Columnar Jointing - Icelandic Version

Dr. Jesse Reimink and Chris Bolhuis delve into the fascinating geological phenomenon of columnar jointing, sharing insights from Chris's recent trip to Iceland. They discuss the formation, size variations, and unique patterns of these striking hexagonal columns found in basaltic lava flows, addressing questions such as why they form, why some flows exhibit them while others don't, and the conditions that lead to different column orientations. The conversation also covers historical theories and modern understanding of the physics behind columnar jointing. Listeners are encouraged to support the podcast via the Camp Geo app and send in any questions they may have about the topic.

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Transcript

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SPEAKER_00 0:01

Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you. We are recording. Christopher, we're recording, man. It's been a while.

SPEAKER_02 0:18

I know. It's I know. I'm I feel like uh I haven't done this in a long time. I'm a little nervous. I know. Not really.

SPEAKER_00 0:24

I'm not I'm not nervous. No, no, no. You're not nervous. Of course not. Uh what's up, man? It's been a bit. You've come back. Well, before we get into it, we're back, I guess, doing regular recordings. We recorded a bunch as we've done the last couple summers, especially you. You you went everywhere this summer. You were gone for most of the summer. And so we pre-recorded a bunch of stuff, and now we're back. This is what August 11. We're recording this, and this will come out the same week. So that's the first time this has happened in a while.

SPEAKER_02 0:54

I know it's I know. Yeah, we front end uh loaded this for uh, you know, we did this back in May, right? I mean, we just jammed them and and crammed them in, and now here we are, back to the old grind.

SPEAKER_00 1:06

Yeah, it is. That's right. So you, Chris, you know, you went on summer science, and we'll talk about that later. But mainly it was Iceland. I uh you just got back from Iceland recently. That was the big trip of the summer in the Bull Hass household. How'd it go?

SPEAKER_02 1:16

It was amazing. Um we were there, well, we ended up being there for over three weeks, but that was because getting back was a bit of a nightmare. Cancelled flights and Hurricane Debbie played a played a role in that whole situation. So that was uh that was a struggle. But Iceland was unbelievable. There were things that I saw that that were really just humbling for me and sometimes even like emotional. I don't know, the diversity of geologic things that I was exposed to was just um just amazing. We did get beat up by the weather though.

SPEAKER_00 1:52

Let me interrupt you real quick there. Uh were these things that you were you know amazed by, are they mostly geological things or were they other natural phenomena or cultural things?

SPEAKER_02 2:03

Like what were the Yeah, that's a good point. Um, all of the above, I guess. What I was referring to specifically though was the geologic things that I'd seen. You know, I saw glaciers that I've never seen glaciers of that magnitude. I mean, they were just so big, so thick. I've never seen that. You know, I've only seen pathetic little remnants that you get like in the western Rockies or the northern Rockies, like in Glacier National Park, but they're really kind of sad. Yeah. And these glaciers were were not sad. I mean, they were they were full-on just awe-inspiring. I mean, the blue of the ice was just that's one thing that jumps to mind, you know, and then seeing the calved off sections as the glacier pushes into the lagoon and they break off. And so I've never seen stuff like that before. That's what I was referring to specifically.

SPEAKER_00 2:56

Uh that's a a very um I've never been to Iceland. I mean, we talked about this before in our our sort of intro to Iceland. I've never been, uh, but it's hallowed ground for geologists for many reasons because A, it's so unique, both tectonically has this tectonically totally unique setting, lots of volcanoes. So the Volcan Island just love it, um, and some unique volcanoes. And then it also sits in the northern latitude, so you get this sort of amazing ice-sculpted landscape and lots of interactions between volcanoes and glaciers, which is a very unique place on Earth to get that interaction. That's not a typical interaction, so it's an interesting one to study from that point of view, too. So, yeah, well, I'm I that's awesome. I mean, it's a very, very cool place, I'd imagine, to go and spend three weeks of camping.

SPEAKER_02 3:39

Yeah, not all of it was camping, but like the first week was for sure, because we just we hiked the Lagovigger trail, and um, I'm just gonna say the weather was the real deal. You know, we had it was cold, it was raining, it was windy, and that's not always a good combination, and that happened every single day. But then during the same day, we would we would get little little splashes of sun, and I'd see my shadow, I'd be like, What the heck is that? I I think I see my shadow, you know. So good. Um, but it the weather was the real deal, and and I guess this summer is the worst that it's been in a very long time. Oh, you picked a good time to go. Nice. Yeah, perfect. Of course. That's what I do. Yeah, yeah, yeah. Perfect, perfect. And that, like, you know, what we saw in Iceland is kind of what gave me the idea to pitch to you. Uh Jenny and I saw so many columnar jointing structures in mostly basaltic flows that uh Jesse, it was everywhere. And it was one of the coolest things because they weren't the same. I mean, they all looked so different. The sizes of the columns, the geometry of the columns, it was just a spectacular thing. And I as I'm looking at these these features, I looked at it from the perspective of what do people think when they look at this that don't have a like a deep geology background.

