Columnar Joints - Icelandic Version
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[00:00:00]
We are recording. Christopher, we're recording man. It's been a while.
Chris Bolhuis: I know. It's, I know. I feel like, uh, I haven't done this in a long
time. I'm a little nervous.
Dr. Jesse Reimink: I
know. Yeah.
Chris Bolhuis: I'm not, I'm not
Dr. Jesse Reimink: no, no, no. You're not nervous, Of course not. Uh, what's up, man? It's been a bit. [00:00:30] 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 know, You, you, you went everywhere this summer.
You were gone for most of the summer. and so we prerecorded 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, a
Chris Bolhuis: I know it's, I know, yeah, we front end, uh, loaded this for, uh, you know, we did this [00:01:00] back in May,
right? I mean, we just, just jammed them and, and crammed them in and
now
here we are back to the old
Dr. Jesse Reimink: Yeah, 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.
you just got back from Iceland recently. That was the big trip of the summer in the Bolhuis household. How'd it go?
Chris Bolhuis: 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.
canceled flights
and, and, uh, Hurricane Debbie played a, played a role in that whole
[00:01:30] situation. So that was, uh, that was a struggle, but, Iceland was, uh, 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.
Dr. Jesse Reimink: Let me interrupt you real quick there. Were these things that you were, you know, amazed by, are they mostly geological things or were [00:02:00] they, other natural phenomenon or cultural things, like what were the,
Chris Bolhuis: yeah. That's a good point. Um, all of the above, I guess
what I was referring to specifically though, was, 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 [00:02:30] Glacier National Park, but they're really kind of sad.
Um, 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.
Dr. Jesse Reimink: That's a very, um. I've never been to [00:03:00] Iceland. I mean, we talked about this before in our sort of intro to Iceland. I've never been, uh, but It's hallowed ground for geologists for many reasons because it's so unique, both tectonically, it has this, this tectonically totally unique setting, lots of volcanoes.
So the volcanologists love it. Um, and some unique volcanoes. And then it also sits in the Northern latitude. So you get, 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 [00:03:30] it's a interesting one to study from that point of view too. So, yeah, well, I, it's awesome. I mean, it's a very, very cool place. I'd imagine to go and spend three weeks of camping.
Chris Bolhuis: Yeah, not all of it was camping, but like the first week was for sure, because we just, we hiked the Lagavigure trail and, um, I'm just going to say the weather was the real deal. It, 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 [00:04:00] 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 think I see my shadow,
you know, it was, um, but the weather was the real deal. And I guess this summer is the worst that it's been in a very long time.
Dr. Jesse Reimink: Oh, you picked a good time to go. Nice.
Chris Bolhuis: Yeah.
Dr. Jesse Reimink: Perfect.
Chris Bolhuis: Of course. That's what I do.
Dr. Jesse Reimink: yeah yeah. Perfect. Perfect.
Chris Bolhuis: And that, like, You know, what we saw in Iceland, is kind of what [00:04:30] gave me the idea to pitch to you. Jenny and I saw so many columnar
structures in mostly basaltic flows that Jesse, it was everywhere. And it was one of the coolest things, because the 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, looked at it [00:05:00] from the perspective of what do people think when they look at this, that don't have a, like a deep geology background,
you know, what's going on in their
heads. And that's kind of the angle that I took when I, when I pitched it to you a couple of days
Dr. Jesse Reimink: 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 columnar jointing phenomenon. So 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, [00:05:30] 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 a free, Many dozens of hours of content, lots of episodes with images there.
And you can also purchase access to some of our other audio books as well, but leave us a [00:06:00] rating and a review on our app. We would really appreciate that. Chris, columnar joint. So we've talked about this on the podcast before. I can't even remember what episode it was, maybe. St. Helens we're talking or something like that.
I don't remember when we
Chris Bolhuis: no, I don't think so. I think it was devil's tower.
I think it was Devil's Tower.
in
Dr. Jesse Reimink: right. Yeah Yeah, okay, which is a famous one of you know, the top couple places on the earth that have columnar But there's many there's many places that have this kind of feature. So what we're if you haven't seen columnar What we're talking about is [00:06:30] 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
Chris Bolhuis: 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.[00:07:00]
Dr. Jesse Reimink: 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 big, 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, 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 [00:07:30] 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, intro 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, [00:08:00] right? there's all sorts of, stories from going back to indigenous communities with Devil's Tower and Devil's Postpile, 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?
Chris Bolhuis: 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 [00:08:30] 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?
Dr. Jesse Reimink: 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 What
Chris Bolhuis: point. [00:09:00] So Why are they six sided? That's a question.
first of all, like an overview of how do these columns form?
