faulted them and just made them spectacular. And then when Pangea began to break apart, the mountain building is done and the pattern in geology, when the mountain building's done, erosion takes over. And that's where we're at right now. So erosion has been going on now since the breakup Pangea. And, I want to be really clear about this. I, I love the Smokies. I love the Appalachians. We said that they're not a muscular range anymore. They used to be, they're not anymore, but not to take away from that. They're just different. These mountains look different, but I absolutely love them.

Jesse Reimink: Absolutely there go there. They're beautiful. They're really, really, really spectacular. And there's really cool geoscience to be seen and learned in the region. For sure. Um, [00:38:00] so Chris, that's a great one. We'll wrap up by saying as usual, if you like PlanetGeo, follow us on all the social medias, give us a rating and a review. Those help the algorithm. Visit our new website planet geo cast.com. Send us an email planet geo cast@gmail.com and our social media intern is Olivia Leon. She's been doing a great job. Check out all the social medias at planet geo cast.

Chris Bolhuis: And most importantly, share this with somebody that you think would like it.

Jesse Reimink: Yeah.

Chris Bolhuis: Cheers.