SPEAKER_00 5:07

Oh, okay.

SPEAKER_02 5:07

You know, what's going on in their heads? Yeah, yeah, yeah. And that's kind of the angle that I took when I when I pitched it to you a couple days ago.

SPEAKER_00 5:14

So I mean it's a great we've we've kind of briefly touched on this, I think, before, but not really in detail. Not the we haven't dove deep into the Klumner jointing phenomenon. So we'll discuss that a little bit, and that'll be kind of the that's centering our episode here today. But before we get to that, thanks for listening to this podcast, first of all. And if you're looking for ways to support us, there's one big one we would ask of you at the moment, which is go to our Camp Geo app, download the mobile app. There's a first link in your show notes. You can just click on that, download the app, and give us a review and a rating there. That would really help us. We have tons of free content there as well. Listening to the intro to geology is free, you know, many dozens of hours of content, lots of episodes with images there, and you can also purchase access to some of our other audiobooks as well. But leave us a rating and review on our app. We would really appreciate that. Chris, Columnar Join. So we've talked about this on the podcast before. I can't even remember what episode it was, maybe St. Helens we were talking, or something like that. I don't remember when we discussed it.

SPEAKER_02 6:11

Oh, I don't think so. I think it was Devil's Tower. Devil's Tower. I think it was Devil's Tower, Wyoming.

SPEAKER_00 6:16

Yeah, yeah, yeah. Okay, which is a famous, one of you know the top couple places on the earth that have columnar jointing. But there's many, there's many places that have this kind of feature. So what we're if you haven't seen columnar jointing, what we're talking about is often lava flows, basalt flows, typically, but not always, that have this usually hexagonal six-sided column jointing pattern. So the rock breaks apart into these big six-sided columns, and they can be big. The columns themselves can be between centimeters to three meters wide. So they can be big, big blocks.

SPEAKER_02 6:49

And even bigger than that, yeah. You know, Devil's Tower has columnar joints that are much larger than three meters across. So they can be unbelievably huge.

SPEAKER_00 6:59

Yeah, big, big, big columns that that are called columnar jointing. And it's jointing, so the rock is all the same. It's a jointing pattern in the rock. These are breaks in the rock that create these columns. So they run either vertically, or Chris, you said so you saw some horizontally. We also saw some together. We're going way back now, uh, a couple different places, but I think we saw some in Colorado and we saw some in the Columbia River Gorge, was the main place we've seen the spectacular columnar jointing in the Columbia River flood basalts there. So there's many places to see these things, I think, is my point. But that's what we're describing. Columns that are fra the rock is fracturing in this columnar pattern, hence the name columnar jointing. So, Chris, when you're standing there in Iceland, you and Jenny, and you're like thinking about this as as if you were not a geologist or if you're you've never thought about columnar jointing, what are the main questions do you think that I don't know, inter-level student or somebody who's there and has not thought about geology, what are they asking themselves, you think, looking at these columns? Because, you know, these are like these are mystical features, right? There's all sorts of of stories from going back to indigenous communities with Devil's Tower and Devil's Post Pile, where they, you know, they had stories about how these formed. They're kind of mystical features. So you could come up with some wild ideas about how they formed. What do you think the average person's thinking?

SPEAKER_02 8:17

Well, this is purely my own thoughts. Actually, not really though, because Jenny is standing right next to me as we're as we're looking at these very diverse columnar joints in Iceland. And so this kind of comes from some of the questions she was asking. And so I don't know, it's kind of like a combination of questions Jenny asked and me wondering what would people you can't mistake this pattern that you see right in front of you. I mean, you look at that, you're like, wow, what is that?

SPEAKER_00 8:45

One quick interruption. I mean, Jenny's not a normal human, so let's not let's not say that you know this isn't her perspective is coming from a normal human. But with that with that caveat, that's that's a question. What is she wondering?

SPEAKER_02 8:59

So why are they six-sided? That's a question.

SPEAKER_00 9:02

Okay.

SPEAKER_02 9:03

First of all, like an overview of how do these columns form? That's a question.

SPEAKER_00 9:08

Which are kind of related, those two, I would say. The answer at least is kind of related, right? Yeah.