That's a
Dr. Jesse Reimink: Which are kind of related, those two, I would say. The answer at least is kind of related, right? Yep.
Chris Bolhuis: yes. And then 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.
So what determines the size of the columns? and then. Why don't [00:09:30] 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
Dr. Jesse Reimink: one. Yeah, that's a good one.
Chris Bolhuis: 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 a, they, they form this kind
of fanning out pattern from a central point. so why do you get these irregularities and
in [00:10:00] columns? 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.
Dr. Jesse Reimink: 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 Rhyolite, we've seen them, uh, sort of hand sized, something along that size.
why don't all flows have columns? And then, uh, [00:10:30] 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?
Chris Bolhuis: Yeah. Let's, let's go back up to the top and let's start with like this kind of, I think have a better perspective on like the historical view of these things. And then let's just kind of take it in order.
Does that sound good?
Dr. Jesse Reimink: I, 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 [00:11:00] for many, many centuries, cause there's 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 [00:11:30] 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 Neptunus versus Plutonus 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
Chris Bolhuis: on, Jesse. Hold on. I gotta, I gotta go back to something. Cause you're dropping big words here and, and like, what, what is this Neptunist and Plutonist [00:12:00] view? What does that mean
Dr. Jesse Reimink: there's, I don't want to, I don't think we need to get lost in the weeds. Mike Akerson did a great job explaining it in that episode, but it was people who were debating.
Chris Bolhuis: to have Mike on again, by
Dr. Jesse Reimink: Yeah, yeah, and talk about columnar joints. 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 Plutonus. If you're interested in that, I would say, go back and listen to Mike Ackerson. The point of these [00:12:30] 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. but
Chris Bolhuis: Oh, I thought, okay. I thought you were going to give a crack at me.
Dr. Jesse Reimink: I should have. Man, I missed opportunity.
You know, I'm really out
of a [00:13:00] practice. I'm really rusty. Dang
it. That was a big
missed opportunity there. Ah,
Chris Bolhuis: that's right. So I think what you're talking about is columns are going to 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 [00:13:30] lava,
the point where it's turned from orange to
Dr. Jesse Reimink: put a number on this. 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.
Chris Bolhuis: 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 [00:14:00] at the basics of, why do these columns begin
to develop?
So, as it cools, it's going to begin to contract. But remember, Rock is not very elastic, It can't just, 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
Dr. Jesse Reimink: Yeah. Shrinking. we have [00:14:30] this big, massive rock that's cooling and shrinking. And what's happening is we're formed tensional stress. What's called tension. You 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.
So, something's got to give. You said rock's not elastic, so something's got to give. It's going to break eventually, and there's a lot of people who've studied the physics of this stuff in detail, but basically, this is where the six sided nature comes in, or the most commonly six [00:15:00] sided nature. Now, nature is full of irregularities, so 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?
Chris Bolhuis: Yes. Yeah, absolutely. Yeah. Yeah. In fact, 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 [00:15:30] driving in rain. It was just miserable. And I put my raincoat on, put my pants on. Jenny gets out there and 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, the, They were old, they were crumbly, they just weren't very spectacular, but I was all excited [00:16:00] because it was the first ones that I'd, I'd seen, out of the
Dr. Jesse Reimink: Yeah, I mean, So
cool, though. Yeah, oh, of course, of course you were. I mean, so cool. So, 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 [00:16:30] possible that run through the rock 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. it was popular. I mean, it's still popular as people, but it was a fun board game that our family got into for awhile and it has these six sided pieces board game that has six sided pieces and you put it all together and it has these six sided pieces and that's just most efficient way to fill a space, with the fewest [00:17:00] amount of sort of lines possible.
and this is
Chris Bolhuis: Can I, can I give a crack at it? the math is very complicated, for something that is cracking this way, that were 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 [00:17:30] break while releasing the greatest amount of
energy.
Dr. Jesse Reimink: 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 [00:18:00] 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 So, three minerals touching, they have these 120 degree angles in the minerals, and if you, 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 rock. And this is all over nature. The 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 [00:18:30] scenario is a lava flow.
And that's all that. Cooled down, 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 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 [00:19:00] 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 full, the whole package is cooling. So it's not mud cracks, we get.
these little chips because the surface is the only one drying out. 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 [00:19:30] itself and create these columns.
Chris Bolhuis: you touched on this, but I want to make sure that we double click on that, the columns are going to grow and propagate perpendicular to the cooling
surface. So if you have a lava flow that then crystallizes, 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 [00:20:00] be just the air.
Dr. Jesse Reimink: that's exactly right. And we're going to come back to that point, Chris. I want to like set that aside, set that on the shelf a minute. We're going to 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, [00:20:30] 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?
Chris Bolhuis: the little ones.