SPEAKER_02 9:13

Yes. And then we saw a huge diversity in terms of like the diameter of the columns. Some were quite small. You could almost palm the columns, and some were, you know, a couple of meters across. Oh, right. So what determines the size of the columns? And then why don't all lava flows, if you have just basalt, which is what you have a you know, a dominance of basalt in Iceland, why don't all the flows have columns then? Why don't they all have this columnar jumping?

SPEAKER_00 9:40

Okay, that's a good one. Yeah, that's a good one.

SPEAKER_02 9:41

And then lastly, you have columns that are straight up and down, you have columns that are almost like horizontal, and then you have columns that kind of look like a pinwheel or uh they they form this kind of fanning out pattern from a central point. So why do you get these irregularities and in columns? Yeah, yeah. And I I think that's where I left it in terms of the questions that people would want to have answered if they're sitting there looking at them.

SPEAKER_00 10:07

I think that's a great you know, series of questions. So again, it's just so how did they form? Why are they six-sided? Those are kind of the the same question in many ways. What determines the size? You said there's this huge range that you saw just in Iceland, and we've seen ranges we've seen, I think in a Ryolite, we've seen them uh sort of hand-sized, something uh along that size. Why don't all flows have columns? And then why the irregularities? Is that right? That's the last question. Why the fan structure? Why the horizontal ones, why the vertical ones? Okay, cool. Should we start at the basics, like how do these things form and the sort of history of them then?

SPEAKER_02 10:42

Yeah, let's go back up to the top and let's start with like this kind of I think you have a better perspective on like the historical view of these things, and then let's just kind of take it in order.

SPEAKER_00 10:52

Does that sound good? Absolutely. It's kind of one of these things in geology, one of the few I would say in geology, where there's been ideas for many, many centuries because they're such a strange phenomenon, right? You look at them and you're like, whoa, that is crazy. So people since the 1600s have been writing about these things. There's been many models over the years of how they formed, including little convection cells that were kind of imagine a convection cell that would kind of spiral upwards. That was one idea. Another one suggested that they were crystallization patterns. So the magma started to form little balls and nucleate around them, little plastic balls as the magma was crystallizing that eventually formed columns. And this, if you go back to our interview with Mike Akerson, he talked about the sort of early debates about how magmas formed, whether there was such a thing as magmas or not, this Neptunist versus Plutonist kind of model, and and the Columnar joints were kind of really involved in that debate. There was debate about how columnar joints formed. There is a widely accepted. Hold on, Jesse. Hold on.

SPEAKER_02 11:52

I gotta I gotta go back to something because you're dropping big words here, and and like, what is this Neptunist and Plutonist view? What does that mean?

SPEAKER_00 12:01

Well, there's I I don't want to, I don't think we need to get lost in the weeds. Mike Ackerson did a great job explaining it in that episode, but it was people who are debating. We need to have Mike on again, by the way. Yeah, yeah. Yeah, yeah, for sure. People debating going back centuries now, talking about how igneous rocks, what we think of now as igneous rocks, how did they form? There's kind of many schools of thought, and one of them was called the Neptunus and Plutinus. So if you're interested in that, I would say go back and listen to Mike Ackererson. The point of these columnar joints, though, is that we have a widely accepted model. It's a cooling feature, meaning the rock is hot, it's fully crystalline, so it's a crystallized rock, but it's hot, and it starts to cool down, and then these joints start to form. That's been around since 1776, Chris. So you might say it's an idea that's been around that's as old as America itself. Um but it's oh I thought okay.

SPEAKER_02 12:54

I thought you were gonna give a crack at me. Oh, I should have.

SPEAKER_00 12:56

Oh man, it's a missed opportunity. You know, I'm really out of rusty. I'm really rusty. Dang it. That was a big missed opportunity there. Uh bummer.

SPEAKER_02 13:04

That's right. So I think what you're talking about is columns are gonna start to think about forming when the rock turns from orange to black, let's say. So the flow has become stagnant. It's turning color now because it's going from lava now to crystalline rock. At that point, then it's still super hot. You know, you wouldn't want to walk up and touch it, but it's no longer lava.

SPEAKER_00 13:30

The point where it's turned from orange to black. Put a number on this. Basaltic rock is fully crystallized at about 800, 800. I mean, it depends a lot on the composition, but we're talking 850 degrees centigrade here, 800 degrees. That's really, really hot. And then it's got to cool down to surface temperature. So there's a big interval of not crystallization, but cooling that happens here.

SPEAKER_02 13:50

And then that that begs the question as this superheated rock continues to cool, what happens then? That's the question. And then that's really like gets at the the basics of why do these columns begin to develop? So as it cools, it's gonna begin to contract. But remember, rock is not very elastic. It can't just uh change form. So what it's doing is as it's cooling, it's building up stress. Building up more stress, cools off more, more stress is built up because the rock is really contracting and kind of like pulling into a central point.

SPEAKER_00 14:28

Yeah, shrinking. We have this big massive rock that's cooling and shrinking, and what's happening is we're formed tensional stress, what's called tension pulling things apart, basically. It's kind of analogous to that. It's like the rock is being stretched apart, but it's not, it's it's just shrinking internally. Something's gotta give. You said rock's not elastic, so something's gotta give. It's gonna break eventually. And there's a lot of people who studied the physics of this stuff in detail, but basically, this is where the six-sided nature comes in, or the the most commonly six-sided nature. Now, nature is full of irregularities, so you know it's not always perfect six-sided columns. But Chris, I'm sure you saw some perfect six-sided columns, and then you saw some that were irregular as well, right? I'm guessing.

SPEAKER_02 15:11

Yes, yeah, absolutely. Yeah, yeah. In fact, uh, just a real quick side note, I don't mean to distract you because you're I can see that you're on a roll here. But um, when we first got there and we had rented our car and we're driving, and we see some columnar joints along the roadside. I was so excited. I'm like, well, let's pull off. And it was driving rain. It was just miserable. And I put my raincoat on, put my pants on. Jenny gets out there and and we we hike up to where we can like look at these things up close. And when I think about it later on as the trip moves on, that was kind of a dumb thing because these columnar joints that we had first gotten so excited about were rather pathetic compared to all of the other ones that we saw as the trip moved on. I mean, they they were old, they were crumbly, they they just weren't very spectacular, but I was all excited because it was the first ones that I'd I'd seen out of the country.

SPEAKER_00 16:03

So yeah, I mean, so cool. I was happy. Yeah, oh of course, of course you were. I mean, so cool. So the these these beautiful columns, they form by contraction, the rock is cooling down, it's gonna break, something's gotta give, it's gotta break, and the commonly six-sided nature of it is just to do with the physics of how you break a rock or how basically it's how can you put breaks in the rock with as few of breaks as possible that run through the rock and and kind of make a nice mesh. And I think Chris, you ever play the game board game Settlers of Catan? Did you guys play that game as a family ever? No? Okay. Well, it's this board game that has six sides.

SPEAKER_02 16:42

Not that I remember. No.

SPEAKER_00 16:44

It was popular, I mean it's still popular as people, but it was a fun board game that our family got into for a while, and it has these six-sided pieces. Board game that has six-sided pieces, you put it all together and it has these six-sided pieces, and that's just the most efficient way to fill a space with the fewest amount of sort of lines possible.

SPEAKER_02 17:02

And this is similar. Can I can I give a crack at it? The math is very complicated. For something that is cracking this way, that where the tensional stress of the contraction exceeds the strength of the rock itself, and so cracks will begin. Hexagonal shapes, it releases the greatest amount of energy along the shortest lines, I guess, along the shortest cracks. It's the most efficient way to break while releasing the greatest amount of energy.

SPEAKER_00 17:33

So, Chris, when we talk about in sort of petrology terms, when we're looking at rocks and looking at minerals, there's the exact same thing happens when you crystallize a rock, or when you in metamorphic geology, when you recrystallize a rock, when you put heat in there and the minerals are recrystallizing, it wants to be as energetically efficient as possible. And the way to minimize this free energy, what we call Gibbs free energy, is to have the least amount of grain boundary interactions. And the way to do that is to form what are called triple junctions, where you have three minerals that come together in a point, and so three minerals touching, they have these 120 degree angles in the minerals, and if you add that up, you get a six-sided thing. It's just the the most energetically efficient way to either break a rock or recrystallize minerals in a rock, and this is all over nature. This six-sided thing is kind of all over the natural system because it is energetically most efficient way to do it. So the ideal, the perfect scenario is a lava flow that's cooled down to so it's crystalline, it's fully crystalline, and it's sitting there, and it's a thick lava flow, so it's hot inside, quite hot. The surface is cooling down, both actually the bottom and top surfaces are cooling down. And as those cool down, the top and bottom start to contract. The inside's still hot, so it's not contracted yet, but it's starting to, as the whole body cools down, these fracture networks kind of happen. And Chris, there's a good analogy here with mud cracks. When we look at mud cracks where there's a muddy layer on the top and it starts to dry out, it shrinks, it desiccates out. It's doing the same thing, and the physics are very, very similar. The mud crack will form these six-sided mud cracks. That's like the energetically efficient way to do it, at least. Except in a basalt flow, the whole package is cooling. So it's not mud cracks, we get these little chips because the surface is the only one that's drying out. But in a basalt flow, the whole thing cools down. So you get these vertical columns and they kind of propagate their way down into the lava flow itself and create these columns.