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 waterfalls. [00:21:00] 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 10 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
and 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 [00:21:30] 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 to rate of
Dr. Jesse Reimink: And Chris, we actually saw, read a paper that people had [00:22:00] noticed in a chert 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 could see it with your naked eye too, the idea was that this chert 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 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 [00:22:30] cooling, the further away the joint sets can be from one another, and still be energetically
efficient.
Chris Bolhuis: 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 gorge, you're going to have a relatively, thick lava flow that is not very wide
it affects the rate of cooling or maybe the [00:23:00] chemistry. Of the lava flow itself, whether it's, andesitic versus, more mafic and basalt, that kind of thing
can affect rate of cooling. and then, other variables may be 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 going to affect the rate of
Dr. Jesse Reimink: 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, [00:23:30] perfect ones that you loved were in narrower or thinner
Chris Bolhuis: thinner. Yes,
Dr. Jesse Reimink: Yeah. Okay.
Chris Bolhuis: absolutely. I did.
Yeah.
Dr. Jesse Reimink: 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.
Chris Bolhuis: That's right. Because, the case of Devil's Tower, you one of the leading theories is that this was an intrusion,
right? It was a shallower intrusion, but [00:24:00] 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 going to insulate it and cool much, much, much slower than if it was just exposed to the air.
Cause it loses heat
readily to the air.
Dr. Jesse Reimink: And that's a great one, Chris, that we'll, I think we'll come back to again where 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 [00:24:30] why don't all flows have columns. And I think this is a, this is a, Interesting question that there's not a clear answer to because, you know, if you think of a lava flow, it's eventually all lava flows are going to be solid and they're still going to 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 [00:25:00] we can identify these are really striking features and 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, these really nice columns.
So anytime you have like a jumbly lava flow or a thin lava flow is very unlikely to probably form these columns because it cools down too quickly to form this. It probably flowed in the top [00:25:30] crystallized. We formed A A or Bolhuis. 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 vesicles. So that would disrupt the physics of this column forming jointing process.
those are some [00:26:00] reasons why not all lava flows would have this in relatively thin ones are often ones that don't have this process. You need 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.
Chris Bolhuis: because if you, mentioned Pahoehoe, Pahoehoe 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 [00:26:30] Pahoehoe, it's kind of this smooth ropey or, 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 going to disrupt any kind of columnar jointing that would have happened,
it has to be a, you know, rather stationary flow. So lava flowed, stopped, solidified, and then columnar jointing took place after the material turned from [00:27:00] orange to
black.
Dr. Jesse Reimink: Yeah, yeah, That's right.
Chris Bolhuis: I have a question for you, Jesse, that I'm going to, I'm going to throw this at you and you don't know what I'm going to
ask. So let's see how you
do.
Dr. Jesse Reimink: All right. All right.
Chris Bolhuis: 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?
Dr. Jesse Reimink: Meaning the lines, the joints were running horizontally. Is that what you mean?
Chris Bolhuis: Yeah, they were not vertical columns. These were horizontal
Dr. Jesse Reimink: So this, I think, Chris leads very [00:27:30] nicely into the last question. Like, how do you get these irregular patterns? You talked about these fan shaped ones. 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 [00:28:00] sediment or 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 [00:28:30] 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.
Chris Bolhuis: 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,
the geologic setting. [00:29:00] Okay. So sills are these igneous intrusions that run parallel to the rocks that intrudes. 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 going to get vertical columns,
but a dike cuts across the rock often vertically across it. And so the cooling surface is now on the sides.
And so you get these columns that extend and [00:29:30] they look more horizontal. So
that's another way that you can get this kind of irregular pattern to it.
Um, and I dunno, 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
Dr. Jesse Reimink: we, not the full, not the full circle. We saw like half [00:30:00] circles in the Columbia River Gorge, with our buddy Andy.
Chris Bolhuis: Okay.
Dr. Jesse Reimink: the, I've not seen the full circle.
Chris Bolhuis: 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, would have are these, uh, lava flows, and then you'd have a sudden, like a flooding event and the water [00:30:30] would interact with the lava flow affected its cooling
and its cooling rate and its cooling direction, which kind of formed this kind of pinwheel look to it.
Does that make
Dr. Jesse Reimink: Yeah, yeah, no, absolutely. 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 to it. Patterns that are vertically stacked and then we call these like colonnades.
So the top and the bottom, remember the [00:31:00] 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. The entire package started to cool. And I saw, Chris, the most spectacular kilometer joints I've ever seen was a really, really thick lava flow. It's on the east, what's called the east arm of the Great Slave Lake up in the [00:31:30] Northwest Territories of Canada.