SPEAKER_02 19:31

You touched on this, but I want to make sure that we double-click on that. The columns are gonna grow and propagate perpendicular to the cooling surface. So if you have a lava flow that then crystallizes, the cooling surface is the air. So it's relatively flat, right? And it's losing heat very efficiently to the air above it, and there's your cooling. And so that's where the cooling starts, and the columns then will propagate downward from that horizontal cooling surface, which in this case would be just the air.

SPEAKER_00 20:00

That's exactly right. And we're gonna come back to that point, Chris. I want to like set that aside, set that on the shelf a minute. We're gonna come back to that in one of the later answers to one of the later questions. But remember that the top is cooling, but also the bottom is cooling. When this lava flow comes in, and this is a lava flow in this instance, the ground is cold too compared to the lava. So the top and bottom are cold, and the middle is the hot part. Let's like leave that there for now and come back to that to answer one of the later questions. But Chris, the size. What determines the size of these things? You said you saw a variety of sizes. What range, what were the coolest ones, maybe? Which ones do you like, the big ones or the little ones?

SPEAKER_02 20:39

I like the little ones.

SPEAKER_00 20:40

Oh, yeah.

SPEAKER_02 20:40

I I don't know. To me, they seemed to be more perfect, more idealistic, I guess. I'm getting excited thinking about this again because I'm reliving where I saw these things. You know, and Iceland is so well known for all the waterfalls. Well, waterfalls and rivers, they cut gorges down through these old basaltic lava flows, right? Which exposes then the guts of the lava flow. So you can see a layer of columnar jointing, maybe five to ten meters thick, and then down deeper below that, another layer of columnar jointing and so on and so on and so on. And it was just really, really cool. I liked the smaller ones. Okay, interesting. And they they seem to be more perfect to me. You know, that does beg the question: why do you have this diversity in terms of how big the columns are? Because Devil's Tower, several meters across, is not uncommon at all. Well, it turns out that the size of the columns is inversely related to the rate of cooling. So, in other words, if you have a lava flow that cools very fast, the columns will be small. If you have lava that cools really, really slow, the columns then are going to be much larger. So it's inversely related to rate of cooling.

SPEAKER_00 21:55

And Chris, we actually saw read a paper that people had noticed. In a chirt layer, they'd found very, very tiny columns, like really, really small millimeter kind of columns that you'd see under a microscope. I mean, you can see it with your naked eye too. The idea was that this chirt layer had gotten heated and then cooled down really quickly by an ash layer that was kind of decomposing beneath it and dumping heat into this chert thing. So there's all sorts of different rocks that form this type of thing. And some of them can be really, really tiny. Those are fast cooling. The big ones are slower cooling. And the slower cooling, again, it's kind of this physics thing. The slower the cooling, the further away the joint sets can be from one another and still be energetically efficient.

SPEAKER_02 22:35

That's right. And then your mind maybe thinks about well, what would cause different cooling rates of, let's say, lava, right? Well, the geologic setting of a lava flow can affect the rate of cooling. For instance, like if you have a lava flow that enters a gorge, you're gonna have a relatively thick lava flow that is not very wide. It affects the rate of cooling, or maybe the chemistry of the lava flow itself, whether it's and acidic versus or mafic and basalt, that kind of thing, can affect rate of cooling. And then other variables maybe like the amount of vesicles or gas pockets that are in the lava is going to affect the quality of the columnar jointing, and it's also gonna affect the rate of cooling.

SPEAKER_00 23:19

And I think, but probably Chris, and I'm curious if you noticed a relationship here, the flow size, like the thickness of a lava flow, would probably be a major component. Did you notice that the little perfect ones that you loved were in narrower or thinner flows or not really? Yeah, okay. Absolutely, I did. Yeah, absolutely. And so if we go back to Devil's Tower, you know, this huge, I mean, Devil's Tower is a huge slug of magma. A big basaltic intrusion has a lot of heat in it, and so it'll take longer to cool down. So that's why those are much bigger than some of the small ones you probably saw.

SPEAKER_02 23:52

That's right. Because in the case of Devil's Tower, one of the leading theories is that this was an intrusion, right? It was a shallower intrusion, but that means that the cooling surface was not air. And rock is an excellent insulator. So, in other words, if lava intrudes or magma intrudes country rock or rock around it, it's gonna insulate it and cool much, much, much slower than if it was just exposed to the air because it loses heat readily to the air.

SPEAKER_00 24:20

And that's a great one, Chris, that we'll I think we'll come back to again when we talk about some of the irregularities or irregular patterns. But let's talk about why. I think this is a nice transition to talk about why don't all flows have columns. And I think this is a this is an interesting question that there's not a clear answer to because you know, if you think of a a lava flow, it's eventually all lava flows are going to be solid and they're still gonna be hot at that point, and then they will be cooling down in this way. It's an interesting question. Why don't we see this more frequently? And I think the answer probably is that you need a really perfect or near-perfect cooling setting to form columns that we can identify. These are really striking features and they they grab your eye when you see them, but you need to have a really nice, very kind of clean lava flow that is solidified and pretty thick, and then have a consistent cooling pattern after that in order to create these cut these really nice columns. So anytime you have like a jumbly lava flow or a thin lava flow, it's very unlikely to probably form these columns because it cools down too quickly to form this. It probably flowed in the top crystallized. We formed aa or pohoi, you know, lava on top, and then it got jumbled into the mix. So you have this irregular cooling pattern as the lava is flowing downhill, and then therefore it's not a big, thick, 10-meter thick package that's consistently cooling from the top down. It's kind of a mix, and there's little convection cells, and it's doing all this other stuff. Maybe there's a lot of vesicles, so that would disrupt the physics of this column-forming jointing process. Those are some reasons why not all lava flows would have this. And relatively thin ones are often ones that don't have this process. You you need a big batch of lava that cools down and is cool and solidifies in place and then cools from there to surface temperature consistently and in a stable way.

SPEAKER_02 26:18

Because uh, if you mentioned Pohoihoy, Pohoihoy is this it's one of my favorite flow textures that you can get in a basaltic rock. But it's exactly that. That this texture that you get with Pohoihoy, it's kind of this smooth, ropey or twisted, kind of braided appearance. You can actually see the flow of the lava that's preserved in the rock when you look at that and you hold that in your hand. That kind of flow texture is gonna disrupt any kind of columnar jointing that would have happened. It has to be a you know a rather stationary flow. So lava flowed, stopped, solidified, and then columnar jointing took place after the material turned from orange to black.

SPEAKER_00 27:00

Yeah, yeah, yeah. That's right.

SPEAKER_02 27:02

I have a question for you, Jesse, then I'm gonna I'm gonna throw this at you and you don't know what I'm gonna ask. So let's see how you do it. Okay, all right, all right. So we saw this, okay? We saw relatively thin layer of columnar jointing, but the columnar joints were horizontal. What do you make of that?

SPEAKER_00 27:19

Meaning the lines, the joints were running horizontally. Is that what you mean?

SPEAKER_02 27:23

Yeah, they were not vertical columns, these were horizontal.

SPEAKER_00 27:27

So this, I think, Chris, leads very nicely into the last question. Like, how do you get these irregular patterns? You talked about these fan-shaped ones, the the horizontal ones are, I would say, irregular. They're not the normal pattern. And the physics here, I think, are just exactly the same. Jointing has to be perpendicular to the cooling, the cool side. So if you imagine a fan, what does that tell us? A fan where the joints are kind of fanning outwards, that tells us that all sides were cool. The flow punched into like a sediment, or it punched into something where it cooled consistently from the outside. Imagine like a plug of magma kind of bulging out into a sediment package, and then it's cool on all sides of that, and it starts to cool radially inwards, and the joint sets will be perpendicular to the cool surface and then come back in. So that's one way. So then horizontal, this is quite common in cooling lava, is that eventually as the top cools, it'll crack, right? And those cracks will allow water to get down in, and you can get these big water circulation paths, which the water is a great cooling element. And so if you have a crack that's going vertically down and the rock is still hot, but that cold water is circulating, it's cooling down horizontally. So you can get horizontal joints that come off from that hydrothermal water crack, basically.

SPEAKER_02 28:50

Exactly. That's one way. In the case that I'm thinking of specifically in my head, is the difference between a sill and a dike, a geologic setting. Right, right. Okay, so sills are these igneous intrusions that run parallel to the rocks that intruse. They tend to be more horizontal. And so with that kind of intrusion where it's like a relatively flat horizontal layer, the cooling surface is the rock above it and the rock below it, and so you're gonna get vertical columns. But a dike cuts across the rock layers, often vertically across it, and so the cooling surface is now on the sides, and so you get these columns that extend and they look more horizontal. So that's another way that you can get this kind of irregular pattern to it.

SPEAKER_00 29:36

Okay.

SPEAKER_02 29:37

Um I don't know. My favorite thing though, Jesse, were these kind of what I described as pinwheel or kind of this radiating out from a central point, columnar joints. Those I've never seen them before in real life. Have you ever seen this or not? Like firsthand, have you seen that?

SPEAKER_00 29:56

Not the full, not the full circle. We saw like half circles in the Columbia River Gorge with our buddy Andy. But yeah, not the I've not seen the full circle.