It's this huge basalt flow formed 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 surface. It was spectacular. Like looking out the helicopter window, just, I mean, it was just, 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, [00:32:00] 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, cause he's flying next to the cliff. You know, it's kind of fun. So
Chris Bolhuis: So is that your first and only time of seeing that kind of entablature look to columnar
joints?
Dr. Jesse Reimink: it like that, in that textbook way where it's like colonnades on top and
entire, you know, that, that was the first
time seeing like, 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 [00:32:30] 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 caler, 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 [00:33:00] kilometer 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.
Chris Bolhuis: boy, I don't know for sure.
I would, I probably would say, I would probably say Devil's Tower. I
think.
Dr. Jesse Reimink: know if there's any up in
Chris Bolhuis: know of anything.
Dr. Jesse Reimink: at all in any of
Chris Bolhuis: No, I don't.
I have not seen columnar joint in there. I've,
you know, lots of pillows.
Which are really cool structures
too. And you know, we saw some pillows in, in Iceland as well.
And [00:33:30] I, I'm a huge fan of pillow lavas. The story that that rock has
to tell is just, I don't
Dr. Jesse Reimink: Okay. Don't, get distracted. Don't, don't get distracted. by that. Yeah. That's a, that's a whole nother thing. Um, okay. That's interesting. I mean, cause 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.
So,
Chris Bolhuis: be closer to me too. Yeah.
Dr. Jesse Reimink: okay?
Chris Bolhuis: that.
Dr. Jesse Reimink: Yeah,
there's,
Chris Bolhuis: has
Dr. Jesse Reimink: they've got some good ones. If I remember correctly, it's like, a few outcrops [00:34:00] 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.
Chris Bolhuis: So can I tell you a story about Iceland real
quick here that's relevant to the discussion? So there is a, a famous outcrop right along the ocean. 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 [00:34:30] 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 and 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 back country or all over the place and other places where we saw them for free. Right. But I had to do it [00:35:00] anyway. So Jenny wants to get this picture of me sitting on a column. So I get to this column, it's busy. People 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
Dr. Jesse Reimink: Yeah, yeah. And also,
Chris Bolhuis: anyway. So.
Dr. Jesse Reimink: a bit of a hermit loner in your old age, too, I think.
Chris Bolhuis: 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 [00:35:30] 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 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.
Dr. Jesse Reimink: That's good.
Chris Bolhuis: to anybody
nicer. And
Dr. Jesse Reimink: it's true. I [00:36:00] do. Nobody deserves to get soaked up to their knees while trying to take a photo of their husband more than Jenny Bolhuis. That is the best. And what a great way to
experience columnar basalts is just, you know, having Jenny take a photo and getting
Chris Bolhuis: Yes.
Dr. Jesse Reimink: great. That makes me
Chris Bolhuis: 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
Dr. Jesse Reimink: Yeah,
Chris Bolhuis: It
Dr. Jesse Reimink: I want to see the
photo, I want to see the photo series of, you know, you [00:36:30] looking, hurry up, Jenny, sprinting
Chris Bolhuis: Yes.
Dr. Jesse Reimink: the time lapse, that'd be great.
Chris Bolhuis: 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 costs her
here,
you know, the, the time.
Dr. Jesse Reimink: Yeah. That serves her right. Serves her right. That's great. Well, Chris, I think this is probably the first of many of a sort of a [00:37:00] Iceland, or let's say our summer trips inspired episodes. I've got a couple too that I'll pitch your way based on stuff we've been, we did.
But, Yeah, I think that's a probably a wrap on columnar jointing. We hit the basics. There's a lot to know. And I think one other thing I'd 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
will Yeah, kind of cool, right?
It'll cool down, it'll dry out, and you can form columnar joints. I
didn't look it up, there must be like
[00:37:30] a,
know, you could do this at home, I'm guessing. You could replicate this experiment at home and form columnar joints in a start. 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.
Chris Bolhuis: it looked like fun.
Dr. Jesse Reimink: Totally.
Chris Bolhuis: joints in that starch was Really
Dr. Jesse Reimink: Really cool. Really cool. I mean, maybe that's
an exercise we should do in your intro to geology class, Chris, and, and do that as a
lab at some
point. That'd be kind of fun. that this semester and let us know how it goes.
That'd be cool.
Um, but people have studied these things. it's cool. There's a lot of different ways to [00:38:00] 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.
Chris Bolhuis: 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,
Dr. Jesse Reimink: Yeah, absolutely. And, of you who have sent us [00:38:30] 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 of 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. It's 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 [00:39:00] that, it's audio books 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 Camp Geo app. 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, planetgeocast. com that you can support us there. We always appreciate it. And like Chris said, send us an email planetgeocastatgmail. com. Thanks.
Chris Bolhuis: Cheers.
Dr. Jesse Reimink: Peace. [00:39:30]