SPEAKER_02 30:04

It's something that it's it's got a name, it's called entablature. These kinds of columns that have this irregular fanning kind of appearance. And you're right, this is a different geologic setting. And it often involves the interaction with lava or magma and water. And in the case of Iceland, what you would have are these lava flows, and then you'd have a sudden like a flooding event, and the water would interact with the lava flow and affected its cooling and its cooling rate and its cooling direction, which kind of formed this kind of pinwheel look to it. If it does does that make sense, yeah, yeah, no, absolutely.

SPEAKER_00 30:43

Absolutely. And just to touch on that entabulature word that you just said, the sort of textbook example of this is if you have a really thick flow, the top will have beautiful columnar joints patterns that are vertically stacked, and then we call these like colonnades. So the top and the bottom, remember the bottom is a cooling surface as well. So those will form this kind of sandwich of colonnades, these beautiful perfect ones. And then inside you'll have this kind of irregular pattern, this entabulature. And that's where the top cracked and you got water circulating down. It started to get more complicated down in the middle part as the entire package started to cool. And I saw, Chris, the most spectacular columnar joints I've ever seen was a really, really thick lava flow. It's on the eat, what's called the east arm of the Great Slave Lake, up in the Northwest Territories of Canada. It's this huge basalt flow forms this big cliff. And so we're flying in a helicopter over the lake, but right next to this cliff. And it's just huge columnar colonnades with this entabulature thing down near the water's surface. It was spectacular. Like looking out the helicopter window, just I mean, it's just one of those like surreal moments where you're like, What the hell am I doing here? Like, this is crazy. Flying over this ultra deep lake, this huge geological, amazing geological phenomenon to the left side. It was just so cool. And I think our helicopter pilot got a kick out of it too, because he was flying next to the cliff. You know, it's kind of fun.

SPEAKER_02 32:08

So is that your first and only time of seeing that kind of entablature look to columnar joints?

SPEAKER_00 32:15

Seeing it like that that in that textbook way where it's like colonnades on top and entire, you know, that that was the first time seeing like I mean, you and I saw them just after I graduated college. We saw the complicated pinwheels and fans and stuff, but the like the full package of entablature, that was the the best time I've seen it for sure. Let me just summarize this again, Chris. The irregular patterns, the non-vertical patterns, the physics are the same. It just points to a different cooling direction or a more complicated cooling pattern in the columnar jointed basalt or lava flow or whatever the thing is that's being jointed. So the physics are the same, cooling pattern is perpendicular to the jointing, and so it just points to some different cooling pattern. Chris, maybe to wrap up, I have a question for you. Where are the closest columnar joints to you right now in Hudsonville, Michigan? I don't know. I'm I'm I'm asking. I don't I don't have an answer.

SPEAKER_02 33:06

Boy. I don't know for sure. I would I probably would say I would probably say Devil's Tower, I I think.

SPEAKER_00 33:14

Okay. I I didn't know if there's any up in the upper peninsula at all in any of the flood, the basalts of I have not seen Columnar Jointing there.

SPEAKER_02 33:22

I've no lots of pillows, yeah, which are really cool structures too. And you know, we saw some pillows in in Iceland as well. And I I'm a huge fan of pillow lavas. The story that that rock has to tell is just I don't know.

SPEAKER_00 33:35

Oh yeah, don't get distracted. Don't don't get distracted by that. Yeah, that's that's a whole nother thing. Um okay, that's interesting. I mean, because Yellowstone, I mean, there's a lot of places out west that have them. Yellowstone Rhyolites have them. I think the closest to me is Shenandoah National Park, has some has some good ones there out there in Virginia.

SPEAKER_02 33:51

Okay, I guess that would be closer to me too. Oh, is that I didn't know that. Yeah, I didn't know Shenandoah has that.

SPEAKER_00 33:56

They've got some good ones, if I remember correctly, it's like a few outcrops that have like a roof overhang, so the columns are kind of over your head in some ways, too. They're like they're pretty big ones, but they're 550 million-year-old basalt package there.

SPEAKER_02 34:09

So, can I tell you a story about Iceland real quick here that's relevant to the discussion? So there is a famous outcrop right along the ocean. It's a black sand beach. Then you have just these beautiful columns. This is hilarious, Jesse. It made my whole day. So, first of all, I was a little pissed when we got there because you had to pay to park there. Okay. And I'm not happy about that. But you know, I'm like, well, this it's so famous an outcrop that I have to go. I'd never been there before. I don't know if I'll ever be back. I have to go. So we get there, and I'm like, oh man, this was a waste. Because the columns are cool, but they are not cool like the columns we saw in the backcountry or all over the place and other places where we saw them for free, right? But I had to do it anyway. So uh Jenny wants to get this picture of me sitting on a column. And so I get to this column and it's busy, people are everywhere, which that didn't, you know, lighten my mood either. I was like, we had we'd spent so much time like alone and away from everyone. It was spectacular.

SPEAKER_00 35:16

So you're turning into a bit of a hermit loner in your old age, too, I think.

SPEAKER_02 35:20

I know, but this Jesse is the best. So Jenny is trying to get a picture of me, and she's trying to like crop everybody else out of it, right? And I'm like, Jenny, hurry up, hurry up, hurry up. Because there's the ocean, there was a this rogue wave, and it was just crashing towards. So Jenny has her back to the ocean. I'm looking at it, and I I just waited until the last possible second. I jumped off the column and I just ran as fast as I could. Jenny soaked up to her knees. It was just the best.

SPEAKER_00 35:55

That's good.

SPEAKER_02 35:56

It couldn't happen to anybody nicer. And you know that because you know Jenny so well.

SPEAKER_00 36:00

So nobody deserves to get soaked up to their knees while trying to take a photo of their husband more than Jenny Boyce. That is the best. I and what a great way to experience columnar basalts is just you know having Jenny take a photo against so that's great. That makes me very happy.

SPEAKER_02 36:13

Oh my gosh. She was so mad, and I was so happy. I'm like, this was worth every penny we spent to park here because you got absolutely demolished by a wave.

SPEAKER_00 36:25

It was like I want to see the photo, I want to see the photo series of you know, you looking hurry up, Jenny, sprinting away, you know, the time-lapse. That'd be great.

SPEAKER_02 36:34

Yeah, I don't know if she got me jumping off the column, but I'll certainly send those. I think there are two pictures that she managed to take. And it's so funny too, because she's notoriously like it takes her a long time to take a picture. It cost her big time, cost her dearly. The time was so good. Serves her right. It serves her right worth every penny.

SPEAKER_00 36:54

That's great. Well, Chris, I think this is probably the first of many of uh a sort of uh Iceland or let's say our summer trips inspired podcast episodes. I've got a couple too that I'll I'll pitch your way based on stuff we've been doing we did. Uh, but yeah, I think that's uh probably a wrap on columnar jointing. We hit the basics, there's a lot to know, and I think one other thing I like to touch on, Chris, is that people have studied this a lot, the physics of this. And they do both experiments like starch. They can do it with you know a starch slurry. Yeah, no, that's crazy, isn't it? Yeah, kind of cool, right? It'll cool down and dry out, and you can form columnar joints. I didn't look it up. There must be like a you know, you could do this at home, I'm guessing. You could replicate this experiment at home and form columnar joints in a starch. I don't know what the recipe is. Maybe we'll have to find a point. Somebody on YouTube must have done it at some point.

SPEAKER_02 37:40

It looked like fun. The columnar joints in that starch was really cool. Really cool. I got a feeling.

SPEAKER_00 37:46

Maybe that's an exercise we should do in your intro to geology class, Chris, and do that as a label. I think you're right at some point. That'd be kind of fun. Do that this semester and let us know how it goes. That'd be cool. Okay. But people have studied. I'm actually gonna do it. It's cool. There's a lot of different ways to understand the physics, and and these things are kind of everywhere. This hexagonal shape is sort of just a fundamental natural phenomenon. So it's kind of cool.

SPEAKER_02 38:06

Before we exit out of this, I just want to say to our listeners that if you have questions that we didn't answer about columnar joints, send them our way and we can maybe tack this on to another episode. You know, if we if we skimmed over something that you didn't maybe understand, or you have a different question that would pop into your head as you were looking at columnar joints, send it our way.

SPEAKER_00 38:27

Yeah, absolutely. And those of you who have sent us questions, we've aggregated them all. We've gotten a lot this summer. We appreciate it, and we're getting to them. Let's put it that way. We're working our way through the the question list for episodes here. So if you don't hear it, you know, the next couple weeks, that's okay. It's still probably coming, and answers probably coming your way, and we appreciate the questions. If you're looking to support our podcast, you can do that two ways. You can head over to our mobile app. You can download the mobile app, this is the Camp Geo Mobile app. First link in your show notes. There we have a bunch of stuff for sale. We have basically the entire intro to geology course for free as well. If you want to listen to that, it's audiobooks with images. We think the images are, particularly for geology, really important and really add something to the listening experience. So we've been producing those. We continue to produce more in the background here that we're working on. Head over to our CampGeo app, leave us a rating and a review if you do that. You can also head to our website. There's a support us link at our website, planetegeocast.com, that you can support us there. We always appreciate it. And like Chris said, send us an email, planetgeocast at gmail.com. Thanks. Cheers.